Research Of Ploymizationg Reactor Control System On Sliding Mode Variable Structure

The PVC polymerization process is an kind of complex object, having time-varying,nonlinear,large time delay and variable parameter's characteristic, Studied this complex object which is one of the most challenging subjects in the processing control domain. Sliding mode control has the peculiarity such as reduced order,better robustness and quickly reponse, and it has been broadly used in the field of control with the development of computer technology and the production of high speed switching circuit,but it is few applied in complex processing control.In this paper , Sliding mode control is used to control the process object and the application of sliding mode control is especially studied.The main factors influencing polymerization reaction is the reactor temperature influenceing the quality and output of the products directly, which is key and difficult. Duing to the comparatively complicated chemical reaction mechanism of polymerization reacting process, especially the process relating to materials, energy balance, reaction kinetic etc. Before studying on the sliding control temperature of PVC, by adopting mechanism modelling, the paper founds an dynamic model for suspension polymerization of vinyl chloride basing on reactor thermal balance to use the easily measured process parameters such as temperature,flow and so on.Sliding mode control in the actual application of the outstanding obstacle is the chattering problems,which can be avoided effectively or weaken by combining fuzzy control and sliding control. In order to improve and enhance the quality of control, on the basis of temperature control single-loop control of sliding mode control, using temperature-flow cascade control, and taking temperature deviation of inlet cooling water as feed-forward compensation, which make temperature control system has strong anti-jamming, improve control accuracy while reducing adjustor wave frequency and optimize accordingly the whole system. According to the analysis of simulation curves and the contrast between PID controller with disturbance,it can be concluded that the new control method not only has better robusness to the disturbance and varying parameter,but also has quick response and applying to the system with strict demand of export parameter under variational condition.