Design And Evaluation Method Research Of Pumping Units Based On Drive Motor Characteristics And Special Working Conditions

Pumping unit being one of the key equipment of mechanical oil production,at present the design of the pumping unit is usually according to the conventional mechanical analysis.The conventional mechanical analysis is based on the motor's uniform speed working condition,because the pumping unit belongs to the low speed machinery and the motor's characteristics is generally hard,so it can meet the requirement of general mechanics analysis.But on account of the shortage of the load loss kinetic analysis and the reversing shock in the pumping units designed with the conventional kinetic analysis,some components' load carrying situation get worse in some types of pumping units while load loss,even leading to serious accident.It is the problem demanding prompt solution.Currently used pumping units in oil field are various but short of the uniform performance and reliability test and evaluation standard,so comparing different pumping units in performance and reliability further the model selection accordance of pumping units can't be realized.To solve these problems,the equivalent kinetic model of the conventional pumping units were established with considering the real movement of the motor;the kinetic analysis of the reversing impact and extreme cases(load loss)was conducted;the design method based on the real motion kinetic analysis on typical pumping unit was studied;the self-learning load test platform was designed;the test and evaluation method of the pumping units was established.The balance weight has great potential energy in beam balance pumping unit after load loss,in the process of impact,the connecting rod suffers from tension to compression,which is easy to cause instability.The impact can destroy the pump unit,further leading to the serious accident.Aiming at the beam balance pumping unit,the kinetic analysis and structure redesign proceeded under the real motion condition,thus the design method based on kinetic analysis of real motion was put forward.Firstly,the dynamic static analysis on beam balance pumping unit was conducted,solving the initial stress according to the given indicator diagram;secondly,the structure and size was preliminarily designed on the basis of dynamic static analysis results,the moment of inertia being calculated;thirdly,the equivalent dynamics model was established on considering the motor's non-uniform rotating,and the kinetic analysis about the real motion and load loss was carried out,the force on the key components such as connecting rod,being solved;finally,according to the result of the loss of load analysis,the main bearing force members in the structure was conducted on the strength and stiffness analysis and structure redesign,the beam balance pumping unit design scheme meeting the worse working conditions such as load loss,being obtained.The design idea was applied to analyze CYJ12-4.8-73 beam balance pumping unit in the structural modification and redesign.The kinetic design methods for both motor commuting pumping unit and chain drive pumping unit under extreme working condition were proposed.Firstly,the dynamic static analysis was carried out and the preliminary design for the structure was conducted,the rotational inertia of the components being obtained on the basis of the preliminary design and analysis;secondly,the equivalent kinetic models of the motor commutation pumping unit and the chain drive pumping unit,was set up on considering the motor's non uniform rotation,bring out the law of the reversing velocity and acceleration after dynamic performance;finally,the kinetic about the reversing shock and the load loss was analyzed,and the strength and stiffness analysis of the main components were conducted for both motor commuting pumping unit and chain pumping unit;finally,for the two types of pumping units,the main structures such as motor,reducer and braking system were selected and redesigned according to the real motion and load loss kinetic analysis.Based on the structure safety and applicability principles of currently used pumping units,the key nodes and technical index of the pumping unit performance test were determined.Through the comparison and analysis with the current standard test system,the main supporting parts' design safety index,the energy consumption test index and test method was determined on the basis of the simulating indicator diagram,and the performance test index system and method was perfected.Through the computation and analysis for the polished rod load characteristics and the analysis for the advantage and disadvantage of the existing load test methods,the AC electrical dynamometer load scheme was proposed on the basis of the direct torque control.According to the laws of the load simulation about the pumping unit polished load,the whole design and computation of the AC electrical dynamometer was obtained.The test platform being developed,the test verified the feasibility of the AC electrical dynamometer load scheme and electric energy feedback scheme.The maximum deviation between the test platform indicator diagram and the theoretical simulating indicator diagram,being less than 3%,the AC electrical dynamometer transducer output level signal has the perfect consistency with the theoretical signal.The generator group's feedback system runs stably,and the high energy feedback efficiency ensures the pumping unit test and evaluation with an efficient platform.