EQMULTI - Continuous Equilibrium Multistage Extraction

A countercurrent multistage extraction system is to be modelled as a cascade of equilibrium stages. 

As in example EQEX, the mass transfer capacity coefficient KLa may be set high to obtain near equilibrium stage conditions. 

Note that the program is written such that the number of stages in the cascade, Nstage, can be varied as an additional parameter in the simulation. The stage numbers can be plotted versus the final values by choosing [i] as the X-axis. In this way the steady state concentration profiles can be graphed. A part of the program is shown below. 

Run the model for the five-stage model and ascertain if equilibrium is attained for each stage. Reduce Kl3 by a factor of 10 and check again. Reduce L and G by the same factor. Explain the effects in terms of the process time constants. 

Confirm that the overall solute balance is satisfied at steady state. 

As explained in Sec. 3.3.1.4, the unsteady-state solute balance equations for each phase are defined for any stage n by 

As in example EQEX, the constant K is set sufficiently large to obtain equilibrium, for the compositions, Xn and Y , of the streams leaving each stage. 

FIVE STAGE COUNTERCURRENT EXTRACTION CASCADE EQUILIBRIUM STAGE MODEL 

PHASE VOLUMES IN EACH STAGE VOLUMETRIC FLOW RATES INLET CONCENTRATIONS EQUIL AND MASS TRANSFER 

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EQMULTI - Continuous Equilibrium Multistage Extraction System... 

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