Operating Processes of Low-Speed Piston Compressors

In the paper, process booster piston compressors based on low-speed long-stroke machines with a linear drive have been discussed. The peculiarity of booster machines is that gas is supplied to the suction with some pressure and temperature that is most often higher than the ambient temperature. Currently, booster machines are most often multistage piston compressors, which complicate the process flow diagram due to interstage communications and heat exchange equipment. An alternative to existing designs of booster compressors can be a low-speed stage, which allows for an increased pressure ratio (up to 120) under acceptable temperature conditions due to minimizing the effect of a dead volume on productivity and a reduced piston speed to improve heat removal from the compressed gas. Based on the generalized model previously developed by the author for calculating low-speed compressors, which underwent comprehensive testing through experiments, the operation of low-speed compressors as boosters has been analyzed. Studies have shown that at an elevated temperature at the compressor inlet up to 400 K, the low-speed stage is capable of reducing the gas temperature during the compression-chamber filling process by 70 K, playing the role of a kind of heat exchanger in this process, which will accordingly allow obtaining an acceptable gas temperature at the compressor outlet up to 430–450 K. Using the example of such gases as methane, air, and carbon dioxide, it has been shown that, in the considered ranges of operating parameters, most of the studied low-speed booster compressor stages correspond to existing standards and trends both in temperature conditions and in the efficiency of the operating process. It should be noted that the experimental studies confirmed a decrease in gas temperature during the suction process.