Research On The Intercepted Air Device Protect Water Hammer On Pump Water Supply Systems

Water hammer accidents is often occursin long-distance pump water supply systemdue to accidental pump-stop,which causes damage topressure pipelines,pumps and valves,etc,resulting in significant losses,such as water supplydisruption.Therefore,in order to ensure the safe operation of pump water supply system,it is an important subject of pump station engineering design and research to adopt safe,reliable and economical water hammer protection measures.Pump-stop water hammer of pump water supply system isa transition process that negative pressure wave for the first and then the positive pressure wave appears,if we can timely to prevent pressure drop,the pressure risecan be effectively reduced.In view of the above problemsof the existing technology,an interceptedairdevice for water hammer protection of pump water supply system is proposed.Combined with engineering examples,the numerical simulation is carried out by MATLAB,focusing on the protection effect of interceptedair hammer protection measure.Also proposed a numerical method tocalculate centrifugal pump operating point,it is compared with the graphic method in the example.The main results are as follows:1)An interceptedairdeviceas a new water hammer protection measure is put forward.It including compressed air tank,pressure reducing valve,air valve,air pipeline and electromagnetic valve,etc.It is mainly used for water hammer protection of pressure water pipeline.The mathematical model of interceptedairdevice is established based on the characteristic method.The method of determining the installation location of the interceptedairdeviceis given.The source program of pumping station pump-stop water hammer analysis with the interceptedairdeviceis prepared by MATLAB software.2)Correct determination of operating points of centrifugal pumps is a prerequisite for optimizations of pump type selection,pumping station design and its safe and economic operation.Specifically,the head-discrete performance curve of centrifugal pump was described by discrete points while the parameters belong to non-discrete points were obtained by cubic spline interpolation.Then,according to the hydraulics principles,equations to calculating operating points of single,parallel and series centrifugal pumps were established,with detailed procedures of dichotomy numerical calculation.A new method to calculate operating points of centrifugal pumps is proposed in this study.Finally,the established equations,programming with MATLAB,was applied in a water intake pumping station to get the operating points from any one of twelve identical parallel pumps distributing in four wells.The results indicated that the proposed numerical method was feasible to calculate the operating points of centrifugal pumps.3)Contrapose the fourth-stage pumping station of the water supply project.put forward three kinds of different water hammer protection screames,numerical simulation is carried out by MATLAB software.It isshowedthat the bigger of pressure reducing valve outlet set pressure,the greater of the intercept air quality,and the smaller of the pipeline pressure boost value.The intercept air water hammer protection measureis by raising the minimum pipeline pressure to reduce the maximum pipeline pressure.The effect of intercept air water hammer protection is obviously better than the air valve.Through the comparative analysis of the optimal protection effect of different water hammer protection scheme,choosing a reasonable and safewater hammer protection scheme,and finally calculate the parameters of intercept air water hammer protection measures,which can provide reference for similar projects.