| With the rapid development of ultra-supercritical thermal power plants and nuclear power plants,the traditional labyrinth control valves in China can no longer meet the requirements of stable operation under special conditions such as high temperature,high pressure and high flow.Under the support of the scientific research project of Liaoning Provincial Department of Education “Key Technology Application Research on Reengineering of Minimum Flow Valve of Boiler Feed Water Pump in Power Plant”(LJKZ1087),this thesis takes the labyrinth minimum flow control valve in the 600 MW unit of Kangping Power Generation Co.,Ltd.as the research object.Aiming at the problems of cavitation and erosion of the control valve,the computational fluid dynamics(CFD)and metal 3D printing technology are combined to optimize the design of the labyrinth disc of the labyrinth control valve and the manufacture of the new labyrinth-hedge combined disc,so as to improve the stability and reliability of the valve.The main research contents are as follows :(1)The problems of cavitation,erosion and vibration in the labyrinth control valve are explored,and the main pressure-reducing parts of the control valve are optimized.The finite element software is used to analyze and study the pressure-reducing ability and flow characteristics of the labyrinth,the opposed and the modified labyrinth-opposed combined flow channel.The results show that the pressure-reducing and speed-controlling ability of the labyrinth-opposed combined flow channel is obviously better than that of the labyrinth and the opposed flow channel.(2)The influence of structural parameters on flow characteristics is studied.The influence of flow channel structure parameters on flow characteristics was studied by establishing models of maze-impingement combination flow channels with different structural parameters.The effects of structural parameters such as pressure reduction stages,channel depth,Chamfering,Inlet width,Outlet width on flow characteristics are analyzed.The results show that: With the increase of the pressure reduction stage,the flow resistance of the flow channel will increase,and the pressure reduction performance of the flow channel will be improved.When the inlet and outlet pressures are constant,the depth of the flow channel has the greatest influence on the flow rate,and the outlet width has the least influence on the flow rate.(3)Research on the flow regulation characteristics of the new labyrinth control valve,modeling the overall structure of the new labyrinth control valve and CCI DRAG labyrinth control valve,using finite element software to simulate the flow regulation characteristics of CCI DRAG labyrinth control valve,comparing the simulation data with the actual data,the results show that: the flow coefficient curve obtained through simulation is consistent with the given flow coefficient curve,and all are within the specified error,Verify the rationality of simulation.In this thesis,the flow characteristics and capacity of a new type of maze regulator are studied by simulation method,and the influence of the number of maze plates and flow channels on the flow coefficient of the regulator is analyzed.The results showed that the flow coefficient of the new labyrinth control valve was higher than that of the CCI DRAG labyrinth control valve,and the flow capacity of the new labyrinth control valve was stronger.(4)Aiming at the processing and manufacturing of the new type of labyrinth-hedge combined disc,three different manufacturing processes of SLM-316 L without heat treatment,SLM-316 L heat treatment and rolling 316 L were compared.The influence of material density and mechanical properties was analyzed.It was concluded that the comprehensive performance of SLM-316 L heat treatment was better.Finally,the labyrinth-hedge combined disc was manufactured by UM250 test equipment,which provided a new idea for the application of 3D printing technology and the design and manufacture of valves. |
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