Modelagem, simulação e controle do processo de pressure swing distillation com integração total para o sistema acetonitrila-água.

Abstract

The binary mixture composed of acetonitrile (MeCN) and water (H2O) forms a minimum azeotrope highly sensitive to pressure variations, suitable for separation through Pressure Swing Distillation (PSD). This process is considered highly energy-efficient due to the possibilities of thermal integration, particularly between the condenser and reboiler of the columns, known as Fully Heat-Integrated PSD (FHIPSD); furthermore, as it does not use solvents, it is regarded as an environmentally friendly process. However, despite the energy-saving benefits, integration reduces process control flexibility, potentially leading to pressure fluctuations in the highpressure column. This study evaluates the use of a partially flooded reboiler/condenser and hotvapor bypass as means to regain a degree of freedom in the process. Five control structures for FHIPSD were assessed, including one without high-pressure column pressure control, three employing different hot-vapor bypass configurations, and one with a partially flooded reboiler/condenser. The study analyzed the ability to control the high-pressure column pressure under disturbances in feed flow rate and composition, also assessing the capacity to maintain product specifications. Based on the results obtained through simulations using Aspen Plus DynamicsTM, it was concluded that both strategies (partially flooded reboiler/condenser and hot-vapor bypass) effectively recover a degree of freedom that can be utilized for high-pressure column pressure control.