Stop Pumping Water Hammer Calculation Of Circulating Water System In Thermal Power Plants And Research

This paper refers to the basis of the researcher results and experience of the formerresearchers,calculates and analyses the stopping pump transition process in the coolingwater system that easily occurs the phenomenon of the cut-out bridge water hammer,and according to the results of the simulation calculation，we choose effective measuresthat prevent water hammering to ensure the system safe and stable.This paper’s mainwork are as follows:1. Established the analysis and calculation model of hydraulic transition process byapplying the method of characteristic line, additionally, mathematical modeling theboundary conditions of the circulating pump, condenser, butterfly valves and otherrelated equipment.2. According to the established calculation model,we checked the steady stateoperation. we also analysed the condition of the valves closed and a pump stopped andnone pump stopped and none valve closed on the basis of validating the model,3. We analysed the possibility of occuring pump power shuts down which causedthe water hammer accident in the actual operation of the power plant, and we also madeforecast for the pipe hammer hump points of which easily occur cut-out bridge waterhammer and the import and export of the condenser to liquid column separation.4. We calculated the stopped pumping water hammer under the work condition ofthe system which was equipped with hydraulic control butterfly valve and without otherprotective measures by using the free gas-discrete model.At last,we explained theoccurrence and development process of the pressure of the steam chamber and collapse.5. We made a computional comparison of the schemes of the closed valve of thehydraulic control butterfly valve, and preliminarily put forward the scope of applicationof the hydraulic controlled butterfly valve.6. According to the characteristics of the cooling water system and the calculationresults, selecting the scheme of the prevention of water hammer that set pressureregulating box on the pipeline hump point and set air valve in the import and export ofthe condenser, and comparing the scheme of the closed valves that select the commonlinear closing butterfly valve with that select the two-phase closed hydraulic controlbutterfly valveAccording to the characteristics of the cooling water system and the calculation results, selecting the scheme of the prevention of water hammer is feasible. Free gas--discreted model is able to predict where and when the water column separates,what ismore,it can also predicts the steam cavity collapse pressure in advance.Therefore,making a theoretical basis for the selection of appropriate protective measures. thehydraulic control butterfly valve should be used with caution in the pumping systemwhich is easily occuring the water hammer cavitiation. If the system is equipped with ahydraulic control valve, the two stage closing mode and closed angle should be incomputer simulation to determine.In the circulating water system in thermal powerplant which prones to occure water pumping cavition,the application of one-way surgetank and the air valve can effectively prevent water column separation and prevent thesystem from bearing the huge water hammer pressure.