Design and control of an alternative intensified process configuration for separation of butanol-butyl acetate-methyl isobutyl ketone system

Butanol/butyl acetate/methyl isobutyl ketone mixture forms two binary azeotropes at atmospheric pressure with a distillation boundary on the residue curve map. Conventionally, this mixture is separated by a process configuration including five distillation columns. Alternatively, this mixture can be separated by a modified process configuration including three distillation columns and two recycle streams, when an extra amount of MIBK is added into the system. However, this modified configuration increases both the capital and energy costs because of the recycled MIBK in the process. Thus, an alternative intensified process configuration is proposed in this study to separate this ternary system without adding any azeotropic agent. The effect of pressure on the azeotropic compositions is used to develop the proposed triple-column pressure swing distillation process. The economic evaluation shows that the proposed configuration reduces both the capital and energy costs significantly compared with the triple-column pressure swing distillation configuration given in the literature. In addition to the steady-state design, a plantwide control structure is developed and tested for robustness. The dynamic simulation results show that an effective base-level regulatory control is achieved with a control structure including composition controllers.