Evaluation of the PRICO liquefaction process using exergy-based methods

The PRICO process is a single mixed-refrigerant process used for small-scale LNG plants, including offshore terminals. The working fluid (refrigerant) is a mixture of methane, ethane, butane and nitrogen. The behavior of the mixture in processes such as cooling, heating, compression, evaporation and condensation depends on its composition and on the part of the chemical constituents of the mixture that are in the gas and liquid phases. The state-of-the art for the evaluation and optimization of the PRICO process is discussed. Exergy-based analyses, i.e. exergetic, exergoeconomic and exergoenvironmental analyses, are applied to the evaluation of the PRICO liquefaction process of natural gas. The purpose of the paper is to identify options for improving the PRICO process and to demonstrate the application of exergy-based methods to the improvement of an LNG plant. The perspectives from the thermodynamic, economic and environmental impact points of view are discussed.