Research On Top-down Design And Method Of Reciprocating Compressor Mainframe

With the rapid development of natural gas exploitation, the demands of high speed and large powerful reciprocating natural gas compressors which used in oil and gas fields in China are increasing, while some related agents about such research lag behind in this field, and the present products were designed and manufactured have a certain gap compared with products of foreign industry. The power and work pressure of domestic reciprocating compressors are insufficient, and the life is short when put it into service, and the large numbers of vulnerable parts, which will hindered the development of oil and gas fields in China. As an crucial equipment in the production of natural gas industry, the performance of reciprocating compressor have a significant impact on the production of natural gas, consequently, there is a great significance to enhance the research and design level of domestic reciprocating compressors and strengthen its quality and performance, which have a great significance for the development of the domestic natural gas industry.In this paper, a kind of high speed and large powerful reciprocating natural gas compressor was studied, with the top-down design and simulation research carried out, the specific content and research results are as follows.(1) The reciprocating compressor was designed by parameters which mainly use top-down design method in Creo software, the model design of compressor was completed through the concept design, skeleton model design and assembly design, such as this top-down design process, and the bottom three dimensional model controled by the top layer design information was realized, and the changes of design parameters can be quickly reflected in the model, and the modification of the model become convenient and quick, so the design efficiency of the compressor improved.(2) The design parameters of reciprocating compressor were calculated and transmited based on seamless integration of Mathcad and Creo, the initial design parameters are rapidly and accurately transformed to the main geometric dimensions of the model, and the model geometry were drived atuomatically, and the model of the current design parameters is obtained quickly, which further raise the efficiency design.(3)The 1D simulation model of crankshaft system, cylinder and gas valve of reciprocating compressor was established in AMESim software, and the 1D simulation model of the compressor was built on this basis, the characteristics of cylinder gas was simulated and analysed, and got the gas pressure curves of the shaft side and cover side of cylinder, and analysed it by compared with the theoretical calculation, which verifies the accuracy of the simulation.(4)The multi rigid body dynamics model of the reciprocating compressor is established in the Motion software, and the dynamic simulation analysis of the crankshaft system of reciprocating compressor was carried out based on the co-simulation method of AMESim 1D and Motion 3D, and got the motion laws of piston and the change rules of main dynamic force,such as lateral force, crank pin force, spindle neck force,etc.(5)The rigid flexible coupling dynamics model of reciprocating compressor which comprising a flexible crankshaft was simulated and analysed, and the inherent characteristics of crankshaft were received, it showed that the intrinsic amplitude of input end of the crankshaft is largest, we found that the flexible crankshaft can more truly reflect the dynamic characteristics of crankshaft though comparative analysis the simulation results of the rigid flexible coupling dynamics and rigid body dynamics simulation results. The stress analysis on the crankshaft shows that the maximum stress on the crankshaft is located at the right side transition fillet of the crank pin corresponding to the sixth column of the compressor, and increased the fillet radius 5mm, the maximum stress was reduced by 17.1%.(6)The torsional vibration response of the crankshaft was studied based on the dynamic simulation analysis of rigid flexible coupling of reciprocating compressor crankshaft system,the maximum torsion angle of the crankshaft is 1.3°,which located in the input end of the crankshaft, this torsion angle is small, and have a little harm to the compressor. Then through the analysis of the frequency response of the torsional vibration curve, it is found that the maximum torsional angle caused by the 6 harmonic excitation is 0.306°, and the second is the 2 and 3 harmonic. And the influence of different length of input end of the crankshaft on the torsional vibration of the crankshaft was analyzed, we found that when the length of the input end is about 350mm, the torsional vibration amplitude of the input terminal reaches a minimum of 1.084°.