Thermodynamic Analysis of LNG Regasification Process

Abstract

Liquified Natural Gas (LNG) plays a vital role in the transition toward a sustainable energy future due to its reduced emissions compared to coal. Due to the low storage temperature (-162 °C) during LNG shipping, there is an ample amount of cold exergy (800-900 kJ/kg) embodied in LNG. The regasification process of LNG usually does not utilize this cold exergy. In this study, a detailed thermodynamic analysis of the LNG regasification process with secondary literature data is done. This process is modelled in Aspen Plus for a 2.77 MMTPA LNG regasification plant using the Peng-Robinson equation of state to calculate the thermodynamic properties. It is found that 1,024 kJ/kg of LNG is available in the form of physical exergy, which is equivalent to 0.131 kWh of power. From the obtained results, the energy and exergy flows are represented through Sankey and Grassmann diagrams. The maximum exergy loss is 40 %, originated from the LNG heat exchanger. The present study delineates the pathway for future work of cold exergy utilization to the potential cold consumers (e.g., data centre cooling, food storage etc.) with minimum destruction of exergy.