Process Model and the Solution Method

Tran and Mujtaba (1997), Mujtaba et al. (1997) and Mujtaba (1999) have used an extension of the Type IV- CMH model described in Chapter 4 and in Mujtaba and Macchietto (1998) in which few extra equations related to the solvent feed plate are added. The model accounts for detailed mass and energy balances with rigorous thermophysical properties calculations and results to a system of Differential and Algebraic Equations (DAEs). For the solution of the optimisation problem the method outlined in Chapter 5 is used which uses CVP techniques. Mujtaba (1999) used both reflux ratio and solvent feed rate (in semi-continuous feeding mode) as the optimisation variables. Piecewise constant values of these variables over the time intervals concerned are assumed. Both the values of these variables and the interval switching times (including the final time) are optimised in all the SDO problems mentioned in the previous section. 

The example problems are taken from Tran and Mujtaba (1997) and Mujtaba (1999) and only binary feed mixtures are considered in all three examples. 

Note Lang et al. (1994, 1995) provided case studies to show the effect of reflux ratio and solvent flow on the separation of azeotropic mixtures using repetitive simulation. The readers are directed to the original references for more case studies. 

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