Thermodynamic analysis of a gas turbine inlet air cooling and recovering system in gas turbine and CO2 combined cycle using cold energy from LNG terminal

Abstract

Research on the CO2 cycle has been conducted in various fields, such as nuclear power plants, centralized solar power plants, coal-fired power plants, waste heat recovery, combined cycle, and LNG cold energy recovery. In contrast to the steam Rankine cycle, the CO2 cycle is able to utilize the sub-zero temperature heat sink using LNG cold energy. Inthis study, a novel configuration is proposed that the gas turbine-carbon dioxide combined cycle power plant (GT-CO2 CCPP) with a gas turbine inlet air cooling (TIAC) and heat recovering (HR) system when using LNG cold energy. The TIAC and HR system cools the gas turbine inlet air using condensate CO2 to enhance the power output while air energy is simultaneously recovered to the CO2 bottoming cycle for additional power output and higher efficiency. To determine the capacity of this type of plant, the most commonly implemented LNG terminal is investigated, and the 62 MW medium-size gas turbine is selected for a simulation case study. The thermal performance potential of the proposed configuration is analyzed and compared to a conventional GT-steam CCPP, a GT- CO2 CCPP without the TIAC and HR system. The results show that the relative power output is enhanced by 14.9% and that the efficiency is improved by 2.1% (1.4%p) compared to the GT- CO2 CCPP without it. Meanwhile, this system enables higher power output and efficiency by 25.4% and 11.5% (6.8%p), respectively, compared to the conventional GT-steam CCPP, and the effect is increased according to the ambient temperature.