INSTRUMENTATION FOR P&ID’s

But first.... Design pressures... It’s best to group equipment and give it all the same maximum op. pressure What groups would you create? What would the max op. pressure be?

Ground rules for additional equipment Send non-useful gases (Gas_purge 200 kg/hr, Lights 51 kg/hr) for combustion in the syngas htr (it’s a fired heater) Send Fusil_oil (19 kg/hr) to waste treatment plant or to the syngas htr (need tank & pump) - implications?

Ground rules for additional equipment Storage Tanks Provide an ‘off spec’ tank for the Product sized for 12 hours of hold-up at normal rates In addition, provide at least 2 tanks for the Product Provide an 8 hour storage tank for the Recovr_water Storage Tanks can have L/D = 1 (or less) Show product storage tanks sending material to “existing truck and railcar loading” Show Recovr_water storage tank sending water to “waste treatment” plant - recycle issues?

Ground rules for additional equipment Pumps Put a pump on the “acetone column” bottoms product so we can run it at as low a pressure as possible (at simulation stated pressures) to ensure we remove all lights etc. don’t put a pump on “degasser” bottoms (let’s increase the pressure accordingly) what are the trade-off’s? Provide a pump on the “off spec” storage tank to recirc material back to the Acetone column feed. This will help us during start-up or upsets

Ground rules for additional equipment ? hrs ? hrs 12 hrs 8 hrs

Now Back to our regularly scheduled show...

Instrumentation Cookbook Instrumentation Why Are We Doing This ESTIMATOR - To Size The Pumps We Need To Include “Inline” Instrumentation Provide A Basic Understanding Of Controls Nomenclature and Their Application PI FE

Instrumentation Cookbook Instrumentation Objective: To Produce A Viable Control Scheme in a way that uses and improves our understanding of the simulation and gives us essential information to size the pumps To have some examples of controls that could be applied to our process To understand why these control schemes were selected so that you can form your own judgement

Instrumentation Cookbook Control Loop A Simple Feedback Control Loop Set Point Often not shown Measured Variable (temp, pressure, flow...) Controller Manipulated Variable FE FIT FIC FV

Instrumentation Naming Instrument Society Of America (ISA) ISA Typical Letter Combinations.xls

Instrumentation Cookbook P&ID’s - Symbology Equipment Symbology Instrumentation Symbology See the document “P&ID Symbols and Photos.DOC”

Instrumentation Cookbook P&ID’s - Symbology Located in DCS (process control computer) LIC Software Signal Physically located ‘in field’ LT Physical wire “hardwired”

Instrumentation Cookbook The “Control Valve” Actuator - driven by Compressed Air Elec Signal To valve (4-20 mA DC signal) Valve

Instrumentation Cookbook Typical Controls Level Flow Pressure Temperature Composition

Instrumentation Cookbook Level Control Purpose Prevent the tank from overfilling / running dry LT LIC LV

Instrumentation Cookbook Level Control Purpose Hold a liquid “Seal” LT LIC No Gas! LV

Instrumentation Cookbook Level Control Purpose Prevent pump from running dry and thus being destroyed LT LIC LV Note: - valve always on disch to prevent flashing on pump suction - pump may also require a minimum flow bypass

Control Systems Aside - Speed Measured Variable can be slow to measure (I.e. the composition using an analyser) or fast (pressure) The Manipulated Variable can be slow too (I.e. adjusting the hot water tap in your shower) The level in a tank can take hours to change (slow)

Control Systems Aside - Speed Slow Things Say > few seconds Reducing Pressure by Opening a valve on a large gas filled tank Measure Composition (analysers) Change Level In Large Tank Fast Things Less than a second Measure Pressure Measure Flow (Diff Press) Measure Temp (?) But…. It’s all RELATIVE !!

Instrumentation Cookbook Flow Control Purpose: Ensure steady material flow rate Smooth feed to columns Set Production rate Fast to Measure Flow Changes usually require a control valve to change it’s position which can take seconds. Vapour systems have a ‘capacitance’ that need to be overcome before the flow changes are experienced everywhere in the system

Instrumentation Cookbook Flow Control FT FIC FE FIC M FT I FV SIC FE Variable Speed Drive Mount FE upstream in vapour systems to minimize pressure/density effects

Instrumentation Cookbook - Ratio Flow Control SP FIC Set one flow rate Other flow is proportionally controlled to first flow Ensure correct mixture / recipes FT FRIC SP FV FE FIC SP FT FV FE

Instrumentation Cookbook Pressure Control Similar to Level (control of material inventory) Very fast for incompressible fluids Hard to say for compressible fluids, depends on system volume but probably slow

Instrumentation Cookbook Pressure Control Control Upstream | Control Downstream PIC PIC PT PT PV PV Need to downstream (header or process) pressure Need to control vessel pressure

Instrumentation Cookbook Pressure Control Condensable Gas PIC PV PT Need to control vessel pressure Fast or slow?

Instrumentation Cookbook Pressure Control Liquid Pressure Control PIC PT PV Control pump discharge pressure - not very useful

Instrumentation Cookbook Pressure Control Liquid Pressure Control PIC FIC PT Pressure control on pump provides a steady pressure to the flow control valve Essentially the pump flow is fixed through this scheme. By making the pressure at the inlet of the FV constant the flow control will be better (more linear). Show pump curve dropping as flow increases. FT PV Control pump discharge pressure - ensure constant feed pressure to FV FV FE

Instrumentation Cookbook Temperature Control Normally control the ‘flow’ of one fluid to change the temperature of another In Reality it’s an LMTD change that affects the exchanger duty Q = U A Tln Increase in hot flow rate in second box

Instrumentation Cookbook Temperature Control Liquid / Liquid - control on cooling media Bottom box shows decrease in hot stream flow rate and corresponding - decrease in LMTD to reduce overall duty of exchanger - increase in c/w outlet to reduce LMTD -decrease in cooling water flow C/w

Instrumentation Cookbook Temperature Control Liquid / Liquid - control on process C/w

Instrumentation Cookbook Temperature Control Steam Pressure Control T Increase Stm Pressure

Instrumentation Cookbook Temperature Control Condensate Level Control Reduce flooded Area

Instrumentation Cookbook Cascade Control Example - Driving to Montreal You’re driving / steering the car Someone else is telling you which roads to drive on and when to turn

Instrumentation Cookbook Cascade Control One Control Loop Determines Setpoint of a Second Loop FT -Using the flow through the pump to control the rotational speed of the pump FE FIC M SP Flow DP High Speed Low Speed I SIC SP Variable Speed Drive

Instrumentation Cookbook Cascade Control PIC FIC FT FE FV PT Common Around Distillation Columns Where There Are Slow Loops

Instrumentation Cookbook Controller Interaction Many Controllers Interact but some configurations Interfere with each other I.e. the control of reflux flow interacts with the column bottom level control but two flow controllers on the same pipe will interfere with each other (they duel for control of the flow)

Instrumentation Cookbook Controller Interaction Duelling Control ? LT LIC FIC LV FT FE

Instrumentation Cookbook Controller Interaction Duelling Control ? LIC LT FIC FT FE LV

Instrumentation Cookbook Controller Interaction Duelling Control ? SP= 75 psig SP= 35 psig PIC PIC PT PT 100 psig Compressed Air User 2 User 3 User 1 PV PV

P&ID Cookbook -By Equipment

P&ID Cookbook - Pumps PRV M I HS PI

Pump - Min Flow Bypass RO PI LT PI LIC LV HS I M HS

Reflux Tanks Set@ From Condenser TO LV I To Pump PI TI LIT Vent to Safe Locn Set@ PI From Condenser From Pump LAHL HLL = 4’-6” TI TO LV LIC NLL = 3’-6” LIT LLL = 2’-0” LLLL = 2’-0” LSLL I LALL Pump S/D To Pump

Compressors - Centrifugal For our purposes treat controls as a black box But... Provide an input control signal (cascade) Remember cooling water req’d (lube system...) CWS CWR Control From ? SIC M By Vendor By Owner

Columns Level control Pressure control Put a control scheme to ensure Treat the top and bottom independently of each other Pressure control Level control Composition control Put a control scheme to ensure Feed rate is constant or is slowly changing

Columns - Bottoms FT LIT TE FIC LIC TIC Put level control on bottoms outflow when outflow rate > 10 x boil up rate Put level control on Steam control boilup rate > 10 x outflow rate otherwise either scheme okay Columns - Bottoms FIC FT HHLL 5 bar Stm HLL LIT NLL Cascade temperature to steam flow LLL LLLL Low P Cond T TE LAHL LIC TIC

Columns - Overhead FV FT TE TIC FIC CWS CWR PV PT PIC RO

Instrumentation Cookbook Column Control If a flow rate dominates use it to control the level Column Overhead Control - Scheme 1 when the draw rate is 10 x > reflux rate Manipulate Distillate draw rate to control Reflux level Manipulate reflux rate to control Column Composition

Instrumentation Cookbook Column Control Column Overhead Control - Scheme 2 when the reflux rate is 10 x > draw rate Manipulate Distillate draw rate to Manipulate Column Composition Manipulate reflux rate to control control Reflux Drum level

Instrumentation Cookbook Tanks - Storage PRV Temperature Control May Be Required -does material freeze / boil? LAHH LSHH I LY TI LSHH s LI LSLL LAHL LIT I M LV

Workshop Draw the level control that should go on a storage tank Hand this in at the end of class... Draw the level control that should go on a storage tank Provide a different control scheme for the reactor / condenser / flasher P&ID draw it explain how your scheme works and responds to upsets explain the pros/cons of your scheme using a BFD, including the syngas process, show how pressure control can be done

END

Instrumentation Cookbook Tanks - Process Surge PSV Consider Pressure Control LT LIC LV

Heat Exchangers - Condenser Vent to Safe Locn TV TIC CWS TV on condenser outlet to prevent c/w flashing inside condenser during turndown TAHL TE