Application Of SIMATIC PCS7 System In PVC Production

Polyvinyl chloride(PVC)is the introduction of chlorine atom in macromolecules,so that it surpasses polyethylene in the aspects of flame resistant,transparency,folding and mechanical properties,and it is also one of the five general thermoplastic resins in the world.The production of PVC has a strong continuous control,so there are many variables to operate and adjust.And according to the process demand of PVC production,the onsite implementing agencies will have complex control logic structure.Considering that the production of polyvinyl chloride will also involve the proportion and transmission of toxic and harmful gases such as chlorine,so the control system itself will have high stability and sensitivity.The change of temperature is the key factor affecting the degree of polymerization,if the temperature is not good in the range of production process temperature curve,then the product will have quality problem.Therefore,the focus and difficulty of this topic is: first how to establish a mathematical model of temperature;then find a suitable algorithm to simulate and optimize the mathematical model of temperature,and prove that the algorithm has an ideal control demand.The main work of this paper is: First,the production process of polyvinyl chloride is briefly introduced,paving the way to establish the mathematical model of polymerization temperature;Secondly,according to the heat change of polymerization reaction stage,the mathematical model of temperature change is established using foundation treatment modeling and the transfer function will be used to control polymerization temperature;Third,using the method of PID parameters tuning based on immune particle swarm optimization to control the opening of the circulating water valve,so that the polymerization temperature is fluctuated within the allowed range.Through MATLAB simulation of transfer function,it is found that the dynamic performance index of the immune particle swarm optimization algorithm is superior to the system performance index before setting.At the same time,the method is put into practice and found that the polymerization temperature can be maintained within 0.2 ? of the optimum temperature;Fourth,the control of the fine chemical industry,from two aspects of hardware and software design.In the hardware,the height redundancy is used in the control cabinet to ensure the reliability of the system.In the software design,through the design of upper computer and lower computer,the software part can be well integrated with hardware part.Because the hardware and software are highly redundant design,when the PCS7 control system is applied to the control process of PVC production,the stability of the system is obviously improved.Due to the existence of control system redundancy,the standby controller,field bus and server can be used in the system fault or maintenance equipment,so that the production process is not shutdown operation.;Fifth,in the process of the implementation of the control scheme of polymerization reaction stage,through the use of powerful WINCC manmachine interface,can well understand the production situation,and the production link can be interfered through operator panel.Through the introduction of the control scheme of polymerization reaction stage,the application of PCS7 control system is running well in PVC production.At the same time,the various control links of production are explained by the procedures and using WINCC graphics card monitor production.Using PCS7 control system and immune particle swarm optimization algorithm to control the production of PVC,the annual production of PVC is nearly doubled,the failure rate of the system is reduced to 0.4 / 100,000,the utilization of cooling water is reduced by 20 %,the reaction time is 24 % lower than the original,and the economic benefits and the quality of products have been significantly improved.