Design And Realization Of Automatic Water-adding Reform For Sintering Flue Gas Desulfurization In Capital Iron And Steel

The contradiction between population and resources,economic development and ecological environment has become the most restrictive factor in China's modernization.In order to maintain sustainable development,the iron and steel industry must reduce environmental pollution.Reducing sulfur dioxide emissions is one of the key links to reduce environmental pollution in the iron and steel industry.The desulfurization of sintering machine flue gas in the iron industry is a key project for the prevention and control of acid rain and sulfur dioxide pollution in the country.Strict legal responsibility and prevention and control of pollution according to law will promote the emission standards of pollutants in the iron and steel industry.It is imperative to control flue gas desulfurization.Before reforming the automatic water-adding system for sintering flue gas desulfurization,constant pressure water supply system was adopted.Two pumps were used one by one.By detecting the pressure of water supply main pipe,the frequency of frequency converter was controlled by PID to keep the pressure of main pipe constant.Because of the sudden change of the on-off of the solenoid valve,the amount of water added becomes ladder-shaped,the linear relationship between the current of bucket elevator and the amount of water added is poor,which makes the amount of water added and the desulfurizer unable to reach the optimum ratio,and the amount of water added has little effect on the desulfurization efficiency and can not meet the requirements of environmental protection indicators.The large amount of water added resulted in silos and caking in desulfurization tower,which greatly increased the workload of post personnel in dealing with silos.Therefore,the automatic water adding control of desulfurization system is particularly important.In this thesis,the existing problems of the original desulfurization automatic water adding control system are analyzed in depth,and on this basis,the transformation scheme is given.(1)Eliminate the solenoid valve and shut-off at the top of desulfurization tower,add four pumps to water two series of four humidifiers,install separate pump-controlled flowmeter on each pump pipeline,judge the amount of ash in the bucket-lift according to the current of the bucket-lift,and control the speed of the pump through the frequency converter to achieve the purpose of controlling the amount of water added.(2)According to the approximate principle of water pump,the relationship between water supply and pump motor frequency is deduced.The relationship between current of bucket elevator and water supply is established to achieve the purpose of adjusting water supply by adjusting frequency of frequency converter.(3)Based on the fuzzy control,the closed-loop control system of automatic water-adding based on the fuzzy controller is designed.The closed-loop control elements are formed between the current of bucket elevator,the flow of water-adding and the frequency of frequency converter,which achieves the purpose of intelligent control and improves the control accuracy.Through the transformation of existing equipment and PLC control system,the transformation task has been completed.According to the actual operation effect,the amount of water added can be changed according to the change of electric current of bucket elevator,and the desulfurization efficiency is obviously improved.After shutdown,the inside of desulfurization tower was inspected,and there was no silo problem,so the purpose of transformation was achieved.