Design and application of acetonitrile refining process and computer intelligent control system

A continuous process for refining high purity acetonitrile synthesized by dimethyl sulphate and sodium cyanide was designed, and the advanced computer monitoring technology and intelligent control technology were used to monitor and control this process in real time. The continuous process resolved the difficulties of low product purity and yield efficiently by using some distillation techniques, such as pressure swing azeotropic distillation, etc. On which the computer supervisory and control system was built by high reliability and real-time S7-300 PLC, iFIX configuration software and industrial control computer IPC, which ensured that the system was running stable and real-time. Meanwhile, in order to improve the steady-state accuracy and adaptive ability of control system, a self-adaptive intelligent fuzzy-Smith control strategy with integrator was applied in the temperature control systems with big inertia and pure time delay. Industrial applications showed that the process and control system were efficient and ensured that the water content of acetonitrile was lower than 0.05% (wt), purity reached 99.9% (wt) or more, recovery rate reached 90% (wt) or more, and the economic benefits was obvious.