Thermodynamic analysis on the process of regasification of LNG and its application in the cold warehouse

Abstract

Recently, with the rapid development of LNG (liquefied natural gas) industry, the utilization of LNG cold energy is becoming increasingly important because of the huge amount of energy released in the regasification process. LNGCW (LNG cold warehouse) system, as a common by-product of LNG, is often used with the benefit of energy saving. De facto, few comprehensive and quantitative researches on the LNGCW system are seen in open literature, thus it is necessary to analyze and evaluate the thermal performance of LNGCW system in depth. In this paper, some important results of regasification under different pressures were revealed, including LNG cold energy released, LNG cold exergy released and UA value of LNGHX (LNG heat exchanger). Secondly, a three-stage parallel LNGCW system was proposed and R23 was selected as the intermediate working fluid for this system. When the regasification pressure is 7.0MPa, thermodynamic analysis showed that the LNGCW system exergy efficiency was 64.75%, and the COP was 1.41. Moreover, both the COP and exergy efficiency of the LNGCW system rose as the LNG regasification pressure increased. Finally, a qualitative analysis showed that LNGCW system as the subsequent stages was more favorable.