Investigation On The Method Of Suppressing Gas Pulsation In The Reciprocating Compressor And Its Piping System

Reciprocating compressors are widely used in the petroleum,chemical,metallurgy,aviation,national defense and other fields.They are the essential energy equipment in the manufacturing industry.The intermittent and periotic suction and exhaust generate the gas pulsation in the compressor and its piping system.The pulsating airflow periodically impacts the equipment and the piping system,directly triggering the structural vibration.At present,with the widespread use of the reciprocating compressors,the gas pulsation frequently causes the piping vibration.The domestic and foreign scholars have carried out corresponding theoretical research and put forward some suppression methods,in order to effectively suppress the gas pulsation in the piping systems.However,because of the complex working conditions and the changeable process requirements,the piping vibration caused by the gas pulsation often has its specific reasons and engineering background,which is difficult to generalize.It makes the suppression effect of the gas pulsation in the reciprocating compressor and its piping system not ideal.In our country,the problem of pipeline vibration caused by the gas pulsation still occurs,and is accompanied by the leakage of toxic and harmful,flammable and explosive gas,the fracture of the pipe support and even the intense explosion.At the same time,the process compressor and its subsidiary equipment are large,and the support foundations are mostly poured by cement,so it also greatly increases the difficulty to modify the pipes and equipment.Therefore,in this thesis,for the widely existing gas pulsation in the reciprocating compressor and its piping system,the targeted pulsation suppression methods and structures were put forward.The more in-depth theoretical and experimental research was carried out,and the suppression methods were applied to the engineering practice to prove the effectiveness of the proposed methods and structures.The specific studies are as follows:(1)Study on pressure pulsation suppression of the single surge tank.The theory of the plane wave impedance of the reflux expansion cavity was proposed.A number of mathematical models for describing the dynamic transmission of the single surge tank with different suction and exhaust forms were constructed.The influence of the tank's layout on the pressure pulsation in the piping system was studied,which provides the theoretical guidance for on-site rational selection of the surge tank configuration and piping layout.A rapid numerical method of pressure pulsation based on particle swarm optimization(PSO)was proposed.The correctness of the model was proved by the experimental study and three-dimensional transient numerical simulation.It is shown that the numerical solution could predict the distribution of pressure pulsation in the whole piping system,and the numerical method has a higher solution precision and iterative speed.The results show that the performance of suppressing pulsation using the single surge tank with the axial suction and radial exhaust under the same volume is relatively prominent.On this basis,the influence of the characteristic structural parameters on pulsation suppression using the radial exhaust surge tank is revealed,which is beneficial to make fully use of the effect of the tank on suppressing pulsation and guide the engineering practice.(2)Research on pressure pulsation characteristics of the volume-internal element-volume suppressors.Based on the structure characteristics and the suppression principle of the internal orifice plate and internal pipe,the volume-perforated pipe-volume suppressor was proposed,which can effectively solve the problem that due to the limitation of the cost and space,the volume of the surge tank near the compact reciprocating compressor is small,and the performance of suppressing pressure pulsation is limited or invalid.The pulsation suppression ability of the original single surge tank is to be improved.In order to evaluate the effect of pulsation suppression,the characteristics of pulsation suppression were deeply analyzed.The mathematical model of the gas pulsation dynamic transmission in the piping system was used to predict the distribution trend of the pulsating pressure in the piping system.The correctness of the theoretical model was verified by the experimental research.On the premise of maintaining the piping layout,it is proved that the internal elements are generally applicable to modify the original single surge tank and improve the suppressing ability.The results further show that the relative suppression ratio of the piping system with a volume-perforated pipe-volume suppressor is about 20%higher than that of the other two suppressors.(3)Research on pressure pulsation characteristics of the double surge tank.The double-tank element structure is proposed to solve the specific problem that because of the limited site space,the surge tank is far away from the compressor and the performance of pulsation suppression is restrained,and to avoid the high pressure drop and increasing manufacturing cost by replacing a large surge tank.By means of experimental study and numerical simulation,the correctness of the comprehensive model of pressure pulsation transfer was fully verified,and the characteristics of the pressure pulsation suppression using the double-tank element structure were analyzed.Based on the advantage of suppressing pulsations using the single surge tank with axial intake and radial exhaust,the elbow-shaped surge tank element was further proposed,which can suppress pulsations effectively in the special situation that the double-tank element could not be adopted because of the limited space.The mathematical model of calculating pressure pulsations was constructed.Compared with the two-tank element,the peak-to-peak pressure pulsations at the points with the largest pressure pulsation intensity in the upstream and downstream pipelines with the elbow-shaped surge tank element can be reduced by 41.37%and 27.37%,respectively.The effective performance of suppressing gas pulsation was achieved.The pulse response method was applied.The theoretical sweep frequency excitation was given to analyze the response distribution in the piping system.The transmission characteristics of the pressure wave were studied to verify the feasibility of the method and provide a reliable theoretical basis for the engineering application.(4)Experimental study.Using the double acting reciprocating compressor as the excitation source,the experimental setups were built to simulate the behavior of gas pulsation in the piping systems between the compressor stages in the factory.The scales of the reciprocating compressor and its pipelines were close to the scales of the equipment in the engineering site.The measurement points were distributed evenly in the testing pipeline.The sixteen channel high speed synchronous acquisition system was used to collect the pressure signals.Based on the time and frequency analysis methods,the distribution of the pressure pulsation in the whole piping system was obtained,which is beneficial to verify the theoretical results of this subject rationally and effectively.The chamber with multiple pipe joints was designed and processed to realize the free combination of different inner elements and various arrangement forms of the chamber.It will provide operational support for field application and guidance for practice.(5)The application of pulsation suppression methods in engineering practice.The suppression methods proposed in this paper were applied to the engineering practice,and guided to solve the vibration problems of reciprocating compressor and piping systems caused by gas pulsation.According to the actual working conditions and technical requirements of the field,the theoretical model was built to predict the pressure pulsation distribution the whole piping system.The concrete damping scheme was formulated in combination with the suppression structures proposed in this subject.The compressor runs smoothly and the vibration of the pipeline system decreases remarkably after the transformation,which proves that the research methods and the suppression structures can effectively solve the actual pulsation problems in the field.The phenomenon of gas pulsations in the reciprocating compressor and its piping systems in the engineering field was comprehensively analyzed.According to the present situation that the existing research results have not been well applied in the field practice yet,the study on the suppression methods and structures of gas pulsation was carried out,and the suppression characteristics of the methods and structures proposed in this work were thoroughly analyzed.The theoretical research,experimental verification and numerical simulation were performed to provide support for suppressing the gas pulsation in the reciprocating compressor and its piping system.