Control of a Heat-Integrated Pressure-Swing Distillation Process for the Separation of a Maximum-Boiling Azeotrope

Abstract

Methanol and trimethoxysilane form a maximum-boiling homogeneous azeotrope whose composition changes fairly significantly with pressure, so separation into high-purity products is viable using pressure-swing distillation. Heat integration of the two columns can be used to reduce energy costs since they operate at different temperatures. The pressure in the high-pressure column is not controlled but “floats” depending on conditions in the base of the low-pressure column. An auxiliary reboiler is required to balance the heat duty in the low-pressure column. Since pressure affects the composition of the azeotropic, this variable pressure increases the complexity of the required control structure. The purpose of this paper is to develop a control scheme that can effectively handle large disturbances in feed flow rate and feed composition.