OPTIMISATION OF BATCH DISTILLATION OPERATIONS

The maximum principle of Pontryagin has been used to calculate the optimal route through a batch distillation under specified conditions. These are: (1) A binary mixture with no hold-up and constant boil up rate. (2) A binary mixture with no hold-up but the boil up rate is a linear function of the still composition. (3) A multicomponent mixture with no hold-up and constant boil up rate, (4) A binary mixture with condenser hold-up considered and with a constant boil up rate. Each of the four operations has been compared with the equivalent constant reflux ratio and with the constant overhead product purity operation. The time advantage of the optimal route over the constant overhead composition route varies from 0·3 to 5·7 per cent in the four cases considered. The advantage over the constant reflux ratio route is greater varying from 8·3 to 13·5 per cent. © 1969.