Research On Water Hammer Prevention And Energy Saving Of Pumping Water Supply System

China is not rich in water resources. The water resource amount per capita is small and the resource distribution is seriously uneven both in temporal and spatial over the country. Every year China suffers seriously damage in industry and agriculture for shortage of water. With the economic development, China has built many pumping station works. Water hammer can do great harm to pumping water supply system. Energy saving of pumping station is the main method to reduce the cost of water supply. Therefore water hammer prevention and energy saving of pumping water supply system are the main topics of this study. The major contents are as follows:(1)Hydraulic transient processes of two pump sets in a high-lift pumping station were separately measured by modern testing technology when two pump sets accidentally be closed down. Hydraulic transient calculation was conducted by using method of characteristics with test wave speed and closedown procedure of butterfly valve used as parameters. The results of calculation and test are well matched. Therefore the close procedure of butterfly valves can be optimized. According to formula in existence, water hammer wave velocity is 1041m/s in pressure conduit and 321.33m/s in PP-R pipe, which is 12% less than the test speed 1178m/s, and 26% less than the test speed 435.01m/s respectively.(2) According to research on effects of characteristics of air valve on hydraulic transient, the concept of air valve group and method of water hammer protection by sets of valves are put forward. Installation site and optimum parameters of air valves used to prevent water hammer in a long distance water supply pipeline are presented.(3) Predictive linear regressive model of the complete characteristic curves of centrifugal pumps is put forward by using specific speed n_S, relative flow angle, and the complete characteristic parameters of zero flow rate as independent variables. Correlation analysis shows that the model is reasonable.(4)Dynamic programming model about economic operation of a multi-stage pumping station, which has no water diversion between each stage, is established, and the optimum operation schedule of pumping stations is also given. It is suggested that adding both smaller pumps and return pipes for each station is the most suitable technical alteration plan.Optimum operating pump impeller cutting calculation model with minimum pump power consuming as objective function is set up. Thus solves the problem of flow rate matching of cascade pumping stations.