High Pressure-Driven Batch Distillation Optimal Control for Methylacetate-Methanol Separation
Keywords:pressure-swing, batch distillation, methylacetate, methanol, optimal control, direct method
The pressure-swing distillation process with high-pressurized batch columns (HHP), with and or without a recycling stream, for separating methyl acetate-methanol is studied from the aspect of optimal control. The results show that even though not heat integrated, the HHP process benefits productivity. Based on the maximum recovery, the dynamic controllability without any kind of heat integration is researched. The optimal cyclic reflux ratio operating policy is extended to the separation of a third non-ideal minimum boiling azeotrope and close boiling mixture of industrial importance, and it shows significant reductions in energy expenditure since the derived discontinuous energy function tends to show cyclic "behavior" again. The proposed process, however, has the economic potential of both capital and energy by internal heat integration, ie. connecting the reboiler of the lower high-pressurized column to the condenser of the higher high-pressurized column. In the future, even more azeotropes, both minimum and/or maximum boilers, should be investigated in order to establish a "heuristic guidance" for HHP design and industrial usage.