Research On Anti-clogging System Of Pressure Pipeline Exhaust Valve

The Yellow River Diversion project in Jiaodong Region of Shandong Province is an important part of the eastern route of the National South-to-North Water Diversion Project.Due to the diversion of water from the Yellow River,the impurities in the water are complex.During the period of water supply,the maintenance summary analysis caused by debris blockage in the exhaust valve accounts for about 80%of the overall failure rate.Therefore,the existing exhaust valve is partially improved,and the backwash filter device is designed to be combined with the exhaust valve and applied to the pressure water pipeline,so as to minimize the exhaust valve failure caused by debris blockage.This paper relies on the project of "Pressure Pipeline Exhaust Valve Anti-blocking System Test Research(220200008)" of Yantai Water Diversion Sub-Center,Shandong Province.Fluent was used to conduct numerical simulation research on gas-liquid two-phase transient flow in pressure pipeline.According to the simulation results,the backwash filter device protecting the exhaust valve is designed.The results of numerical simulation and physical test were compared to select the optimal backwash structure device.The main conclusions are as follows:(1)Fluent was used to conduct numerical simulation of transient water filling process of pressure straight pipe and pressure T-shaped pipe,and numerical simulation of scale model was carried out according to scale 11:1.The results show that it is feasible to carry out physical model test according to 11:1 scale.Meanwhile,the data of flow pattern and pressure are provided for physical model test,and the data of exhaust volume and pressure are provided for the design of backwash structure.(2)Design the backwash filter device according to the data of exhaust volume and pressure,The diameter of inlet and outlet water is 350mm,the diameter of sewage outlet is 250mm,the diameter of filter screen is 330mm.The filter screen is made of stainless steel,and the casing of the device is made of cast steel;Fluent was used to simulate the pore diameter of the filter screen 5mm-10mm and the thickness of the filter screen 3mm-8mm.The results show that the thickness of the filter is inversely proportional to the pressure difference,and the pore diameter of the filter is inversely proportional to the pressure difference.According to the simulation results,the optimal selection of the pore diameter of 10mm,filter mesh thickness of 5mm.(3)Fluent is used to simulate the water-filling filtration process and backwashing process of punching plate,arc form and basket type backwashing filter device.The arc-shaped backwash filter is the optimal structure.The filtering effect is 100%,and the maximum internal pressure of the device is 0.9mpa during filtering.The backwashing effect is 100%,and the maximum internal pressure of the device is 0.7mpa during washing.(4)Establish the physical model of the pressure pipeline,the comparison between the experimental results and the numerical simulation results shows that the pressure fitting difference is within 1.5%.Establish a physical model of the backwash filter,The filtration effect and backwashing effect of the three devices reach 100%,and the time error between numerical simulation and test is within 1.5%.According to the results,the arc-shaped backwash filter structure is the best choice.