Research On Operating Performance Of Sliding Vane Pump And Design Optimization Of Its Lifting System

Sliding vane pump(SVP)is a rotary hydraulic pump.Its operating principle is to use the periodic change of the volume of its inner sealed chamber to complete the suction,pressurization,and discharge of oil.Compared with the traditional lifting technology,SVP can adjust the displacement by changing the eccentricity,and can change the number of stages to meet different production systems.SVP has many advantages such as thermostability,small flow pulsation,simple structure.However,it also has a few disadvantages like the imbalance of radial hydraulic force.To date,research on SVP,a new type of mechanical equipment for oil recovery,is still in the exploratory stage.The operating performance of the pump and the design of the corresponding lifting system remain to be improved.Thus,it is necessary to carry out systematic studies on the lifting technology.Based on the mechanical structure and operating principle of SVP,the theoretical models of key performance indicators are established,and the three-dimensional lifting process is simulated by using the computational fluid dynamics.The results from theoretical models show that the theoretical displacement of SVP is proportional to the effective volume and the rotating speed.The theoretical torque of SVP depends solely on the displacement per revolution and lifting pressure difference.The rotor angular velocity is the ratio of instantaneous power to instantaneous torque.The pressure difference on vane is determined by the position of itself and its adjacent vanes,and the pressure difference of vane at any position is obtained by piecewise calculation.The leakage model under clearance fit,the fullness model of pump,and the mechanical model of viscous friction and mechanical contact friction are established,which provide theoretical basis for the analysis of the working efficiency of SVP.The results from numerical simulations show that the displacement,torque,and hydraulic power of SVP are stable.There is a large pressure difference between the chambers at the smallest and largest volume,which reflects the unbalanced radial hydraulic force in SVP.The volume efficiency of SVP can be effectively improved by increasing the fluid viscosity properly.However,a larger fluid viscosity can lead to a larger unbalanced radial hydraulic force.Under the condition of low gas-liquid ratio,SVP has good resistance to gas.The torque is proportional to the lifting pressure difference,and the torque loss is positive correlated with the lifting pressure difference.The flow pulsation rate of SVP is small at various speeds,which indicates that the pump displacement is stable.The multistage SVP is pressurized step by step from the bottom to the top with increasing gas fraction in each stage.Therefore,the damage risk caused by pressure or gas is positively related to the amount of stage in SVP.The direction of radial hydraulic force of adjacent stages in multistage SVP is opposite,in order to reduce the influence of the unbalanced force on lifting system,it is recommended to use even-numbered multistage pump when the total number of stages is small,and to use odd-numbered multistage pump when the total number of stages is large.The mechanical structure parameters of SVP are optimized.It is concluded that a larger eccentricity can lead to a greater displacement,which aggravates the unbalanced radial hydraulic force.The design of concentricity of stator and rotor eliminates the unbalanced radial hydraulic force,but at the same time,the function of adjusting displacement by using eccentricity is lost.Besides,the concentricity of stator and rotor will degrade the kinetic characteristic of vane.At the same gas-liquid ratio,a larger rotor groove radius can result in a lower volume efficiency,and the effect of rotor groove on volume efficiency is more significant at high gas-liquid ratio.More vanes can not only increase the mean value of instantaneous displacement,but also shorten the discharge period and reduce the flow pulsation.Compared with adjacent even amount of vanes,the odd amount of vanes has a more uniform instantaneous displacement.By improving the position of inlet(outlet),the chamber begins to pre-expanded(pre-compression)once it is separated from the inlet(outlet),which avoids the phenomenon of ineffective suction and backflow effectively.The calculation model of axial load and circumferential torque of the rod string is established,and the design method of rod string is proposed based on the strength theory.Considering the energy consumption in energy transfer process,the model of the lifting system efficiency is established.Based on the IPR and the multiphase flow,the lifting scheme of SVP production system is designed.The purpose of this paper is to study the new lifting technology of SVP in-depth,and to provide theoretical implications and technical guidance for its popularization and application.