| With the increase of labor cost and the development of automatic technology, With the increase of labor cost and the development of automatic technology, the automation of domestic chemical industry ushers the spring. Many medium-sized chemical enterprises begin to introduce advanced equipment and technology to improve the level of automation, reduce staff labor intensity, improve production efficiency. Temperature control of batch reactor is the key of chemical production process, and its control effect directly affects the efficiency of production and quality of the product. This thesis studies the application technology of the temperature control strategy of the aircraft deicer reactor, analyzes the difficulties and key points in the temperature control of the reactor and establishes the mathematical model of temperature control system. Finally, this thesis designs a set of advanced batch reactor temperature control system based on the Siemens S7-400. The main research of this thesis is as follows:(1) Analyse the key points and difficulties about technological process and control of batch reactor.This part shows the main factors and the difficulties about temperature control of batch reactor through analyzing the overall structure and production technology of batch reactor. In the heating stage, it is not only to ensure the heating rate, but also to avoid the temperature overshoot and shock, because there is time-delay in the heat transfer process. As a result, it is difficult to ensure the heating rate and the stability of the system at the same time. In the constant temperature stage, the temperature is affected by the temperature fluctuation of the cooling water and the nonlinear chemical reaction of the material in the reactor, so accuracy and stability of the temperature control system is poor, which seriously affects the quality of the product.(2) Establish the mathematical model of the reactor temperature control system.This part analyses the intrinsic mechanism of the controlled object, according to the principle of heat conservation in the temperature control system of batch reactor, and establishes mathematical models of the reactor in heating stage and constant temperature stage.(3) Research of the algorithm for batch reactor temperature control.This part shows the plan according to the analysis of the difficulty in the temperature control system of batch reactor. In the traditional production process, the temperature control system can’t take into account both heating rate and system stability. To solve the problem, this paper proposes the control scheme of Smith variable structure PID. In addition, because of the characteristics of nonlinear and large time-delay in the reactor constant temperature control system, this paper proposes SDP (Smith-DMC-PID) control algorithm to improve the system stability and control accuracy. Finally, because of the reactor’s complex structure and heat transfer lag, it is likely to cause uneven temperature inside the reactor, so the control scheme of stirring motor based on Fuzzy control is proposed.(4) Implement of the batch reactor control system.Based on the development platform of Siemens Step7+WinCC, this paper constructs the communication network of Profibus-DP and Profinet. The control algorithm is realized by OPC technology, and the automation system of the reactor is built.In this paper, the temperature control system of batch reactor is studied. Then, the paper establishes the mathematical models of the reactor temperature control system and proposes three kinds of emperature control strategies. In addition, this thesis designs and selects the hardware that required by the control system and builds the communication network by Profibus-DP and Profinet in order to realize the application of the control algorithm. The results show that the control system has good stability and high control precision, and there is a certain significance for the batch reactor temperature control system and other system. |
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