A Pinch Analysis-Based Method for LNG Cold Energy Multi-Level Temperature Cascade Utilisation

Abstract

LNG releases much cold energy during regasification, which has great valorisation potential. Efficient use of LNG cold energy is a crucial way to achieve future clean energy transition. In this study, existing methods for LNG cold energy utilisation are reviewed. This includes air separation process technology, cold energy in power generation, light hydrocarbon separation, cryogenic CO2 capture, cryogenic comminution of waste rubber, dry ice production, seawater desalination process, and cold storage. Then the LNG cold energy cascade utilisation is studied using Pinch Analysis. Based on the method, this study proposes a cryogenic air separation – cold energy in a power cycle two-stage cascade utilisation process. The total temperature of the cold energy cascade utilisation and integration system is optimised to achieve the target of fully utilising LNG cold energy resources. A case of cryogenic air separation - cold energy in power generation in an LNG cold energy cascade utilisation system is studied to test how much cold energy is left. The results showed that the Pinch Point temperature is -150 °C, and 44.6 kW residual cold energy.