Optimization Design And Internal Flow Research Of High Pressure Pump For Large Scale RO Desalination

Reverse osmosis seawater desalination technology is the mainstream seawater desalination technology and plays an important role in resolving water resources crisis.The seawater desalination high-pressure pump is the core power component of the reverse osmosis seawater desalination system,and its performance directly affects the operation energy consumption of the desalination system.In this paper,the research on the excellent hydraulic model and internal flow of the large-scale seawater desalination high-pressure pump is of great significance for improving the performance of the high-pressure pump and reducing the energy consumption of water production.Based on the "Thirteenth Five-Year" national key research and development plan "Development of large-scale membrane desalination key equipment and components"(2017YFC0403703),based on CFD technology and experimental measurement,this paper studied high-pressure pump excellent hydraulic model selection,internal flow,impeller and the matching characteristics of guide vanes,axial force,radial force and pressure pulsation distribution law provide a reference for the optimal design of high-pressure pumps.The main work of this article is as follows:(1)Analyzed the principle of reverse osmosis seawater desalination technology and the operation mode of high-pressure pump,studied the influence of seawater desalination operation pressure on the operation of high-pressure pump with the change of water temperature in four seasons,and pointed out that the hydraulic design of high-pressure pump should have a wide high-efficiency area,and The highest efficiency point of the high-pressure pump should be biased towards large flow conditions.(2)Combining similarity conversion algorithm and pump hydraulic design software to design 3 groups of impeller and guide vane structures,forming 9 groups of schemes for screening excellent hydraulic models.According to the external characteristics obtained by numerical calculation and the streamline distribution of each scheme under different working conditions,scheme 3 is determined as the best scheme.The external characteristics test was carried out on the solid pump of the hydraulic model processing scheme 3,and the test results were in good agreement with the numerical calculation results,which verified the reliability of the numerical calculation.(3)Based on the hydraulic model of scheme 3,the impeller and guide vane blade width were changed,the number of impeller and guide vane blades,the ratio of the impeller and guide vane throat area,etc.,and the matching characteristics of the impeller and guide vane were studied.Combined with the external characteristic curve,pressure distribution,streamline distribution and turbulent kinetic energy distribution,the numerical calculation results and flow field distribution rules of various schemes were analyzed,and the optimal parameter combination was selected.(4)Select the model with the best matching performance and assemble it into a multistage pump for numerical simulation and performance prediction,and obtain the external characteristics and internal flow field distribution.Combined with the external characteristics,streamline and turbulent kinetic energy distribution,the differences of each stage of the multistage pump were studied.Calculated and analyzed the axial force of the impellers at all levels,studied the distribution of each axial component and the total axial force,and found that the total axial force does not change linearly with the flow rate,its size and the pump's operating state Closely related,the axial force is smaller at the highest efficiency point.(5)Calculate the indefinite constant value of the multi-stage pump,set the monitoring points in the impellers,positive and negative guide vane flow channels at all levels,and analyze the time and frequency domain changes of the pressure pulsation at each monitoring point between different stages under different working conditions.The radial force of the impellers at all levels was calculated and analyzed,and it was found that the radial resultant force of the impeller changed periodically with time.The peaks and troughs were consistent with the number of blades under low flow conditions,and the radial resultant force increased under high flow conditions.The number of peaks and troughs increases,and the radial resultant force is the smallest under design conditions.