Minimizing power consumption of boil off gas (BOG) recondensation process by power generation using cold energy in liquefied natural gas (LNG) regasification process

Abstract During the process of storage and transportation of liquefied natural gas (LNG), boil off gas (BOG) is generated. The presence of BOG causes the rise of pressure of the storage tank, and makes the LNG receiving terminal have a large safety hazard, which needs to be condensed and recovered. BOG recondensation process is a high power-consumption process, and meanwhile LNG regasification process releases a large amount of cold energy, which can be used to generate electricity. In order to reduce the power consumption of BOG recondensation process, this paper proposes the idea of power generation using cold energy in LNG regasification process to drive the compressors and LNG pumps in BOG recondensation process. Firstly, the cold energy recovery potentials of four different BOG recondensation processes are determined through parameter analysis and power consumption comparison. Based on this, four BOG recondensation and LNG cold energy power generation integrated systems are proposed, and the parameters and working fluids of the integrated system are optimized. Results show that the power consumptions of the integrated systems are significantly lower than those of the original BOG recondensation systems at different BOG contents. In most cases, the proposed system can meet the power requirement of the BOG recondensation process, and at the same time has the ability to output electrical energy. The power reduction rate of the integrated system decreases as the BOG content increases. When the BOG content is 0.03, the power reduction rate can be up to 250%. When the BOG content is 0.15, the power reduction rate can be up to 120%.