Control of an energy-saving side-stream extractive distillation process with different disturbance conditions

It is important to study the dynamic controllability for the side-stream extractive distillation due to its superiority of energy saving. Control structures of the side-stream extractive distillation process are special and complex due to the instability of side-stream flow rate. In this work, the dynamic control of the side-stream extractive distillation was explored for separating azeotropic mixture of acetone and methanol. The detailed control structures were used to investigate the control strategies of side-stream extractive distillation. During the whole design process, the control of flow rate on side stream is a key factor for achieving this process efficient control. A new control structure combining a component controller and a side-stream throughput valve was proposed to achieve good dynamic performance for the side-stream extractive distillation process when ±10% disturbances were introduced, but it is difficult to control the ±20% feed disturbances. In addition, the side-stream extractive distillation takes about a longer time to reach a steady state while maintaining the purity of products, compared with conventional process. Research on control performance is of great significance to the development of energy saving technology for side-stream extractive distillation.