COLCON - Extraction Cascade with Backmixing and Control

5 COLCON - Extraction Cascade with Backmixing and Control 

A five-stage extraction column with control on the outlet raffinate phase is to be simulated. The solute balance equations for each phase are formulated according to Sec. 3.3.1.5. 

Allowing for the backmixing flow contributions in the inflow and outflow terms, the continuity equations for each phase, in stage n, are given by 

Proportional plus integral control manipulates the solvent flow rate based on the exit solute concentration in the raffinate. Thus G is a function of GO, KC, 

The simulation starts with the extractor operating at steady-state conditions, but with a relatively high outlet raffinate concentration. Control is implemented in order to reduce the raffinate concentration in accordance with a lower controller set point. 

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