Application of Exergy Analysis for LNG Plants and Receiving Terminals

Natural gas liquefaction is an energy-intensive process. New world scale LNG plant usually has multiple trains with each train has a very high capacity (up to 8 million tons per annum of LNG). Increasing the plant efficiency can increase LNG plant output and economics, with reduced greenhouse gas emission.

On the other hand at LNG receiving terminals, LNG needs to be regasified to be put in pipelines to deliver to customers. LNG has a great cold energy potential. This cold energy can be used to generate power. The power generation scheme needs to be optimized to fully utilize the LNG cold energy potential.

Exergy analysis is based on the Second Law of Thermodynamics. It can identify the exergy loss distribution in the whole LNG plant or receiving terminals. Improving exergy efficiency for the unit operations with highest exergy loss will result in increased production, lower power consumption and better overall economics. For power generation using LNG cold energy, exergy analysis can identify the best power generation scheme for different LNG feed, composition and required delivery pressure.

This paper first review applications of exergy analysis in LNG plants and import terminals and then present major exergy analysis results and discoveries. Finally, recommendations for improving exergy efficiency in both LNG plants and receiving terminals are proposed.