Advanced Process Control Development For Chloromethanes Process And Air Separation Unit

Chloromethanes(CMS)is an essential organic chlorine product and chemical raw material in the industry.It is also an indispensable chlorine product in the chlor-alkali industry.The production of methane chloride in China mainly adopts the methanol process.This process requires refined products obtained through methanol hydrochlorination,methyl chloride polychlorination two-step reaction and continuous multi-stage distillation process.Due to the complex reactions and lardge disturbance affection,it is difficult to achieve the control target with the PID controller.The air separation unit(ASU)is an air separation plant whose gas products are used as important production auxiliary materials in many industries.Its production process uses air as raw material,adopts cryogenic technology,utilizes different boiling points of various components,and finally separates oxygen,nitrogen,and argon through rectification.In the entire production process,the production load often needs to be adjusted to satisfy the downstream user's demand.Affected by the production process and other factors,the fluctuation range is large,the control variances are large,and the production process is difficult to control.For the production process of the above two processes,it is found that the traditional single-loop PID control strategy cannot meet the site control requirements.Therefore,an advanced process control strategy are in need.According to the real industrial processes,the advanced process control systems were developed in this work.The main contributions of this thesis are as follows:(1)According to the actual production processes of methane chloride and air separation,the production process and on-site production conditions have been analyzed,and the objectives,implementation scope,control strategies and control schemes for advanced control have been determined.A step test has been done.(2)Based on advanced control objectives and control schemes,using the identified process model,the advanced process control has been developed,and a good control effect has been achieved.By comparing the production data of the advanced control before and after the investment,the effectiveness and feasibility of the developed advanced process control scheme have been verified.(3)For the application of advanced control in industrial practice,a multivariable advanced control software has been developed using C#language.Using the established control model,the application of advanced control software has been applied to verify the feasibility and effectiveness of the software.(4)Aiming at the problem of model mismatch in the advanced control and the optimization problem of the controlled system after entering the steady state,a method based on correlation integral optimization has been studied to realize real-time optimization of the steady state during the implementation of advanced control.The simulation results has verified its feasibility.