The Research And Design On The Control System Of Spray Cooling Based On PLC

With the increasing of greenhouse effect in recent years, the summer weather in north China is drought and less rain, there is a phenomenon of high temperature and dry air, which brings a lot of trouble to people’s life and production activities, especially in the case that the cost of cooling in the production process of some enterprises is increased. The spray cooling control system is developed for the cooling device in the dry climate region, which is low energy consumption and no pollution and has a wide range of promotional value and development potential. Based on the coal chemical project cooperated with XX company, the key technology of realize the automatic control of spray cooling is investigated in this thesis.The main research work and innovative conclusions include the following five aspects:(1) A large number of literatures at home and abroad were referred, and the application fields of spray system at home and abroad in recent years were also summarized. According to the present development situation of spray cooling system and the field environment and process requirements were considered, a spray cooling control system was designed.(2) In the basis of referring plenty of literatures, from the perspective of improving cooling effect, the spray cooling device was selected, the installation of some the key points were determined and the control strategy of the spray cooling system was formulated.(3) According to the principle of spray cooling and the field environment, the relationship between the temperature and the amount of water was established and control object was determined. In order to improve the cooling effect, the factors that influence the spray cooling effect were analyzed and the fuzzy self-tuning PID control algorithm was used to make the cooling control system work in the optimal state.(4) The S7-200 PLC was selected as the central controller and the touch screen was taken as a machine, combined with the control points on the module configuration, the temperature, the pressure, the flow sensor and the liquid level switch and so on were selected. The process of electrical design was illustrated and the hardware part of the spray cooling control system was designed in this thesis.(5) Through the analysis of the spray cooling process, the software design of automatic spray cooling control system was completed. The PLC programming software was used to write the symbol table and design the flow program. The EB8000 software was used to design the PC monitoring picture. Finally, this system was debugging.The developed system is mainly suitable for the high temperature and dry areas, which can be used to reduce the environmental temperature of chemical plant. The developed system has the merits of high degree of automation, accurate controlling, saving water, reducing the working environment temperature, cutting down the workload of operator. The developed system also has good control function and high cost performance.