Thermodynamic Analysis of Liquefied Natural Gas(LNG)Production Cycle in APCI Process

The appropriate production of liquefied natural gas(LNG)with least consuming energy and maximum efficiency is quite important.In this paper,LNG production cycle by means of APCI Process has been studied.Energy equilibrium equations and exergy equilibrium equations of each equipment in the APCI cycle were established.The equipments are described using rigorous thermodynamics and no significant simplification is assumed.Taken some operating parameters as key parameters,influences of these parameters on coefficient of performance(COP)and exergy efficiency of the cascading cycle were analyzed.The results indicate that COP and exergy efficiency will be improved with the increasing of the inlet pressure of MR(mixed refrigerant)compressors,the decreasing of the NG and MR after precooling process,outlet pressure of turbine,inlet temperature of MR compressor and NG temperature after cooling in main cryogenic heat exchanger(MCHE).The COP and exergy efficiency of the APCI cycle will be above 2% and 40%,respectively,after optimizing the key parameters.