Presentation is loading. Please wait.

Presentation is loading. Please wait.

©2000 AspenTech. All Rights Reserved. Introduction to Flowsheet Simulation Objective: Introduce general flowsheet simulation concepts and Aspen Plus features.

Similar presentations


Presentation on theme: "©2000 AspenTech. All Rights Reserved. Introduction to Flowsheet Simulation Objective: Introduce general flowsheet simulation concepts and Aspen Plus features."— Presentation transcript:

1 ©2000 AspenTech. All Rights Reserved. Introduction to Flowsheet Simulation Objective: Introduce general flowsheet simulation concepts and Aspen Plus features

2 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

3 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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)

4 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 General Simulation Problem

5 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

6 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

7 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Important Features of Aspen Plus Rigorous Electrolyte Simulation Solids Handling Petroleum Handling Data Regression Data Fit Optimization User Routines

8 ©2000 AspenTech. All Rights Reserved. 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 The User Interface Objective: Become comfortable and familiar with the Aspen Plus graphical user interface

9 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Run ID Tool Bar Title Bar Menu Bar Select Mode button Model Library Model Menu Tabs Process Flowsheet Window Next Button Status Area The User Interface Reference: Aspen Plus User Guide, Chapter 1, The User Interface

10 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus RStoic Model Heater Model Flash2 Model Filename: CUMENE.BKP REACTOR FEED RECYCLE REAC-OUT COOL COOL-OUT SEP PRODUCT Cumene Flowsheet Definition

11 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

12 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

13 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

14 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

15 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

16 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus When finished, save in backup format (Run-ID.BKP). filename: BENZENE.BKP FL1 Heater Model Flash2 Model Flash2 Model COOL FEEDCOOL VAP1 LIQ1 FL2 VAP2 LIQ2 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.

17 ©2000 AspenTech. All Rights Reserved. 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 Basic Input Objective: Introduce the basic input required to run an Aspen Plus simulation

18 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

19 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

20 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 The User Interface (Continued)

21 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus The Data Browser Menu tree Previous sheet Next sheet Status area Parent buttonUnits Go back Go forward Comments Next Description area Status

22 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

23 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

24 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

25 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Status Indicators 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. SymbolStatus

26 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Cumene Production Conditions Q = 0 Btu/hr Pdrop = 0 psi C6H6 + C3H6 = C9H12 Benzene Propylene Cumene (Isopropylbenzene) 90% Conversion of Propylene T = 130 F Pdrop = 0.1 psi P = 1 atm Q = 0 Btu/hr Benzene: 40 lbmol/hr Propylene: 40 lbmol/hr T = 220 F P = 36 psia Use the RK-SOAVE Property Method Filename: CUMENE.BKP REACTOR FEED RECYCLE REAC-OUT COOL COOL-OUT SEP PRODUCT

27 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

28 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Setup Specifications Form

29 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Stream Report Options Stream report options are located on the Setup Report Options Stream sheet.

30 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Setup Run Types

31 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

32 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

33 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Components Specifications Form

34 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

35 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Find Find performs an AND search when more than one criterion is specified.

36 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Parameters missing from the first selected databank will be searched for in subsequent selected databanks. Pure Component Databanks

37 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

38 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Properties Specifications Form

39 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

40 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Streams Input Form

41 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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).

42 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Block Form

43 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

44 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

45 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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)

46 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

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

48 ©2000 AspenTech. All Rights Reserved. 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

49 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

50 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Mixers/Splitters

51 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Separators

52 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Heat Exchangers * Requires separate license

53 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Columns - Shortcut

54 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Columns - Rigorous * Requires separate license + Input language only in Version 10.0

55 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Reactors

56 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Pressure Changers

57 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Manipulators

58 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Solids

59 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

60 ©2000 AspenTech. All Rights Reserved. Aspen Plus References: Unit Operation Models Reference Manual, Chapter 4, Columns RadFrac Objective: Discuss the minimum input required for the RadFrac fractionation model, and the use of design specifications and stage efficiencies

61 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

62 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus RadFrac Flowsheet Connectivity Vapor Distillate Top-Stage or 1 Condenser Heat DutyHeat (optional) Liquid Distillate Water Distillate (optional) Feeds Reflux Products (optional) Heat (optional) Pumparound Decanters Heat (optional) Product Heat (optional) Return Boil-up Bottom Stage or Nstage Reboiler Heat Duty Heat (optional) Bottoms

63 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus RadFrac Setup Configuration Sheet Specify: – Number of stages – Condenser and reboiler configuration – Two column operating specifications – Valid phases – Convergence

64 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

65 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Feed Convention On-stage n Above-stage (default) n-1 n Vapor Feed n-1 Liquid Feed

66 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus RadFrac Setup Pressure Sheet Specify one of: – Column pressure profile – Top/Bottom pressure – Section pressure drop

67 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Kettle Reboiler T = 65 C P = 1 bar Water: 100 kmol/hr Methanol: 100 kmol/hr 9 Stages Reflux Ratio = 1 Distillate to feed ratio = 0.5 Column pressure = 1 bar Feed stage = 6 RadFrac specifications Filename: RAD-EX.BKP Methanol-Water RadFrac Column Use the NRTL-RK Property Method COLUMN FEED OVHD BTMS Total Condenser

68 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

69 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

70 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Plot Wizard Demonstration Use the plot wizard on the column to create a plot of the vapor phase compositions throughout the column.

71 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

72 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

73 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

74 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Filename: RADFRAC.BKP Use the NRTL-RK Property Method COLUMN FEED DIST BTMS Feed: 63.2 wt% Water 36.8 wt% Methanol Total flow = 120,000 lb/hr Pressure 18 psia Saturated liquid 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 RadFrac Workshop Part A Perform a rating calculation of a Methanol tower using the following data:

75 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus RadFrac Workshop (Continued) Part B Set up design specifications within the column so the following two objectives are met: – wt% methanol in the distillate – 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 :_________

76 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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)

77 ©2000 AspenTech. All Rights Reserved. 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 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Reactor Overview Reactors Balance Based RYield RStoic Equilibrium Based REquil RGibbs Kinetics Based RCSTR RPlug RBatch

79 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 70 lb/hr H 2 O 20 lb/hr CO 2 60 lb/hr CO 250 lb/hr tar 600 lb/hr char 1000 lb/hr Coal IN OUT RYield 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)

80 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 2 CO + O2 -- > 2 CO2 C + O2 -- > CO2 2 C + O2 -- > 2 CO C, O2 IN OUT RStoic C, O2, CO, CO2 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

81 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

82 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

83 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

84 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

85 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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:

86 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

87 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

88 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Temp = 70 C Pres = 1 atm Feed: Water: kmol/hr Ethanol: kmol/hr Acetic Acid: kmol/hr Length = 2 meters Diameter = 0.3 meters Volume = 0.14 Cu. M. 70 % conversion of ethanol When finished, save as filename: REACTORS.BKP Use the NRTL-RK property method Reactor Workshop (Continued)

89 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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: C6H6+3 H2 =C6H12 BenzeneHydrogenCyclohexane 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.

90 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus C 6 H H 2 = C 6 H 12 Benzene Hydrogen Cyclohexane Use the RK-SOAVE property method When finished, save as filename: CYCLOHEX.BKP Bottoms rate = 99 kmol/hr P = 25 bar T = 50 C Molefrac H2 = N2 = CH4 = 0.02 Total flow = 330 kmol/hr T = 40 C P = 1 bar Benzene flow = 100 kmol/hr T = 150C P = 23 bar T = 200 C Pdrop = 1 bar Benzene conv = T = 50 C Pdrop = 0.5 bar 92% flow to stream H2RCY 30% flow to stream CHRCY Specify cyclohexane mole recovery in PRODUCT stream equal to by varying Bottoms rate from 97 to 101 kmol/hr Theoretical Stages = 12 Reflux ratio = 1.2 Partial Condenser with vapor distillate only Column Pressure = 15 bar Feed stage = 8 REACT FEED-MIX H2IN BZIN H2RCY CHRCY RXIN RXOUT HP-SEP VAP COLUMN COLFD LTENDS PRODUCT VFLOW PURGE LFLOW LIQ Cyclohexane Production Workshop

91 ©2000 AspenTech. All Rights Reserved. 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 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Correct choice of physical property models and accurate physical property parameters are essential for obtaining accurate simulation results. FEED OVHD BTMS COLUMN 5000 lbmol/hr 10 mole % acetone 90 mole % water Specification: 99.5 mole % acetone recovery Case Study - Acetone Recovery Ideal Approach Equation of State Approach Activity Coefficient Model Approach Predicted number of stages required Approximate cost in dollars , , , 000

93 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus How to Establish Physical Properties Choose a Property Method Check Parameters/Obtain Additional Parameters Confirm Results Create the Flowsheet

94 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

95 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Approaches to representing physical properties of components Choice of model types depends on degree of non-ideal behavior and operating conditions. Physical Property Models IdealEquation of State (EOS) Models Activity Coefficient Models Special Models Physical Property Models

96 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus x y x y x y 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)

97 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Comparison of EOS and Activity Models

98 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Common Property Methods Equation of State Property Methods – PENG-ROB – RK-SOAVE Activity Coefficient Property Methods – NRTL – UNIFAC – UNIQUAC – WILSON

99 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

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

101 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Choosing a Property Method - Example Choose an appropriate Property Method for the following systems of components at ambient conditions.

102 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus How to Establish Physical Properties Choose a Property Method Check Parameters/Obtain Additional Parameters Confirm Results Create the Flowsheet

103 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

104 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

105 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

106 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus PHYSICAL PROPERTIES SECTION PROPERTY PARAMETERS PARAMETERS ACTUALLY USED IN THE SIMULATION PURE COMPONENT PARAMETERS COMPONENT ID: BENZENE FORMULA: C6H6 NAME: C6H6 SCALAR PARAMETERS PARAM SET DESCRIPTIONS VALUE UNITS SOURCE NAME NO. API 1 STANDARD API GRAVITY PURE10 CHARGE 1 IONIC CHARGE E+00 AQUEOUS CHI 1 STIEL POLAR FACTOR E+00 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 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.

107 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

108 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus How to Establish Physical Properties Choose a Property Method Check Parameters/Obtain Additional Parameters Confirm Results Create the Flowsheet

109 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

110 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Property Analysis - Common Plots y-x diagram for TOLUENE / WATER LIQUID MOLEFRAC TOLUENE VAPOR MOLEFRAC TOLUENE (PRES = 14.7 PSI) XY Plot Showing 2 liquid phases: Ideal XY Plot:XY Plot Showing Azeotrope:

111 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus How to Establish Physical Properties Choose a Property Method Check Parameters/Obtain Additional Parameters Confirm Results Create the Flowsheet

112 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

113 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.)

114 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

115 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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. Specifying Property Sets

116 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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:

117 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

118 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

119 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

120 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 (70 o F, 1atm), and have the following flow rates of the various components: Water515 lb/hr Oil4322 lb/hr CO2751 lb/hr N243 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.

121 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

122 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

123 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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)

124 ©2000 AspenTech. All Rights Reserved. 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 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus COLUMN FEED OVHD BTMS Why Access Variables? 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

126 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

127 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Variable Categories

128 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

129 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

130 ©2000 AspenTech. All Rights Reserved. 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 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

132 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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? Filename: CUMENE-S.BKP » Cooler outlet temperature » Purity (mole fraction) of cumene in product stream REACTOR FEED RECYCLE REAC-OUT COOL COOL-OUT SEP PRODUCT Sensitivity Analysis Example

133 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Sensitivity Analysis Results What is happening below 75 F and above 300 F?

134 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

135 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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).

136 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

137 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

138 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 1.0. 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.

139 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Cyclohexane Production Workshop C 6 H H 2 = C 6 H 12 Benzene Hydrogen Cyclohexane Use the RK-SOAVE property method Bottoms rate = 99 kmol/hr P = 25 bar T = 50 C Molefrac H2 = N2 = CH4 = 0.02 Total flow = 330 kmol/hr T = 40 C P = 1 bar Benzene flow = 100 kmol/hr T = 150C P = 23 bar T = 200 C Pdrop = 1 bar Benzene conv = T = 50 C Pdrop = 0.5 bar 92% flow to stream H2RCY 30% flow to stream CHRCY Specify cyclohexane mole recovery of by varying Bottoms rate from 97 to 101 kmol/hr Theoretical Stages = 12 Reflux ratio = 1.2 Partial Condenser with vapor distillate only Column Pressure = 15 bar Feed stage = 8 LIQ

140 ©2000 AspenTech. All Rights Reserved. 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 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

142 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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? Filename: CUMENE-D.BKP » Cooler outlet temperature » Mole fraction of cumene in stream PRODUCT » Mole fraction of cumene in stream PRODUCT = 0.98 REACTOR FEED RECYCLE REAC-OUT COOL COOL-OUT SEP PRODUCT Design Specification Example

143 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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).

144 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

145 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

146 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

147 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.)

148 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

149 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Cyclohexane Production Workshop C 6 H H 2 = C 6 H 12 Benzene Hydrogen Cyclohexane Use the RK-SOAVE property method Bottoms rate = 99 kmol/hr P = 25 bar T = 50 C Molefrac H2 = N2 = CH4 = 0.02 Total flow = 330 kmol/hr T = 40 C P = 1 bar Benzene flow = 100 kmol/hr T = 150C P = 23 bar T = 200 C Pdrop = 1 bar Benzene conv = T = 50 C Pdrop = 0.5 bar 92% flow to stream H2RCY 30% flow to stream CHRCY Specify cyclohexane mole recovery of by varying Bottoms rate from 97 to 101 kmol/hr Theoretical Stages = 12 Reflux ratio = 1.2 Partial Condenser with vapor distillate only Column Pressure = 15 bar Feed stage = 8 LIQ

150 ©2000 AspenTech. All Rights Reserved. Calculator Blocks 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 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

152 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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. Calculator Block DELTA-P = * V 2 V Filename: CUMENE-F.BKP or CUMENE-EXCEL.BKP DELTA-P REACTOR FEED RECYCLE REAC-OUT COOL COOL-OUT SEP PRODUCT Calculator Block Example

153 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 » Volumetric flow is imported » Pressure drop is exported Calculator Block Example (Continued)

154 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Import Variables Export Variable =(-10^-9)*B6^2 =FLOW/DENS Connect Current Cell to a Defined Variable Aspen Plus toolbar in Excel Excel

155 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

156 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

157 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Increasing Diagnostics Calculator Block F-1 VALUES OF ACCESSED VARIABLES VARIABLE VALUE ======== ===== DP FLOW DENS RETURNED VALUES OF VARIABLES VARIABLE VALUE ======== ===== DP Increase Calculator defined variables Diagnostics message level in Control Panel or History file to 8. In the Control Panel or History File

158 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

159 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

160 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

161 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

162 ©2000 AspenTech. All Rights Reserved. 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 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

164 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

165 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

166 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

167 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

168 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

169 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

170 ©2000 AspenTech. All Rights Reserved. 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

171 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

172 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

173 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

174 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

175 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

176 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

177 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

178 ©2000 AspenTech. All Rights Reserved. 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 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

180 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

181 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 Vapor fraction

182 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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, 0 means bubble point

183 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

184 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

185 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

186 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Working with the HeatX Model (Continued) HeatX cannot: – Perform design calculations – Perform mechanical vibration analysis – Estimate fouling factors

187 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

188 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

189 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

190 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Two Heaters versus One HeatX

191 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

192 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

193 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

194 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Heat Curves Tabular Results

195 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Heat Curve Plot

196 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

197 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus RHEATX RHOT-IN RCLD-INRCLD-OUT RHOT-OUT SHEATX SHOT-IN SCLD-INSCLD-OUT SHOT-OUT HEATER-1 HCLD-IN Q-TRANS HCLD-OUT HEATER-2 HHOT-INHHOT-OUT 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. When finished, save as filename: HEATX.BKP HeatX Workshop (Continued)

198 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

199 ©2000 AspenTech. All Rights Reserved. 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 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

201 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

202 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

203 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

204 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

205 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

206 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

207 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

208 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

209 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

210 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Filename: CUMENE-P.BKP REACTOR FEED RECYCLE REAC-OUT COOL COOL-OUT SEP PRODUCT COMPR RECYCLE2 VALVE RECYCLE3 Outlet Pressure = 3 psig Polytropic compressor model using GPSA method Discharge pressure = 5 psig Pressure Changers Block Example Add a Compressor and a Valve to the cumene flowsheet.

211 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Pressure Changers Workshop Objective: Add pressure changer unit operations to the Cyclohexane flowsheet. Start with the Cyclohexane Workshop flowsheet (CYCLOHEX.BKP)

212 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus FEED-MIX H2IN CHRCY3 H2RCY2 BZIN2 RXIN REACT RXOUT HP-SEP LIQ VAP COLUMN COLFD LTENDS PRODUCT VFLOW H2RCY PURGE LFLOW CHRCY PUMP CHRCY2 PIPE COMP FEEDPUMP BZIN VALVE PURGE2 When finished, save as filename: PRESCHNG.BKP Pump efficiency = 0.6 Driver efficiency = 0.9 Performance Curve HeadFlow [m][cum/hr] Carbon Steel Schedule 40 1-in diameter 25-m length 26 bar outlet pressure 20 bar outlet pressure Globe valve V810 equal percent flow 1.5-in size Isentropic 4 bar pressure change Pressure Changers Workshop (Continued)

213 ©2000 AspenTech. All Rights Reserved. Flowsheet Convergence Objective: Introduce the idea of convergence blocks, tear streams and flowsheet sequences Aspen Plus References User Guide, Chapter 17, Convergence

214 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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...

215 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 BROYDEN NEWTON – To converge design specifications and tear streams: BROYDEN NEWTON – For optimization: SQP COMPLEX Global convergence options can be specified on the Convergence ConvOptions Defaults form.

216 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

217 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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. S1S2S3 S6 S4 S7 S5 MIXER B1 MIXER B2 FSPLIT B3 FSPLIT B4 Tear Streams

218 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

219 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

220 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Objective – Converge this flowsheet. – Start with the file CONVERGE.BKP. LIQ VAPOR FEED-HT FEED BOT DIST BOT-COOL GLYCOL COLUMN PREHEATR PREFLASH T=165 F P=15 psia 100 lbmol/hr XH20 = 0.4 XMethanol = 0.3 XEthanol = 0.3 Area = 65 sqft DP=0 Q=0 Theoretical Stages = 10 Reflux Ratio = 5 Distillate to Feed Ratio = 0.2 Feed Stage = 5 Column Pressure = 1 atm Total Condenser Use NRTL-RK Property Method T=70 F P=35 psia 50 lbmol/hr Ethylene Glycol When finished, save as filename: CONV-R.BKP Convergence Workshop

221 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.)

222 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

223 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

224 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

225 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

226 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Full-Scale Plant Modeling Workshop

227 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus M2 SATURATE FEEDHTR REFORMER NATGAS H2OCIRC MKUPST CH4COMP CO2 CO2COMP From Furnace To BOILER M1 Part 1: Front-End Section

228 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 – Mole Fraction 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 – Pressure = 26 bar – 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.

229 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Part 1: Front-End Section (Continued) Carbon Dioxide Compressor - CO2COMP – Discharge Pressure = 27.5 bar – Compressor Type = 2 stage Natural Gas Compressor - CH4COMP – Discharge Pressure = 27.5 bar – 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

230 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Part 1: Front-End Section Check

231 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Part 2: Heat Recovery Section

232 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus FL1 Pressure Drop = 0 bar Heat Duty = 0 MMkcal/hr FL2 Exit Pressure = 17.7 bar Heat Duty = 0 MMkcal/hr FL3 Exit Pressure = 17.4 bar Heat Duty = 0 MMkcal/hr SYNCOM Two Stage Polytropic compressor Discharge Pressure = 82.5 bar Intercooler Exit Temperature = 40 C 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 Exit Pressure = 18 bar 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

233 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Part 2: Heat Recovery Section Check

234 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Part 3: Methanol Synthesis Section

235 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

236 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Part 3: Methanol Synthesis Section Check

237 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Part 4: Distillation Section

238 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 dutySpecified by the heat stream – Reboiler heat dutyis 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.

239 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 dutyis 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 Pressure5 bar – Heat Duty0 MMkcal/hr M4 – For water addition to the crude methanol

240 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Part 4: Distillation Section Check

241 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus FURNACE Fuel Air From FL5 From SPLIT2 To REFORMER Part 5: Furnace Section

242 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

243 ©2000 AspenTech. All Rights Reserved. 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 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus File Formats in Aspen Plus

245 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 – Transferable between operating systems – Upwardly compatible – Readable, can be edited – Intended to be printed

246 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus How to Store a Simulation Three ways to store simulations: DocumentBackupInput (*.apw)(*.bkp)(*.inp) Simulation definitionYesYesYes Convergence infoYesNoNo ResultsYesYesNo Flowsheet GraphicsYesYesYes/No User readableNoNoYes Open/save speedHighLowLowest Space requirementsHighLowLowest

247 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

248 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

249 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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. Maintaining Your Computer

250 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

251 ©2000 AspenTech. All Rights Reserved. Customizing the Look of Your Flowsheet Objective: Introduce several ways of annotating your flowsheet to create informative Process Flow Diagrams Aspen Plus References: User Guide, Chapter 14, Annotating Process Flowsheets Related Topics: User Guide, Chapter 37, Working with Other Windows Programs

252 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

253 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

254 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

255 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Example of a Stream Table

256 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Temperature (F) Pressure (psi) Flow Rate (lb/hr) QDuty (Btu/hr) 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.

257 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

258 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

259 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

260 ©2000 AspenTech. All Rights Reserved. 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

261 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

262 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

263 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

264 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

265 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

266 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

267 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus C2C2 C1C1 C4C4 C3C3 O5O5 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.

268 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

269 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Atom Types Current available atom types: Atom TypeDescription CCarbonPPhosphorous OOxygenZnZinc NNitrogenGaGallium SSulfurGeGermanium BBoronAsArsenic SiSiliconCdCadmium FFluorineSnTin CLChlorineSbAntimony BrBromineHgMercury IIodinePbLead AlAluminumBiBismuth

270 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

271 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus  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.

272 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

273 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

274 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus   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.

275 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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)

276 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

277 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus When finished, save as filename: PCES.BKP 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

278 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

279 ©2000 AspenTech. All Rights Reserved. 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

280 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Electrolytes Examples Solutions with acids, bases or salts Sour water solutions Aqueous amines or hot carbonate for gas sweetening

281 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

282 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Types of Components Solvents - Standard molecular species – Water – Methanol – Acetic Acid Soluble Gases - Henry’s Law components – Nitrogen – Oxygen – Carbon Dioxide

283 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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) – CaSO42H2O (gypsum) – Na2CO3NaHCO3 2H2O (trona)

284 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

285 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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)

286 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

287 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

288 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

289 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

290 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

291 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus FLASH2 FLASH MIXED VAPOR LIQUID MIXER MIX NAOH HCL Temp = 25 C Pres = 1 bar 10 kmol/hr H2O 1 kmol/hr HCl P-drop = 0 Adiabatic Isobaric Molar vapor fraction = 0.75 Filename: ELEC1.BKP Temp = 25 C Pres = 1 bar 10 kmol/hr H2O 1.1 kmol/hr NaOH 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.

292 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

293 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Steps for Using Electrolytes (Continued)

294 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Steps for Using Electrolytes (Continued) Step 1: Define base components and select reaction generation options.

295 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Steps for Using Electrolytes (Continued) Step 2: Remove any undesired species or reactions from the generated list.

296 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Steps for Using Electrolytes (Continued) Step 3: Select simulation approach for electrolyte calculations.

297 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Steps for Using Electrolytes (Continued) Step 4: Review physical properties specifications and modify the generated Henry components list and reactions.

298 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus B1 WASTEWAT LIME LIQUID Temperature = 25C Pressure = 1 bar Flowrate = 10 kmol/hr 5 mole% lime (calcium hydroxide) solution Temperature = 25C Pressure = 1 bar Flowrate = 10 kmol/hr 5 mole% sulfuric acid solution Temperature = 25C P-drop = 0 Note: Remove from the chemistry: CaSO 4 (s) CaSO 4 1:2W:A(s) When finished, save as filename: ELEC.BKP 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.

299 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

300 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus On stage 10 P = 15 psia Vapor frac = 1 2,000 lbs/hr Above stage 3 P = 15 psia 10,000 lbs/hr Mass fractions: H2O0.997 NH H2S0.001 CO Saturated vapor Theoretical trays: 9 (does not include condenser) Partial condenser Reflux Ratio (Molar): 25 No reboiler B1 SOURWAT STEAM BOTTOMS VAPOR 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.

301 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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?

302 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Save as: SOURWAT.BKP 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.

303 ©2000 AspenTech. All Rights Reserved. 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

304 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

305 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

306 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

307 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

308 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

309 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

310 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Component Attribute Descriptions

311 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

312 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

313 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 Solids Properties - Conventional Solids

314 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 – Uses a mass fraction weighted average – Based on the GENANAL attribute – Parameter name: DENGEN

315 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

316 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Built-in Material Stream Classes * system default

317 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

318 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Solids Workshop 1 Objective: Model a conventional solids dryer. Dry SiO 2 from a water content of 0.5% to 0.1% using air. Notes – Change the Stream class type to: MIXCISLD. – Put the SiO 2 in the CISOLID substream. – The pressure and temperature has to be the same in all the sub-streams of a stream.

319 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus When finished, save as filename: SOLIDWK1.BKP Temp = 70 F Pres = 14.7 psia 995 lb/hr SiO 2 5 lb/hr H 2 O FLASH2 DRYER AIR WET DRY AIR-OUT Pressure Drop = 0 Adiabatic Temp = 190 F Pres = 14.7 psia Flow = 1 lbmol/hr 0.79 mole% N mole% O 2 Design specification: Vary the air flow rate from 1 to 10 lbmol/hr to achieve 99.9 wt.% SiO 2 [SiO 2 /(SiO 2 +Mixed)] Use the SOLIDS Property Method Solids Workshop 1 (Continued)

320 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

321 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus When finished, save as filename: SOLIDWK2.BKP Temp = 650 C Pres = 1 bar Gas Flowrate = 1000 kmol/hr Ash Flowrate = 200 kg/hr Composition (mole-frac) CO0.19 CO20.20 H20.05 H2S0.02 O20.03 CH40.01 H2O0.05 N20.35 SO20.10 Particle size distribution (PSD) Size limit wt. % [mu] Solids Workshop 2 (Continued)

322 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

323 ©2000 AspenTech. All Rights Reserved. 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

324 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

325 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Desired Product C$ 1.30 / lb By-product D$ 0.11 / lb Waste Product E$ /lb FEED PRODUCT REACTOR A, B A + B -- > C + D + E A, B, C, D, E 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.

326 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

327 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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).

328 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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).

329 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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 100. 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.

330 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

331 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

332 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus When finished, save as filename: OPT.BKP STEAM1 FEED TOP1 BOT1 TOP2 EFFLUENT STEAM2 TOWER1 TOWER2 Optimization Workshop (Continued)

333 ©2000 AspenTech. All Rights Reserved. RadFrac Convergence Objective: Introduce the convergence algorithms and initialization strategies available in RadFrac Aspen Plus References: Unit Operation Models Reference Manual, Chapter 4, Columns

334 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

335 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus MethodAlgorithmInitialization StandardStandardStandard Petroleum / Wide-boilingSum-RatesStandard Strongly non-ideal liquidNonidealStandard AzeotropicNewtonAzeotropic CryogenicStandardCryogenic Customselect anyselect any Convergence Methods (Continued)

336 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus RadFrac Convergence Algorithms RadFrac provides four convergence algorithms: – Standard (with Absorber=Yes or No) – Sum-Rates – Nonideal – Newton

337 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

338 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

339 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

340 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

341 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

342 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

343 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

344 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

345 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

346 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Specialized Initialization Methods Four specialized Initialization methods are available. Use:For: CrudeWide boiling systems with multi-draw columns ChemicalNarrow boiling chemical systems AzeotropicAzeotropic distillation columns CryogenicCryogenic applications

347 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.

348 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus Composition Estimates The following example illustrates the need for composition estimates in an extremely wide-boiling point system:

349 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

350 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

351 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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

352 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus feed on stage kg/h 50 C, 18 bar, HCl19.5%wt VCM33.5%wt EDC47.0%wt mass reflux ratio:0.7 flow : HCl in feed max 10 ppm VCM max 5 ppm HCl bar bar When finished, save as filename: VCMHCL1.BKP (step 1) and VCMHCL2.BKP (step 2) Use the PENG-ROB Property method RadFrac Convergence Workshop (Continued)

353 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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: CH 2 Cl-CH 2 Cl HCl + CHCl=CH 2 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. Vinyl Chloride Monomer (VCM) Workshop

354 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 1000 kmol/hr EDC 20C 30 bar CRACK FEED RECYCIN REACTOUT PUMP RECYCLE QUENCH COOLOUT COL1 HCLOUT VCMIN COL2 VCMOUT RStoic Model Heater Model Pump Model RadFrac Model 30 bar outlet pressure 500 C 30 bar EDC Conv. = 55% 10 deg C subcooling 0.5 bar pressure drop 10 stages Reflux ratio = Distillate to feed ratio = Feed enters above stage 7 Column pressure = 8 bar 15 stages Reflux ratio = Distillate to feed ratio = Feed enters above stage 8 Column pressure = 25 bar When finished, save as filename: VCM.BKP Use RK-SOAVE property method CH 2 Cl-CH 2 Cl HCl + CHCl=CH 2 EDCHCl VCM VCM Workshop (Continued)

355 ©2000 AspenTech. All Rights Reserved. Introduction to Aspen Plus 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.


Download ppt "©2000 AspenTech. All Rights Reserved. Introduction to Flowsheet Simulation Objective: Introduce general flowsheet simulation concepts and Aspen Plus features."

Similar presentations


Ads by Google