Optimization And Experimental Study On Key Friction Pairs Of Energy Recovery Device For Desalination

The energy recovery device is an important part of the reverse osmosis desalination system.It can transfer the pressure of the high-pressure concentrated brine through the reverse osmosis membrane to the low-pressure fresh seawater,so as to achieve the purpose of energy recovery and reduce the energy consumption of the system water production.Because of its high efficiency,flexible processing capacity,simple and reliable structure,the rotor type energy recovery device based on the rotating positive displacement principle is the mainstream product in the market of reverse osmosis desalination.In this paper,the distribution pair of pressure exchanger booster pump integrated energy recovery device(PPX)is taken as the main research object.Aiming at the flow characteristics of the fluid in PPX and the sealing problem of the end face of the distribution pair,the key friction pairs of the energy recovery device are optimized by means of numerical analysis,CFD analysis and experimental verification,in order to obtain the energy of PPX device Volume efficient conversion and high quality flow output.The main contents of this paper include:1)This paper introduces the components of the reverse osmosis desalination system,compares the performance characteristics and research status of the rotor type energy recovery device at home and abroad,summarizes the research progress of the key friction pairs of the rotor type energy recovery device,and puts forward the main research contents and key technical issues of this paper.(2)An integrated energy recovery device prototype of motor driven pressure exchanger booster pump is designed,and the energy exchange process of fluid in the rotor passage on the distribution pair is analyzed;the dynamic characteristic equation of pressure field and leakage with the size of sealing belt is established under different clearance conditions of wedge-shaped water film of distribution pair;and the clearance and sealing belt scale of different distribution pair are analyzed by numerical calculation The effect of dimension on the performance and leakage of end face seal.(3)The tribological properties of 17-4PH stainless steel,Cr₃C₂-NiCr,WC-10Co-4Cr,Cr₂O₃ and Al₂O₃-13TiO₂ coated CF-PEEK composite in water were compared.The friction and wear properties of CF-PEEK/Al₂O₃-13TiO₂ composite under the condition of water lubrication are the best by changing the rotating speed and loading force.(4)Based on the software Pump Linx,a joint fluid simulation model of PPX is established,which simulates the pressure field and the concentration field of sea water components of PPX,analyzes the formation process of liquid piston and the characteristics of mixing phenomenon;compares and analyzes the influence of the unloading groove of port plate on the flow fluctuation at the outlet,studies the pressure distribution of the end face seal structure,the clearance between port plate and energy recovery The effect of rotating speed on leakage.(5)A small-scale reverse osmosis desalination experiment system with PPX as the core of energy recovery device was built,and the influence of reverse osmosis membrane group experiment on water production rate and working pressure of reverse osmosis membrane was studied;the influence of spring preload on section sealing performance was investigated through section sealing performance experiment,and the change trend of end face leakage and leakage rate with working pressure was obtained;the fluid pressure was developed The trend of PPX mixing rate and energy recovery rate under different component concentrations was analyzed.Finally,the energy consumption performance curve of the experimental system was obtained.In this study,under the working pressure of 4 MPa,the water production rate,energy recovery rate and mixing rate of PPX prototype experimental system are 15.3%,68.9%and 15%.