Research On Energy-saving Control Strategy Of Water Pump In Pre-cooling System

Air-cooling system as an important part of air separation units, its heat transfer effects the whole system stable operation directly. The energy consumption of air-cooling system has always been concerned, they mainly in three aspects:consumption of cold in water-air heat transfer process, loss of water in the closed circle, consumption of electric power of water pump motor. The key to reduce energy consumption is new control technology; generalized predictive control algorithm (GPC) has become the new trend in the application of air-cooling system.Based on the working principle of air-cooling system, analyze energy consumption of water-air process, and establish the mathematical model of heat transfer by using the energy analysis method, express the inner regular of status parameters and process parameters by mathematical relations, in order to further analysis and research the heat transfer process.Secondly, confirm the control plan of air-cooling system heat transfer process. Select the flow of pre-cooling pump as operating variable、the export gas temperature of air-cooling tower as the controlled variable, and the quantity of gas into tower as the disturbance variable, those form a double closed loop control system to control the flow of cooling water and temperature of export gas. According to the analysis of water-air heat transfer system, The entire generalized process is a non-linear、hysteretic quality、slowly time-varying and random disturbance object, choose GPC algorithm as a controller of this system, GPC algorithm is easy to implement in practical application, and stronger robustness. Introduce the basic principle of GPC, and perform related simulation experiment.Again, through the comparison of cooling water pump motor throttling and the variable speed regulation, pointing out the principle of energy-saving of the vector control variable frequency speed, getting current decoupling pump motor model by vector control method, and realizing the optimal control of the flow of cooling water through the rotate speed adjustment.Finally, based on hybrid simulation platform, Acquire output signal of analog circuit by data sampling card, Verify the effectiveness of the GPC in air-cooling system heat transfer process. Modify parameters of GPC on-line, monitor the dynamic behavior of water-air heat transfer process.