A case study of thermal performance of gas-steam combined cycle with gas turbine inlet air cooling and condenser deep cooling

Abstract

To enhance power generation during high summer temperatures and address the power supply and demand imbalance in gas-steam combined cycle, this study explored the exhaust gas waste heat refrigeration scheme, along with the optimal scheduling of cooling capacity between the precooling of inlet air for the gas turbines and deep cooling for condenser in steam cycle. Using the Ebsilon software, we investigate the thermal performance of the gas cycle, steam cycle, and the overall gas-steam combined cycle under various off-design operating conditions, including varying cooling capacity distributions, ambient temperatures, and generation loads. Based on our calculations, it is advisable to prioritize cooling capacity for precooling the ambient air for the gas cycle, balancing power generation and thermal efficiency. After the transformation, the power generation of the gas-steam combined cycle remains relatively stable across varying ambient temperatures, achieving a significant 10.9 % increase compared to pre-transformation levels under a 39 °C ambient temperature and 100 % generation load. Furthermore, the thermal efficiency of the gas-steam combined cycle improves by 1.11 % under a 40 % generation load condition. As ambient temperatures rise, the benefits of the inlet air cooling scheme become more apparent, validating its effectiveness in addressing the inherent summer power supply and demand challenges.

Keywords

• Thermodynamic performance
• Thermal cycle configuration
• Gas-steam combined cycle
• Inlet air pre-cooling
• Energy cascade utilization