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Introduction to Flowsheet Simulation

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1 Introduction to Flowsheet Simulation
Introduction to Aspen Plus v10.2 Course Notes Introduction to Flowsheet Simulation Objective: Introduce general flowsheet simulation concepts and Aspen Plus features August 28th,2000

2 Introduction to Aspen Plus v10.2
Course Notes Flowsheet Simulation What is flowsheet simulation? Use of a computer program to quantitatively model the characteristic equations of a chemical process Uses underlying physical relationships Mass and energy balance Equilibrium relationships Rate correlations (reaction and mass/heat transfer) Predicts Stream flowrates, compositions, and properties Operating conditions Equipment sizes Build slide? Ask class the questions about what are the physical relationships that need to be solved and what can be predicted by the simulation? Removed bullet: - Predicts - Equipment sizes and costs Introduction to Aspen Plus August 28th,2000

3 Advantages of Simulation
Introduction to Aspen Plus v10.2 Course Notes Advantages of Simulation Reduces plant design time Allows designer to quickly test various plant configurations Helps improve current process Answers “what if” questions Determines optimal process conditions within given constraints Assists in locating the constraining parts of a process (debottlenecking) Remove bullet - Predicts plant costs and economic feasibility Introduction to Aspen Plus August 28th,2000

4 General Simulation Problem
Introduction to Aspen Plus v10.2 Course Notes General Simulation Problem What is the composition of stream PRODUCT? To solve this problem, we need: Material balances Energy balances REACTOR FEED RECYCLE REAC-OUT COOL COOL-OUT SEP PRODUCT Introduction to Aspen Plus August 28th,2000

5 Approaches to Flowsheet Simulation
Introduction to Aspen Plus v10.2 Course Notes Approaches to Flowsheet Simulation Sequential Modular Aspen Plus is a sequential modular simulation program. Each unit operation block is solved in a certain sequence. Equation Oriented Aspen Custom Modeler (formerly SPEEDUP) is an equation oriented simulation program. All equations are solved simultaneously. Combination Aspen Dynamics (formerly DynaPLUS) uses the Aspen Plus sequential modular approach to initialize the steady state simulation and the Aspen Custom Modeler (formerly SPEEDUP) equation oriented approach to solve the dynamic simulation. - Use the previous page if you need to explain this. Introduction to Aspen Plus August 28th,2000

6 Good Flowsheeting Practice
Introduction to Aspen Plus v10.2 Course Notes Good Flowsheeting Practice Build large flowsheets a few blocks at a time. This facilitates troubleshooting if errors occur. Ensure flowsheet inputs are reasonable. Check that results are consistent and realistic. - Also, mention that there need not be a one-to-one correspondence between pieces of equipment in the plant and Aspen Plus blocks. - garbage in = garbage out - You as an engineer are still ultimately responsible for the numbers that come out of Aspen Plus. Introduction to Aspen Plus August 28th,2000

7 Important Features of Aspen Plus
Introduction to Aspen Plus v10.2 Course Notes Important Features of Aspen Plus Rigorous Electrolyte Simulation Solids Handling Petroleum Handling Data Regression Data Fit Optimization User Routines - Mention that these are just SOME of the features. Introduction to Aspen Plus August 28th,2000

8 Introduction to Aspen Plus v10.2
Course Notes The User Interface Objective: Become comfortable and familiar with the Aspen Plus graphical user interface Aspen Plus References: User Guide, Chapter 1, The User Interface User Guide, Chapter 2, Creating a Simulation Model User Guide, Chapter 4, Defining the Flowsheet August 28th,2000

9 Introduction to Aspen Plus v10.2
Course Notes The User Interface Title Bar Run ID Menu Bar Next Button Tool Bar - Start Aspen Plus and go through all of the elements on the main menu: type, models, pull-down menus, mouse-buttons, help line, status line. - The cumene flowsheet should be created. This should be done as a guided example or as a demonstration. - The next few slides do not necessarily need to be shown since the information should be covered during the cumene example; however, they can be used as a review of the topics covered in the example. - Verify that everyone is familiar with using the mouse. Select Mode Model Menu Status Area button Model Library Tabs Process Flowsheet Window Reference: Aspen Plus User Guide, Chapter 1, The User Interface Introduction to Aspen Plus August 28th,2000

10 Cumene Flowsheet Definition
Introduction to Aspen Plus v10.2 Course Notes Cumene Flowsheet Definition REACTOR FEED RECYCLE REAC-OUT COOL COOL-OUT SEP PRODUCT Flash2 Model RStoic Heater Model Model - When you ask them to save this file is a good time to tell them about quick restart and backup file types. Recommend that they always use the backup files and explain why. - Make sure you save your file after setting up this example, so that you can open it for the next example. Filename: CUMENE.BKP Introduction to Aspen Plus August 28th,2000

11 Introduction to Aspen Plus v10.2
Course Notes Using the Mouse Left button click - Select object/field Right button click - Bring up menu for selected object/field, or inlet/outlet - Cancel placement of streams or blocks on the flowsheet Double left click - Open Data Browser object sheet Reference: Aspen Plus User Guide, Chapter 1, The User Interface For the references, tell the users that all of the chapters in the User Guides can be found by selecting Help Topics from the Help menu and then choosing the Using Aspen Plus book. The topics in the help are listed in the same order as the chapters in the manual.. More on Help is in the next chapter. Introduction to Aspen Plus August 28th,2000

12 Graphic Flowsheet Operations
Introduction to Aspen Plus v10.2 Course Notes Graphic Flowsheet Operations To place a block on the flowsheet: 1. Click on a model category tab in the Model Library. 2. Select a unit operation model. Click the drop-down arrow to select an icon for the model. 3. Click on the model and then click on the flowsheet to place the block. You can also click on the model icon and drag it onto the flowsheet. 4. Click the right mouse button to stop placing blocks. - Tell them that they can use this page as a guide when doing the following workshop. Introduction to Aspen Plus August 28th,2000

13 Graphic Flowsheet Operations (Continued)
Introduction to Aspen Plus v10.2 Course Notes Graphic Flowsheet Operations (Continued) To place a stream on the flowsheet: 1. Click on the STREAMS icon in the Model Library. 2. If you want to select a different stream type (Material, Heat or Work), click the down arrow next to the icon and choose a different type. 3. Click a highlighted port to make the connection. 4. Repeat step 3 to connect the other end of the stream. 5. To place one end of the stream as either a process flowsheet feed or product, click a blank part of the Process Flowsheet window. 6. Click the right mouse button to stop creating streams. Introduction to Aspen Plus August 28th,2000

14 Graphic Flowsheet Operations (Continued)
Introduction to Aspen Plus v10.2 Course Notes Graphic Flowsheet Operations (Continued) To display an Input form for a Block or a Stream in the Data Browser: 1. Double click the left mouse button on the object of interest. To Rename, Delete, Change the icon, provide input or view results for a block or stream: 1. Select object (Block or Stream) by clicking on it with the left mouse button. 2. Click the right mouse button while the pointer is over the selected object icon to bring up the menu for that object. 3. Choose appropriate menu item. Reference: Aspen Plus User Guide, Chapter 4, Defining the Flowsheet Introduction to Aspen Plus August 28th,2000

15 Automatic Naming of Streams and Blocks
Introduction to Aspen Plus v10.2 Course Notes Automatic Naming of Streams and Blocks Stream and block names can be automatically assigned by Aspen Plus or entered by the user when the object is created. Stream and block names can be displayed or hidden. To modify the naming options: Select Options from the Tools menu. Click the Flowsheet tab. Check or uncheck the naming options desired. Introduction to Aspen Plus August 28th,2000

16 Benzene Flowsheet Definition Workshop
Introduction to Aspen Plus v10.2 Course Notes Benzene Flowsheet Definition Workshop Objective - Create a graphical flowsheet Start with the General with English Units Template. Choose the appropriate icons for the blocks. Rename the blocks and streams. Heater Model Flash2 COOL FEED VAP1 LIQ1 FL2 VAP2 LIQ2 FL1 Remind them to save the file since it will be used in the next workshop. When finished, save in backup format (Run-ID.BKP). filename: BENZENE.BKP Introduction to Aspen Plus August 28th,2000

17 Introduction to Aspen Plus v10.2
Course Notes Basic Input Objective: Introduce the basic input required to run an Aspen Plus simulation Aspen Plus References: User Guide, Chapter 3, Using Aspen Plus Help User Guide, Chapter 5, Global Information for Calculations User Guide, Chapter 6, Specifying Components User Guide, Chapter 7, Physical Property Methods User Guide, Chapter 9, Specifying Streams User Guide, Chapter 10, Unit Operation Models User Guide, Chapter 11, Running Your Simulation August 28th,2000

18 Introduction to Aspen Plus v10.2
Course Notes The User Interface Menus Used to specify program options and commands Toolbar Allows direct access to certain popular functions Can be moved Can be hidden or revealed using the Toolbars dialog box from the View menu Data Browser Can be moved, resized, minimized, maximized or closed Used to navigate the folders, forms, and sheets - The next few slides can be used as a preview before the example is started in Aspen Plus. Introduction to Aspen Plus August 28th,2000

19 The User Interface (Continued)
Introduction to Aspen Plus v10.2 Course Notes The User Interface (Continued) Folders Refers to the root items in the Data Browser Contain forms Forms Used to enter data and view results for the simulation Can be comprised of a number of sheets Are located in folders Sheets Make up forms Are selected using tabs at the top of each sheet Introduction to Aspen Plus August 28th,2000

20 The User Interface (Continued)
Introduction to Aspen Plus v10.2 Course Notes The User Interface (Continued) Object Manager Allows manipulation of discrete objects of information Can be created, edited, renamed, deleted, hidden, and revealed Next Button Checks if the current form is complete and skips to the next form which requires input Introduction to Aspen Plus August 28th,2000

21 Introduction to Aspen Plus v10.2
Course Notes The Data Browser Next sheet Go back Go forward Comments Parent button Units Previous sheet Status Next Menu tree Status area Description area Introduction to Aspen Plus August 28th,2000

22 Introduction to Aspen Plus v10.2
Course Notes Help Help Topics Contents - Used to browse through the documentation. The User Guides and Reference Manuals are all included in the help. All of the information in the User Guides is found under the “Using Aspen Plus” book. Index - Used to search for help on a topic using the index entries Find - Used to search for a help on a topic that includes any word or words “What’s This?” Help Select “What’s This?” from the Help menu and then click on any area to get help for that item. Introduction to Aspen Plus August 28th,2000

23 Functionality of Forms
Introduction to Aspen Plus v10.2 Course Notes Functionality of Forms When you select a field on a form (click left mouse button in the field), the prompt area at the bottom of the window gives you information about that field. Click the drop-down arrow in a field to bring up a list of possible input values for that field. Typing a letter will bring up the next selection on the list that begins with that letter. The Tab key will take you to the next field on a form. Introduction to Aspen Plus August 28th,2000

24 Introduction to Aspen Plus v10.2
Course Notes Basic Input The minimum required inputs (in addition to the graphical flowsheet) to run a simulation are: Setup Components Properties Streams Blocks Data can be entered on input forms in the above order by clicking the Next button. These inputs are all found in folders within the Data Browser. These input folders can be located quickly using the Data menu or the Data Browser buttons on the toolbar. These are the required inputs. This slide can be used as a road map to show them what information will need to be added to the flowsheet. Introduction to Aspen Plus August 28th,2000

25 Introduction to Aspen Plus v10.2
Course Notes Status Indicators Symbol Status Input for the form is incomplete Input for the form is complete No input for the form has been entered. It is optional. Results for the form exist. Results for the form exist, but there were calculation errors. Results for the form exist, but there were calculation warnings. Results for the form exist, but input has changed since the results were generated. Introduction to Aspen Plus August 28th,2000

26 Cumene Production Conditions
Introduction to Aspen Plus v10.2 Course Notes Cumene Production Conditions REACTOR FEED RECYCLE REAC-OUT COOL COOL-OUT SEP PRODUCT P = 1 atm T = 220 F Q = 0 Btu/hr P = 36 psia Benzene: 40 lbmol/hr Q = 0 Btu/hr Pdrop = 0 psi C6H6 + C3H = C9H12 Benzene Propylene Cumene (Isopropylbenzene) 90% Conversion of Propylene T = 130 F Propylene: 40 lbmol/hr Pdrop = 0.1 psi Go Slowly!! The example. This is the same flowsheet that was created graphically as the example in the previous chapter. Open the previous example. Aspen Plus should be entered and all of the forms for the flowsheet should be filled out. Go over the input that needs to be added and all of the other inputs on each form. Once the inputs have been added, run the flowsheet and show the results forms. Note the required and optional forms (overall and for each block). You can refer back to the road map of required inputs. Show that there are multiple ways to get to each form. Show how the Next key works both when the form is complete and incomplete. Note the status line and the help line. Show what help is available. The previous few slides can be shown after the example as a review. Filename: CUMENE.BKP Use the RK-SOAVE Property Method Introduction to Aspen Plus August 28th,2000

27 Introduction to Aspen Plus v10.2
Course Notes Setup Most of the commonly used Setup information is entered on the Setup Specifications Global sheet: Flowsheet title to be used on reports Run type Input and output units Valid phases (e.g. vapor-liquid or vapor-liquid-liquid) Ambient pressure Stream report options are located on the Setup Report Options Stream sheet. Setup form: mention - substreams and stream types moleflow, molefrac, etc. printing in stream table stream format units prop-sets Also a good place for the instructor to give a quick discussion/warning about the use of standard liquid volumes. Introduction to Aspen Plus August 28th,2000

28 Setup Specifications Form
Introduction to Aspen Plus v10.2 Course Notes Setup Specifications Form Introduction to Aspen Plus August 28th,2000

29 Introduction to Aspen Plus v10.2
Course Notes Stream Report Options Stream report options are located on the Setup Report Options Stream sheet. Setup form: mention - substreams and stream types moleflow, molefrac, etc. printing in stream table stream format units prop-sets Also a good place for the instructor to give a quick discussion/warning about the use of standard liquid volumes. Introduction to Aspen Plus August 28th,2000

30 Introduction to Aspen Plus v10.2
Course Notes Setup Run Types Show that this information is given in the help prompt for the different run types. Introduction to Aspen Plus August 28th,2000

31 Introduction to Aspen Plus v10.2
Course Notes Setup Units Units in Aspen Plus can be defined at 3 different levels: 1. Global Level (“Input Data” & “Output Results” fields on the Setup Specifications Global sheet) 2. Object level (“Units” field in the top of any input form of an object such as a block or stream 3. Field Level Users can create their own units sets using the Setup Units Sets Object Manager. Units can be copied from an existing set and then modified. Introduction to Aspen Plus August 28th,2000

32 Introduction to Aspen Plus v10.2
Course Notes Components Use the Components Specifications form to specify all the components required for the simulation. If available, physical property parameters for each component are retrieved from databanks. Pure component databanks contain parameters such as molecular weight, critical properties, etc. The databank search order is specified on the Databanks sheet. The Find button can be used to search for components. The Electrolyte Wizard can be used to set up an electrolyte simulation. Components Main form - show partial matching - search for a component by name and by formula - mention type of component - different databanks - spacebar clears a field Introduction to Aspen Plus August 28th,2000

33 Components Specifications Form
Introduction to Aspen Plus v10.2 Course Notes Components Specifications Form Introduction to Aspen Plus August 28th,2000

34 Introduction to Aspen Plus v10.2
Course Notes Entering Components The Component ID is used to identify the component in simulation inputs and results. Each Component ID can be associated with a databank component as either: Formula: Chemical formula of component (e.g., C6H6) (Note that a suffix is added to formulas when there are isomers, e.g. C2H6O-2) Component Name: Full name of component (e.g., BENZENE) Databank components can be searched for using the Find button. Search using component name, formula, component class, molecular weight, boiling point, or CAS number. All components containing specified items will be listed. Cumene is C9H12-2 (Isopropylbenzene) Introduction to Aspen Plus August 28th,2000

35 Introduction to Aspen Plus v10.2
Course Notes Find Find performs an AND search when more than one criterion is specified. Introduction to Aspen Plus August 28th,2000

36 Pure Component Databanks
Introduction to Aspen Plus v10.2 Course Notes Pure Component Databanks Parameters missing from the first selected databank will be searched for in subsequent selected databanks. Databank Contents Use PURE10 Data from the Design Institute for Physical Property Data (DIPPR) and AspenTech Primary component databank in Aspen Plus AQUEOUS Pure component parameters for ionic and molecular species in aqueous solution Simulations containing electrolytes SOLIDS Pure component parameters for strong electrolytes, salts, and other solids electrolytes and solids INORGANIC Thermochemical properties for inorganic components in vapor, liquid and solid states Solids, electrolytes, and metallurgy applications PURE93 delivered with Aspen Plus 9.3 For upward compatibility PURE856 delivered with Aspen Plus 8.5-6 ASPENPCD Databank delivered with Aspen Plus 8.5-6 Show that this information is available under help on Databanks. Introduction to Aspen Plus August 28th,2000

37 Introduction to Aspen Plus v10.2
Course Notes Properties Use the Properties Specifications form to specify the physical property methods to be used in the simulation. Property methods are a collection of models and methods used to describe pure component and mixture behavior. Choosing the right physical properties is critical for obtaining reliable simulation results. Selecting a Process Type will narrow the number of methods available. Property Specification form - Mention concept of Property Method and that it will be covered in more detail tomorrow - Property Method designation can be changed at every level of the simulation: global, section and block - Show help and prompt. Introduction to Aspen Plus August 28th,2000

38 Properties Specifications Form
Introduction to Aspen Plus v10.2 Course Notes Properties Specifications Form Introduction to Aspen Plus August 28th,2000

39 Introduction to Aspen Plus v10.2
Course Notes Streams Use Stream Input forms to specify the feed stream conditions and composition. To specify stream conditions enter two of the following: Temperature Pressure Vapor Fraction To specify stream composition enter either: Total stream flow and component fractions Individual component flows Specifications for streams that are not feeds to the flowsheet are used as estimates. Stream - Composition basis can be changed. - If using a -FRAC basis, then total flowrate is needed. - If fractions don’t add up to 1, then there will be a warning and values will be normalized. - Note that pressure can be in absolute or gauge units (new for 9.3). - Show the two different ways to get to the stream input, other than the next key (I.e. from the Data menu and from the graphical worksheet). - Show the units at the top of the input form. Introduction to Aspen Plus August 28th,2000

40 Introduction to Aspen Plus v10.2
Course Notes Streams Input Form Introduction to Aspen Plus August 28th,2000

41 Introduction to Aspen Plus v10.2
Course Notes Blocks Each Block Input or Block Setup form specifies operating conditions and equipment specifications for the unit operation model. Some unit operation models require additional specification forms All unit operation models have optional information forms (e.g. BlockOptions form). Block input - For each block, there is both required and optional information. Introduction to Aspen Plus August 28th,2000

42 Introduction to Aspen Plus v10.2
Course Notes Block Form Introduction to Aspen Plus August 28th,2000

43 Introduction to Aspen Plus v10.2
Course Notes Starting the Run Select Control Panel from the View menu or press the Next button to be prompted. The simulation can be executed when all required forms are complete. The Next button will take you to any incomplete forms. - It is always a good idea to save a .bkp file before running. (Save early and save often) Running - Using Run or better using Control Panel Introduction to Aspen Plus August 28th,2000

44 Introduction to Aspen Plus v10.2
Course Notes Control Panel The Control Panel consists of: A message window showing the progress of the simulation by displaying the most recent messages from the calculations A status area showing the hierarchy and order of simulation blocks and convergence loops executed A toolbar which you can use to control the simulation Introduction to Aspen Plus August 28th,2000

45 Introduction to Aspen Plus v10.2
Course Notes Reviewing Results History file or Control Panel Messages Contains any generated errors or warnings Select History or Control Panel on the View menu to display the History file or the Control Panel Stream Results Contains stream conditions and compositions For all streams (/Data/Results Summary/Streams) For individual streams (bring up the stream folder in the Data Browser and select the Results form) Block Results Contains calculated block operating conditions (bring up the block folder in the Data Browser and select the Results form) Results - forms: status, stream-summary, results for each block - control panel - history file is similar to what is on the control panel - report file and input file can be exported Introduction to Aspen Plus August 28th,2000

46 Benzene Flowsheet Conditions Workshop
Introduction to Aspen Plus v10.2 Course Notes Benzene Flowsheet Conditions Workshop Objective: Add the process and feed stream conditions to a flowsheet. Starting with the flowsheet created in the Benzene Flowsheet Definition Workshop (saved as BENZENE.BKP), add the process and feed stream conditions as shown on the next page. Questions: 1. What is the heat duty of the block “COOL”? _________ 2. What is the temperature in the second flash block “FL2”? _________ Note: Answers for all of the workshops are located in the very back of the course notes in Appendix C. - This workshop builds on the graphical flowsheet created in the last workshop. - Optional part is for those who finish early. It is not necessary to complete them. Introduction to Aspen Plus August 28th,2000

47 Benzene Flowsheet Conditions Workshop
Introduction to Aspen Plus v10.2 Course Notes Benzene Flowsheet Conditions Workshop FL1 COOL FEED VAP1 LIQ1 FL2 VAP2 LIQ2 T = 100 F P = 500 psia Feed T = 200 F P = 1 atm T = 1000 F Pdrop = 0 Q = 0 P = 550 psia Hydrogen: 405 lbmol/hr Methane: 95 lbmol/hr Benzene: 95 lbmol/hr Toluene: 5 lbmol/hr Use the PENG-ROB Property Method When finished, save as filename: BENZENE.BKP Introduction to Aspen Plus August 28th,2000

48 Introduction to Aspen Plus v10.2
Course Notes Unit Operation Models Objective: Review major types of unit operation models Aspen Plus References: User Guide, Chapter 10, Unit Operation Models Unit Operation Models Reference Manual August 28th,2000

49 Unit Operation Model Types
Introduction to Aspen Plus v10.2 Course Notes Unit Operation Model Types Mixers/Splitters Separators Heat Exchangers Columns Reactors Pressure Changers Manipulators Solids User Models Reference: The use of specific models is best described by on-line help and the documentation. Aspen Plus Unit Operation Models Reference Manual Introduction to Aspen Plus August 28th,2000

50 Introduction to Aspen Plus v10.2
Course Notes Mixers/Splitters Introduction to Aspen Plus August 28th,2000

51 Introduction to Aspen Plus v10.2
Course Notes Separators Introduction to Aspen Plus August 28th,2000

52 Introduction to Aspen Plus v10.2
Course Notes Heat Exchangers * Requires separate license Introduction to Aspen Plus August 28th,2000

53 Introduction to Aspen Plus v10.2
Course Notes Columns - Shortcut Introduction to Aspen Plus August 28th,2000

54 Introduction to Aspen Plus v10.2
Course Notes Columns - Rigorous * Requires separate license + Input language only in Version 10.0 Introduction to Aspen Plus August 28th,2000

55 Introduction to Aspen Plus v10.2
Course Notes Reactors Introduction to Aspen Plus August 28th,2000

56 Introduction to Aspen Plus v10.2
Course Notes Pressure Changers Introduction to Aspen Plus August 28th,2000

57 Introduction to Aspen Plus v10.2
Course Notes Manipulators Introduction to Aspen Plus August 28th,2000

58 Introduction to Aspen Plus v10.2
Course Notes Solids Introduction to Aspen Plus August 28th,2000

59 Introduction to Aspen Plus v10.2
Course Notes User Models Proprietary models or 3-rd party software can be included in an Aspen Plus flowsheet using a User2 unit operation block. Excel Workbooks or Fortran code can be used to define the User2 unit operation model. User-defined names can be associated with variables. Variables can be dimensioned based on other input specifications (for example, number of components). Aspen Plus helper functions eliminate the need to know the internal data structure to retrieve variables. Introduction to Aspen Plus August 28th,2000

60 Introduction to Aspen Plus v10.2
Course Notes RadFrac Objective: Discuss the minimum input required for the RadFrac fractionation model, and the use of design specifications and stage efficiencies Aspen Plus References: Unit Operation Models Reference Manual, Chapter 4, Columns August 28th,2000

61 RadFrac: Rigorous Multistage Separation
Introduction to Aspen Plus v10.2 Course Notes RadFrac: Rigorous Multistage Separation Vapor-Liquid or Vapor-Liquid-Liquid phase simulation of: Ordinary distillation Absorption, reboiled absorption Stripping, reboiled stripping Azeotropic distillation Reactive distillation Configuration options: Any number of feeds Any number of side draws Total liquid draw off and pumparounds Any number of heaters Any number of decanters Introduction to Aspen Plus August 28th,2000

62 RadFrac Flowsheet Connectivity
Introduction to Aspen Plus v10.2 Course Notes RadFrac Flowsheet Connectivity Vapor Distillate Top-Stage or 1 Condenser Heat Duty Heat (optional) Liquid Distillate Water Distillate (optional) Feeds Reflux Heat (optional) Products (optional) Pumparound Decanters Heat (optional) Heat (optional) Product This is the help screen that can be accessed in Aspen Plus. Important to talk about stage convention. Start up Aspen Plus and create a flowsheet like the Methanol-Water example and show them the input required and optional. - show ports on icon (point out liquid and vapor distillate options) - different icons can be chosen; icons do not influence input. - help forms, flowsheet connectivity help - required forms: main, feed/product, pressure - optional forms for more complex configurations, specs, stage efficiencies, sizing and rating, etc. - note stage 1 is at the top and stage N is at the bottom The next few slides can be used as a preview or a review of the material covered in the example. Boil-up Return Bottom Stage or Nstage Heat (optional) Reboiler Heat Duty Bottoms Introduction to Aspen Plus August 28th,2000

63 RadFrac Setup Configuration Sheet
Introduction to Aspen Plus v10.2 Course Notes RadFrac Setup Configuration Sheet Specify: Number of stages Condenser and reboiler configuration Two column operating specifications Valid phases Convergence Emphasize help and help prompt. - Show help on Number of stages. Introduction to Aspen Plus August 28th,2000

64 RadFrac Setup Streams Sheet
Introduction to Aspen Plus v10.2 Course Notes RadFrac Setup Streams Sheet Specify: Feed stage location Feed stream convention (see Help) ABOVE-STAGE: Vapor from feed goes to stage above feed stage Liquid goes to feed stage ON-STAGE: Vapor & Liquid from feed go to specified feed stage Show how to navigate these forms with - expert system - menu tree - sheet tabs - arrow buttons - Maybe we should add a slide to pictorially show the feed stage convention? Introduction to Aspen Plus August 28th,2000

65 Introduction to Aspen Plus v10.2
Course Notes Feed Convention Above-stage (default) On-stage n-1 n-1 Vapor Feed Liquid n Feed n Introduction to Aspen Plus August 28th,2000

66 RadFrac Setup Pressure Sheet
Introduction to Aspen Plus v10.2 Course Notes RadFrac Setup Pressure Sheet Specify one of: Column pressure profile Top/Bottom pressure Section pressure drop - Note that interpolation is used on the pressure profile. - single pressure implies constant pressure column (zero P-drop.) - Point out spec/vary forms and efficiency forms during the example. - Explain interpolation on efficiency form, too. Introduction to Aspen Plus August 28th,2000

67 Methanol-Water RadFrac Column
Introduction to Aspen Plus v10.2 Course Notes Methanol-Water RadFrac Column COLUMN FEED OVHD BTMS RadFrac specifications Total Condenser Kettle Reboiler 9 Stages T = 65 C Reflux Ratio = 1 P = 1 bar Distillate to feed ratio = 0.5 Column pressure = 1 bar Water: 100 kmol/hr Feed stage = 6 Methanol: 100 kmol/hr - When looking at the results for this run is a good time to show them the plotting features. - You can stop after this example, and rather than continue with the slides, have them do Part A of the workshop. Once they have done part A, cover the rest of the slides and then do the rest of the workshop. Use the NRTL-RK Property Method Filename: RAD-EX.BKP Introduction to Aspen Plus August 28th,2000

68 Introduction to Aspen Plus v10.2
Course Notes RadFrac Options To set up an absorber with no condenser or reboiler, set condenser and reboiler to none on the RadFrac Setup Configuration sheet. Either Vaporization or Murphree efficiencies on either a stage or component basis can be specified on the RadFrac Efficiencies form. Tray and packed column design and rating is possible. A Second liquid phase may be modeled if the user selects Vapor-liquid-liquid as Valid phases. Reboiler and condenser heat curves can be generated. A common way to get a converged column with wrong results is to not check for vapor-liquid-liquid equilibrium. Introduction to Aspen Plus August 28th,2000

69 Introduction to Aspen Plus v10.2
Course Notes Plot Wizard Use Plot Wizard (on the Plot menu) to quickly generate plots of results of a simulation. You can use Plot Wizard for displaying results for the following operations: Physical property analysis Data regression analysis Profiles for all separation models RadFrac, MultiFrac, PetroFrac and RateFrac Click the object of interest in the Data Browser to generate plots for that particular object. The wizard guides you in the basic operations for generating a plot. Click on the Next button to continue. Click on the Finish button to generate a plot with default settings. - plot wizard for streams is only for polymers things (yet) - there should be more plot wizards in 10.1 Introduction to Aspen Plus August 28th,2000

70 Plot Wizard Demonstration
Introduction to Aspen Plus v10.2 Course Notes Plot Wizard Demonstration Use the plot wizard on the column to create a plot of the vapor phase compositions throughout the column. Introduction to Aspen Plus August 28th,2000

71 RadFrac DesignSpecs and Vary
Introduction to Aspen Plus v10.2 Course Notes RadFrac DesignSpecs and Vary Design specifications can be specified and executed inside the RadFrac block using the DesignSpecs and Vary forms. One or more RadFrac inputs can be manipulated to achieve specifications on one or more RadFrac performance parameters. The number of specs should, in general, be equal to the number of varies. The DesignSpecs and Varys in a RadFrac are solved in a “Middle loop.” If you get an error message saying that the middle loop was not converged, check the DesignSpecs and Varys you have entered. Introduction to Aspen Plus August 28th,2000

72 RadFrac Convergence Problems
Introduction to Aspen Plus v10.2 Course Notes RadFrac Convergence Problems If a RadFrac column fails to converge, doing one or more of the following could help: 1. Check that physical property issues (choice of Property Method, parameter availability, etc.) are properly addressed. 2. Ensure that column operating conditions are feasible. 3. If the column err/tol is decreasing fairly consistently, increase the maximum iterations on the RadFrac Convergence Basic sheet. - Emphasize that the first and second points are frequently the cause of the convergence problem. Introduction to Aspen Plus August 28th,2000

73 RadFrac Convergence Problems (Continued)
Introduction to Aspen Plus v10.2 Course Notes RadFrac Convergence Problems (Continued) 4. Provide temperature estimates for some stages in the column using the RadFrac Estimates Temperature sheet (useful for absorbers). 5. Provide composition estimates for some stages in the column using the RadFrac Estimates Liquid Composition and Vapor Composition sheet (useful for highly non-ideal systems). 6. Experiment with different convergence methods on the RadFrac Setup Configuration sheet. Note: When a column does not converge, it is usually beneficial to Reinitialize after making changes. Introduction to Aspen Plus August 28th,2000

74 Introduction to Aspen Plus v10.2
Course Notes RadFrac Workshop Part A Perform a rating calculation of a Methanol tower using the following data: COLUMN FEED DIST BTMS Column specification: 38 trays (40 stages) Feed tray = 23 (stage 24) Total condenser Top stage pressure = 16.1 psia Pressure drop per stage = 0.1 psi Distillate flowrate = 1245 lbmol/hr Molar reflux ratio = 1.3 Feed: 63.2 wt% Water 36.8 wt% Methanol Total flow = 120,000 lb/hr Pressure 18 psia Saturated liquid - When looking at the results for this run is a good time to show them the plotting features. - You can stop after this example, and rather than continue with the slides, have them do Part A of the workshop. Once they have done part A, cover the rest of the slides and then do the rest of the workshop. Use the NRTL-RK Property Method Filename: RADFRAC.BKP Introduction to Aspen Plus August 28th,2000

75 RadFrac Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes RadFrac Workshop (Continued) Part B Set up design specifications within the column so the following two objectives are met: 99.95 wt% methanol in the distillate 99.90 wt% water in the bottoms To achieve these specifications, you can vary the distillate rate ( lbmol/hr) and the reflux ratio (0.8-2). Make sure stream compositions are reported as mass fractions before running the problem. Note the condenser and reboiler duties: Condenser Duty :_________ Reboiler Duty :_________ JLM - Do your results agree with mine (obtained in R9)? Condenser duty = E7 Btu/hr Reboiler duty = E7 “ Introduction to Aspen Plus August 28th,2000

76 RadFrac Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes RadFrac Workshop (Continued) Part C Perform the same design calculation after specifying a 65% Murphree efficiency for each tray. Assume the condenser and reboiler have stage efficiencies of 90%. How do these efficiencies affect the condenser and reboiler duties of the column? Part D Perform a tray sizing calculation for the entire column, given that Bubble Cap trays are used. (When finished, save as filename: RADFRAC.BKP) - People will ask if they need to specify efficiencies for all 40 stages. Tell them to look at the bottom prompt and figure it out. - Get them to do the optional part D since it does not take very long. Introduction to Aspen Plus August 28th,2000

77 Reactor Models Objective:
Introduce the various classes of reactor models available, and examine in some detail at least one reactor from each class Aspen Plus References Unit Operation Models Reference Manual, Chapter 5, Reactors

78 Introduction to Aspen Plus v10.2
Course Notes Reactor Overview Reactors Balance Based RYield RStoic Equilibrium Based REquil RGibbs Kinetics Based RCSTR RPlug RBatch Introduction to Aspen Plus August 28th,2000

79 Balanced Based Reactors
Introduction to Aspen Plus v10.2 Course Notes Balanced Based Reactors RYield Requires a mass balance only, not an atom balance Is used to simulate reactors in which inlets to the reactor are not completely known but outlets are known (e.g. to simulate a furnace) 1000 lb/hr Coal RYield 70 lb/hr H2O 20 lb/hr CO2 60 lb/hr CO 250 lb/hr tar 600 lb/hr char IN - RYield has no predictive capabilities, yield must be exactly specified. OUT Introduction to Aspen Plus August 28th,2000

80 Balanced Based Reactors (Continued)
Introduction to Aspen Plus v10.2 Course Notes Balanced Based Reactors (Continued) RStoic Requires both an atom and a mass balance Used in situations where both the equilibrium data and the kinetics are either unknown or unimportant Can specify or calculate heat of reaction at a reference temperature and pressure RStoic C, O2 2 CO + O2 --> 2 CO2 C + O2 --> CO2 2 C + O2 --> 2 CO IN - Heat of reaction calculation is a new for 9.3 feature. - There is no prediction. Extent or conversion must be specified by the user. - If the stoichiometry of the reactions is specified incorrectly, when the flowsheet is run there will be a mass imbalance error or warning. C, O2, CO, CO2 OUT Introduction to Aspen Plus August 28th,2000

81 Equilibrium Based Reactors
Introduction to Aspen Plus v10.2 Course Notes Equilibrium Based Reactors GENERAL Do not take reaction kinetics into account Solve similar problems, but problem specifications are different Individual reactions can be at a restricted equilibrium REquil Computes combined chemical and phase equilibrium by solving reaction equilibrium equations Cannot do a 3-phase flash Useful when there are many components, a few known reactions, and when relatively few components take part in the reactions Introduction to Aspen Plus August 28th,2000

82 Equilibrium Based Reactors (Continued)
Introduction to Aspen Plus v10.2 Course Notes Equilibrium Based Reactors (Continued) RGibbs Unknown Reactions - This feature is quite useful when reactions occurring are not known or are high in number due to many components participating in the reactions. Gibbs Energy Minimization - A Gibbs free energy minimization is done to determine the product composition at which the Gibbs free energy of the products is at a minimum. Solid Equilibrium - RGibbs is the only Aspen Plus block that will deal with solid-liquid-gas phase equilibrium. - Tell them that it is recommended that they use RGibbs as much as possible over REquilL Introduction to Aspen Plus August 28th,2000

83 Introduction to Aspen Plus v10.2
Course Notes Kinetic Reactors Kinetic reactors are RCSTR, RPlug and RBatch. Reaction kinetics are taken into account, and hence must be specified. Kinetics can be specified using one of the built-in models, or with a user subroutine. The current built-in models are Power Law Langmuir-Hinshelwood-Hougen-Watson (LHHW) A catalyst for a reaction can have a reaction coefficient of zero. Reactions are specified using a Reaction ID. Introduction to Aspen Plus August 28th,2000

84 Introduction to Aspen Plus v10.2
Course Notes Using a Reaction ID Reaction IDs are setup as objects, separate from the reactor, and then referenced within the reactor(s). A single Reaction ID can be referenced in any number of kinetic reactors (RCSTR, RPlug and RBatch.) To set up a Reaction ID, go to the Reactions Reactions Object Manager Introduction to Aspen Plus August 28th,2000

85 Power-law Rate Expression
Introduction to Aspen Plus v10.2 Course Notes Power-law Rate Expression Example: Forward reaction: (Assuming the reaction is 2nd order in A) coefficients: A: B: C: D: exponents: A: B: C: D: Reverse reaction: (Assuming the reaction is 1st order in C and D) coefficients: C: D: A: B: exponents: C: D: A: B: Introduction to Aspen Plus August 28th,2000

86 Introduction to Aspen Plus v10.2
Course Notes Heats of Reaction Heats of reaction need not be provided for reactions. Heats of reaction are typically calculated as the difference between inlet and outlet enthalpies for the reactor (see Appendix A). If you have a heat of reaction value that does not match the value calculated by Aspen Plus, you can adjust the heats of formation (DHFORM) of one or more components to make the heats of reaction match. Heats of reaction can also be calculated or specified at a reference temperature and pressure in an RStoic reactor. Introduction to Aspen Plus August 28th,2000

87 Introduction to Aspen Plus v10.2
Course Notes Reactor Workshop Objective - Compare the use of different reactor types to model one reaction. Reactor Conditions: Temperature = 70 C Pressure = 1 atm Stoichiometry: Ethanol + Acetic Acid <--> Ethyl Acetate + Water Kinetic Parameters: Forward Reaction: Pre-exp. Factor = 1.9 x 108, Act. Energy = 5.95 x 107 J/kmol Reverse Reaction: Pre-exp. Factor = 5.0 x 107, Act. Energy = 5.95 x 107 J/kmol Reactions are first order with respect to each of the reactants in the reaction (second order overall). Reactions occur in the liquid phase. Composition basis is Molarity. Hint: Check that each reactor is considering both Vapor and Liquid as Valid phases. From Emmanuel: On the intro course, I found that the kinetic parameters for the reaction example are from one of the files of the aspen plus benchmark (no I did not look all the examples, it is just by chance!) reacdist.inp: ***COLUMN-2: *** (EXAMPLE TAKEN FROM HOLLAND, FUNDAMENTALS OF MULTICOMPONENT DISTILLATION, MCGRAW-HILL BOOK COMPANY, 1981) COMBINED REACTOR/SEPARATION COLUMN TO PRODUCE ETHYL-ACETATE (EA) AND WATER (H2O) FROM ACETIC ACID (AA) AND ETHANOL (ETOH). THE REACTION IS KINETICALLY CONTROLLED AND A USER-KINETIC SUBROUTINE IS PROVIDED. THIS BENCHMARK REQUIRES SUBROUTINES ESTER AND GMU" ester.f RATE1 = HOLDUP* D0 *DEXP(-5.95D7/(PPGLOB_RGAS*T))*X (1)*X(2)/(VOL*VOL) RATE2 = HOLDUP*123D0*DEXP(-5.95D7/(PPGLOB_RGAS*T))*X(3)*X( )/(VOL*VOL) This confirms first that concentration should be used for the reaction rate (kmol/m3). The activation energies are the same as in the workshop, but not the preexponential factors. Maybe we should add in the notes for the instructor the reference (in case) and that the numbers are 'made up' numbers. I remember one attendee asking me. Introduction to Aspen Plus August 28th,2000

88 Reactor Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes Reactor Workshop (Continued) Use the NRTL-RK property method RSTOIC F-STOIC P-STOIC RGIBBS F-GIBBS P-GIBBS RPLUG F-PLUG P-PLUG DUPL FEED F-CSTR RCSTR P-CSTR 70 % conversion of ethanol Temp = 70 C Pres = 1 atm Feed: Water: kmol/hr Ethanol: kmol/hr Acetic Acid: kmol/hr How and where to input reactions depends on the reactor model: RStoic: enter new RXN1: EtOh + AA --> ACETATE + H2O RGibbs: no stoichiometric reaction RPlug and RCSTR: rxn R-1; in liquid phase only EtOh + AA --> ACETATE + H2O and ACETATE + H2O --> EtOH + AA Potential Pitfalls: Make sure that the students check their results and see that some product is being formed in each reactor. 1. Reaction needs to occur in the LIQUID phase (default is VAPOR phase). 2. Ea units are not the default; they can be changed. 6. Check units of all inputs. 7. NRTL --> NRTL-RK changes Binary parameter D-bank search order, and hence results won’t exactly match. 8. Forward and reverse reactions are not needed in the RStoic. Length = 2 meters Diameter = 0.3 meters When finished, save as filename: REACTORS.BKP Volume = 0.14 Cu. M. Introduction to Aspen Plus August 28th,2000

89 Cyclohexane Production Workshop
Introduction to Aspen Plus v10.2 Course Notes Cyclohexane Production Workshop Objective - Create a flowsheet to model a cyclohexane production process Cyclohexane can be produced by the hydrogenation of benzene in the following reaction: C6H H2 = C6H12 Benzene Hydrogen Cyclohexane The benzene and hydrogen feeds are combined with recycle hydrogen and cyclohexane before entering a fixed bed catalytic reactor. Assume a benzene conversion of 99.8%. The reactor effluent is cooled and the light gases separated from the product stream. Part of the light gas stream is fed back to the reactor as recycle hydrogen. The liquid product stream from the separator is fed to a distillation column to further remove any dissolved light gases and to stabilize the end product. A portion of the cyclohexane product is recycled to the reactor to aid in temperature control. Possibly Include a slide that shows stepping through the calculation iterations: .Turn on T, P, flow results view (Tools/Options/Results View). .Set break before mixer unit. .Show breakpoints and step through calculations. Iteration 1: feed to reactor, feed to flash, feed to column = 0; recycle streams =0 Iteration 2: feed to reactor = H2IN + BZIN; recycle streams are non-zero, however are not included in the feed to reactor Iterations 3..n: calculations continue until the value of feed to reactor = S streams fed to mixer (H2IN + BZIN + H2RCY + CHRCY) Make a note of the VAPOR distillate Re-write design spec as: C6H12 mole recovery in PRODUCT stream = Need an explanation on Pressure and Pressure Drop definitions; and why to use DP over P here. Absolute: 22 bar, fixed pressure Relative: -1 bar, Pout = Pin – 1 Introduction to Aspen Plus August 28th,2000

90 Cyclohexane Production Workshop
Introduction to Aspen Plus v10.2 Course Notes Cyclohexane Production Workshop C6H H = C6H12 Benzene Hydrogen Cyclohexane PURGE Total flow = 330 kmol/hr 92% flow to stream H2RCY T = 50 C P = 25 bar H2RCY VFLOW Molefrac H2 = 0.975 N2 = 0.005 CH4 = 0.02 VAP H2IN FEED-MIX REACT RXIN HP-SEP LTENDS RXOUT T = 50 C T = 150C BZIN Pdrop = 0.5 bar P = 23 bar T = 200 C Theoretical Stages = 12 Pdrop = 1 bar Reflux ratio = 1.2 LIQ T = 40 C Benzene conv = Bottoms rate = 99 kmol/hr - choose MetCBar template. - Mention that Flowsheeting Options can be used to turn off the automatic creation of stream or block Ids. - Explain or get the students as a group to figure out which unit operations need to be used for each block. - Show how to rotate icons. Potential Pitfalls - Make sure students choose correct block types. - Units of Column must be Met or MetCBar to correctly specify bounds of design-spec. - Column specification is mole-recovery not mole-fraction. - Product, cyclohexane, comes out of the bottom of the column. - Pressure drop is negative pressure when the pressure units are absolute. 0.998 Partial Condenser with vapor distillate only P = 1 bar CHRCY COLFD Benzene flow = 100 kmol/hr LFLOW Column Pressure = 15 bar Feed stage = 8 30% flow to stream CHRCY PRODUCT Use the RK-SOAVE property method COLUMN When finished, save as filename: CYCLOHEX.BKP Specify cyclohexane mole recovery in PRODUCT stream equal to by varying Bottoms rate from 97 to 101 kmol/hr Introduction to Aspen Plus August 28th,2000

91 Physical Properties Objectives:
Introduce the ideas of property methods and physical property parameters Identify issues involved in the choice of a property method Cover the use of Property Analysis for reporting physical properties Aspen Plus References: User Guide, Chapter 7, Physical Property Methods User Guide, Chapter 8, Physical Property Parameters and Data User Guide, Chapter 29, Analyzing Properties

92 Case Study - Acetone Recovery
Introduction to Aspen Plus v10.2 Course Notes Case Study - Acetone Recovery Correct choice of physical property models and accurate physical property parameters are essential for obtaining accurate simulation results. OVHD COLUMN FEED 5000 lbmol/hr 10 mole % acetone BTMS 90 mole % water Specification: mole % acetone recovery JLM - Should we be mentioning cost, after we dropped this feature? - cost done with the costing system in Aspen Plus. Ideal Approach Equation of State Approach Activity Coefficient Model Approach Predicted number of stages required Approximate cost in dollars 11 520, 000 7 390, 000 42 880, 000 Introduction to Aspen Plus August 28th,2000

93 How to Establish Physical Properties
Introduction to Aspen Plus v10.2 Course Notes How to Establish Physical Properties Choose a Property Method Check Parameters/Obtain Additional Parameters Confirm Results This is a road map for the slides that follow. - Mention that the first three steps can and should be completed before building the flowsheet. Create the Flowsheet Introduction to Aspen Plus August 28th,2000

94 Introduction to Aspen Plus v10.2
Course Notes Property Methods A Property Method is a collection of models and methods used to calculate physical properties. Property Methods containing commonly used thermodynamic models are provided in Aspen Plus. Users can modify existing Property Methods or create new ones. Introduction to Aspen Plus August 28th,2000

95 Physical Property Models
Introduction to Aspen Plus v10.2 Course Notes Physical Property Models Approaches to representing physical properties of components Choice of model types depends on degree of non-ideal behavior and operating conditions. Physical Property Models Ideal Equation of State (EOS) Models Activity Coefficient Models Special Models Introduction to Aspen Plus August 28th,2000

96 Ideal vs. Non-Ideal Behavior
Introduction to Aspen Plus v10.2 Course Notes Ideal vs. Non-Ideal Behavior What do we mean by ideal behavior? Ideal Gas law and Raoult’s law Which systems behave as ideal? Non-polar components of similar size and shape What controls degree of non-ideality? Molecular interactions e.g. Polarity, size and shape of the molecules How can we study the degree of non-ideality of a system? Property plots (e.g. TXY & XY) y x y y x x Introduction to Aspen Plus August 28th,2000

97 Comparison of EOS and Activity Models
Introduction to Aspen Plus v10.2 Course Notes Comparison of EOS and Activity Models Introduction to Aspen Plus August 28th,2000

98 Common Property Methods
Introduction to Aspen Plus v10.2 Course Notes Common Property Methods Equation of State Property Methods PENG-ROB RK-SOAVE Activity Coefficient Property Methods NRTL UNIFAC UNIQUAC WILSON Introduction to Aspen Plus August 28th,2000

99 Introduction to Aspen Plus v10.2
Course Notes Henry's Law Henry's Law is only used with ideal and activity coefficient models. It is used to determine the amount of a supercritical component or light gas in the liquid phase. Any supercritical components or light gases (CO2, N2, etc.) should be declared as Henry's components (Components Henry Comps Selection sheet). The Henry's components list ID should be entered on Properties Specifications Global sheet in the Henry Components field. - Point out that this is a two step process (list the components on components.henry-comps and specify the list on Properties.Main ). - Also, point out that you can type in a new Henry ID on the Properties.Main form, and then the expert system will automatically take you to the Components.Henry-comps form. Introduction to Aspen Plus August 28th,2000

100 Choosing a Property Method - Review
Introduction to Aspen Plus v10.2 Course Notes Choosing a Property Method - Review Do you have any polar components in your system? N Y Are the operating conditions near the critical region of the mixture? Y Use EOS Model N Do you have light gases or supercritical components in your system? Y N Use activity coefficient model with Henry’s Law Use activity coefficient model References: Aspen Plus User Guide, Chapter 7, Physical Property Methods, gives similar, more detailed guidelines for choosing a property Method. Introduction to Aspen Plus August 28th,2000

101 Choosing a Property Method - Example
Introduction to Aspen Plus v10.2 Course Notes Choosing a Property Method - Example Choose an appropriate Property Method for the following systems of components at ambient conditions. System Property Method ethanol-water any activity coefficient model benzene-toluene any EOS acetone, water, CO2 any activity coefficient model with Henry’s law water, cyclohexane any activity coefficient model except Wilson's (this system will form 2 liquid phases) Introduction to Aspen Plus August 28th,2000

102 How to Establish Physical Properties
Introduction to Aspen Plus v10.2 Course Notes How to Establish Physical Properties Choose a Property Method Check Parameters/Obtain Additional Parameters Confirm Results - Verify that everyone is comfortable choosing an appropriate class of Property Method. Create the Flowsheet Introduction to Aspen Plus August 28th,2000

103 Pure Component Parameters
Introduction to Aspen Plus v10.2 Course Notes Pure Component Parameters Represent attributes of a single component Input in the Properties Parameters Pure Component folder. Stored in databanks such as PURE10, ASPENPCD, SOLIDS, etc. (The selected databanks are listed on the Components Specifications Databanks sheet.) Parameters retrieved into the Graphical User Interface by selecting Retrieve Parameter Results from the tools menu. Examples Scalar: MW for molecular weight Temperature-Dependent: PLXANT for parameters in the extended Antoine vapor pressure model I recommend running a quick example to illustrate Retrieving Parameter Results. And discuss the difference between this, and just visiting the parameter input form for binary params. Introduction to Aspen Plus August 28th,2000

104 Introduction to Aspen Plus v10.2
Course Notes Binary Parameters Used to describe interactions between two components Input in the Properties Parameters Binary Interaction folder Stored in binary databanks such as VLE-IG, LLE-ASPEN Parameter values from the databanks can be viewed on the input forms in the Graphical User Interface. Parameter forms that include data from the databanks must be viewed before the flowsheet is complete. Examples Scalar: RKTKIJ for the Rackett model Temperature-Dependent: NRTL for parameters in the NRTL model - Run through a quick example (e.g. methanol, water and nitrogen) in the GUI. Ask the students not to follow along and illustrate how the expert system takes you to the binary parameter forms. Explain what to look for on the forms (e.g. why doesn’t nitrogen have any activity coefficient parameters, and why are methanol-water parameters not on the Henry parameter form). - Point out the temperature limits on the parameter forms. - Discuss what additional pairs would be required if you added another light gas such as methane. (Gammas for each solvent-solvent pair, and henry’s for each gas-solvent pair.) Introduction to Aspen Plus August 28th,2000

105 Displaying Property Parameters
Aspen Plus does not display all databank parameters on the parameter input forms. Select Retrieve Parameter Results from the Tools menu to retrieve all parameters for the components and property methods defined in the simulation. All results that are currently loaded will be lost. They can be regenerated by running the simulation again. The parameters are viewed on the Properties Parameters Results forms. Introduction to Aspen Plus

106 Introduction to Aspen Plus v10.2
Course Notes Reporting Parameters To get a Report of the retrieved parameters in a text file. Select Retrieve Parameter Results from the Tools menu, Select Report from the View menu. Select display report for Simulation and click Ok. PHYSICAL PROPERTIES SECTION PROPERTY PARAMETERS PARAMETERS ACTUALLY USED IN THE SIMULATION PURE COMPONENT PARAMETERS COMPONENT ID: BENZENE FORMULA: C6H NAME: C6H6 SCALAR PARAMETERS PARAM SET DESCRIPTIONS VALUE UNITS SOURCE NAME NO. API STANDARD API GRAVITY PURE10 CHARGE 1 IONIC CHARGE E AQUEOUS CHI STIEL POLAR FACTOR E DEFAULT DCPLS 1 DIFFERENCE BETWEEN LIQUID AND CAL/MOL-K PURE10 SOLID CP AT TRIPLE POINT DGFORM 1 IDEAL GAS GIBBS ENERGY KCAL/MOL PURE10 OF FORMATION Introduction to Aspen Plus August 28th,2000

107 Reporting Physical Property Parameters
Introduction to Aspen Plus v10.2 Course Notes Reporting Physical Property Parameters Follow this procedure to obtain a report file containing values of ALL pure component and binary parameters for ALL components used in a simulation: 1. On the Setup Report Options Property sheet, select All physical property parameters used (in SI units) or select Property parameters’ descriptions, equations, and sources of data. 2. After running the simulation, export a report (*.rep) file (Select Export from the File menu). 3. Edit the .rep file using any text editor. (From the Graphical User Interface, you can choose Report from the View menu.) The parameters are listed under the heading PARAMETER VALUES in the physical properties section of the report file. JLM - Lorie, The terms PARAMS and PARAMS-PLUS are no longer used in the GUI. We need to find another way to distinguish and abbreviate these two reports. I couldn’t think of a good way, so I took the lazy way out, and just wrote this comment… Also, in the table, we need to change the capitalization of A+. Introduction to Aspen Plus August 28th,2000

108 How to Establish Physical Properties
Introduction to Aspen Plus v10.2 Course Notes How to Establish Physical Properties Choose a Property Method Check Parameters/Obtain Additional Parameters Confirm Results - Verify that everyone is comfortable with this second step before continuing. Create the Flowsheet Introduction to Aspen Plus August 28th,2000

109 Introduction to Aspen Plus v10.2
Course Notes Property Analysis Used to generate simple property diagrams to validate physical property models and data Diagram Types: Pure component, e.g. Vapor pressure vs. temperature Binary, e.g. TXY, PXY Ternary residue maps Select Analysis from the Tools menu to start Analysis. Additional binary plots are available under the Plot Wizard button on result form containing raw data. When using a binary analysis to check for liquid-liquid phase separation, remember to choose Vapor-Liquid-Liquid as Valid phases. Property analysis input and results can be saved as a form for later reference and use. - Demonstrate a pure-component plot and a binary plot. - Show that on the Pure Analysis dialog box, the property abbreviations are described (as highlighted) in the description area. - Emphasize the Valid phases selection. - Illustrate the two result windows, and how the Plot Wizard is accessed from the data result window. - Demonstrate generating an XY plot from the plot wizard. - Demonstrate saving analysis as a form. Introduction to Aspen Plus August 28th,2000

110 Property Analysis - Common Plots
Introduction to Aspen Plus v10.2 Course Notes Property Analysis - Common Plots Ideal XY Plot: XY Plot Showing Azeotrope: y-x diagram for METHANOL / PROPANOL LIQUID MOLEFRAC METHANOL 0.2 0.4 0.6 0.8 1 VAPOR MOLEFRAC METHANOL (PRES = 14.7 PSI) y-x diagram for ETHANOL / TOLUENE LIQUID MOLEFRAC ETHANOL 0.2 0.4 0.6 0.8 1 VAPOR MOLEFRAC ETHANOL (PRES = 14.7 PSI) XY Plot Showing 2 liquid phases: y-x diagram for TOLUENE / WATER 0.2 0.4 0.6 0.8 1 VAPOR MOLEFRAC TOLUENE (PRES = 14.7 PSI) - explain why the 2-liquid phase plot looks the way that it does (I.e. compositions are not changing, only the amounts are changing) LIQUID MOLEFRAC TOLUENE Introduction to Aspen Plus August 28th,2000

111 How to Establish Physical Properties
Introduction to Aspen Plus v10.2 Course Notes How to Establish Physical Properties Choose a Property Method Check Parameters/Obtain Additional Parameters Confirm Results Create the Flowsheet Introduction to Aspen Plus August 28th,2000

112 Establishing Physical Properties - Review
Introduction to Aspen Plus v10.2 Course Notes Establishing Physical Properties - Review 1. Choose Property Method - Select a Property Method based on Components present in simulation Operating conditions in simulation Available data or parameters for the components 2. Check Parameters - Determine parameters available in Aspen Plus databanks 3. Obtain Additional Parameters (if necessary) - Parameters that are needed can be obtained from Literature searches (DETHERM, etc.) Regression of experimental data (Data Regression) Property Constant Estimation (Property Estimation) 4. Confirm Results - Verify choice of Property Method and physical property data using Physical Property Analysis - Prompt for questions before continuing. - Mention that there is one last topic before the workshop (Prop-sets). Introduction to Aspen Plus August 28th,2000

113 Introduction to Aspen Plus v10.2
Course Notes Property Sets A property set (Prop-Set) is a way of accessing a collection, or set, of properties as an object with a user-given name. Only the name of the property set is referenced when using the properties in an application. Use property sets to report thermodynamic, transport, and other property values. Current property set applications include: Design specifications, Fortran blocks, sensitivity Stream reports Physical property tables (Property Analysis) Tray properties (RadFrac, MultiFrac, etc.) Heating/cooling curves (Flash2, MHeatX, etc.) - Step through a quick example in the GUI and show how qualifiers only apply to properties where applicable (e.g. setup PL and PHIMX). - Also, illustrate that reporting prop-sets to the stream report is another 2-step process like Henry-comps. Introduction to Aspen Plus August 28th,2000

114 Properties included in Prop-Sets
Introduction to Aspen Plus v10.2 Course Notes Properties included in Prop-Sets Properties commonly included in property sets include: VFRAC - Molar vapor fraction of a stream BETA Fraction of liquid in a second liquid phase CPMX - Constant pressure heat capacity for a mixture MUMX - Viscosity for a mixture Available properties include: Thermodynamic properties of components in a mixture Pure component thermodynamic properties Transport properties Electrolyte properties Petroleum-related properties Reference: Aspen Plus Physical Property Data Reference Manual, Chapter 4, Property Sets, has a complete list of properties that can be included in a property set. Introduction to Aspen Plus August 28th,2000

115 Specifying Property Sets
Introduction to Aspen Plus v10.2 Course Notes Specifying Property Sets Use the Properties Prop-Sets form to specify properties in a property set. The Search button can be used to search for a property. All specified qualifiers apply to each property specified, where applicable. Users can define new properties on the Properties Advanced User-Properties form by providing a Fortran subroutine. Introduction to Aspen Plus August 28th,2000

116 Predefined Property Sets
Introduction to Aspen Plus v10.2 Course Notes Predefined Property Sets Some simulation Templates contain predefined property sets. The following table lists predefined property sets and the types of properties they contain for the General Template: Introduction to Aspen Plus August 28th,2000

117 Stream Results Options
Introduction to Aspen Plus v10.2 Course Notes Stream Results Options On the Setup Report Options Stream sheet, use: Flow Basis and Fraction Basis check-boxes to specify how stream composition is reported Property Sets button to specify names of property sets containing additional properties to be reported for each stream Introduction to Aspen Plus August 28th,2000

118 Introduction to Aspen Plus v10.2
Course Notes Definition of Terms Property Method - Set of property models and methods used to calculate the properties required for a simulation Property - Calculated physical property value such as mixture enthalpy Property Model - Equation or equations used to calculate a physical property Property Parameter - Constant used in a property model Property Set (Prop-Set) - A method of accessing properties so that they can be used or tabulated elsewhere Introduction to Aspen Plus August 28th,2000

119 Introduction to Aspen Plus v10.2
Course Notes Aspen Properties Aspen Properties is now a stand-alone product. In addition to the standard property features available in Aspen Plus, Aspen Properties includes: Excel Interface Web Interface Excel Interface is an Excel Add-In that has Excel functions to do property calculations such as: Flash at a given set of conditions Calculate a property such as density or viscosity Web Interface is currently only available for pure components. Introduction to Aspen Plus August 28th,2000

120 Physical Properties Workshop
Introduction to Aspen Plus v10.2 Course Notes Physical Properties Workshop Objective: Simulate a two-liquid phase settling tank and investigate the physical properties of the system. A refinery has a settling tank that they use to decant off the water from a mixture of water and a heavy oil. The inlet stream to the tank also contains some carbon-dioxide and nitrogen. The tank and feed are at ambient temperature and pressure (70o F, 1atm), and have the following flow rates of the various components: Water 515 lb/hr Oil lb/hr CO lb/hr N2 43 lb/hr Use the compound n-decane to represent the oil. It is known that water and oil form two liquid phases under the conditions in the tank. - CO2 and N2 should be declared as Henry comps. - UNIQUAC or NRTL Property Methods can be used - Stress that each step should be completed and fully understood before proceeding to the next step. Encourage them to ask questions if they don’t understand something. - Point out the limits for the NRTL parameters don’t encompass 70F. This does not mean that you can’t use NRTL. - Why is Beta reported as 1 for the feed stream? (Because NPHASE=2 on the stream input form.) - Mention that NPHASE can be set globally under Setup.Sim-Options (new for 9.3). Introduction to Aspen Plus August 28th,2000

121 Physical Properties Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes Physical Properties Workshop (Continued) 1. Choose an appropriate Property Method to represent this system. Check to see that the required binary physical property parameters are available. 2. Retrieve the physical property parameters used in the simulation and determine the critical temperature for carbon dioxide and water. TC(carbon dioxide) = _______; TC(water) = _______ 3. Using the property analysis feature, verify that the chosen physical property model and the available parameters predict the formation of 2 liquid phases. 4. Set up a simulation to model the settling tank. Use a Flash3 block to represent the tank. 5. Modify the stream report to include the constant pressure heat capacity (CPMX) for each phase (Vapor, 1st Liquid and 2nd Liquid), and the fraction of liquid in a second liquid phase (BETA), for all streams. Introduction to Aspen Plus August 28th,2000

122 Physical Properties Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes Physical Properties Workshop (Continued) This Portion is Optional Objective: Generate a table of compositions for each liquid phase (1st Liquid and 2nd Liquid) at different temperatures for a mixture of water and oil. Tabulate the vapor pressure of the components in the same table. In addition to the interactive Analysis commands under the Tools menu, you also can create a Property Analysis manually, using forms. Manually generated Generic Property Analysis is similar to the interactive Analysis commands, however it is more flexible regarding input and reporting. Detailed instructions are on the following slide. JLM - Lorie, please look over this carefully. I totally rewrote it. May want to mention that this is what is created when you save an interactive Analysis as Forms. Introduction to Aspen Plus August 28th,2000

123 Physical Properties Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes Physical Properties Workshop (Continued) Problem Specifications: 1. Create a Generic type property analysis from the Properties/Analysis Object manager. 2. Generate points along a flash curve. 3. Define component flows of 50 mole water and 50 mole oil. 4. Set Valid phases to Vapor-liquid-liquid. 5. Click on the Range/List button, and vary temperature from 50 to 400 F. 6. Use a vapor fraction of zero. 7. Tabulate a new property set that includes: a. Mole fraction of water and oil in the 1st and 2nd liquid phases (MOLEFRAC) b. Mole flow of water and oil in the 1st and 2nd liquid phases (MOLEFLOW) c. Beta - the fraction of the 1st liquid to the total liquid (BETA) d. Pure component vapor pressures of water and oil (PL) Introduction to Aspen Plus August 28th,2000

124 Objective: Become familiar with referencing flowsheet variables
Accessing Variables Objective: Become familiar with referencing flowsheet variables Aspen Plus References: User Guide, Chapter 18, Accessing Flowsheet Variables Related Topics: User Guide, Chapter 20, Sensitivity User Guide, Chapter 21, Design Specifications User Guide, Chapter 19, Calculator Blocks and In-Line Fortran User Guide, Chapter 22, Optimization User Guide, Chapter 23, Fitting a Simulation Model to Data

125 Introduction to Aspen Plus v10.2
Course Notes Why Access Variables? COLUMN FEED OVHD BTMS What is the effect of the reflux ratio of the column on the purity (mole fraction of component B) of the distillate? To perform this analysis, references must be made to 2 flowsheet quantities, i.e. 2 flowsheet variables must be accessed: 1. The reflux ratio of the column 2. The mole fraction of component B in the stream OVHD Introduction to Aspen Plus August 28th,2000

126 Introduction to Aspen Plus v10.2
Course Notes Accessing Variables An accessed variable is a reference to a particular flowsheet quantity, e.g. temperature of a stream or duty of a block. Accessed variables can be input, results, or both. Flowsheet result variables (calculated quantities) should not be overwritten or varied. The concept of accessing variables is used in sensitivity analyses, design specifications, calculator blocks, optimization, etc. You might need an example to clarify why result variables should not be over written or varied. This is obvious to some; others just don’t see why. Introduction to Aspen Plus August 28th,2000

127 Introduction to Aspen Plus v10.2
Course Notes Variable Categories JLM - Why the heck is the Costing category still in the GUI? I guess since it is there, we have to discuss it here... Introduction to Aspen Plus August 28th,2000

128 Variable Definition Dialog Box
Introduction to Aspen Plus v10.2 Course Notes Variable Definition Dialog Box When completing a Define sheet, such as on a Calculator, Design specification or Sensitivity form, specify the variables on the Variable Definition dialog box. You cannot modify the variables on the Define sheet itself. On the Variable Definition dialog box, select the variable category and Aspen Plus will display the other fields necessary to complete the variable definition. If you are editing an existing variable and want to change the variable name, click the right mouse button on the Variable Name field. On the popup menu, click Rename. JLM - This chapter needs something... We have a couple slides on choosing a category, but none on choosing a type. (in fact, I think the 3rd bullet above is actually referring to variable type rather than category.) I like slide 122 in the old course because it lists the most common variable types. (Block-var, stream-var, moleflow/frac, massflow/frac, and stream-prop.) I recommend we have a similar slide, where we can focus the discussion on the most common variable types. The distinction between the flow/frac variables, and stream variables is always confusing for the new user. Overall, I would downplay the selection of category, and concentrate on choosing the correct variable type. Introduction to Aspen Plus August 28th,2000

129 Introduction to Aspen Plus v10.2
Course Notes Notes 1. If the Mass-Frac, Mole-Frac or StdVol-Frac of a component in a stream is accessed, it should not be modified. To modify the composition of a stream, access and modify the Mass-Flow, Mole- Flow or StdVol-Flow of the desired component. 2. If duty is specified for a block, that duty can be read and written using the variable DUTY for that block. If the duty for a block is calculated during simulation, it should be read using the variable QCALC. 3. PRES is the specified pressure or pressure drop, and PDROP is pressure drop used in calculating pressure profile in heating or cooling curves. 4. Only streams that are feeds to the flowsheet should be varied or modified directly. - Note 4 is similar to not overwriting or varying results. Introduction to Aspen Plus August 28th,2000

130 Sensitivity Analysis Objective:
Introduce the use of sensitivity analysis to study relationships between process variables Aspen Plus References: User Guide, Chapter 20, Sensitivity Related Topics: User Guide, Chapter 18, Accessing Flowsheet Variables User Guide, Chapter 19, Calculator Blocks and In-Line Fortran

131 Introduction to Aspen Plus v10.2
Course Notes Sensitivity Analysis Allows user to study the effect of changes in input variables on process outputs. Results can be viewed by looking at the Results form in the folder for the Sensitivity block. Results may be graphed to easily visualize relationships between different variables. Changes made to a flowsheet input quantity in a sensitivity block do not affect the simulation. The sensitivity study is run independently of the base-case simulation. Located under /Data/Model Analysis Tools/Sensitivity Introduction to Aspen Plus August 28th,2000

132 Sensitivity Analysis Example
Introduction to Aspen Plus v10.2 Course Notes Sensitivity Analysis Example What is the effect of cooler outlet temperature on the purity of the product stream? What is the manipulated (varied) variable? What is the measured (sampled) variable? REACTOR FEED RECYCLE REAC-OUT COOL COOL-OUT SEP PRODUCT Filename: CUMENE-S.BKP - This flowsheet starts with the cumene example problem from day 1. - Be sure to turn on molefrac in flow/frac options on Setup.Main. - Run through example in GUI. - Vary cooler temperature from 50 to 400. - Illustrate how the base case results don’t change. - Mention how each sensitivity point has to converge the recycle stream. - Show how to plot the results. - Illustrate some features of the plots: Draw a box on a portion of the plot or zoom in on an area. Click on the graph to get the coordinates. Etc. » Cooler outlet temperature » Purity (mole fraction) of cumene in product stream Introduction to Aspen Plus August 28th,2000

133 Sensitivity Analysis Results
Introduction to Aspen Plus v10.2 Course Notes Sensitivity Analysis Results What is happening below 75 F and above 300 F? Introduction to Aspen Plus August 28th,2000

134 Uses of Sensitivity Analysis
Introduction to Aspen Plus v10.2 Course Notes Uses of Sensitivity Analysis Studying the effect of changes in input variables on process (model) outputs Graphically representing the effects of input variables Verifying that a solution to a design specification is feasible Rudimentary optimization Studying time varying variables using a quasi-steady-state approach - Should uses be before example problem? Introduction to Aspen Plus August 28th,2000

135 Steps for Using Sensitivity Analysis
Introduction to Aspen Plus v10.2 Course Notes Steps for Using Sensitivity Analysis 1. Specify measured (sampled) variable(s) These are quantities calculated during the simulation to be used in step 4 (Sensitivity Input Define sheet). 2. Specify manipulated (varied) variable(s) These are the flowsheet variables to be varied (Sensitivity Input Vary sheet). 3. Specify range(s) for manipulated (varied) variable(s) Variation for manipulated variable can be specified either as equidistant points within an interval or as a list of values for the variable (Sensitivity Input Vary sheet). 4. Specify quantities to calculate and tabulate Tabulated quantities can be any valid Fortran expression containing variables defined in step 1 (Sensitivity Input Tabulate sheet). - Refer to this as a quick reference and as help for doing the workshop. Introduction to Aspen Plus August 28th,2000

136 Introduction to Aspen Plus v10.2
Course Notes Plotting 1. Select the column containing the X-axis variable and then select X-Axis Variable from the Plot menu. 2. Select the column containing the Y-axis variable and then select Y-Axis Variable from the Plot menu. 3. (Optional) Select the column containing the parametric variable and then select Parametric Variable from the Plot menu. 4. Select Display Plot from the Plot menu. Note: To select a column, click on the heading of the column with the left mouse button. Introduction to Aspen Plus August 28th,2000

137 Introduction to Aspen Plus v10.2
Course Notes Notes 1. Only quantities that have been input to the flowsheet should be varied or manipulated. 2. Multiple inputs can be varied. 3. The simulation is run for every combination of manipulated (varied) variables. Introduction to Aspen Plus August 28th,2000

138 Sensitivity Analysis Workshop
Introduction to Aspen Plus v10.2 Course Notes Sensitivity Analysis Workshop Objective: Use a sensitivity analysis to study the effect of the recycle flowrate on the reactor duty in the cyclohexane flowsheet Part A Using the cyclohexane production flowsheet Workshop (saved as CYCLOHEX.BKP), plot the variation of reactor duty (block REACT) as the recycle split fraction in LFLOW is varied from 0.1 to 0.4. Optional Part B In addition to the fraction split off as recycle (Part A), vary the conversion of benzene in the reactor from 0.9 to Tabulate the reactor duty and construct a parametric plot showing the dependence of reactor duty on the fraction split off as recycle and conversion of benzene. Note: Both of these studies (parts A and B) should be set up within the same sensitivity analysis block. When finished, save as filename: SENS.BKP. Introduction to Aspen Plus August 28th,2000

139 Cyclohexane Production Workshop
Introduction to Aspen Plus v10.2 Course Notes Cyclohexane Production Workshop C6H H = C6H12 Benzene Hydrogen Cyclohexane REACT FEED-MIX H2IN BZIN H2RCY CHRCY RXIN RXOUT HP-SEP VAP COLUMN COLFD LTENDS PRODUCT VFLOW PURGE LFLOW Total flow = 330 kmol/hr 92% flow to stream H2RCY T = 50 C P = 25 bar Molefrac H2 = 0.975 N2 = 0.005 CH4 = 0.02 T = 50 C T = 150C Pdrop = 0.5 bar P = 23 bar T = 200 C Theoretical Stages = 12 Pdrop = 1 bar LIQ Reflux ratio = 1.2 T = 40 C At this point add the Sensitivity Analysis input only. Design specs will be added later. The Define variable is QCALC and not DUTY. DUTY is an Input variable. QCALC is a Results variable. Benzene conv = Bottoms rate = 99 kmol/hr 0.998 Partial Condenser with vapor distillate only P = 1 bar Benzene flow = 100 kmol/hr Column Pressure = 15 bar Feed stage = 8 30% flow to stream CHRCY Use the RK-SOAVE property method Specify cyclohexane mole recovery of by varying Bottoms rate from 97 to 101 kmol/hr Introduction to Aspen Plus August 28th,2000

140 Design Specifications
Objective: Introduce the use of design specifications to meet process design requirements Aspen Plus References User Guide, Chapter 21, Design Specifications Related Topics User Guide, Chapter 18, Accessing Flowsheet Variables User Guide, Chapter 19, Calculator Blocks and In-Line Fortran User Guide, Chapter 17, Convergence

141 Design Specifications
Introduction to Aspen Plus v10.2 Course Notes Design Specifications Similar to a feedback controller Allows user to set the value of a calculated flowsheet quantity to a particular value Objective is achieved by manipulating a specified input variable No results associated directly with a design specification Located under /Data/Flowsheeting Options/Design Specs Introduction to Aspen Plus August 28th,2000

142 Design Specification Example
Introduction to Aspen Plus v10.2 Course Notes Design Specification Example REACTOR FEED RECYCLE REAC-OUT COOL COOL-OUT SEP PRODUCT Filename: CUMENE-D.BKP What should the cooler outlet temperature be to achieve a cumene product purity of 98 mole percent? What is the manipulated (varied) variable? What is the measured (sampled) variable? What is the specification (target) to be achieved? » Cooler outlet temperature - Make sure Molefrac is on in Setup.Main. - Start with the cumene with sensitivity example. - Recall results of sensitivity to know limits for manipulated variable. - HIDE sensitivity block before creating Design-Spec. - Give bounds of for cooler temperature (the same limits used in the Sensitivity). - Illustrate how there are no “results” for Design-Spec. Results button on object manager is grayed out. - Show how cooler results are changed and the product purity is 0.98. » Mole fraction of cumene in stream PRODUCT » Mole fraction of cumene in stream PRODUCT = 0.98 Introduction to Aspen Plus August 28th,2000

143 Steps for Using Design Specifications
Introduction to Aspen Plus v10.2 Course Notes Steps for Using Design Specifications 1. Identify measured (sampled) variables These are flowsheet quantities, usually calculated quantities, to be included in the objective function (Design Spec Define sheet). 2. Specify objective function (Spec) and goal (Target) This is the equation that the specification attempts to satisfy (Design Spec Spec sheet). The units of the variable used in the objective function are the units for that type of variable as specified by the Units Set declared for the design specification. 3. Set tolerance for objective function The specification is said to be converged if the objective function equation is satisfied to within this tolerance (Design Spec Spec sheet). - Quick reference and help for workshop. Introduction to Aspen Plus August 28th,2000

144 Steps for Using Design Specifications (Continued)
Introduction to Aspen Plus v10.2 Course Notes Steps for Using Design Specifications (Continued) 4. Specify manipulated (varied) variable This is the variable whose value the specification changes in order to satisfy the objective function equation (Design Spec Vary sheet). 5. Specify range of manipulated (varied) variable These are the lower and upper bounds of the interval within which Aspen Plus will vary the manipulated variable (Design Spec Vary sheet). The units of the limits for the varied variable are the units for that type of variable as specified by the Units Set declared for the design specification. Introduction to Aspen Plus August 28th,2000

145 Introduction to Aspen Plus v10.2
Course Notes Notes 1. Only quantities that have been input to the flowsheet should be manipulated. 2. The calculations performed by a design specification are iterative. Providing a good estimate for the manipulated variable will help the design specification converge in fewer iterations. This is especially important for large flowsheets with several interrelated design specifications. 3. The results of a design specification can be found under Data/Convergence/Convergence, by opening the appropriate solver block, and choosing the Results form. Alternatively, the final values of the manipulated and/or sampled variables can be viewed directly on the appropriate Stream/Block results forms. Introduction to Aspen Plus August 28th,2000

146 Introduction to Aspen Plus v10.2
Course Notes Notes (Continued) 4. If a design-spec does not converge: a. Check to see that the manipulated variable is not at its lower or upper bound. b. Verify that a solution exists within the bounds specified for the manipulated variable, perhaps by performing a sensitivity analysis. c. Check to ensure that the manipulated variable does indeed affect the value of the sampled variables. d. Try providing a better starting estimate for the value of the manipulated variable. Introduction to Aspen Plus August 28th,2000

147 Introduction to Aspen Plus v10.2
Course Notes Notes (Continued) e. Try narrowing the bounds of the manipulated variable or loosening the tolerance on the objective function to help convergence. f. Make sure that the objective function does not have a flat region within the range of the manipulated variable. g. Try changing the characteristics of the convergence block associated with the design-spec (step size, number of iterations, algorithm, etc.) Introduction to Aspen Plus August 28th,2000

148 Design Specification Workshop
Introduction to Aspen Plus v10.2 Course Notes Design Specification Workshop Objective: Use a design specification in the cyclohexane flowsheet to fix the heat load on the reactor by varying the recycle flowrate. The cyclohexane production flowsheet workshop (saved as CYCLOHEX.BKP) is a model of an existing plant. The cooling system around the reactor can handle a maximum operating load of 4.7 MMkcal/hr. Determine the amount of cyclohexane recycle necessary to keep the cooling load on the reactor to this amount. Note: The heat convention used in Aspen Plus is that heat input to a block is positive, and heat removed from a block is negative. When finished, save as filename: DES-SPEC.BKP Must use MetCBar units to specify this target duty. Introduction to Aspen Plus August 28th,2000

149 Cyclohexane Production Workshop
Introduction to Aspen Plus v10.2 Course Notes Cyclohexane Production Workshop C6H H = C6H12 Benzene Hydrogen Cyclohexane REACT FEED-MIX H2IN BZIN H2RCY CHRCY RXIN RXOUT HP-SEP VAP COLUMN COLFD LTENDS PRODUCT VFLOW PURGE LFLOW Total flow = 330 kmol/hr 92% flow to stream H2RCY T = 50 C P = 25 bar Molefrac H2 = 0.975 N2 = 0.005 CH4 = 0.02 T = 50 C T = 150C Pdrop = 0.5 bar P = 23 bar T = 200 C Theoretical Stages = 12 Pdrop = 1 bar Reflux ratio = 1.2 LIQ Benzene conv = Bottoms rate = 99 kmol/hr T = 40 C 0.998 Partial Condenser with vapor distillate only P = 1 bar Benzene flow = 100 kmol/hr Column Pressure = 15 bar Feed stage = 8 30% flow to stream CHRCY Use the RK-SOAVE property method Specify cyclohexane mole recovery of by varying Bottoms rate from 97 to 101 kmol/hr Introduction to Aspen Plus August 28th,2000

150 Objective: Introduce usage of Excel and Fortran Calculator blocks
Aspen Plus References: User Guide, Chapter 19, Calculator Blocks and In-Line Fortran Related Topics: User Guide, Chapter 20, Sensitivity User Guide, Chapter 21, Design Specifications User Guide, Chapter 18, Accessing Flowsheet Variables User Guide, Chapter 22, Optimization

151 Introduction to Aspen Plus v10.2
Course Notes Calculator Blocks Allows user to write equations in an Excel spreadsheet or in Fortran to be executed by Aspen Plus Results of the execution of a Calculator block must be viewed by directly examining the values of the variables modified by the Calculator block. Increasing the diagnostics for the Calculator block will print the value of all input and result variables in the Control Panel. Located under /Data/Flowsheeting Options/Calculator Introduction to Aspen Plus August 28th,2000

152 Calculator Block Example
Introduction to Aspen Plus v10.2 Course Notes Calculator Block Example Use of a Calculator block to set the pressure drop across a Heater block. Pressure drop across heater is proportional to square of volumetric flow into heater. REACTOR FEED RECYCLE REAC-OUT COOL COOL-OUT SEP PRODUCT V DELTA-P - Start with Cumene example and set up this example Potential Pitfalls: - Don’t use integer names for real variables. This can cause very strange results. - You can add write statements to print variables. If you use an unformatted write statement, the Fortran will be compiled rather than interpreted. - When doing the example, note the two options for defining volumetric flow described on the next page. Calculator Block DELTA-P = * V2 Filename: CUMENE-F.BKP or CUMENE-EXCEL.BKP Introduction to Aspen Plus August 28th,2000

153 Calculator Block Example (Continued)
Introduction to Aspen Plus v10.2 Course Notes Calculator Block Example (Continued) Which flowsheet variables must be accessed? When should the Calculator block be executed? Which variables are imported and which are exported? » Volumetric flow of stream REAC-OUT This can be accessed in two different ways: 1. Mass flow and mass density of stream REAC-OUT 2. A prop-set containing volumetric flow of a mixture » Pressure drop across block COOL » Before block COOL Import/Export variable types are defined by the user through radio buttons on the Sequence tab or the Variable tab-Define field. Set variable fefinitions as: FLOW = Mass flow of stream REACT-OUT DENS = Density (wt) of stream REACT-OUT Volumetric flow, VFLOW = FLOW/DENS Pressure drop across Cooler, DP = -1e-9*VFLOW Two sequence options: 1.Use import/export variables. 2.Before unit operation, Cooler. » Volumetric flow is imported » Pressure drop is exported Introduction to Aspen Plus August 28th,2000

154 Introduction to Aspen Plus v10.2
Course Notes Excel Aspen Plus toolbar in Excel Connect Current Cell to a Defined Variable Import Variables =FLOW/DENS =(-10^-9)*B6^2 Export Variable Introduction to Aspen Plus August 28th,2000

155 Steps for Using Calculator Blocks
Introduction to Aspen Plus v10.2 Course Notes Steps for Using Calculator Blocks 1. Access flowsheet variables to be used within Calculator All flowsheet quantities that must be either read from or written to, must be identified (Calculator Input Define sheet). 2. Write Fortran or Excel Fortran includes both non-executable (COMMON, EQUIVALENCE, etc) Fortran (click on the Fortran Declarations button) and executable Fortran (Calculator Input Calculate sheet) to achieve desired result. 3. Specify location of Calculator block in execution sequence (Calculator Input Sequence sheet) Specify directly, or Specify with import and export variables Introduction to Aspen Plus August 28th,2000

156 Uses of Calculator Blocks
Introduction to Aspen Plus v10.2 Course Notes Uses of Calculator Blocks Feed-forward control (setting flowsheet inputs based on upstream calculated values) Calling external subroutines Input / output to and from external files Writing to an external file, or the Control Panel, History File, or Report File Custom reports Introduction to Aspen Plus August 28th,2000

157 Increasing Diagnostics
Introduction to Aspen Plus v10.2 Course Notes Increasing Diagnostics Increase Calculator defined variables Diagnostics message level in Control Panel or History file to 8. Calculator Block F-1 VALUES OF ACCESSED VARIABLES VARIABLE VALUE ======== ===== DP FLOW DENS RETURNED VALUES OF VARIABLES DP In the Control Panel or History File Introduction to Aspen Plus August 28th,2000

158 Introduction to Aspen Plus v10.2
Course Notes Excel Excel workbook is embedded into simulation for each Calculator block. When saving as a backup (.bkp file), a .apmbd file is created. This file needs to be in the working directory. Full functionality of Excel is available including VBA and Macros. Cells that contain Import variables have a green border. Cells that contain Export variables have a blue border. Cells that contain Tear variables have an orange border. Introduction to Aspen Plus August 28th,2000

159 Introduction to Aspen Plus v10.2
Course Notes Excel (Continued) Variables can be defined in Aspen Plus on the Define sheet or in Excel using the Aspen Plus toolbar. (It is generally faster to add variables inside Aspen Plus.) No Fortran compiler is needed. Introduction to Aspen Plus August 28th,2000

160 Excel Aspen Plus Toolbar
Introduction to Aspen Plus v10.2 Course Notes Excel Aspen Plus Toolbar Connect Cell Combo Box Use this Combo Box to attach the current cell on the Excel spreadsheet to a Defined Variable. If the Defined Variable chosen is already connected to another cell, the link between that cell and the Defined Variable is broken. Define Button Click the Define Button to create a new Defined Variable or to edit an existing one. If this cell is already connected to a Defined Variable, clicking on this button will allow you to edit it. If this cell is not connected to a Defined Variable, clicking on this button will create a new Defined Variable. Unlink Button Click the Unlink Button to remove the link between a cell and a Defined Variable. Clicking on this button does not delete the Defined Variable. Introduction to Aspen Plus August 28th,2000

161 Excel Aspen Plus Toolbar (Continued)
Introduction to Aspen Plus v10.2 Course Notes Excel Aspen Plus Toolbar (Continued) Delete Button Click the Delete Button to remove the link between a cell and a Defined variable and delete the Defined Variable. Refresh Button Click the Refresh Button to refresh the list of Defined Variables in the Connect Cell Combo Box. You should click this button if you have changed the list of Defined Variables by making changes on the Calculator Define sheet. Changed Button Click the Changed Button to set the "Input Changed" flag of this Calculator block. This will cause the Calculator to be re-executed the next time you run the simulation. You should click this button if, after the calculator block is executed, you make changes to the Excel spreadsheet without making any changes on the Calculator block forms. Introduction to Aspen Plus August 28th,2000

162 Windows Interoperability
Objective: Introduce the use of windows interoperability to transfer data easily to and from other Windows programs. Aspen Plus References User Guide, Chapter 37, Working with Other Windows Programs User Guide, Chapter 38, Using the Aspen Plus ActiveX Automation Server

163 Windows Interoperability
Introduction to Aspen Plus v10.2 Course Notes Windows Interoperability Copying and pasting simulation data into spreadsheets or reports Copying and pasting flowsheet graphics and plots into reports Creating active links between Aspen Plus and other Windows applications OLE - Object Linking and Embedding ActiveX automation Introduction to Aspen Plus August 28th,2000

164 Windows Interoperability - Examples
Introduction to Aspen Plus v10.2 Course Notes Windows Interoperability - Examples Copy simulation results such as column profiles and stream results into Spreadsheet for further analysis Word processor for reports and documentation Design program Database for case storage and management Copy flowsheet graphics and plots into Word processor for reports Slide making program for presentations Copy tabular data from spreadsheets into Aspen Plus for Data Regression, Data-Fit, etc. Copy plots or tables into the Process Flowsheet Window. JLM - Table lines are too thick, obstructing some of the text. Introduction to Aspen Plus August 28th,2000

165 Benefits of Windows Interoperability
Introduction to Aspen Plus v10.2 Course Notes Benefits of Windows Interoperability Benefits of Copy/Paste/Paste Link Live data links can be established that update these applications as the process model is changed to automatically propagate results of engineering changes. The benefits to the engineer are quick and error-free data transfer and consistent engineering results throughout the engineering work process. Introduction to Aspen Plus August 28th,2000

166 Steps for Using Copy and Paste
Introduction to Aspen Plus v10.2 Course Notes Steps for Using Copy and Paste 1. Select Select the data fields or the graphical objects. Multiple fields of data or objects can be selected by holding down the CTRL key while clicking the mouse on the fields. Columns of data can be selected by clicking the column heading, or an entire grid can be selected by clicking on the top left cell. 2. Copy Choose Copy from the Edit menu or type CTRL-C. 3. Paste Click the mouse in the input field where you want the information and choose Paste from the Edit menu or click CTRL-V. Introduction to Aspen Plus August 28th,2000

167 OLE - Object Linking and Embedding
Introduction to Aspen Plus v10.2 Course Notes OLE - Object Linking and Embedding What is OLE? Applications can be used within applications. Uses of OLE Aspen Plus as the OLE server: Aspen Plus flowsheet graphics can be embedded into a report document, or stream data into a CAD drawing. The simulation model is actually contained in the document, and could be delivered directly with that document. Aspen Plus as the OLE container: Other windows applications can be embedded within the Aspen Plus simulation. JLM - Doesn’t the acronym OLE include the word embedding? If so, this makes the phrase “OLE embedding” redundant. Also, when you say “OLE server” and “OLE container”, does this really mean “Aspen Plus as the OLE server”, and vice versa? This is sort of confusing. Introduction to Aspen Plus August 28th,2000

168 Introduction to Aspen Plus v10.2
Course Notes OLE (Continued) Examples of OLE OLE server: If the recipient of an engineering report, for example, wanted to review the model assumptions, he could access and run the embedded Aspen Plus model directly from the report document. OLE container: For example, Excel spreadsheets and plots could be used to enhance Aspen Plus flowsheet graphics. Introduction to Aspen Plus August 28th,2000

169 Embedding Objects in the Flowsheet
Introduction to Aspen Plus v10.2 Course Notes Embedding Objects in the Flowsheet You can embed other applications as objects into the Process Flowsheet window. You can do this in two ways: Using Copy and Paste Using the Insert dialog box You can edit the object embedded in the flowsheet by double clicking on the object to edit it inside Aspen Plus. You can also move, resize or attach the object to a block or stream in the flowsheet. JLM - What do you mean in the second bullet when you say you can use the Insert dialog box? Should we clarify this? I’m not sure what that means. Introduction to Aspen Plus August 28th,2000

170 Copy and Paste Workshop 1
Introduction to Aspen Plus v10.2 Course Notes Copy and Paste Workshop 1 Objectives: Use copy and paste to copy and paste the stage temperatures into a spreadsheet. Use the Cyclohexane flowsheet workshop (saved as CYCLOHEX.BKP) Copy the temperature profile from COLUMN into a spreadsheet. Generate a plot of the temperature using the plot wizard and copy and paste the plot into the spreadsheet. Save the spreadsheet as CYCLOHEX-result.xls August 28th,2000

171 Copy and Paste Workshop 2
Introduction to Aspen Plus v10.2 Course Notes Copy and Paste Workshop 2 Objective: Use copy and paste to copy the stream results to a stream input form. Use the Cyclohexane flowsheet workshop (saved as CYCLOHEX.BKP) Copy the stream results from stream RXIN into the input form. Copy the compositions, the temperature and the pressure separately. Note: Reinitialize before running the simulation in order to see how many iterations are needed before and after the estimate is added. Introduction to Aspen Plus August 28th,2000

172 Introduction to Aspen Plus v10.2
Course Notes Creating Active Links When copying and pasting information, you can create active links between input or results fields in Aspen Plus and other applications such as Word and Excel. The links update these applications as the process model is modified to automatically propagate results of engineering changes. Introduction to Aspen Plus August 28th,2000

173 Steps for Creating Active Links
Introduction to Aspen Plus v10.2 Course Notes Steps for Creating Active Links 1. Open both applications. 2. Select the data (or object) that you want to paste and link. 3. Choose Copy from the Edit menu. 4. In the location where you want to paste the link, choose Paste Special from the Edit menu. 5. In the Paste Special dialog box, click the Paste Link radio button. JLM - Should also mention how to Re-sync (or Reset) the PFD diagram with the true simulation diagram. Introduction to Aspen Plus August 28th,2000

174 Paste Link Demonstration
Introduction to Aspen Plus v10.2 Course Notes Paste Link Demonstration Objective: Create an active link from Aspen Plus Results into a spreadsheet. Start with the cumene flowsheet demonstration. Open a spreadsheet and create a cell with the temperature for the cooler in it. Copy and paste the link into the Aspen Plus flowsheet. Copy and paste a link with the flow and composition of cumene in the product stream into the spreadsheet. Change the temperature in the spreadsheet and then rerun the flowsheet. Notice the changes. Should probably ask the students not to follow along, to make the demonstration go quicker. Introduction to Aspen Plus August 28th,2000

175 Introduction to Aspen Plus v10.2
Course Notes Paste Link Workshop Objective: Create an active link from Aspen Plus results into a spreadsheet Use the Cyclohexane flowsheet workshop (saved as CYCLOHEX.BKP) Copy the Condenser and Reboiler duty results from the RadFrac COLUMN Summary sheet. Use Copy with Format and copy the value, the label and the units. Paste the results into the CYCLOHEX-results.xls spreadsheet as a link. Use Paste Special and choose Link. Change the Reflux ratio in the column to 2 and rerun the flowsheet. Check the spreadsheet to see that the results have changed there also. Notice that the temperature profile results have not changed since they were not pasted as a link. Introduction to Aspen Plus August 28th,2000

176 Saving Files with Active Links
Introduction to Aspen Plus v10.2 Course Notes Saving Files with Active Links Be sure to save both the link source file and the link container file. If you save the link source with a different name, you must save the link container after saving the link source. If you have active links in both directions between the two applications and you change the name of both files, you must do three Save operations: Save the first application with a new name. Save the second application with a new name. Save the first application again. Introduction to Aspen Plus August 28th,2000

177 Running Files with Active Links
Introduction to Aspen Plus v10.2 Course Notes Running Files with Active Links When you open the link source file, there is nothing special that you need to do. When you open the link container file, you will usually see a dialog box asking you if you want to re-establish the links. You can select Yes or No. To make a link source application visible: Select Links, from the Edit menu in Aspen Plus. In the Links dialog box, select the source file and click Open Source. Note: The Process Flowsheet must be the active window. Links is not an option on the Edit menu if the Data Browser is active. - This is a good section to add if there is time. - Virtually everyone will have convergence problems at some point. - The workshop is designed more towards an independent study approach. There are questions and answers in the workshop. Introduction to Aspen Plus August 28th,2000

178 Heat Exchangers Objective:
Introduce the unit operation models used for heat exchangers and heaters. Aspen Plus References: Unit Operation Models Reference Manual, Chapter 3, Heat Exchangers

179 Heat Exchanger Blocks Heater - Heater or cooler
HeatX - Two stream heat exchanger MHeatX - Multi-stream heat exchanger Hetran - Interface to B-JAC Hetran block Aerotran - Interface to B-JAC Aerotran block Introduction to Aspen Plus

180 Working with the Heater Model
Introduction to Aspen Plus v10.2 Course Notes Working with the Heater Model The Heater block mixes multiple inlet streams to produce a single outlet stream at a specified thermodynamic state. Heater can be used to represent: Heaters Coolers Valves Pumps (when work-related results are not needed) Compressors (when work-related results are not needed) Heater can also be used to set the thermodynamic conditions of a stream. Introduction to Aspen Plus August 28th,2000

181 Heater Input Specifications
Introduction to Aspen Plus v10.2 Course Notes Heater Input Specifications Allowed combinations: Pressure (or Pressure drop) and one of: Outlet temperature Heat duty or inlet heat stream Vapor fraction Temperature change Degrees of subcooling or superheating Outlet Temperature or Temperature change and one of: Pressure Heat Duty Introduction to Aspen Plus August 28th,2000

182 Heater Input Specifications (Continued)
Introduction to Aspen Plus v10.2 Course Notes Heater Input Specifications (Continued) For single phase use Pressure (drop) and one of: Outlet temperature Heat duty or inlet heat stream Temperature change Vapor fraction of 1 means dew point condition, means bubble point Introduction to Aspen Plus August 28th,2000

183 Introduction to Aspen Plus v10.2
Course Notes Heat Streams Any number of inlet heat streams can be specified for a Heater. One outlet heat stream can be specified for the net heat load from a Heater. The net heat load is the sum of the inlet heat streams minus the actual (calculated) heat duty. If you give only one specification (temperature or pressure), Heater uses the sum of the inlet heat streams as a duty specification. If you give two specifications, Heater uses the heat streams only to calculate the net heat duty. Introduction to Aspen Plus August 28th,2000

184 Working with the HeatX Model
Introduction to Aspen Plus v10.2 Course Notes Working with the HeatX Model HeatX can perform simplified or rigorous rating calculations. Simplified rating calculations (heat and material balance calculations) can be performed if exchanger geometry is unknown or unimportant. For rigorous heat transfer and pressure drop calculations, the heat exchanger geometry must be specified. Introduction to Aspen Plus August 28th,2000

185 Working with the HeatX Model (Continued)
Introduction to Aspen Plus v10.2 Course Notes Working with the HeatX Model (Continued) HeatX can model shell-and-tube exchanger types: Counter-current and co-current Segmental baffle TEMA E, F, G, H, J and X shells Rod baffle TEMA E and F shells Bare and low-finned tubes HeatX performs: Full zone analysis Heat transfer and pressure drop calculations Sensible heat, nucleate boiling, condensation film coefficient calculations Built-in or user specified correlations Introduction to Aspen Plus August 28th,2000

186 Working with the HeatX Model (Continued)
Introduction to Aspen Plus v10.2 Course Notes Working with the HeatX Model (Continued) HeatX cannot: Perform design calculations Perform mechanical vibration analysis Estimate fouling factors Introduction to Aspen Plus August 28th,2000

187 HeatX Input Specifications
Introduction to Aspen Plus v10.2 Course Notes HeatX Input Specifications Select one of the following specifications: Heat transfer area or Geometry Exchanger duty For hot or cold outlet stream: Temperature Temperature change Temperature approach Degrees of superheating / subcooling Vapor fraction Introduction to Aspen Plus August 28th,2000

188 Working with the MHeatX Model
Introduction to Aspen Plus v10.2 Course Notes Working with the MHeatX Model MHeatX can be used to represent heat transfer between multiple hot and cold streams. Detailed, rigorous internal zone analysis can be performed to determine pinch points. MHeatX uses multiple Heater blocks and heat streams to enhance flowsheet convergence. Two-stream heat exchangers can also be modeled using MHeatX. Introduction to Aspen Plus August 28th,2000

189 Introduction to Aspen Plus v10.2
Course Notes HeatX versus Heater Consider the following: Use HeatX when both sides are important. Use Heater when one side (e.g. the utility) is not important. Use two Heaters (coupled by heat stream, Calculator block or design spec) or an MHeatX to avoid flowsheet complexity created by HeatX. Introduction to Aspen Plus August 28th,2000

190 Two Heaters versus One HeatX
Introduction to Aspen Plus v10.2 Course Notes Two Heaters versus One HeatX - For the case with the HeatX, there is a recycle loop. - For the case with the two Heaters, there is NO recycle loop. If the information went in the other direction (HOT-SIDE to CLD-SIDE Heater), then there would be a recycle loop; however, the loop would be easier to converge since only the enthalpy of the heat stream needs to be converged in the tear. Introduction to Aspen Plus August 28th,2000

191 Working with Hetran and Aerotran
Introduction to Aspen Plus v10.2 Course Notes Working with Hetran and Aerotran The Hetran block is the interface to the B-JAC Hetran program for designing and simulating shell and tube heat exchangers. The Aerotran block is the interface to the B-JAC Aerotran program for designing and simulating air-cooled heat exchangers. Information related to the heat exchanger configuration and geometry is entered through the Hetran or Aerotran standalone program interface. Introduction to Aspen Plus August 28th,2000

192 Introduction to Aspen Plus v10.2
Course Notes Working with HTRI-IST The HTRIIST block called HTRI IST as a subroutine for licensed IST users only. Aspen Plus properties are used. Users can create a new IST model or access an existing model. Key IST results are retrieved and reported inside Aspen Plus. Introduction to Aspen Plus August 28th,2000

193 Introduction to Aspen Plus v10.2
Course Notes Heat Curves All of the heat exchanger models are able to calculate Heat Curves (Hcurves). Tables can be generated for various independent variables (typically duty or temperature) for any property that Aspen Plus can generate. These tables can be printed, plotted, or exported for use with other heat exchanger design software. JLM - Do we still have an interface to other heat exchanger design software? If so, we should changed the third bullet to read: - These tables can be printed, plotted, or exported for use with other heat exchanger design software. HvW - HTXINT interfaces to BJAC, HTFS and HTRI. Introduction to Aspen Plus August 28th,2000

194 Heat Curves Tabular Results
Introduction to Aspen Plus v10.2 Course Notes Heat Curves Tabular Results Also, are we sure OLE automation is something that we should give an example for in the intro? Seems a little advanced for the new user. Lorie: Feel free to skip this demo. I left it here in case some users are curious. HvW - We always get questions on how to get heat exch results into design programs. Thats why I like to show this. Introduction to Aspen Plus August 28th,2000

195 Introduction to Aspen Plus v10.2
Course Notes Heat Curve Plot JLM - Should add some instructor notes here to aid in interpretation of the plot. HvW - Not much to add, I think: - X-axis runs from low to high, therefor inlet is at right. - One can see three sections: colling gas, condensing and subcooling liquid. - Dew and bubble points are inserted. Introduction to Aspen Plus August 28th,2000

196 Introduction to Aspen Plus v10.2
Course Notes HeatX Workshop Objective: Compare the simulation of a heat exchanger that uses water to cool a hydrocarbon mixture using three methods: a shortcut HeatX, a rigorous HeatX and two Heaters connected with a Heat stream. Hydrocarbon stream Temperature: 200 C Pressure: 4 bar Flowrate: kg/hr Composition: 50 wt% benzene, 20% styrene, 20% ethylbenzene and 10% water Cooling water Temperature: 20 C Pressure: 10 bar Flow rate: kg/hr Composition: 100% water Introduction to Aspen Plus August 28th,2000

197 HeatX Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes HeatX Workshop (Continued) When finished, save as filename: HEATX.BKP HEATER-1 HCLD-IN HCLD-OUT SHOT-OUT RHOT-OUT SHEATX RHEATX SCLD-IN SCLD-OUT RCLD-IN RCLD-OUT Q-TRANS HEATER-2 HHOT-IN HHOT-OUT SHOT-IN RHOT-IN Start with the General with Metric Units Template. Use the NRTL-RK Property Method for the hydrocarbon streams. Specify that the valid phases for the hydrocarbon stream is Vapor-Liquid-Liquid. Specify that the Steam Tables are used to calculate the properties for the cooling water streams on the Block BlockOptions Properties sheet. Introduction to Aspen Plus August 28th,2000

198 HeatX Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes HeatX Workshop (Continued) Shortcut HeatX simulation: Hydrocarbon stream exit has a vapor fraction of 0 No pressure drop in either stream Two Heaters simulation: Use the same specifications as the shortcut HeatX simulation Rigorous HeatX simulation: Hydrocarbons in shell leave with a vapor fraction of 0 Shell diameter 1 m, 1 tube pass 300 bare tubes, 3 m length, pitch 31 mm, 21 mm ID, 25 mm OD All nozzles 100 mm 5 baffles, 15% cut Create heat curves containing all info required for thermal design. Change the heat exchanger specification to Geometry and re-run. Should give a couple of quick demos during the discussion outlined on this slide. HvW ??? About what (apart from explaining the workshop) Introduction to Aspen Plus August 28th,2000

199 Pressure Changers Objective:
Introduce the unit operation models used to change pressure: pumps, compressors, and models for calculating pressure change through pipes and valves. Aspen Plus References: Unit Operation Models Reference Manual, Chapter 6, Pressure Changers

200 Pressure Changer Blocks
Pump - Pump or hydraulic turbine Compr - Compressor or turbine MCompr - Multi-stage compressor or turbine Valve - Control valve Pipe - Single-segment pipe Pipeline - Multi-segment pipe Introduction to Aspen Plus

201 Working with the Pump Model
Introduction to Aspen Plus v10.2 Course Notes Working with the Pump Model The Pump block can be used to simulate: Pumps Hydraulic turbines Power requirement is calculated or input. A Heater model can be used for pressure change calculations only. Pump is designed to handle a single liquid phase. Vapor-liquid or vapor-liquid-liquid calculations can be specified to check outlet stream phases. JLM - The last two bullets seem to contradict each other. Introduction to Aspen Plus August 28th,2000

202 Pump Performance Curves
Introduction to Aspen Plus v10.2 Course Notes Pump Performance Curves Rating can be done by specifying scalar parameters or a pump performance curve. Specify: Dimensional curves Head versus flow Power versus flow Dimensionless curves: Head coefficient versus flow coefficient Introduction to Aspen Plus August 28th,2000

203 Working with the Compr Model
Introduction to Aspen Plus v10.2 Course Notes Working with the Compr Model The Compr block can be used to simulate: Polytropic centrifugal compressor Polytropic positive displacement compressor Isentropic compressor Isentropic turbine MCompr is used for multi-stage compressors. Power requirement is calculated or input. A Heater model can be used for pressure change calculations only. Compr is designed to handle both single and multiple phase calculations. Introduction to Aspen Plus August 28th,2000

204 Working with the MCompr Model
Introduction to Aspen Plus v10.2 Course Notes Working with the MCompr Model The MCompr block can be used to simulate: Multi-stage polytropic centrifugal compressor Multi-stage polytropic positive displacement compressor Multi-stage isentropic compressor Multi-stage isentropic turbine MCompr can have an intercooler between each stage, and an aftercooler after the last stage. You can perform one-, two-, or three- phase flash calculations in the intercoolers. Each cooler can have a liquid knockout stream, except the cooler after the last stage. Intercooler specifications apply to all subsequent coolers. Introduction to Aspen Plus August 28th,2000

205 Compressor Performance Curves
Introduction to Aspen Plus v10.2 Course Notes Compressor Performance Curves Rating can be done by specifying a compressor performance curve. Specify: Dimensional curves Head versus flow Power versus flow Dimensionless curves: Head coefficient versus flow coefficient Compr cannot handle performance curves for a turbine. Introduction to Aspen Plus August 28th,2000

206 Introduction to Aspen Plus v10.2
Course Notes Work Streams Any number of inlet work streams can be specified for pumps and compressors. One outlet work stream can be specified for the net work load from pumps or compressors. The net work load is the sum of the inlet work streams minus the actual (calculated) work. Introduction to Aspen Plus August 28th,2000

207 Working with the Valve Model
Introduction to Aspen Plus v10.2 Course Notes Working with the Valve Model The Valve block can be used to simulate: Control valves Pressure drop The pressure drop across a valve is related to the valve flow coefficient. Flow is assumed to be adiabatic. Valve can perform single or multiple phase calculations. Introduction to Aspen Plus August 28th,2000

208 Working with the Valve Model (Continued)
Introduction to Aspen Plus v10.2 Course Notes Working with the Valve Model (Continued) The effect of head loss from pipe fittings can be included. There are three types of calculations: Adiabatic flash for specified outlet pressure (pressure changer) Calculate valve flow coefficient for specified outlet pressure (design) Calculate outlet pressure for specified valve (rating) Valve can check for choked flow. Cavitation index can be calculated. Introduction to Aspen Plus August 28th,2000

209 Working with the Pipe Model
Introduction to Aspen Plus v10.2 Course Notes Working with the Pipe Model The Pipe block calculates the pressure drop and heat transfer in a single pipe segment. The Pipeline block can be used for a multiple-segment pipe. Pipe can perform single or multiple phase calculations. If the inlet pressure is known, Pipe calculates the outlet pressure. If the outlet pressure is known, Pipe calculates the inlet pressure and updates the state variables of the inlet stream. Entrance effects are not modeled. Introduction to Aspen Plus August 28th,2000

210 Pressure Changers Block Example
Introduction to Aspen Plus v10.2 Course Notes Pressure Changers Block Example Add a Compressor and a Valve to the cumene flowsheet. COMPR RECYCLE VALVE Polytropic compressor model using GPSA method Discharge pressure = 5 psig RECYCLE2 RECYCLE3 Outlet Pressure = 3 psig FEED - Start with Cumene example and set up this example REAC-OUT COOL-OUT SEP COOL REACTOR PRODUCT Filename: CUMENE-P.BKP Introduction to Aspen Plus August 28th,2000

211 Pressure Changers Workshop
Introduction to Aspen Plus v10.2 Course Notes Pressure Changers Workshop Objective: Add pressure changer unit operations to the Cyclohexane flowsheet. Start with the Cyclohexane Workshop flowsheet (CYCLOHEX.BKP) Introduction to Aspen Plus August 28th,2000

212 Pressure Changers Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes Pressure Changers Workshop (Continued) Isentropic 4 bar pressure change VALVE PURGE PURGE2 COMP H2RCY VFLOW 20 bar outlet pressure Globe valve V810 equal percent flow 1.5-in size H2IN H2RCY2 VAP FEED-MIX REACT RXIN FEEDPUMP HP-SEP BZIN2 RXOUT BZIN CHRCY3 LTENDS Pump efficiency = 0.6 Driver efficiency = 0.9 Performance Curve Head Flow [m] [cum/hr] 40 20 250 10 300 5 400 3 LIQ PIPE PUMP JLM - Workshop looks good. CHRCY2 CHRCY COLFD Carbon Steel Schedule 40 1-in diameter 25-m length LFLOW PRODUCT 26 bar outlet pressure COLUMN When finished, save as filename: PRESCHNG.BKP Introduction to Aspen Plus August 28th,2000

213 Flowsheet Convergence
Objective: Introduce the idea of convergence blocks, tear streams and flowsheet sequences Aspen Plus References User Guide, Chapter 17, Convergence

214 Introduction to Aspen Plus v10.2
Course Notes Convergence Blocks Every design specification and tear stream has an associated convergence block. Convergence blocks determine how guesses for a tear stream or design specification manipulated variable are updated from iteration to iteration. Aspen Plus-defined convergence block names begin with the character “$.” User defined convergence block names must not begin with the character “$.” To determine the convergence blocks defined by Aspen Plus, look under the “Flowsheet Analysis” section in the Control Panel messages. User convergence blocks can be specified under /Data/Convergence/Convergence... . Introduction to Aspen Plus August 28th,2000

215 Convergence Block Types
Introduction to Aspen Plus v10.2 Course Notes Convergence Block Types Different types of convergence blocks are used for different purposes: To converge tear streams: WEGSTEIN DIRECT BROYDEN NEWTON To converge design specifications: SECANT To converge design specifications and tear streams: For optimization: SQP COMPLEX Global convergence options can be specified on the Convergence ConvOptions Defaults form. Introduction to Aspen Plus August 28th,2000

216 Introduction to Aspen Plus v10.2
Course Notes Flowsheet Sequence To determine the flowsheet sequence calculated by Aspen Plus, look under the “COMPUTATION ORDER FOR THE FLOWSHEET” section in the Control Panel, or on the left-hand pane of the Control Panel window. User-determined sequences can be specified on the Convergence Sequence form. User-specified sequences can be either full or partial. Introduction to Aspen Plus August 28th,2000

217 Introduction to Aspen Plus v10.2
Course Notes Tear Streams Which are the recycle streams? Which are the possible tear streams? A tear stream is one for which Aspen Plus makes an initial guess, and iteratively updates the guess until two consecutive guesses are within a specified tolerance. Tear streams are related to, but not the same as recycle streams. S7 B1 B2 B3 B4 S1 S2 S3 S4 S5 MIXER MIXER FSPLIT FSPLIT S6 - The best tear stream choice is stream S3. If this stream is used, you only need one tear stream instead of two. Introduction to Aspen Plus August 28th,2000

218 Tear Streams (Continued)
Introduction to Aspen Plus v10.2 Course Notes Tear Streams (Continued) To determine the tear streams chosen by Aspen Plus, look under the “Flowsheet Analysis” section in the Control Panel. User-determined tear streams can be specified on the Convergence Tear form. Providing estimates for tear streams can facilitate or speed up flowsheet convergence (highly recommended, otherwise the default is zero). If you enter information for a stream that is in a “loop,” Aspen Plus will automatically try to choose that stream to be a tear stream. - If you enter initial estimates for an internal process stream, Aspen Plus will preferentially choose that stream (if it can) over other possible tear streams with no initial estimates. This feature is illustrated in the workshop. Introduction to Aspen Plus August 28th,2000

219 Reconciling Streams Simulation results for a stream can be copied onto the its input form. Select a stream on the flowsheet, click the right mouse button and select “Reconcile” from the list to copy stream results to the input form. Two state variables must be selected for the stream flash calculation. Component flows, or component fractions and total flow can be copied. Mole, mass, or standard liquid volume basis can be selected. Introduction to Aspen Plus

220 Introduction to Aspen Plus v10.2
Course Notes Convergence Workshop Objective Converge this flowsheet. Start with the file CONVERGE.BKP. 100 lbmol/hr T=70 F COLUMN T=165 F P=35 psia P=15 psia 50 lbmol/hr Ethylene Glycol FEED GLYCOL XH = 0.4 DIST XMethanol = 0.3 PREHEATR Theoretical Stages = 10 XEthanol = 0.3 Reflux Ratio = 5 BOT-COOL Distillate to Feed Ratio = 0.2 Column Pressure = 1 atm Area = 65 sqft VAPOR Feed Stage = 5 PREFLASH Total Condenser FEED-HT DP=0 Q=0 LIQ BOT When finished, save as filename: CONV-R.BKP Use NRTL-RK Property Method Introduction to Aspen Plus August 28th,2000

221 Convergence Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes Convergence Workshop (Continued) Hints for Convergence Workshop Questions to ask yourself: What messages are displayed in the control panel? Why do some of the blocks show zero flow? What is the Aspen Plus-generated execution sequence for the flowsheet? Which stream does Aspen Plus choose as a tear stream? What are other possible tear streams? Recommendation Give initial estimates for a tear stream. Of the three possible tear streams you could choose, which do you know the most about? (Note: If you enter information for a stream that is in a “loop,” Aspen Plus will automatically choose that stream to be a tear stream and set up a convergence block for it.) Introduction to Aspen Plus August 28th,2000

222 Convergence Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes Convergence Workshop (Continued) Questions to ask yourself: Does the flowsheet converge after entering initial estimates for the tear stream? If not, why not? (see control panel) How is the err/tol value behaving, and what is its value at the end of the run? Does it appear that increasing the number of convergence iterations will help? What else can be tried to improve this convergence? Recommendation Try a different convergence algorithm (e.g. Direct, Broyden, or Newton). Note: You can either manually create a convergence block to converge the tear stream of your choice, or you can change the default convergence method for all tear streams on the Convergence Conv Options Defaults Default Methods sheet. Introduction to Aspen Plus August 28th,2000

223 Full-Scale Plant Modeling Workshop
Objective: Practice and apply many of the techniques used in this course and learn how to best approach modeling projects Introduction to Aspen Plus

224 Full-Scale Plant Modeling Workshop
Introduction to Aspen Plus v10.2 Course Notes Full-Scale Plant Modeling Workshop Objective: Model a methanol plant. The process being modeled is a methanol plant. The basic feed streams to the plant are Natural Gas, Carbon Dioxide (assumed to be taken from a nearby Ammonia Plant) and Water. The aim is to achieve the methanol production rate of approximately 62,000 kg/hr, at a purity of at least % wt. This is a large flowsheet that would take an experienced engineer more than an afternoon to complete. Start building the flowsheet and think about how you would work to complete the project. It is important to set expectations. This is a big workshop. The students are only expected to complete one or maybe two sections. They can think about the other sections. Let the students feel free to simplify any way that they want to get things running. Introduction to Aspen Plus August 28th,2000

225 Introduction to Aspen Plus v10.2
Course Notes General Guidelines Build the flowsheet one section at a time. Simplify whenever possible. Complexity can always be added later. Investigate the physical properties. Use Analysis. Check if binary parameters are available. Check for two liquid phases. Use an appropriate equation of state for the portions of the flowsheet involving gases and use an activity coefficient model for the sections where non-ideal liquids may be present. Introduction to Aspen Plus August 28th,2000

226 Full-Scale Plant Modeling Workshop
Introduction to Aspen Plus v10.2 Course Notes Full-Scale Plant Modeling Workshop FURNACE Fuel Air MEOHRXR SPLIT1 MIX2 E121 COOL4 FL3 SYNCOMP FL1 FL2 COOL1 COOL3 COOL2 BOILER E122 CIRC E124 E223 FL4 SPLIT2 FL5 M4 MKWATER TOPPING REFINING M2 SATURATE FEEDHTR REFORMER NATGAS H2OCIRC MKUPST CH4COMP CO2 CO2COMP M1 Introduction to Aspen Plus August 28th,2000

227 Part 1: Front-End Section
Introduction to Aspen Plus v10.2 Course Notes Part 1: Front-End Section From Furnace FEEDHTR MKUPST M2 To BOILER REFORMER H2OCIRC CO2COMP CO2 M1 SATURATE NATGAS CH4COMP Introduction to Aspen Plus August 28th,2000

228 Part 1: Front-End Section (Continued)
Introduction to Aspen Plus v10.2 Course Notes Part 1: Front-End Section (Continued) Carbon Dioxide Stream – CO2 Temperature = 43 C Pressure = 1.4 bar Flow = kg/hr Mole Fraction CO H H2O CH N Natural Gas Stream - NATGAS Temperature = 26 C Pressure = 21.7 bar Flow = kg/hr CO CH N C2H C3H Circulation Water - H2OCIRC Pure water stream Flow = kg/hr Temperature = 195 C Pressure = 26 bar Makeup Steam - MKUPST Stream of pure steam Flow = kg/hr Vapor Fraction = 1 Adjust the makeup steam flow to achieve a desired steam to methane molar ratio of 2.8 in the Reformer feed REFFEED. The makeup steam specification can be accomplished using a Fortran block. The air specification will need a design spec. Introduction to Aspen Plus August 28th,2000

229 Part 1: Front-End Section (Continued)
Introduction to Aspen Plus v10.2 Course Notes Part 1: Front-End Section (Continued) Carbon Dioxide Compressor - CO2COMP Discharge Pressure = 27.5 bar Compressor Type = 2 stage Natural Gas Compressor - CH4COMP Compressor Type = single stage Reformer Process Side Feed Stream Pre-Heater - FEEDHTR Exit Temperature = 560 C Pressure drop = 0 Saturation Column - SATURATE 1.5 inch metal pall ring packing. Estimated HETP = 10 x 1.5 inches = 381 mm Height of Packing = 15 meters No condenser and no reboiler. Reformer Reactor - REFORMER Consists of two parts: the Furnace portion and the Steam Reforming portion Exit Temperature of the Steam Reforming portion = 860 C Pressure = 18 bar The reformer is a RGibbs block. Introduction to Aspen Plus August 28th,2000

230 Part 1: Front-End Section Check
Introduction to Aspen Plus v10.2 Course Notes Part 1: Front-End Section Check Introduction to Aspen Plus August 28th,2000

231 Part 2: Heat Recovery Section
Introduction to Aspen Plus v10.2 Course Notes Part 2: Heat Recovery Section COOL4 FL3 SYNCOMP FL1 FL2 COOL1 COOL3 COOL2 BOILER To TOPPING To REFINING To Methanol Loop From Reformer Introduction to Aspen Plus August 28th,2000

232 Part 2: Heat Recovery Section (Continued)
Introduction to Aspen Plus v10.2 Course Notes Part 2: Heat Recovery Section (Continued) This section consists of a series of heat exchangers and flash vessels used to recover the available energy and water in the Reformed Gas stream. BOILER Exit temperature = 166 C Exit Pressure = 18 bar COOL1 Exit temperature = 136 C COOL2 Exit temperature = 104 C Exit Pressure = 17.9 bar COOL3 Exit temperature = 85 C Pressure Drop = 0.1 bar COOL4 Exit temperature = 40 C Exit Pressure = 17.6 bar FL1 Pressure Drop = 0 bar Heat Duty = 0 MMkcal/hr FL2 Exit Pressure = 17.7 bar FL3 Exit Pressure = 17.4 bar SYNCOM Two Stage Polytropic compressor Discharge Pressure = 82.5 bar Intercooler Exit Temperature = 40 C Introduction to Aspen Plus August 28th,2000

233 Part 2: Heat Recovery Section Check
Introduction to Aspen Plus v10.2 Course Notes Part 2: Heat Recovery Section Check Introduction to Aspen Plus August 28th,2000

234 Part 3: Methanol Synthesis Section
Introduction to Aspen Plus v10.2 Course Notes Part 3: Methanol Synthesis Section MEOHRXR SPLIT1 MIX2 E121 From SYNCOMP E122 CIRC E124 E223 FL4 SPLIT2 To Furnace To FL5 Introduction to Aspen Plus August 28th,2000

235 Part 3: Methanol Synthesis Section (Continued)
Introduction to Aspen Plus v10.2 Course Notes Part 3: Methanol Synthesis Section (Continued) Methanol Reactor - MEOHRXR Tube cooled reactor Exit Temperature from the tubes = 240 C No pressure drop across the reactor Reactions CO + H2O <-> CO2 + H2 (Equilibrium) CO2 + 3H2 <-> CH3OH + H2O (+15 C Temperature Approach) 2CH3OH <-> DIMETHYLETHER + H2O (Molar extent 0.2kmol/hr) 4CO + 8H2 <-> N-BUTANOL + 3H2O (Molar extent 0.8kmol/hr) 3CO + 5H2 <-> ACETONE + 2H2O (Molar extent 0.3kmol/hr) E121 Exit Temperature C Exit Pressure - 81 bar E122 Cold Side Exit Temperature C E223 Exit Temperature - 60 C Exit Pressure bar E124 Exit Temperature - 45 C Exit Pressure bar FL4 Exit Pressure = 75.6 bar Heat Duty = 0 MMkcal/hr CIRC Single stage compressor Discharge Pressure = 83 bar Discharge Temperature = 55 C SPLIT1 Split Fraction = 0.8 to stream to E121 SPLIT2 Stream PURGE = 9000 kg/hr Stream RECYCLE = kg/hr The split in SPLIT2 is a flowrate. It may be easier to start with a split fraction to get something running. Using the split flowrate may not work if the feed to the section is not accurate. To improve convergence it may be necessary to use Broyden to converge the tear streams Introduction to Aspen Plus August 28th,2000

236 Part 3: Methanol Synthesis Section Check
Introduction to Aspen Plus v10.2 Course Notes Part 3: Methanol Synthesis Section Check The split in SPLIT2 is a flowrate. It may be easier to start with a split fraction to get something running. Using the split flowrate may not work if the feed to the section is not accurate. The methanol reactor is a REquil. Introduction to Aspen Plus August 28th,2000

237 Part 4: Distillation Section
Introduction to Aspen Plus v10.2 Course Notes Part 4: Distillation Section FL5 M4 MKWATER TOPPING REFINING From COOL2 To Furnace From COOL1 From FL4 Topping column: Data Blocks TOPPING Output TOP_TEMP C Data Blocks TOPPING Output BOTTOM_TEMP C Data Blocks TOPPING Output COND_DUTY MMkcal/hr Data Blocks TOPPING Output REB_DUTY MMkcal/hr Data Blocks TOPPING Output TOP_LFLOW kmol/hr Data Blocks TOPPING Output BOT_LFLOW kmol/hr Data Blocks TOPPING Output TOP_VFLOW kmol/hr Data Blocks TOPPING Output BOT_VFLOW kmol/hr Data Blocks TOPPING Output RR Data Blocks TOPPING Output BU_RATIO Refining column: Data Blocks REFINING Output TOP_TEMP C Data Blocks REFINING Output BOTTOM_TEMP C Data Blocks REFINING Output COND_DUTY MMkcal/hr Data Blocks REFINING Output REB_DUTY MMkcal/hr Data Blocks REFINING Output TOP_LFLOW kmol/hr Data Blocks REFINING Output BOT_LFLOW kmol/hr Data Blocks REFINING Output TOP_VFLOW 0 kmol/hr Data Blocks REFINING Output BOT_VFLOW kmol/hr Data Blocks REFINING Output RR Data Blocks REFINING Output BU_RATIO Introduction to Aspen Plus August 28th,2000

238 Part 4: Distillation Section (Continued)
Introduction to Aspen Plus v10.2 Course Notes Part 4: Distillation Section (Continued) Makeup Steam - MKWATER Stream of pure water Flow = kg/hr Pressure = 5 bar Temperature = 40 C Adjust the make-up water flow (stream MKWATER) to the CRUDE stream to achieve a stream composition of 23 wt.% of water in the stream feeding the Topping column (stream TOPFEED) to achieve 100 ppm methanol in the Refining column BTMS stream. Topping Column - TOPPING Number of Stages = 51 (including condenser and reboiler) Condenser Type = Partial Vapor/Liquid Feed stage = 14 Distillate has both liquid and vapor streams Distillate rate = 1400 kg/hr Pressure profile: stage 1 = 1.5 bar and stage 51 = 1.8 bar Distillate vapor fraction = 99 mol% Stage 2 heat duty = -7 Mmkcal/hr Stage 51 heat duty Specified by the heat stream Reboiler heat duty is provided via a heat stream from block COOL2 Boil-up Ratio is approximately 0.52 Valve trays The column has two condensers. To represent the liquid flow connections a pumparound can be used between stage 1 and 3. Topping column: Data Streams QTOP Output QCALC MMkcal/hr Refining column: Data Streams QREB Output QCALC MMkcal/hr Introduction to Aspen Plus August 28th,2000

239 Part 4: Distillation Section (Continued)
Introduction to Aspen Plus v10.2 Course Notes Part 4: Distillation Section (Continued) Refining Column - REFINING Number of Stages = 95 (including condenser and reboiler) Condenser Type = Total Distillate Rate = 1 kg/hr Feed stage = 60 Liquid Product sidedraw from Stage kg/hr (Stream name – PRODUCT) Liquid Product sidedraw from Stage 550 kg/hr (Stream name – FUSELOIL) Reflux rate = kg/hr Pressure profile: stage 1= 1.5bar and stage 95=2bar Reboiler heat duty is provided via a conventional reboiler supplemented by a heat stream from a heater block to stage 95 Boil-up Ratio is approximately 4.8 Valve trays To meet environmental regulations, the bottoms stream must contain no more than 100ppm by weight of methanol as this stream is to be dumped to a nearby river. FL5 Exit Pressure 5 bar Heat Duty 0 MMkcal/hr M4 For water addition to the crude methanol The Refining column specifications can be done with a spec-vary in the RadFrac block. Introduction to Aspen Plus August 28th,2000

240 Part 4: Distillation Section Check
Introduction to Aspen Plus v10.2 Course Notes Part 4: Distillation Section Check The Refining column specifications can be done with a spec-vary in the RadFrac block. Introduction to Aspen Plus August 28th,2000

241 Introduction to Aspen Plus v10.2
Course Notes Part 5: Furnace Section FURNACE Fuel Air From FL5 From SPLIT2 To REFORMER Introduction to Aspen Plus August 28th,2000

242 Part 5: Furnace Section (Continued)
Introduction to Aspen Plus v10.2 Course Notes Part 5: Furnace Section (Continued) Air to Furnace - AIR Temperature = 366 C Pressure = 1 atm Flow = kg/hr Adjust the air flow to achieve 2%(vol.) of oxygen in the FLUEGAS stream. Fuel to Furnace - FUEL Flow = 9436 kg/hr Conditions and composition are the same as for the natural gas stream The makeup steam specification can be accomplished using a Fortran block. The air specification will need a design spec. Introduction to Aspen Plus August 28th,2000

243 Maintaining Aspen Plus Simulations
Objective: Introduce how to store simulations and retrieve them from your computer environment Aspen Plus References: User Guide, Chapter 15, Managing Your Files

244 File Formats in Aspen Plus
Introduction to Aspen Plus v10.2 Course Notes File Formats in Aspen Plus . Introduction to Aspen Plus August 28th,2000

245 File Type Characteristics
Introduction to Aspen Plus v10.2 Course Notes File Type Characteristics Binary files Operating system and version specific Not readable, not printable ASCII files Transferable between operating systems Upwardly compatible Contain no control characters, “readable” Not intended to be printed Text files Readable, can be edited Intended to be printed Introduction to Aspen Plus August 28th,2000

246 How to Store a Simulation
Introduction to Aspen Plus v10.2 Course Notes How to Store a Simulation Three ways to store simulations: Document Backup Input (*.apw) (*.bkp) (*.inp) Simulation definition Yes Yes Yes Convergence info Yes No No Results Yes Yes No Flowsheet Graphics Yes Yes Yes/No User readable No No Yes Open/save speed High Low Lowest Space requirements High Low Lowest JLM - Whenever possible, I recommend we use this type of format rather than the OLE tables. Much easier to make changes to. Introduction to Aspen Plus August 28th,2000

247 Introduction to Aspen Plus v10.2
Course Notes Template Files Template files are used to set your personal preferences: Units of measurement Property sets for stream reports Composition basis Stream report format Global flow basis for input specifications Setting Free-Water option Selection for Stream-Class Property Method (Required) Component list Other application-specific defaults ANYTHING you can save in a backup file can be stored as a template. Introduction to Aspen Plus August 28th,2000

248 How to Create a Personal Template
Any flowsheet (complete or incomplete) can be saved as a template file. In order to have a personal template appear on the Personal sheet of the New dialog box, put the template file into the Aspen Plus GUI\Templates\Personal folder. The text on the Setup Specifications Description sheet will appear in the Preview window when the template file is selected in the New dialog box. Introduction to Aspen Plus

249 Maintaining Your Computer
Aspen Plus 10 runs best on a healthy computer. Minimum RAM Having more is better -- if near minimum, avoid running too many other programs along with Aspen Plus. Active links increase needed RAM. Introduction to Aspen Plus

250 Maintaining Your Hard Disk
Keep plenty of free space on disk used for: Your Aspen working directory Windows swap files Delete unneeded files: Old .appdf, .his, etc. Aspen document files (*.apw) that aren’t active Aspen temporary files (_4404ydj.appdf, for example) Defragment regularly (once a week), even if Windows says you don’t need to -- make the free space contiguous. Introduction to Aspen Plus

251 Customizing the Look of Your Flowsheet
Introduction to Aspen Plus v10.2 Course Notes Customizing the Look of Your Flowsheet Objective: Introduce several ways of annotating your flowsheet to create informative Process Flow Diagrams JLM - Should add some instructor notes here to aid in interpretation of the plot. Aspen Plus References: User Guide, Chapter 14, Annotating Process Flowsheets Related Topics: User Guide, Chapter 37, Working with Other Windows Programs August 28th,2000

252 Customizing the Process Flow Diagram
Introduction to Aspen Plus v10.2 Course Notes Customizing the Process Flow Diagram Add annotations Text Graphics Tables Add OLE objects Add a titlebox Add plots or diagrams Display global data Stream flowrate, pressure and temperature Heat stream duty Work stream power Block duty and power Use PFD mode Change flowsheet connectivity Introduction to Aspen Plus August 28th,2000

253 Introduction to Aspen Plus v10.2
Course Notes Viewing Use the View menu to select the elements that you wish to view: PFD Mode Global Data Annotation OLE Objects All of the elements can be turned on and off independently. Introduction to Aspen Plus August 28th,2000

254 Introduction to Aspen Plus v10.2
Course Notes Adding Annotation Use the Draw Toolbar to add text and graphics. (Select Toolbar… from the View menu to select the Draw Toolbar if it is not visible.) To create a stream table, click on the Stream Table button on the Results Summary Streams Material sheet. Annotation objects can be attached to flowsheet elements such as streams or blocks. Should give a couple of quick demos during the discussion outlined on this slide. Introduction to Aspen Plus August 28th,2000

255 Example of a Stream Table
Introduction to Aspen Plus v10.2 Course Notes Example of a Stream Table JLM - Table lines are too thick, obstructing some of the text. Introduction to Aspen Plus August 28th,2000

256 Introduction to Aspen Plus v10.2
Course Notes Adding Global Data On the Results View sheet when selecting Options from the Tools menu, choose the block and stream results that you want displayed as Global Data. Check Global Data on the View menu to display the data on the flowsheet. REACTOR Q=0 220 36 4808 FEED 130 15 106 RECYCLE 855 4914 REAC-OUT COOL Q= COOL-OUT SEP PRODUCT Temperature (F) Pressure (psi) Flow Rate (lb/hr) Q Duty (Btu/hr) Introduction to Aspen Plus August 28th,2000

257 Introduction to Aspen Plus v10.2
Course Notes Using PFD Mode In this mode, you can add or delete unit operation icons to the flowsheet for graphical purposes only. Using PFD mode means that you can change flowsheet connectivity to match that of your plant. PFD-style drawing is completely separate from the graphical simulation flowsheet. You must return to simulation mode if you want to make a change to the actual simulation flowsheet. PFD Mode is indicated by the Aqua border around the flowsheet. JLM - Should also mention how to Re-sync (or Reset) the PFD diagram with the true simulation diagram. Introduction to Aspen Plus August 28th,2000

258 Examples of When to Use PFD Mode
Introduction to Aspen Plus v10.2 Course Notes Examples of When to Use PFD Mode In the simulation flowsheet, it may be necessary to use more than one unit operation block to model a single piece of equipment in a plant. For example, a reactor with a liquid product and a vent may need to be modeled using an RStoic reactor and a Flash2 block. In the report, only one unit operation icon is needed to represent the unit in the plant. On the other hand, some pieces of equipment may not need to be explicitly modeled in the simulation flowsheet. For example, pumps are frequently not modeled in the simulation flowsheet; the pressure change can be neglected or included in another unit operation block. Should probably ask the students not to follow along, to make the demonstration go quicker. Introduction to Aspen Plus August 28th,2000

259 Introduction to Aspen Plus v10.2
Course Notes Annotation Workshop Objective: Use annotation to create a process flow diagram for the cyclohexane flowsheet Part A Using the cyclohexane production Workshop (saved as CYCLOHEX.BKP), display all stream and block global data. Part B Add a title to the flowsheet diagram. Part C Add a stream table to the flowsheet diagram. Part D Using PFD Mode, add a pump for the BZIN stream for graphical purposes only. Introduction to Aspen Plus August 28th,2000

260 Estimation of Physical Properties
Introduction to Aspen Plus v10.2 Course Notes Estimation of Physical Properties Objective: Provide an overview of estimating physical property parameters in Aspen Plus Aspen Plus References: User Guide, Chapter 30, Estimating Property Parameters Physical Property Methods and Models Reference Manual, Chapter 8, Property Parameter Estimation August 28th,2000

261 What is Property Estimation?
Introduction to Aspen Plus v10.2 Course Notes What is Property Estimation? Property Estimation is a system to estimate parameters required by physical property models. It can be used to estimate: Pure component physical property constants Parameters for temperature-dependent models Binary interaction parameters for Wilson, NRTL and UNIQUAC Group parameters for UNIFAC Estimations are based on group-contribution methods and corresponding-states correlations. Experimental data can be incorporated into estimation. Introduction to Aspen Plus August 28th,2000

262 Using Property Estimation
Introduction to Aspen Plus v10.2 Course Notes Using Property Estimation Property Estimation can be used in two ways: On a stand-alone basis: Property Estimation Run Type Within another Run Type: Flowsheet, Property Analysis, Data Regression, PROPERTIES PLUS or Assay Data Analysis You can use Property Estimation to estimate properties for both databank and non-databank components. Property Estimation information is accessed in the Properties Estimation folder. - The best tear stream choice is stream S3. If this stream is used, you only need one tear stream instead of two. Introduction to Aspen Plus August 28th,2000

263 Estimation Methods and Requirements
Introduction to Aspen Plus v10.2 Course Notes Estimation Methods and Requirements User Guide, Chapter 30, Estimating Property Parameters, has a complete list of properties that can be estimated, as well as the available estimation methods and their respective requirements. This same information is also available under the on-line help in the estimation forms. - If you enter initial estimates for an internal process stream, Aspen Plus will preferentially choose that stream (if it can) over other possible tear streams with no initial estimates. This feature is illustrated in the workshop. Introduction to Aspen Plus August 28th,2000

264 Steps For Using Property Estimation
Introduction to Aspen Plus v10.2 Course Notes Steps For Using Property Estimation 1. Define molecular structure on the Properties Molecular Structure form. 2. Enter any experimental data using Parameters or Data forms. Experimental data such as normal boiling point (TB) is very important for many estimation methods. It should be entered whenever possible. 3. Activate Property Estimation and choose property estimation options on the Properties Estimation Input form. Introduction to Aspen Plus August 28th,2000

265 Defining Molecular Structure
Introduction to Aspen Plus v10.2 Course Notes Defining Molecular Structure Molecular structure is required for all group-contribution methods used in Property Estimation. You can: Define molecular structure in the general format and allow Aspen Plus to determine functional groups, or Define molecular structure in terms of functional groups for particular methods Reference: For a list of available group-contribution method functional groups, see Aspen Plus Physical Property Data Reference Manual, Chapter 3, Group Contribution Method Functional Groups. Introduction to Aspen Plus August 28th,2000

266 Steps For Defining General Structure
Introduction to Aspen Plus v10.2 Course Notes Steps For Defining General Structure 1. Sketch the structure of the molecule on paper. 2. Assign a number to each atom, omitting hydrogen. (The numbers must be consecutive starting with 1.) 3. Go to the Properties Molecular Structure Object Manager, choose the component, and select Edit. 4. On the Molecular Structure General sheet, define the molecule by its connectivity. Describe two atoms at a time: Specify the types of atoms (C, O, S, …) Specify the type of bond that connects the two atoms (single, double, …) Note: If the molecule is a non-databank component, on the Components Specifications form, enter a Component ID, but do not enter a Component name or Formula. Introduction to Aspen Plus August 28th,2000

267 Example of Defining Molecular Structure
Introduction to Aspen Plus v10.2 Course Notes Example of Defining Molecular Structure Example of defining molecular structure for isobutyl alcohol using the general method Sketch the structure of the molecule, and assign a number to each atom, omitting hydrogen. C2 C1 C4 C3 O5 Introduction to Aspen Plus August 28th,2000

268 Example of Defining Molecular Structure
Introduction to Aspen Plus v10.2 Course Notes Example of Defining Molecular Structure Go to the Properties Molecular Structure Object Manager, choose the component, and select Edit. On Properties Molecular Structure General sheet, describe molecule by its connectivity, two atoms at a time. JLM - Screen shot needs to be updated. Introduction to Aspen Plus August 28th,2000

269 Introduction to Aspen Plus v10.2
Course Notes Atom Types Current available atom types: Atom Type Description Atom Type Description C Carbon P Phosphorous O Oxygen Zn Zinc N Nitrogen Ga Gallium S Sulfur Ge Germanium B Boron As Arsenic Si Silicon Cd Cadmium F Fluorine Sn Tin CL Chlorine Sb Antimony Br Bromine Hg Mercury I Iodine Pb Lead Al Aluminum Bi Bismuth Introduction to Aspen Plus August 28th,2000

270 Introduction to Aspen Plus v10.2
Course Notes Bond Types Current available bond types: Single bond Double bond Triple bond Benzene ring Saturated 5-membered ring Saturated 6-membered ring Saturated 7-membered ring Saturated hydrocarbon chain Note: You must assign consecutive atom numbers to Benzene ring, Saturated 5-membered ring, Saturated 6-membered ring, Saturated 7-membered ring, and Saturated hydrocarbon chain bonds. Introduction to Aspen Plus August 28th,2000

271 Steps For Using Property Estimation
Introduction to Aspen Plus v10.2 Course Notes Steps For Using Property Estimation 1. Define molecular structure on the Properties Molecular Structure form. 2. Enter any experimental data using Parameters or Data forms. Experimental data such as normal boiling point (TB) is very important for many estimation methods. It should be entered whenever possible. 3. Activate Property Estimation and choose property estimation options on the Properties Estimation Input form. Introduction to Aspen Plus August 28th,2000

272 Example of Entering Additional Data
Introduction to Aspen Plus v10.2 Course Notes Example of Entering Additional Data Enter following data for isobutyl alcohol into the simulation to improve the estimated values. Normal boiling point (TB) = C Critical temperature (TC) = C Critical pressure (PC) = 43 bar Introduction to Aspen Plus August 28th,2000

273 Example of Entering Additional Data
Introduction to Aspen Plus v10.2 Course Notes Example of Entering Additional Data Go to the Properties Parameters Pure Component Object Manager and create a new Scalar parameter form. Enter the parameters, the components, and the values. Introduction to Aspen Plus August 28th,2000

274 Steps For Using Property Estimation
Introduction to Aspen Plus v10.2 Course Notes Steps For Using Property Estimation 1. Define molecular structure on the Properties Molecular Structure form. 2. Enter any experimental data using Parameters or Data forms. Experimental data such as normal boiling point (TB) is very important for many estimation methods. It should be entered whenever possible. 3. Activate Property Estimation and choose property estimation options on the Properties Estimation Input form. Introduction to Aspen Plus August 28th,2000

275 Activating Property Estimation
Introduction to Aspen Plus v10.2 Course Notes Activating Property Estimation To turn on Property Estimation, go to the Properties Estimation Input Setup sheet, and select one of the following: Estimate all missing parameters Estimates all missing required parameters and any parameters you may request in the optional Pure Component, T-Dependent, Binary, and UNIFAC-Group sheets Estimate only the selected parameters Estimates on the parameter types you select on this sheet (and then specify on the appropriate additional sheets) Introduction to Aspen Plus August 28th,2000

276 Property Estimation Notes
Introduction to Aspen Plus v10.2 Course Notes Property Estimation Notes You can save your property data specifications, structures, and estimates as backup files, and import them into other simulations (Flowsheet, Data Regression, Property Analysis, or Assay Data Analysis Run-Types.) You can change the Run type on the Setup Specifications Global sheet to continue the simulation in the same file. If you want to change the Run type back to Property Estimation from another Run type, no flowsheet information is lost even though it may not be visible in the Property Estimation mode. Introduction to Aspen Plus August 28th,2000

277 Property Estimation Workshop
Introduction to Aspen Plus v10.2 Course Notes Property Estimation Workshop Objective: Estimate the properties of a dimer, ethycellosolve. Ethylcellosolve is not in any of the Aspen Plus databanks. Use a Run Type of Property Estimation, and estimate the properties for the new component. The formula for the component is shown below, along with the normal boiling point obtained from literature. Formula: CH3 - CH2 - O - CH2 - CH2 - O - CH2 - CH2 - OH TB = 195 C When finished, save as filename: PCES.BKP Introduction to Aspen Plus August 28th,2000

278 Property Estimation Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes Property Estimation Workshop (Continued) 1. Use a Run Type of Property Estimation and enter the structure and data for the Dimer. 2. Run the estimation, and examine the results. Note that the results of the estimation are automatically written to parameters forms, for use in other simulations. 3. Change the Run Type back to Flowsheet. 4. Go to the Properties Estimation Input Setup sheet, and choose Do not estimate any parameters. 5. Optionally, add a flowsheet and use this component. Open a new run, and change the Run Type on the Setup Specifications Global sheet to Property Estimation. Enter a new non-databank component as Component ID DIMER, on the Components Specifications Selection sheet. On the Properties Molecular Structure Object Manager, select DIMER and click Edit. On the General sheet, enter the structure. Go to the Properties Parameters Pure Component Object Manager and create a scalar parameter form. Enter the normal boiling point (TB) of DIMER as 195 C. Run the estimation, and examine the results. Note that the results of the estimation are automatically written to parameters forms, for use in other simulations. Change the Run Type back to Flowsheet on the Setup Specifications Global sheet. Go to the Properties Estimation Input Setup sheet, and choose Do not estimate any parameters. Now, it is possible to add a flowsheet and use this component. Save this file as PCES.BKP. Introduction to Aspen Plus August 28th,2000

279 Introduction to Aspen Plus v10.2
Course Notes Electrolytes Objective: Introduce the electrolyte capabilities in Aspen Plus Aspen Plus References: User Guide, Chapter 6, Specifying Components Physical Property Methods and Models Reference Manual, Chapter 5, Electrolyte Simulation August 28th,2000

280 Electrolytes Examples
Introduction to Aspen Plus v10.2 Course Notes Electrolytes Examples Solutions with acids, bases or salts Sour water solutions Aqueous amines or hot carbonate for gas sweetening Introduction to Aspen Plus August 28th,2000

281 Characteristics of an Electrolyte System
Introduction to Aspen Plus v10.2 Course Notes Characteristics of an Electrolyte System Some molecular species dissociate partially or completely into ions in a liquid solvent Liquid phase reactions are always at chemical equilibrium Presence of ions in the liquid phase requires non-ideal solution thermodynamics Possible salt precipitation Introduction to Aspen Plus August 28th,2000

282 Introduction to Aspen Plus v10.2
Course Notes Types of Components Solvents - Standard molecular species Water Methanol Acetic Acid Soluble Gases - Henry’s Law components Nitrogen Oxygen Carbon Dioxide Introduction to Aspen Plus August 28th,2000

283 Types of Components (Continued)
Introduction to Aspen Plus v10.2 Course Notes Types of Components (Continued) Ions - Species with a charge H3O+ OH- Na+ Cl- Fe(CN)63- Salts - Each precipitated salt is a new pure component. NaCl(s) CaCO3(s) CaSO4•2H2O (gypsum) Na2CO3•NaHCO3 •2H2O (trona) Introduction to Aspen Plus August 28th,2000

284 Apparent and True Components
Introduction to Aspen Plus v10.2 Course Notes Apparent and True Components True component approach Result reported in terms of the ions, salts and molecular species present after considering solution chemistry Apparent component approach Results reported in terms of base components present before considering solution chemistry Ions and precipitated salts cannot be apparent components Specifications must be made in terms of apparent components and not in terms of ions or solid salts Results are equivalent. Introduction to Aspen Plus August 28th,2000

285 Apparent and True Components Example
Introduction to Aspen Plus v10.2 Course Notes Apparent and True Components Example NaCl in water Solution chemistry NaCl --> Na+ + Cl- Na+ + Cl- <--> NaCl(s) Apparent components H2O, NaCl True components: H2O, Na+, Cl-, NaCl(s) Introduction to Aspen Plus August 28th,2000

286 Introduction to Aspen Plus v10.2
Course Notes Electrolyte Wizard Generates new components (ions and solid salts) Revises the Pure component databank search order so that the first databank searched is now ASPENPCD. Generates reactions among components Sets the Property method to ELECNRTL Creates a Henry’s Component list Retrieves parameters for Reaction equilibrium constant values Salt solubility parameters ELECNRTL interaction parameters Henry’s constant correlation parameters Introduction to Aspen Plus August 28th,2000

287 Electrolyte Wizard (Continued)
Introduction to Aspen Plus v10.2 Course Notes Electrolyte Wizard (Continued) Generated chemistry can be modified. Simplifying the Chemistry can make the simulation more robust and decrease execution time. Note: It is the user’s responsibility to ensure that the Chemistry is representative of the actual chemical system. Introduction to Aspen Plus August 28th,2000

288 Simplifying the Chemistry
Introduction to Aspen Plus v10.2 Course Notes Simplifying the Chemistry Typical modifications include: Adding to the list of Henry’s components Eliminating irrelevant salt precipitation reactions Eliminating irrelevant species Adding species and/or reactions that are not in the electrolytes expert system database Eliminating irrelevant equilibrium reactions Introduction to Aspen Plus August 28th,2000

289 Limitations of Electrolytes
Introduction to Aspen Plus v10.2 Course Notes Limitations of Electrolytes Restrictions using the True component approach: Liquid-liquid equilibrium cannot be calculated. The following models may not be used: Equilibrium reactors: RGibbs and REquil Kinetic reactors: RPlug, RCSTR, and RBatch Shortcut distillation: Distl, DSTWU and SCFrac Rigorous distillation: MultiFrac and PetroFrac Introduction to Aspen Plus August 28th,2000

290 Limitations of Electrolytes (Continued)
Introduction to Aspen Plus v10.2 Course Notes Limitations of Electrolytes (Continued) Restrictions using the Apparent component approach: Chemistry may not contain any volatile species on the right side of the reactions. Chemistry for liquid-liquid equilibrium may not contain dissociation reactions. Input specification cannot be in terms of ions or solid salts. Introduction to Aspen Plus August 28th,2000

291 Electrolyte Demonstration
Introduction to Aspen Plus v10.2 Course Notes Electrolyte Demonstration Objective: Create a flowsheet using electrolytes. Create a simple flowsheet to mix and flash two feed streams containing aqueous electrolytes. Use the Electrolyte Wizard to generate the Chemistry. Temp = 25 C Pres = 1 bar 10 kmol/hr H2O 1 kmol/hr HCl Filename: ELEC1.BKP HCL VAPOR MIX FLASH NAOH MIXED Isobaric Molar vapor fraction = 0.75 Temp = 25 C Pres = 1 bar 10 kmol/hr H2O 1.1 kmol/hr NaOH MIXER FLASH2 P-drop = 0 Adiabatic LIQUID Introduction to Aspen Plus August 28th,2000

292 Steps for Using Electrolytes
Introduction to Aspen Plus v10.2 Course Notes Steps for Using Electrolytes 1. Specify the possible apparent components on the Components Specifications Selection sheet. 2. Click on the Elec Wizard button to generate components and reactions for electrolyte systems. There are 4 steps: Step 1: Define base components and select reaction generation options. Step 2: Remove any undesired species or reactions from the generated list. Step 3: Select simulation approach for electrolyte calculations. Step 4: Review physical properties specifications and modify the generated Henry components list and reactions. Introduction to Aspen Plus August 28th,2000

293 Steps for Using Electrolytes (Continued)
Introduction to Aspen Plus v10.2 Course Notes Steps for Using Electrolytes (Continued) Introduction to Aspen Plus August 28th,2000

294 Steps for Using Electrolytes (Continued)
Introduction to Aspen Plus v10.2 Course Notes Steps for Using Electrolytes (Continued) Step 1: Define base components and select reaction generation options. Introduction to Aspen Plus August 28th,2000

295 Steps for Using Electrolytes (Continued)
Introduction to Aspen Plus v10.2 Course Notes Steps for Using Electrolytes (Continued) Step 2: Remove any undesired species or reactions from the generated list. Introduction to Aspen Plus August 28th,2000

296 Steps for Using Electrolytes (Continued)
Introduction to Aspen Plus v10.2 Course Notes Steps for Using Electrolytes (Continued) Step 3: Select simulation approach for electrolyte calculations. Introduction to Aspen Plus August 28th,2000

297 Steps for Using Electrolytes (Continued)
Introduction to Aspen Plus v10.2 Course Notes Steps for Using Electrolytes (Continued) Step 4: Review physical properties specifications and modify the generated Henry components list and reactions. Introduction to Aspen Plus August 28th,2000

298 Introduction to Aspen Plus v10.2
Course Notes Electrolyte Workshop Objective: Create a flowsheet using electrolytes. Create a simple flowsheet to model the treatment of a sulfuric acid waste water stream using lime (Calcium Hydroxide). Use the Electrolyte Wizard to generate the Chemistry. Use the true component approach. B1 WASTEWAT LIME LIQUID Temperature = 25C Pressure = 1 bar Flowrate = 10 kmol/hr 5 mole% lime (calcium hydroxide) solution 5 mole% sulfuric acid solution P-drop = 0 Note: Remove from the chemistry: CaSO4(s) CaSO4•1:2W:A(s) When finished, save as filename: ELEC.BKP Introduction to Aspen Plus August 28th,2000

299 Electrolyte Workshop (Continued)
1. Open a new Electrolytes with Metric units flowsheet. 2. Draw the flowsheet. 3. Enter the necessary components and generate the electrolytes using the Electrolytes Wizard. Select the true approach and remove the solid salts not needed from the generated reactions. Introduction to Aspen Plus

300 Sour Water Stripper Workshop
Objective: Model a sour water stripper using electrolytes. Create a simple flowsheet to model a sour water stripper. Use the Electrolyte Wizard to generate the Chemistry. Use the apparent component approach. On stage 10 P = 15 psia Vapor frac = 1 2,000 lbs/hr Above stage 3 10,000 lbs/hr Mass fractions: H2O 0.997 NH H2S 0.001 CO Saturated vapor Theoretical trays: 9 (does not include condenser) Partial condenser Reflux Ratio (Molar): 25 No reboiler B1 SOURWAT STEAM BOTTOMS VAPOR Introduction to Aspen Plus

301 Sour Water Stripper Workshop (Continued)
1. Open a new Electrolytes with English units flowsheet. 2. Draw the flowsheet. 3. Enter the necessary components and generate the electrolytes using the Electrolytes Wizard. Select the apparent approach and remove all solid salts used in the generated reactions. Questions: Why aren’t the ionic species’ compositions displayed on the results forms? How can they be added? Introduction to Aspen Plus

302 Sour Water Stripper Workshop (Continued)
3. Add a sensitivity analysis a) Vary the steam flow rate from lb/hr and tabulate the ammonia concentration in the bottoms stream. The target is 50 ppm. b) Vary the column reflux ratio from and observe the condenser temperature. The target is 190 F. 4. Create design specifications a) After hiding the sensitivity blocks, solve the column with two design specifications. Use the targets and variables from part 3. Save as: SOURWAT.BKP Introduction to Aspen Plus

303 Introduction to Aspen Plus v10.2
Course Notes Solids Handling Objective: Provide an overview of the solid handling capabilities Aspen Plus References: User Guide, Chapter 6, Specifying Components Physical Property Methods and Models Reference Manual, Chapter 3, Property Model Descriptions August 28th,2000

304 Introduction to Aspen Plus v10.2
Course Notes Classes of Components Conventional Components Vapor and liquid components Solid salts in solution chemistry Conventional Inert Solids (CI Solids) Solids that are inert to phase equilibrium and salt precipitation/solubility Nonconventional Solids (NC Solids) Heterogeneous substances inert to phase, salt, and chemical equilibrium that cannot be represented with a molecular structure Introduction to Aspen Plus August 28th,2000

305 Specifying Component Type
Introduction to Aspen Plus v10.2 Course Notes Specifying Component Type When specifying components on the Components Specifications Selection sheet, choose the appropriate component type in the Type column. Conventional - Conventional Components Solid - Conventional Inert Solids Nonconventional - Nonconventional Solids Introduction to Aspen Plus August 28th,2000

306 Conventional Components
Introduction to Aspen Plus v10.2 Course Notes Conventional Components Components participate in vapor and liquid equilibrium along with salt and chemical equilibrium. Components have a molecular weight. e.g. water, nitrogen, oxygen, sodium chloride, sodium ions, chloride ions Located in the MIXED substream Introduction to Aspen Plus August 28th,2000

307 Conventional Inert Solids (CI Solids)
Introduction to Aspen Plus v10.2 Course Notes Conventional Inert Solids (CI Solids) Components are inert to phase equilibrium and salt precipitation/solubility. Chemical equilibrium and reaction with conventional components is possible. Components have a molecular weight. e.g. carbon, sulfur Located in the CISOLID substream Introduction to Aspen Plus August 28th,2000

308 Nonconventional Solids (NC Solids)
Introduction to Aspen Plus v10.2 Course Notes Nonconventional Solids (NC Solids) Components are inert to phase, salt or chemical equilibrium. Chemical reaction with conventional and CI Solid components is possible. Components are heterogeneous substances and do not have a molecular weight. e.g. coal, char, ash, wood pulp Located in the NC Solid substream JLM - Regarding the second bullet, can this be done in any reactor, or only RYield? I thought all other reactors required an atom balance, which is not possible with NC comps. This may just be my ignorance, but I thought I would ask… Lorie: Reactions are possible, but it is a little bit of a pain to get the mass balance correct since the non-conventional component is on a mass balance and the others are on a mole balance. Introduction to Aspen Plus August 28th,2000

309 Introduction to Aspen Plus v10.2
Course Notes Component Attributes Component attributes typically represent the composition of a component in terms of some set of identifiable constituents Component attributes can be Assigned by the user Initialized in streams Modified in unit operation models Component attributes are carried in the material stream. Properties of nonconventional components are calculated by the physical property system using component attributes. Introduction to Aspen Plus August 28th,2000

310 Component Attribute Descriptions
Introduction to Aspen Plus v10.2 Course Notes Component Attribute Descriptions Introduction to Aspen Plus August 28th,2000

311 Introduction to Aspen Plus v10.2
Course Notes Solid Properties For conventional components and conventional solids Enthalpy, entropy, free energy and molar volume are computed. Property models in the Property Method specified on the Properties Specification Global sheet are used. For nonconventional solids Enthalpy and mass density are computed. Property models are specified on the Properties Advanced NC-Props form. Introduction to Aspen Plus August 28th,2000

312 Solids Properties - Conventional Solids
Introduction to Aspen Plus v10.2 Course Notes Solids Properties - Conventional Solids For Enthalpy, Free Energy, Entropy and Heat Capacity Barin Equations Single parameter set for all properties Multiple parameter sets may be available for selected temperature ranges List INORGANIC databank before SOLIDS Conventional Equations Combines heat of formation and free energies of formation with heat capacity models Aspen Plus and DIPPR model parameters List SOLIDS databank before INORGANIC Introduction to Aspen Plus August 28th,2000

313 Solids Properties - Conventional Solids
Introduction to Aspen Plus v10.2 Course Notes Solids Properties - Conventional Solids Solid Heat Capacity Heat capacity polynomial model Used to calculate enthalpy, entropy and free energy Parameter name: CPSP01 Solid Molar Volume Volume polynomial model Used to calculate density Parameter name: VSPOLY Introduction to Aspen Plus August 28th,2000

314 Solids Properties - Nonconventional Solids
Introduction to Aspen Plus v10.2 Course Notes Solids Properties - Nonconventional Solids Enthalpy General heat capacity polynomial model: ENTHGEN Uses a mass fraction weighted average Based on the GENANAL attribute Parameter name: HCGEN Density General density polynomial model: DNSTYGEN Parameter name: DENGEN Introduction to Aspen Plus August 28th,2000

315 Solids Properties - Special Models for Coal
Introduction to Aspen Plus v10.2 Course Notes Solids Properties - Special Models for Coal Enthalpy Coal enthalpy model: HCOALGEN Based on the ULTANAL, PROXANAL and SULFANAL attributes Density Coal density model: DCOALIGT Based on the ULTANAL and SULFANAL attributes JLM - Should we discuss the following components found in the Solids databank? COAL COAL2 COAL4 By the way, what are these? Introduction to Aspen Plus August 28th,2000

316 Built-in Material Stream Classes
Introduction to Aspen Plus v10.2 Course Notes Built-in Material Stream Classes * system default Introduction to Aspen Plus August 28th,2000

317 Introduction to Aspen Plus v10.2
Course Notes Unit Operation Models General Principles Material streams of any class are accepted. The same stream class should be used for inlet and outlet streams (exceptions: Mixer and ClChng). Attributes (components or substream) not recognized are passed unaltered through the block. Some models allow specifications for each substream present (examples: Sep, RStoic). In vapor-liquid separation, solids leave with the liquid. Unless otherwise specified, outlet solid substreams are in thermal equilibrium with the MIXED substream. Introduction to Aspen Plus August 28th,2000

318 Introduction to Aspen Plus v10.2
Course Notes Solids Workshop 1 Objective: Model a conventional solids dryer. Dry SiO2 from a water content of 0.5% to 0.1% using air. Notes Change the Stream class type to: MIXCISLD. Put the SiO2 in the CISOLID substream. The pressure and temperature has to be the same in all the sub-streams of a stream. Declare SiO2 as a component type of Solid. Introduction to Aspen Plus August 28th,2000

319 Solids Workshop 1 (Continued)
Introduction to Aspen Plus v10.2 Course Notes Solids Workshop 1 (Continued) Temp = 190 F Pres = 14.7 psia Flow = 1 lbmol/hr 0.79 mole% N2 0.21 mole% O2 AIR-OUT Design specification: Vary the air flow rate from 1 to 10 lbmol/hr to achieve 99.9 wt.% SiO2 [SiO2/(SiO2+Mixed)] AIR DRYER WET FLASH2 DRY Temp = 70 F Pres = 14.7 psia 995 lb/hr SiO2 5 lb/hr H2O Design spec: Provide instructor notes for Design spec: SFLOW/(SFLOW+WFLOW) where WFLOW = Stream-Var, DRY, MIXED, MASS-FLOW not Mass-Flow, Dry, Mixed, SiO2, because this is a single cmpt when we really want entire flow of all cmpts in stream. JLM - Also, need to be more specific about the design-spec. Is spec percent on a mass basis or a mole basis? What is to be varied? Also, why did we specify MIXCIPSD if no PSD is given in the problem? Is this a mistake, or should we give them PSD info? Lorie: We should add a demonstration. We should also add a NC solid workshop. Pressure Drop = 0 Adiabatic When finished, save as filename: SOLIDWK1.BKP Use the SOLIDS Property Method Introduction to Aspen Plus August 28th,2000

320 Introduction to Aspen Plus v10.2
Course Notes Solids Workshop 2 Objective: Use the solids unit operations to model the particulate removal from a feed of gasifier off gases. The processing of gases containing small quantities of particulate materials is rendered difficult by the tendency of the particulates to interfere with most operations (e.g., surface erosion, fouling, plugging of orifices and packing). It is therefore necessary to remove most of the particulate materials from the gaseous stream. Various options are available for this purpose (Cyclone, Bag-filter, Venturi-scrubber, and an Electrostatic precipitator) and their particulate separation efficiency can be changed by varying their design and operating conditions. The final choice of equipment is a balance between the technical performance and the cost associated with using a particular unit. In this workshop, various options for removing particulates from the syngas obtained by coal gasification are compared. Introduction to Aspen Plus August 28th,2000

321 Solids Workshop 2 (Continued)
Introduction to Aspen Plus v10.2 Course Notes Solids Workshop 2 (Continued) Temp = 650 C Pres = 1 bar Gas Flowrate = 1000 kmol/hr Ash Flowrate = 200 kg/hr Composition (mole-frac) CO 0.19 CO2 0.20 H2 0.05 H2S 0.02 O2 0.03 CH4 0.01 H2O 0.05 N2 0.35 SO2 0.10 Particle size distribution (PSD) Size limit wt. % [mu] DUPL CYC FAB-FILT ESP V-SCRUB FEED F-CYC F-SCRUB F-ESP F-BF S-BF G-CYC S-CYC G-SCRUB S-SCRUB LIQ G-ESP S-ESP G-BF Temp = 40 C Pres = 1 bar Water Flowrate = 700 kg/hr Design Mode Max. Pres. Drop = bar High Efficiency Separation Efficiency = 0.9 Dielectric constant = 1.5 You can modify default particle size distribution, PSD, or create a new set to match the intervals provided. If you create a new one, however, remember to set this new PSD set as the default set for the NCPSD stream characterization or the program default, PSD, will be used. Important note (I got stumped on this one more than once! It’s not intuitive.): The PSD form for a MIXCISLD stream does not become active until a value for T, P, or x has been entered into the respective fields. JLM - - Do you want them to model ash as a CI or NC component? - - Do you think they will know how to change the PSD size limits, or should we give them some specific instructions for this? - What Property Method should be used? When finished, save as filename: SOLIDWK2.BKP Introduction to Aspen Plus August 28th,2000

322 Solids Workshop 2 (Continued)
Introduction to Aspen Plus v10.2 Course Notes Solids Workshop 2 (Continued) Coal ash is mainly clay and heavy metal oxides and can be considered a non-conventional component. HCOALGEN and DCOALIGT can be used to calculate the enthalpy and material density of ash using the ultimate, proximate, and sulfur analyses (ULTANAL, PROXANAL, SULFANAL). These are specified on the Properties Advanced NC-Props form. Component attributes (ULTANAL, PROXANAL, SULFANAL) are specified on the Stream Input form. For ash, zero all non-ash attributes. The PSD limits can be changed on the Setup Substreams PSD form. Use the IDEAL Property Method. Introduction to Aspen Plus August 28th,2000

323 Introduction to Aspen Plus v10.2
Course Notes Optimization Objective: Introduce the optimization capability in Aspen Plus Aspen Plus References: User Guide, Chapter 22, Optimization Related Topics: User Guide, Chapter 17, Convergence User Guide, Chapter 18, Accessing Flowsheet Variables August 28th,2000

324 Introduction to Aspen Plus v10.2
Course Notes Optimization Used to maximize/minimize an objective function Objective function is expressed in terms of flowsheet variables and In-Line Fortran. Optimization can have zero or more constraints. Constraints can be equalities or inequalities. Optimization is located under /Data/Model Analysis Tools/Optimization Constraint specification is under /Data/Model Analysis Tools/Constraint Introduction to Aspen Plus August 28th,2000

325 Introduction to Aspen Plus v10.2
Course Notes Optimization Example For an existing reactor, find the reactor temperature and inlet amount of reactant A that maximizes the profit from this reactor. The reactor can only handle a maximum cooling load of Q. REACTOR A, B A + B --> C + D + E FEED Desired Product C $ / lb By-product D $ / lb Waste Product E $ /lb A, B, C, D, E PRODUCT Introduction to Aspen Plus August 28th,2000

326 Optimization Example (Continued)
Introduction to Aspen Plus v10.2 Course Notes Optimization Example (Continued) What are the measured (sampled) variables? Outlet flowrates of components C, D, E What is the objective function to be maximized? Maximize 1.30*(lb/hr C) *(lb/hr D) *(lb/hr E) What is the constraint? The calculated duty of the reactor can not exceed Q. What are the manipulated (varied) variables? Reactor temperature Inlet amount of reactant A Introduction to Aspen Plus August 28th,2000

327 Steps for Using Optimization
Introduction to Aspen Plus v10.2 Course Notes Steps for Using Optimization 1. Identify measured (sampled) variables. These are the flowsheet variables used to calculate the objective function (Optimization Define sheet). 2. Specify objective function (expression). This is the Fortran expression that will be maximized or minimized (Optimization Objective & Constraints sheet). 3. Specify maximization or minimization of objective function (Optimization Objective & Constraints sheet). Introduction to Aspen Plus August 28th,2000

328 Steps for Using Optimization (Continued)
Introduction to Aspen Plus v10.2 Course Notes Steps for Using Optimization (Continued) 4. Specify constraints (optional). These are the constraints used during the optimization (Optimization Objective & Constraints sheet). 5. Specify manipulated (varied) variables. These are the variables that the optimization block will change to maximize/minimize the objective function (Optimization Vary sheet). 6. Specify bounds for manipulated (varied) variables. These are the lower and upper bounds within which to vary the manipulated variable (Optimization Vary sheet). Introduction to Aspen Plus August 28th,2000

329 Introduction to Aspen Plus v10.2
Course Notes Notes 1. The convergence of the optimization can be sensitive to the initial values of the manipulated variables. 2. It is best if the objective, the constraints, and the manipulated variables are in the range of 1 to This can be accomplished by simply multiplying or dividing the function. 3. The optimization algorithm only finds local maxima and minima in the objective function. It is theoretically possible to obtain a different maximum/minimum in the objective function, in some cases, by starting at a different point in the solution space. Introduction to Aspen Plus August 28th,2000

330 Introduction to Aspen Plus v10.2
Course Notes Notes (Continued) 4. Equality constraints within an optimization are similar to design specifications. 5. If an optimization does not converge, run sensitivity studies with the same manipulated variables as the optimization, to ensure that the objective function is not discontinuous with respect to any of the manipulated variables. 6. Optimization blocks also have convergence blocks associated with them. Any general techniques used with convergence blocks can be used if the optimization does not converge. Introduction to Aspen Plus August 28th,2000

331 Optimization Workshop
Introduction to Aspen Plus v10.2 Course Notes Optimization Workshop Objective: Optimize steam usage for a process. The flowsheet shown below is part of a Dichloro-Methane solvent recovery system. The two flashes, TOWER1 and TOWER2, are run adiabatically at 19.7 and 18.7 psia respectively. The stream FEED contains 1400 lb/hr of Dichloro-Methane and lb/hr of water at 100oF and 24 psia. Set up the simulation as shown below, and minimize the total usage of steam in streams STEAM1 and STEAM2, both of which contain saturated steam at 200 psia. The maximum allowable concentration of Dichloro-Methane in the stream EFFLUENT from TOWER2 is 150 ppm (mass) to within a tolerance of a tenth of a ppm. Use the NRTL Property Method. Use bounds of 1000 lb/hr to 20,000 lb/hr for the flowrate of the two steam streams. Make sure stream flows are reported in mass flow and mass fraction units before running. Refer to the Notes slides for some hints on the previous page if there are problems converging the optimization. Dave found an error in the Intro optimization workshop. I didn't catch this error since the problem does converge and the constraint is met if the problem is run as specified. It doesn't converge or the problem can converge but exceed the constraint without any error messages if the problem initialization is changed slightly. I made the following changes: o Since the constraint is conc LE 150 ppm +/- 0.1 ppm, the tolerance should be DLOG(150.1E-6) - DLOG(150E-6) instead of DLOG(.1E-6). I actually changed it to DLOG(150.1E-6/150E-6). o I changed the initialization for the steam from Mole-Flow to Mass-Flow since we are varying Mass-Flow in the problem. This will make it a little easier for the instructor since most people will probably choose mass flow. Mark Introduction to Aspen Plus August 28th,2000

332 Optimization Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes Optimization Workshop (Continued) TOP1 STEAM1 TOWER1 FEED TOP2 TOWER2 BOT1 STEAM2 EFFLUENT When finished, save as filename: OPT.BKP Introduction to Aspen Plus August 28th,2000

333 Introduction to Aspen Plus v10.2
Course Notes RadFrac Convergence Objective: Introduce the convergence algorithms and initialization strategies available in RadFrac Aspen Plus References: Unit Operation Models Reference Manual, Chapter 4, Columns August 28th,2000

334 RadFrac Convergence Methods
Introduction to Aspen Plus v10.2 Course Notes RadFrac Convergence Methods RadFrac provides a variety of convergence methods for solving separation problems. Each convergence method represents a convergence algorithm and an initialization method. The following convergence methods are available: Standard (default) Petroleum / Wide-Boiling Strongly non-ideal liquid Azeotropic Cryogenic Custom Introduction to Aspen Plus August 28th,2000

335 Convergence Methods (Continued)
Introduction to Aspen Plus v10.2 Course Notes Convergence Methods (Continued) Method Algorithm Initialization Standard Standard Standard Petroleum / Wide-boiling Sum-Rates Standard Strongly non-ideal liquid Nonideal Standard Azeotropic Newton Azeotropic Cryogenic Standard Cryogenic Custom select any select any Introduction to Aspen Plus August 28th,2000

336 RadFrac Convergence Algorithms
Introduction to Aspen Plus v10.2 Course Notes RadFrac Convergence Algorithms RadFrac provides four convergence algorithms: Standard (with Absorber=Yes or No) Sum-Rates Nonideal Newton Introduction to Aspen Plus August 28th,2000

337 Introduction to Aspen Plus v10.2
Course Notes Standard Algorithm The Standard (default, Absorber=No) algorithm: Uses the original inside-out formulation Is effective and fast for most problems Solves design specifications in a middle loop May have difficulties with extremely wide-boiling or highly non-ideal mixtures Introduction to Aspen Plus August 28th,2000

338 Standard Algorithm (Continued)
Introduction to Aspen Plus v10.2 Course Notes Standard Algorithm (Continued) The Standard algorithm with Absorber=Yes: Uses a modified formulation similar to the classical sum-rates algorithm Applies to absorbers and strippers only Has fast convergence Solves design specifications in a middle loop May have difficulties with highly non-ideal mixtures Introduction to Aspen Plus August 28th,2000

339 Introduction to Aspen Plus v10.2
Course Notes Sum-Rates Algorithm The Sum-Rates algorithm: Uses a modified formulation similar to the classical sum-rates algorithm Solves design specifications simultaneously with the column-describing equations Is effective and fast for wide boiling mixtures and problems with many design specifications May have difficulties with highly non-ideal mixtures JLM - Is the first bullet correct? It’s the same bullet from the last slide. Introduction to Aspen Plus August 28th,2000

340 Introduction to Aspen Plus v10.2
Course Notes Nonideal Algorithm The Nonideal algorithm: Includes a composition dependency in the local physical property models Uses the continuation convergence method Solves design specifications in a middle loop Is effective for non-ideal problems Introduction to Aspen Plus August 28th,2000

341 Introduction to Aspen Plus v10.2
Course Notes Newton Algorithm The Newton algorithm: Is a classic implementation of the Newton method Solves all column-describing equations simultaneously Uses the dogleg strategy of Powell to stabilize convergence Can solve design specifications simultaneously or in an outer loop Handles non-ideality well, with excellent convergence in the vicinity of the solution Is recommended for azeotropic distillation columns Introduction to Aspen Plus August 28th,2000

342 Vapor-Liquid-Liquid Calculations
Introduction to Aspen Plus v10.2 Course Notes Vapor-Liquid-Liquid Calculations You can use the Standard, Newton and Nonideal algorithms for 3-phase Vapor-Liquid-Liquid systems. On the RadFrac Setup Configuration sheet, select Vapor-Liquid-Liquid in the Valid Phases field. Vapor-Liquid-Liquid calculations: Handle column calculations involving two liquid phases rigorously Handle decanters Solve design specifications using: Either the simultaneous (default) loop or the middle loop approach for the Newton algorithm The middle loop approach for all other algorithms JLM - There should be a slide about Free Water. If you want to consider free-water calculations, you don’t choose Vapor-Liquid-Liquid; you choose one of the FreeWater choices for Valid Phases. Introduction to Aspen Plus August 28th,2000

343 Convergence Method Selection
Introduction to Aspen Plus v10.2 Course Notes Convergence Method Selection For Vapor-Liquid systems, start with the Standard convergence method. If the Standard method fails: Use the Petroleum / Wide Boiling method if the mixture is very wide-boiling. Use the Custom method and change Absorber to Yes on the RadFrac Convergence Algorithm sheet, if the column is an absorber or a stripper. Use the Strongly non-ideal liquid method if the mixture is highly non-ideal. Use the Azeotropic method for azeotropic distillation problems with multiple solutions possible. The Azeotropic algorithm is also another alternative for highly non-ideal systems. Introduction to Aspen Plus August 28th,2000

344 Convergence Method Selection (Continued)
Introduction to Aspen Plus v10.2 Course Notes Convergence Method Selection (Continued) For Vapor-Liquid-Liquid systems: Start by selecting Vapor-Liquid-Liquid in the Valid Phases field of the RadFrac Setup Configuration sheet and use the Standard convergence method. If the Standard method fails, try the Custom method with the Nonideal or the Newton algorithm. Introduction to Aspen Plus August 28th,2000

345 RadFrac Initialization Method
Introduction to Aspen Plus v10.2 Course Notes RadFrac Initialization Method Standard is the default Initialization method for RadFrac. This method: Performs flash calculations on composite feed to obtain average vapor and liquid compositions Assumes a constant composition profile Estimates temperature profiles based on bubble and dew point temperatures of composite feed Introduction to Aspen Plus August 28th,2000

346 Specialized Initialization Methods
Introduction to Aspen Plus v10.2 Course Notes Specialized Initialization Methods Four specialized Initialization methods are available. Use: For: Crude Wide boiling systems with multi-draw columns Chemical Narrow boiling chemical systems Azeotropic Azeotropic distillation columns Cryogenic Cryogenic applications Introduction to Aspen Plus August 28th,2000

347 Introduction to Aspen Plus v10.2
Course Notes Estimates RadFrac does not usually require estimates for temperature, flow and composition profiles. RadFrac may require: Temperature estimates as a first trial in case of convergence problems Liquid and/or vapor flow estimates for the separation of wide boiling mixtures. Composition estimates for highly non-ideal, extremely wide-boiling (for example, hydrogen-rich), azeotropic distillation or vapor-liquid-liquid systems. Introduction to Aspen Plus August 28th,2000

348 Composition Estimates
Introduction to Aspen Plus v10.2 Course Notes Composition Estimates The following example illustrates the need for composition estimates in an extremely wide-boiling point system: Introduction to Aspen Plus August 28th,2000

349 RadFrac Convergence Workshop
Introduction to Aspen Plus v10.2 Course Notes RadFrac Convergence Workshop Objective: Apply the convergence hints explained in this section. HCl column in a VCM production plant Feed kg/hr at 50C, 18 bar 19.5%wt HCl, 33.5%wt VCM, 47%wt EDC (VCM : vinyl-chloride, EDC : 1,2-dichloroethane) Column 33 theoretical stages partial condenser (vapor distillate) kettle reboiler pressure : top bar, bottom bar feed on stage 17 This is one of the workshop of the release 9 advanced distillation (workshop 1A, B). Tray rating has been dropped. system is wide boiling, so SUM-RATE is a good choice to converge the column. Without the specs, it is working fine with STANDARD. Newton is working as well. Introduction to Aspen Plus August 28th,2000

350 RadFrac Convergence Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes RadFrac Convergence Workshop (Continued) First Step: Specify the column. Set the distillate flow rate to be equal to the mass flow rate of HCl in the feed. Specify that the mass reflux ratio is 0.7. Use Peng-Robinson equation of state (PENG-ROB). Question: How should these specifications be implemented? Note: Look at the results. Temperature profile Composition profile Advice to look at composition profile to see that HCL and VCM are much too high. Temperature in condenser is negative, ie we need a refrigeration system. Note: you could increase the pressure and study its effect on the separation (left as an exercise). One thing they should notice is the large temperature difference between reboiler and condenser! (wide boiling mixture...) Demonstrate how to implement the distillate ratio spec! Livia; Provide instruction on setting the Distillate flow = HCl flow in feed using ‘Distillate to Feed Ratio’ based on HCL feed, at minimum in the instructor’s notes. Introduction to Aspen Plus August 28th,2000

351 RadFrac Convergence Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes RadFrac Convergence Workshop (Continued) Second step: VCM in distillate and HCl in bottom are much too high! Allow only 5 ppm of HCl in the residue and 10 ppm VCM in the distillate. Question: How should these specifications be implemented? Note: You may have some convergence difficulties. Apply the guidelines presented in this section Use Design-specs in RadFrac. It does not convergence with STANDARD. Convergence method cannot be modified unless ‘Convergence = Custom’ on the Setup Configuration sheet of the Column Block. Notes/Conclusion: Flowsheet will not converge after 25 iterations using the Standard algorithm. It solves after just six iterations using the Sum Rates algorithm. On slide, provide ranges for Vary parameters: Reflux ratio: Distillate to Feed ratio: Introduction to Aspen Plus August 28th,2000

352 RadFrac Convergence Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes RadFrac Convergence Workshop (Continued) Use the PENG-ROB Property method flow : HCl in feed kg/h 50 C, 18 bar, HCl 19.5%wt VCM 33.5%wt EDC 47.0%wt max 10 ppm VCM 17.88 bar mass reflux ratio:0.7 feed on stage 17 18.24 bar max 5 ppm HCl When finished, save as filename: VCMHCL1.BKP (step 1) and VCMHCL2.BKP (step 2) Introduction to Aspen Plus August 28th,2000

353 Vinyl Chloride Monomer (VCM) Workshop
Introduction to Aspen Plus v10.2 Course Notes Vinyl Chloride Monomer (VCM) Workshop Objective: Set up a flowsheet of a VCM process using the tools learned in the course. Vinyl chloride monomer (VCM) is produced through a high pressure, non-catalytic process involving the pyrolysis of 1,2-dichloroethane (EDC) according to the following reaction: CH2Cl-CH2Cl HCl + CHCl=CH2 The cracking of EDC occurs at 500 C and 30 bar in a direct fired furnace kmol/hr of pure EDC feed enters the reactor at 20 C and 30 bar. EDC conversion in the reactor is maintained at 55%. The hot gases from the reactor are subcooled by 10 degrees before fractionation. Two distillation columns are used for the purification of the VCM product. In the first column, anhydrous HCl is removed overhead and sent to the oxy chlorination unit. In the second column, VCM product is removed overhead and the bottoms stream containing unreacted EDC is recycled back to the furnace. Overheads from both columns are removed as saturated liquids. The HCL column is run at 25 bar and the VCM column is run at 8 bar. Use the RK-SOAVE Property Method. Introduction to Aspen Plus August 28th,2000

354 VCM Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes VCM Workshop (Continued) CH2Cl-CH2Cl HCl + CHCl=CH2 EDC HCl VCM 1000 kmol/hr EDC 20C RadFrac Model 30 bar FEED RStoic Model Heater Model HCLOUT RadFrac Model REACTOUT COOLOUT COL1 VCMOUT CRACK RECYCIN QUENCH 500 C VCMIN COL2 10 deg C subcooling 30 bar 0.5 bar pressure drop 15 stages EDC Conv. = 55% Reflux ratio = 1.082 Pump Model Distillate to feed ratio = 0.354 Feed enters above stage 8 10 stages Column pressure = 25 bar Reflux ratio = 0.969 JLM - I like the fact that this workshop has a real-life-like problem description on the previous slide, but I also think it makes it easier for the student when all required information is summarized on the flowsheet above. The only piece of required information missing from this slide is the fact that both distillate products leave as saturated liquids. Do you agree that this info should be added, and can you think of an easy way to add it to the slide above? I tested parts A and B of this workshop, and it looked OK. I didn’t test part C because I don’t have a compiler on my R10 PC. Distillate to feed ratio = 0.550 PUMP 30 bar outlet pressure Feed enters above stage 7 Column pressure = 8 bar RECYCLE When finished, save as filename: VCM.BKP Use RK-SOAVE property method Introduction to Aspen Plus August 28th,2000

355 VCM Workshop (Continued)
Introduction to Aspen Plus v10.2 Course Notes VCM Workshop (Continued) Part A: With the help of the process flow diagram on the previous page, set up a flowsheet to simulate the VCM process. What are the values of the following quantities? 1. Furnace heat duty ________ 2. Quench cooling duty ________ 3. Quench outlet temperature ________ 4. Condenser and Reboiler duties for COL2 ________________ 5. Concentration of VCM in the product stream ________ Part B: The conversion of EDC to VCM in the furnace varies between 50% and 55%. Use the sensitivity analysis capability to generate plots of the furnace heat duty and quench cooling duty as a function of EDC conversion. JLM - Here are the values I obtained: 1. Furnace heat duty MMkcal/hr 2. Quench cooling duty “ 3. Quench outlet temperature C 4. Condenser and Reboiler duties for COL2 and MMkcal/hr 5. Concentration of VCM in the product stream molefrac Livia: It would be advantageous to add two more parts to this VCM exercise, such as, Design Specs, and Optimization. Introduction to Aspen Plus August 28th,2000