Study On Compressor Air Flow Pulsation And Pipe Vibration Based On Plane Wave Theory

The vibration caused by air pulsation are widely found in the process of fluid industrial device,at present,the method of forced pipe restraint is generally adopted to solve the pipeline vibration in China,and there is no way to radically solve the problem of pipe vibration caused by air flow pulsation.Therefore,this subject takes the air pulsation as the object of study.Based on plane wave theory and the analysis of compressor exhaust characteristics,the mathematical model is established.Then the experimental platform of reciprocating compressor is built to measure the actual pressure pulsation in the pipeline,and the air pulsation pressure value of the numerical model is compared with the actual pressure pulsation,it is found that the average error is 7.2%,proved the accuracy of the numerical model.Based on the experimental verification model,the influence of the size of the pipe structure on the air pulsation is analyzed.It is found that the amplitude of the air pressure pulsation decreases 8%-10%when the buffer tank volume increases 20L;when the distance between buffer tank and compressor increase each 100mm,the air pressure pulsation amplitude will rise by 20%-30%;With the increase of the diameter of the pipe between buffer tank and compressor,the air pressure pulsation in pipe will decrease.According to the API618 standard limit of gas pulsation in the pipeline,compressor air pulsation "safe drawing isobars" is established for the very first time,to provided reference for engineers to design safe reciprocating compressor piping system.The numerical simulation method is used to verify the functional effects of three new types of air flow pulsation suppression devices,inc luding the Helmholtz resonator,branched tube structure and the combined expansion chamber,analysis their merits and drawbacks.It was found that when installing the Helmholtz resonator,the air pressure pulsation in the cylinder decreased by 76%;A branch pipe structure is installed on the pipeline of the reciprocating compressor so that the airflow pulsation at the downstream of the branch pipe is reduced to zero;A combined expansion chamber is arranged between the cylinder and the buffer tank and the air pulsation in the buffer tank is reduced by 45%.The three new devices can be used as an effective supplement to the buffer tank.To provide safety evaluation and modification of a compressor system in factory,an calculation of the air pulsation is conducted and found that air pulsation value is severe exceed the allowable limit of the air pulsation pressure in API618 standard.Therefore,the new volume of the buffer tank in the new compressor piping system is determined,reduced the airflow pulsation in the pipeline to the safe range.