Vibration Analysis Of Reciprocating Compressor Piping System

Reciprocating compressor is important mechanical equipment in the petrochemical industry, and the vibration of its pipeline system directly affects the function and safe operation of the equipment. The main vibration sources of reciprocating compressor piping system are the harmonic load caused by the fluctuating pressure of the airflow inside the pipe, the dynamic unbalanced load of the reciprocating compressor and the earthquake load. In this thesis, an experimental pipeline was set up in the discharge of a reciprocating compressor. Static and dynamic analyses were carried out for the the piping system. Support bracket and the buffer tank were added to reduce the vibration of the pipeline system and their advantages and disadvantages are compared. In addition, flexibility analysis for the pipes was also performed to explore the relationship between the vibration passed by the pipe and its flexibility under seismic load conditions. The main work and conclusions are as follows:(1)Static analysis and dynamic analysis for the compressor experimental pipeline system were carried out with the software of CAESARII, and the focus is on the fatigue stress analysis and strength assessment. The vibration measurement results of the experimental pipeline well agree the simulation results of the software, indicating that the simulation method is rational and simulation results are reliable.(2)The vibration reduction performances by adding support bracket or buffer tank in the pipeline system were explored. It is found that without considering the effects of temperature, applying pipeing support bracket can change the natural frequencies of the pipeline system so as to avoid the resonance frequencies range of the compressor excitation, and it can also reduce the vibration displacement and the dynamic fatigue stress. By analyzing the resonance frequency region, the best support installation position for the support bracket can be obtained. Installing the buffer tank can change the pipeline gas column modal and, thus, making the pipeline gas column resonance frequency away from the resonance frequencies range of the compressor excitation. Also, the buffer tank can effectively reduce the pressure pulsation, reduce pipeline vibration force, and remarkably reduce the pipeline vibration level. It is reached from this study that for reducing the vibration of the reciprocating compressor pipeline system, assembling the buffer tank is superior to installing the support bracket in the pipeline. For the design of the reciprocating compressor pipeline, pressure pulsation should be considered firstly.(3)There are different arrangements of pipelines behind the gas distribution equipment, and their relatively flexible coefficients are analyzed with CAESARII. The gas distribution equipment and its postpositioned pipelines were tested under the seismic load. It was found that from the experiments, compared with the identification grade of high frequency random vibration, the gas distribution vibration passed by the pipe at the identification grade of low frequency sine vibration experiment was very small, and it was mainly used to test the natural frequencies of the gas distribution equipment. Therefore, the high frequency random vibration experiment at the identification grade should be considered as the main source of the vibration for assessment of the gas distribution equipment and vibration-proof ability of its postpositioned pipelines. It is found from the flexible coefficient analysis of pipelines and data of the experiments, the vibration passed by the pipe at the identification grade of high frequency random vibration is roughly inversely proportional to the flexibility of the pipe. Or in other words, the higher the flexibility of the pipe, the smaller the vibration passed by pipe from the ground brackets. With the analysis, the best pipeline arrangement can be chosen for different size of the pipes postpositioned at the gas distribution equipment.