Thermodynamic analysis of combined cycle power plant using regasification cold energy from LNG terminal

Abstract

Being increasingly used clean fuel, liquefied natural gas (LNG) release large amount of cold energy during its regasification process, which can be used for performance augment and energy saving towards regasification of LNG. In this paper a triple pressure Combined Cycle Power Plant (CCPP) with the application of the regasification cold energy is thermodynamically analyzed through energy and exergy principles. Three options were considered to investigate the effects of cold energy on thermodynamic performance of CCPP as a function of ambient temperature. The first option consists of utilization of cold energy for gas turbine (GT) inlet air cooling in the gas cycle (GC), the second option for cooling the condenser circulating water in the steam turbine cycle (STC) and the third option is a combined process of cold energy utilization in both GC and STC. The three presented options highlight the use of two heat exchangers one in GC and second in STC intended for utilization of LNG cold energy in CCPP. It is found that the gain in power output is significant from ambient air temperature 29 °C–45 °C (around 8.5% to 10.5%) and the gain in exergy efficiency is 0.09%–2.2% compared to the base case.