Research Of Calculation Analysis Of Water Hammer In Pump Station With High Lift And Protective Measures

With the rapid development of city construction and the continuous improvement of people's living standard,more and more large-scale long distance water conveyance projects appear.Accordingly,an increasing number of engineering detonation problems have come into notice.For example,it's highly likely that water column separation and water hammer of cavities collapsing may happen in water transmission pipeline with high-lift and multi-fluctuation,which leads to serious water hammer damage.therefore,as one of the significant subjects of safe operation of water pipe,it is quite necessary to carry out an in-depth study of water hammer protection in water pipe system with high lift and fluctuations.This paper demonstrates an introduction of the fundamental theories of water hammer and the present available equation methods of characteristic line,on the basis of which it analyzes gas-liquid two-phase hydraulic transient and delves deeply into the main reasons of bubbles formation in the pipe,as well as several mathematical models of gas-liquid two-phase hydraulic transient in common use.Besides,it establishes the mathematical models of water hammer accidents and conducts simulated computation by means of computers.Combining the reconstruction project of water supply pumping station in haiyuan new district,it proposes three types of pipeline plans:1,the original pipeline plan;2,setting up conversion pools at k3+ 800m of the original pipeline plan;3,building pipe bridge in the two deep grooves to raise up the original pipeline.Through the calculation analysis of water hammer accidents via the three mentioned methods,we come to the conclusions as follow:(1)it has no significant effects on the elimination and improvement of water hammer in pumping accident to set up conversion poopls;what's more,it may lead to the waste of pump lift and increase of investment as well as maintenance cost to raise up the high-order position conversion pools.(2)water column fracture could not be eliminated by raising the low elevation,and it could increase investment of pipe bridge construction.(3)the original pipeline plan was determined after the calculation analysis of the three types of plans mentioned above.the optimum operation procedures of value shutoff in two stages of pumping accidents was established as well.Meanwhile,it provides the process curve and relevant data with regard to the maximum and minimum pressure change on the section of pumping stops,offering reliable information for the pump line design at pump station.(4)through the calculation of water hammer,the results indicate that it can effectively control the reverse speed and reverse discharge when pump stops by utilizing two-phrase value shutoff,together with setting up air compensating valve for intake and exhaust along the local high point of the pipe.At the same time,the phenomenon of water column disrupt occurred during unexpected pump-stop can be effectively eliminated.Based on the comprehensive analysis,it's concluded that satisfactory protective effects could be achieved when shutting off two-stage butterfly valve adjustment in the exit of pumps,and setting up gulp valve for air intake and exhaust at certain high point of the pipes.beyond that,when determining the pipeline pressure levels,it's suggested to increase the corresponding pressure in the 200 m range of the pipe section,particularly in the place where water column fracture tend to appear more,which can guarantee promising results for such high-lift water conveyance pipe.