Abstract:

In this study, the performance of conventional extractive distillation, heat integrated pressure-swing extractive distillation, and extractive dividing wall column distillation is investigated for the separation of benzene and cyclohexane with furfural as entrainer. Based on steady state design, the dynamic control of these three systems is studied with assistance of Aspen Dynamics, and several control structures for each system are presented to handle the feed flow rate and feed composition disturbances. The dynamic simulation results reveal that, for the conventional extractive distillation process, control structure with reboiler duty being proportional to the feed flow rate shows its superiority when it comes to the feed disturbances. In the heat integrated pressure-swing extractive distillation process, the system is sensitive to the pressure. For this reason, pressure-compensated temperature control scheme is proposed based on another control structure, and its dynamic responses reveal that the feed disturbances can be objected effectively. For the extractive dividing wall column distillation process, control structure without vapor split ratio as a manipulated variable, which is easier for to be realized in industrial production and can maintain the product purities at their specifications, is chosen rather than the one with vapor split ratio.

Key words: extraction, dividing wall column, heat integrated pressure-swing, azeotrope, control

摘要：

将常规萃取精馏、差压热耦合萃取精馏以及隔壁塔萃取精馏技术应用于以糠醛为萃取剂的苯和环己烷共沸物分离过程。在稳态模型的基础上,利用Aspen Dynamics软件进行控制研究,对三工艺流程提出了若干控制策略。结果表明,对于常规萃取精馏过程,再沸器热负荷与进料量比值控制结构在降低控制过程超调量方面表现出明显优势;对于差压热耦合萃取精馏过程,带有压力-补偿控温策略的方案控制效果更佳;而对于隔壁塔,则选择了无隔板下方气液分离比控制的结构来作为较优的控制策略。

关键词: 萃取精馏, 差压热耦合, 隔壁塔, 共沸物, 控制