Research On Water Hammer Protection Of Water Supply Project In An Industrial Park In Northern Shaanxi

At have a major impact on the normal operation and safe operation of the water supply piping system and often result in significant damage.At the beginning of the design of the water supply pipeline,it is often impossible to predict the occurrence of water hammer,and proper detection and protection in the running water supply system is not easy to achieve.In addition to the complex physical properties of the water hammer,it is often accompanied by great difficulties in the technical and economical adoption of feasible protective equipment and protection methods.Based on this,this paper takes the water supply project of an industrial park in northern Shaanxi as an example to discuss the influence of water hammer in the design process of water supply engineering;and numerical simulation of the transient process of pipeline.After analyzing the water hammer mechanism and reviewing a large number of literatures,the economic operation optimization design model of the pump water supply system based on ant colony algorithm is considered.The model is designed to determine the water hammer transient condition when determining the total cost of a water supply system.Within the study,the research is based on the Matlab2016a ant colony algorithm ant toolbox.Secondly,the electric algorithm program of water hammer calculation is built by the characteristic line method,and the numerical simulation of the pump-stop water hammer of a water supply project in northern Shaanxi is studied to determine the transient pressure value that may be generated by the flow operation of the water supply system.This paper will propose the design of the water hammer protection equipment of the project to provide reliable protection measures to prevent system failure caused by pipe collapse or burst caused by water hammer phenomenon.Through analysis and comparison,this paper has the following conclusions:(1)Considering the water hammer pressure during the design phase will increase the total system cost,and the impact of water hammer boost on the total cost of the pressure flow system is much greater than that of the gravity flow system.For the gravity flow system given in this paper,the valve is closed for 60s.In order to reduce the water hammer boost caused by the valve closing,the total system cost is increased from the original 557,100 yuan to 570,400 yuan,and the total system investment cost is caused by the pipe diameter change.Increased by 14,300 yuan.For the pressure flow system given in this paper,the valve is closed for 60s,and the total cost of the system is increased by 272,400 yuan.(2)For different valve closing time,due to the limitation of the gravity flow rate,the water hammer pressure can no longer be reduced by the increase of the pipe diameter,so the total system cost will not change significantly with the increase of the valve closing time.The difference is that the total cost of the pressure flow system will decrease as the valve closing time increases.(3)In order for the problem to be solved by the ant colony algorithm,the search space must be discretized.The results show that the ant colony optimization algorithm based on ant movement,pheromone update and global search is satisfactory.The simulation results are satisfactory.The algorithm can be used to optimize the economic operation of pump water supply system.The ant colony algorithm provides a solution to the optimization problem that is difficult to solve using the traditional gradient-based method.For the discretization of the search space,the objective function is not divisible,and the invariance of the independent function is applicable.(4)Through the numerical simulation analysis and comparison of the water hammer,it is found that the protective effect of the composite air valve alone on the water hammer is not obvious,and the composite air valve is provided at the obvious convex point of the line to effectively improve the negative pressure condition in the pipeline,but the air When the valve is exhausted,water hammer pressure is still generated due to the collision of the upstream and downstream water columns.For long-distance,high-lift,multi-undulating water supply projects,composite air valves cannot meet their requirements.(5)The optimization of the closing law of the liquid-controlled slow-closing valve and the setting of the air valve can effectively improve the negative pressure condition in the pipeline,but the effect of reducing the maximum water hammer pressure is not obvious,and sometimes even worsens the pipeline.Water hammer pressure,therefore,needs to be used in combination with an overpressure relief valve or a one-way surger with significant pressure reduction.(6)For the engineering studied in this paper,after setting the closing mode(time,angle)of the liquid-controlled slow-closing valve and installing the slow-closing valve at the obvious convex point in the pipeline,the pressure-reducing effect of the one-way pressure regulating tower is higher than the overpressure Pressure relief valve.The first-stage pumping station is equipped with an overpressure relief valve to reduce the maximum water hammer to 203.85m and to 200.33m when using a one-way pressure regulating tower.When the secondary pumping station is equipped with an overpressure relief valve,the maximum water hammer is reduced to 225.77m,and when the single-phase pressure regulating tower is used,it is reduced to 193.12m.