Nonlinear model based control of two-product reactive distillation column

Abstract

Nonlinear feedback control scheme for reactive distillation column has been proposed. The proposed control scheme is derived in the framework of Nonlinear Internal Model Control. The product compositions and liquid and vapor flow rates in sections of the reactive distillation column are estimated from selected tray temperature measurements by an observer. The control scheme is applied to an example reactive distillation column in which two products are produced in a single column and the reversible reaction A+B=C+D occurs. The relative volatilities are favorable for reactive distillation so that the reactants are intermediate boilers between the light product C and the heavy product D. Ideal physical properties, kinetics, and vapor-liquid equilibrium are also assumed. It is shown that the proposed control scheme keeps tight product composition control.

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Abbreviations

A:

reactant component

B:

reactant component; bottoms flow rate [kmol/s]

C:

product component

D:

product component; distillate flow rate [kmol/s]

EB :

activation energy of the reverse reaction [cal/mol]

EF :

activation energy of forward reaction [cal/mol]

EOA :

fresh feed flow rate of reactant A [kmol/s]

FOB :

fresh feed flow rate of reactant B [kmol/s]

kF :

specific reaction rate of the forward reaction [kmol ·-1 · kmol-1]

kB :

specific reaction rate of the reverse reaction [kmol·s-1 · kmol-1]

Ln :

liquid flow rate from tray n [kmol/s]

Mn :

liquid holdup on tray n [kmol]

rs :

liquid flow rate in the stripping section

Vs :

vapor flow rate in the stripping section

rr :

liquid flow rate in the rectifying section

Vr :

vapor flow rate in the rectifying section

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Correspondence to Myungwan Han.

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Han, M., Clough, D.E. Nonlinear model based control of two-product reactive distillation column. Korean J. Chem. Eng. 23, 540–546 (2006). https://doi.org/10.1007/BF02706791

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Key words

  • Reactive Distillation
  • Nonlinear Internal Model Control
  • Dual Composition Control