Design and control of acetonitrile/N-propanol separation system via extractive distillation using N-methyl pyrrolidone as entrainer

The extractive distillation process for separating a binary azeotrope of acetonitrile and n-propanol is investigated using N-methyl pyrrolidone as entrainer. On the basis of multiparameter optimization, a design with optimized operation conditions for the process is presented. Two dynamic control structures are proposed. Feed disturbances are used to evaluate the dynamic performance. The response results reveal that the control structure CS1 with temperature–composition cascade control loop can handle all the disturbances and maintain product purities, except one large transient deviation, while the improved control structure CS2 with average temperature control loop can overcome this obstacle and handle disturbances effectively.