Integration of compressed air energy storage and gas turbine to improve the ramp rate

Manufacturers are trying to increase ramp rates to improve the operational flexibility of gas turbines. However, higher ramp rates lead to rapid variation in the combustion gas temperature and shorten the life of the turbine. To increase the rate without reducing the life, this study considers the use of a compressed air energy storage (CAES). Injecting pressurized air that is stored in CAES into the combustor of a gas turbine increases the power output of the gas turbine without increasing fuel supply. Therefore, the ramp rate of the turbine can be increased while suppressing the temperature change of the combustion gas. The injection schedule was optimized through a dynamic simulation to increase the ramp rate. A genetic algorithm was used in the optimization of the schedule. The optimized schedule turned out to be a simple form consisting of a linear increase and decrease in the injection flow rate. Furthermore, despite the increased ramp rate, the fluctuation of turbine inlet temperature could be maintained under a safe level due to the optimized compressed air injection.