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Name, title of the presentation

Master project: Control structure design for a sequence of distillation columns

Tor Anders MarvikSupervisor: Sigurd SkogestadCo-supervisors: Vladimoros L. Minasidis

Johannes Jäschke

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Optimal control structure of two distillation colums in a sequence

Varying marked conditions

Computer model

Active constraint regions

Self-optimizing variablesRegion 1: V2, V1, xD2,B activeRegion 2: xD2,B active

General/systematic approach?

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The model

Based on column A by Skogestad

41 trayFeed on tray 21Assumtions:

Constant pressureConstant relative volatility Constant molar flows, No vapor holdup, Equlibrium on all stagesTotal condenser

Steady state model in Matlab

Conditions from Jacobsen

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Jacobsen’s map

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V2, V1, xD2,B active

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V2, V1, xD2,B active

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Approach to find self-optimizing variables?

• Brute force• Null space HF=0• Exact local method

• Possible disturbances– F,q,zF, prices,

• CV candiates – Tray temparature, composition, L1, V1, D1, L2, V2 D2, B2– Combination

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Brute force

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Combinations as CV

• Combination of Temperature (As Roal Bræck Leer)– All stages

– Every 5th stage

• Ratio with feed flow

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Size of the measurement error

• Temperature: 1 K• Consentraiton: 5%• Flow: 10%

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To do

• A LOT

• Standard approach• Brute force exact local method

• See how L changes to disturbances when the candiadate CV is fixed

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Thank you

Feedback and questions?