Analysis And Optimization On Axial Load Uniformity Of Electrical Submersible Motor Driven Progressing Cavity Pumping System

Thrust bearing in coupling,as a key component of electrical submersible motor driven progressing cavity pumping system bearing axial load,frequently the axial load is extremely large in actual work,which can easily cause fatigue failure and damage,and even cause the oil production system to lose its working ability.Therefore,improving the bearing capacity of the thrust bearing under the continuous axial load is of great significance to improve the operation stability of electrical submersible motor driven progressing cavity pumping system and prolong the pump inspection time.In this paper,the optimal design is carried out from the perspective of structural design based on the structural characteristics of the coupling system.Based on the design concept of "load-uniform",the structure is innovated,and the original single bearing is replaced by tandem thrust cylindrical roller bearings.The proposed structure is analyzed from three aspects: theory,simulation and experiment.Firstly,based on the mechanical impedance analysis method,the equivalent mechanical model of the bearing set is analyzed,and the corresponding equivalent mechanical network is obtained,which theoretically proves that the tandem bearing set can achieve axial load-uniform;Secondly,the numerical simulation analysis method is used to analyze the load-uniform ratio and load-bearing capacity of the bearing set,and the load-uniform effect of different tandem bearing sets on the axial load is calculated and analyzed.It is found that the tandem bearing set can reduce the bearing stress,and with the increase of the series of the tandem bearing set,the maximum stress borne by the bearing decreases gradually,and the load-uniform rate decreases gradually.The load-uniform rate of the four-stage bearing is 54%,continuing to increase the number of stages will lead to poor load-uniform effect;Finally,the load-uniform experimental equipment is designed for the tandem bearing set and build the loaduniform test to verify the bearing capacity and load-uniform effect of the thrust bearing set.The results show that the load-uniform rate gradually decreases with the increase of the series of bearing sets.The experimental load-uniform rate of the secondary bearing set is 80%,which is2.4% smaller than the simulation value,and the experimental load-uniform rate of the tertiary bearing set is 56%,which is 20% smaller than the simulation value,which prove that the optimization effect of the bearing set structure is remarkable,and the bearing capacity is effectively improved.In order to further improve the bearing life and bearing capacity,the rolling elements of the key components of the bearing set are optimized locally.In view of the uneven distribution of stress along the generatrix of the rolling elements of thrust cylindrical roller bearings,the hollowness and end face trimming of the rolling elements are carried out to obtain the best trimmed rolling elements,which can effectively improve the stress concentration of the rolling elements.Tandem cylindrical roller bearings have better load-uniform effect when the series is low,which can effectively reduce the load on a single bearing in tandem bearings.It solves the limitation of the diving depth of the screw pump due to insufficient bearing life,and provides a feasible solution for other heavy machinery that bears a large axial load in a limited radial space.