Research On Water Quality Control Of Urban Water Supply Network Based On Valve Regulation

With the accelerated progress of urbanization in China and the rapid development of the national economy,China's urban water supply has entered a period of rapid development,and the urban water supply pipe network system is an important infrastructure.The water supply problem is one of the key issues related to China's sustainable development.In order to meet the basic needs of industrial production and resident life,the water supply industry has developed from the original guarantee of sufficient supply of water to improving the safety of water supply,improving water quality,and modern management.Urban water supply system optimization and control is one of the important means to achieve water supply security,improve water quality,and modern management.The precondition for improving the optimization of regulation and control accuracy is the accurate judgment of the flow state of the water in the pipeline.In the pipe network where the valve is installed,a change in the opening degree of the valve may cause a change in the flow state of the water flow.Under certain conditions,the water flow in the pipe network directly affects the turbidity of the water.Therefore,it is of great theoretical significance and application value to analyze and study the water flow state in the ring pipe network under the state of valve regulation for optimal scheduling of water supply system,reduction of water turbidity value,and optimization of water quality.Based on the previous studies,combining the hydraulic conditions in the pipe section and the valve's mode of action in the pipe,this paper explores the influence of different valve control combinations and valve opening changes on the water quality of the pipe network.The main research results are as follows:(1)The basic theory of classical hydraulics was used to analyze the influencing factors of valve flow regulation and concluded that the shorter the pipe section where the valve was located,the stronger the flow control ability of the valve.When the valve of the water supply pipe network was installed at the beginning and end of the pipe,the effect of the valve regulation on the flow state of the water flow was that the loss of the head of the valve in front of the valve and behind the valve was not equal,and the steady state was restored after the fluctuation occured.According to the formula of hydraulic length,the length of hydraulic deflection was closely related to the opening degree of the valve.(2)When regulating the valve in the ring pipe network,if the ratio of the friction resistance of the installed valve pipe section in the ring became larger,the friction resistance of the surrounding pipe section tended to become smaller.When the flow in the pipe section where the valve was installed became smaller,the flow rate in the surrounding pipe section that was in line with the flow direction also became smaller.(3)The relationship between the regulation of valve opening and the water quality in the pipe segment and in the ring pipe network system was established by using the relationship between the valve regulation and flow velocity,flow velocity and water age,water age and water quality.Finally came to the conclusion: control valve opening can control the water quality of the pipe network.(4)An improved water quality control strategy was proposed: the water quality of the pipe network was controlled by controlling the valve opening degree.This method applied the nonlinear mapping theory to the optimization of the valve for the first time.It made full use of this method to consider only the data itself and did not specifically address the characteristics of data types,thus avoiding false classification of other algorithms and improving the selection and optimization reliability of the valve combination.In the process of determining the valve opening degree,matlab programming was used to achieve a comprehensive consideration of water flow rate,water age,valve opening degree of water quality indicators.(5)The implementation steps of the water quality control strategy for the urban water supply pipe network based on valve control were determined.Firstly,understand the current status of the water quality of the water supply network and collect the basic information of the pipeline network.Secondly,establish the water quality model of the water supply pipe network.In the hydraulic calculation of the model,the influence of the hydraulic length of the valve before and after the valve should be considered,and the model should be calibrated.Thirdly,using the method of controlling variables to change valve opening values in order to obtain a series of water turbidity value data,using nonlinear mapping analysis theory to achieve the most representative valve control combination in matlab programming.Finally,the water quality index comprehensively considered the flow velocity,age of the water,and the opening degree of the valve.The determination of the opening degree of the valve was achieved through the simultaneous formula in matlab.(6)Apply improved water quality control strategies to engineering examples.Taking a water supply pipe network in a city in North China as an example,a water quality model of the water supply pipe network was established and calibrated.The non-linear mapping analysis theory was used to cluster the valve and the valve assembly number that regulated the water quality of the water supply network in the city was finally selected: 5,13,60,36,65,41;Then according to the method to determine the valve opening degree,the opening degree of the optimal control valve combination was:60%,50%,70%,50%,80%,40%.Analyzing the effect of the water quality control strategy,we can know that by adjusting the valve combination and the corresponding valve opening degree,the goal of reducing the turbidity value of the water quality of the pipe network can be achieved.