Failure Analysis And System Optimization Of Export Progressing Cavity Pump In South Area Of Sulige Gas Field

The screw pump used in a natural gas collecting station in South of Sulige Operation Branch of Changqing Oilfield is used to pressurize the sewage liquid in the station for outward transmission.However,due to the influence of the conveying medium and working conditions,the screw pump has some failure problems,such as reduced operating pressure,unstable displacement and shortened life of stator and rotor.There are many researches on screw pump failure at home and abroad,but few researches on screw pump used in gas collecting station.Therefore,this paper conducts failure analysis for external transmission of progressing cavity pump and puts forward an optimization scheme.The main research contents are as follows:First of all,the transport medium was studied and analyzed,and its main components are solid particles and water.The failure types of the screw pump were summarized by investigating the field data,and the reasons for the failure were analyzed by fault tree method:solid particles entering the pump body,scaling at the pump outlet,and high-speed operation of the screw pump rotor.The correctness of the analysis results was verified by pump disassembly inspection.Secondly,in view of the screw pump system has been clear about the raise,rotor sealing is the research target,to solve the problem of failure of the finite element method analysis of the amount of interference,eccentricity and stator thickness minimum size to the hirer,sealing and the effect of the rotor and the structural parameters as design variables,set the maximum number of total deformation,rotor contact seal and contact pressure as target variables,The structural parameters of stator and rotor were optimized by multi-objective optimization method based on response surface,and the optimization scheme was determined.Finally,through the numerical simulation of the flow field,the fluid characteristics of the external screw pump before and after optimization were analyzed.The research shows that the solid particles entering the pump body is the main reason for the failure of the outward transmission screw pump.The solid particles in the conveying medium wear the stator and rotor under high-speed operation,which leads to the decrease of the tightness between the stator and rotor,and causes the leakage inside the pump.After optimization,the maximum total deformation between stator and rotor decreases and the maximum contact pressure increases,and the flow field numerical simulation results show that the operating pressure of the external transmission screw pump increases,and the pressure difference between the high-and low-pressure cavities increases,and indicate that the tightness between stator and rotor is improved after optimization.