The Research And Application Of Composite Control In Water Plant Coagulant Dosing Systems

Abstract:The system of coagulant dosing control is indispensability and a key role in the process of drinking water treatment, which directly affects the course of the follow-up treatment. Exact amount of coagulant dosing is the key to getting the qualified effluent quality and good economic benefits for water treatment industry. It is a at large care and desiderate solve problem how to calculate the efficient coagulant dosage according currently raw water qualities in water treatment industry.Based on the actual production of a large mine water supply plant in Shaoguan, in view of the dosing process with a large delay, nonlinear, difficult to establish accurate mathematical model, etc., which often resulting in incomplete purification, excessive dosing and other issues, a composite control strategy is proposed. This approach consists of feed-forward predictive control based on BP neural network and feedback control based on fuzzy PID. Besides, a waterworks automatic dosing system is researched and designed to achieve precise control of coagulant dosage.In this thesis, the background of the thesis choice and the actuality and development of coagulant dosing control methods and manners are first introduced. By analyzing the characters of coagulant process and the schemes of coagulant dosing control, designs the raw water turbidity, temperature, pH, basicity and flux as the import nerve cell parameters of BP neural network model, the export nerve cell parameters is coagulant dosing addition, and designs the deviation and the rate of deviation change of sedimentation tank effluent turbidity as the input of fuzzy PID controller,whose output is coagulant dosing addition,which is a complex control system. Through the relevant data’s collection and collation, the mathematical model of the controlled object is derived. Using it, we carry out the simulation analysis for conventional PID, fuzzy PID control, and feed-forward-feedback of combined control.The combined control can be significantly better than the other two controls. From the complex control system performance to see if it can predict coagulation timely and effective dosage and dosage adjustments based on the raw water quality. This system is used in engineering practice, to achieve a water dispensing automation and automated administration, not only to ensure that the water quality, but also saves dosage drug, significantly reducing administration costs of water, and achieved good economic results for the water plant. The paper contains38figures,20tables, and80references.