| The ninth water plant,as the largest water plant in Beijing,is responsible for more than half of the water supply in Beijing.Due to the heavy workload of daily work,how to ensure the safety of urban water supply has become the first concern.As an important part of the water treatment process in the ninth water plant,the filter section is currently facing the key problems in the production of two major impacts,such as the shortening of the filter fly in summer,which leads to the need for frequent backwashing,and the low control precision of the main control valve with high failure rate of the backwashing of the coal filter.In order to solve these key problems,based on the existing technology and equipment of the three stage filter in the ninth water plant,the automatic backwashing technology of the filter of the ninth water plant is designed and studied in this paper.The specific content of the research work is as follows.First,a whole scheme design of filter automatic control system is put forward.In view of the above two key problems affecting the filter production,and in order to solve some problems of the existing automatic control system,two technical problems related to automatic backwashing are studied.To solve the problem of the main control valve for backwashing of the coal filter,a solution is put forward to adjust the backwashing water quantity by using the frequency control of the recoil pump instead of the main control valve.The PID control algorithm used in the inverter control is studied.Through the establishment of the system model and the use of the Simulink tool of MATLAB,the whole set of variable frequency speed control system is simulated.For the control of frequency converter,according to the actual situation and simulation results,the frequency negative feedback PID control mode is used in the starting or stopping stage of the backwash pump,and the PID control mode with dead zone is used in the normal backwash regulation stage.In order to solve the problem of short filter fly of coal filter in summer,the technical scheme of automatic queuing backwashing process is studied.Through the use of Little’s law to study and analyze the process of backwashing process of filter,A rapid flush method with two or three filter steps staggered while backwashing at the same time was proposed,and the problem of short filter fly of filter in summer is solved from the angle of automatic control.Finally,the hardware and software design of the filter automatic control system was carried out.Including the design of a set of highly reliable industrial Ethernet,a variety of program design in the filter field PLC and public PLC,filter operation monitoring station and touch screen system configuration design.In the programming of the public PLC,the two conclusions of the research are also implemented in the program,and conducted a field test,running well.In this paper,the research on the two key problems affecting the filter production has certain practical value,and can better solve the key problems in the ninth water plant filter at present,and ensure the safety of water supply in the nine factories. |
