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PROCESS MODELLING AND MODEL ANALYSIS © CAPE Centre, The University of Queensland Hungarian Academy of Sciences A Model Building Framework
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PROCESS MODELLING AND MODEL ANALYSIS 2 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences An Overview The process system (SISO, MISO,MIMO) The modelling goal A systematic approach The necessary ingredients
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PROCESS MODELLING AND MODEL ANALYSIS 3 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences The Process System Inputs, u Outputs, y States, x Disturbances, d S u y x y = S[u,d] (SISO, MIMO SS or dynamic) d
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PROCESS MODELLING AND MODEL ANALYSIS 4 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences The Modelling Goal Flowsheeting simulation (rating) design optimization Process control prediction regulation identification diagnosis Application areas Performance specifications real, integer or Boolean indices
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PROCESS MODELLING AND MODEL ANALYSIS 5 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences A Systematic Modelling Procedure Problem definition Controlling factors Problem data Model construction Model solution Model verification Model calibration & validation 1 2 47 5 36
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PROCESS MODELLING AND MODEL ANALYSIS 6 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences Clear description of system establish underlying assumptions Statement of modelling intention intended goal or use acceptable error anticipated inputs/disturbances 1. Problem Definition
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PROCESS MODELLING AND MODEL ANALYSIS 7 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences Definition Example (Step 1) CSTR description details lumped ? dynamic Goal (intent) inlet change range +/-10% accuracy control design
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PROCESS MODELLING AND MODEL ANALYSIS 8 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences A Systematic Modelling Procedure Problem definition Controlling factors Problem data Model construction Model solution Model verification Model calibration & validation 1 2 47 5 36
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PROCESS MODELLING AND MODEL ANALYSIS 9 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences 2. Controlling Factors / Mechanisms Chemical reaction Mass transfer convective, evaporative,... Heat transfer radiative, conductive, … Momentum transfer ASSUMPTIONS
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PROCESS MODELLING AND MODEL ANALYSIS 10 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences Mechanisms - CSTR (step 2) Chemical reaction A P Perfect mixing No heat loss (adiabatic)
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PROCESS MODELLING AND MODEL ANALYSIS 11 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences A Systematic Modelling Procedure Problem definition Controlling factors Problem data Model construction Model solution Model verification Model calibration & validation 1 2 47 5 36
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PROCESS MODELLING AND MODEL ANALYSIS 12 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences 3. Data for the problem Physico-chemical data Reaction kinetics Equipment parameters Plant data
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PROCESS MODELLING AND MODEL ANALYSIS 13 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences Data - CSTR (step 3) Reaction kinetics data: k 0, E, H R Physico-chemical properties specific heats, enthalpies, … Equipment parameters: V
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PROCESS MODELLING AND MODEL ANALYSIS 14 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences A Systematic Modelling Procedure Problem definition Controlling factors Problem data Model construction Model solution Model verification Model calibration & validation 1 2 47 5 36
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PROCESS MODELLING AND MODEL ANALYSIS 15 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences 4. Model construction Assumptions Boundaries and balance volumes Conservation equations mass energy momentum Constitutive equations reaction rates transfer rates property relations balance volume relations control relations & equipment constraints Characterizing Variables Conditions (ICs, BCs) Parameters
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PROCESS MODELLING AND MODEL ANALYSIS 16 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences CSTR Model (step 4) Assumptions A1: perfect mixing A2: first order reaction A3: adiabatic operation A4: equal inflow, outflow A5: constant properties Equations conservation constitutive
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PROCESS MODELLING AND MODEL ANALYSIS 17 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences CSTR Model (step 4) Initial Conditions Parameters and inputs 10% accuracy 30% - 500% accuracy
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PROCESS MODELLING AND MODEL ANALYSIS 18 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences A Systematic Modelling Procedure Problem definition Controlling factors Problem data Model construction Model solution Model verification Model calibration & validation 1 2 47 5 36
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PROCESS MODELLING AND MODEL ANALYSIS 19 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences 5. Model solution Algebraic systems Ordinary differential equations Differential-algebraic equations Partial differential equations Integro-partial differential equations
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PROCESS MODELLING AND MODEL ANALYSIS 20 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences CSTR - Numerical Solution (step 5) Solution of differential-algebraic equations using structuring techniques using direct DAE solution
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PROCESS MODELLING AND MODEL ANALYSIS 21 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences A Systematic Modelling Procedure Problem definition Controlling factors Problem data Model construction Model solution Model verification Model calibration & validation 1 2 47 5 36
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PROCESS MODELLING AND MODEL ANALYSIS 22 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences 6. Model verification Structured programming approach Modular code Testing of separate modules Exercise all code logic conditions Constraints Quality documentation
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PROCESS MODELLING AND MODEL ANALYSIS 23 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences A Systematic Modelling Procedure Problem definition Controlling factors Problem data Model construction Model solution Model verification Model calibration & validation 1 2 47 5 36
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PROCESS MODELLING AND MODEL ANALYSIS 24 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences 7. Model calibration/validation Generate plant data Analyze plant data for quality Parameter or structure estimation Independent hypothesis testing for validation Revise the model until suitable for purpose
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PROCESS MODELLING AND MODEL ANALYSIS 25 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences For Discussion (1) Open tank system
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PROCESS MODELLING AND MODEL ANALYSIS 26 © CAPE Centre, The University of Queensland Hungarian Academy of Sciences For Discussion (2) Closed tank system
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