Optimization and thermodynamic analysis of a cascade PLNG (pressurized liquefied natural gas) process with CO2 cryogenic removal

Wensheng Lin, Xiaojun Xiong and Anzhong Gu

Energy, 2018, vol. 161, issue C, 870-877

Abstract: Based on an increased liquefaction pressure, PLNG (Pressurized liquefied natural gas) technology has the advantages of energy-saving and space-saving. This paper proposes a novel cascade PLNG process with CO2 cryogenic removal, wherein a two-stage cascade refrigeration system is used to replace the conventional three-stage one and a CO2 cryogenic removal unit is integrated with the process to eliminate CO2 pre-treatment facilities. CO2 is removed to 0.5% level at a pressure of 1.5 MPa and temperature of 165.7 K. Three refrigerant options, namely CH4-C2H6, CH4-C2H4 and C2H4-C3H8, are selected for the novel process and three process configurations are designed based on the refrigerants. Taking the specific energy consumption as a target, the three designed processes are simulated and optimized. Results show that C2H4-C3H8 process has the lowest specific power consumption, the best matched composite curves and the smallest heat exchanger size. Under optimum condition, the specific power consumption of C2H4-C3H8 process is 0.2559 kWh/Nm3, 2.5% less than that of conventional CH4-C2H4-C3H8 process. In addition, thermodynamic analyses are conducted for the proposed processes. The COP and exergy efficiency of C2H4-C3H8 process are calculated to be 0.75 and 0.47, respectively, improving by 17% and 38% over that of conventional one.

Keywords: PLNG (pressurized liquefied natural gas); Process simulation; Optimization; Energy consumption; Exergy efficiency (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:161:y:2018:i:c:p:870-877

DOI: 10.1016/j.energy.2018.07.051

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