Experimental study on performance of BOG compressor

The boil-off gas (BOG) compressor is widely used for recycling the excessive boil-off gas of liquefied natural gas (LNG), and the extra-low suction temperature brings about great challenges to design of the BOG compressor. In this paper, a test system was built to examine the effects of low suction temperature on the compressor performance, in which the lowest temperature reached -178°C by means of a plate-fin heat exchanger with liquefied nitrogen. The test results showed that, as the suction temperature decreased from 20°C to -150°C, the volumetric efficiency of the compressor dropped by 37.0%, and the power consumption decreased by 10.0%. The preheat of the gas by the pipe through the suction flange to suction valve was larger than 20°C as the suction temperature was -150°C, and this value increased with the decreased suction temperature. The pressure loss through the suction valve at lower suction temperature was larger than that at ambient temperature while the volume flow rate was kept the same.