Comparative study on implementation technology for enhancing performance of combined cycle power plant in system perspective

In the present study, several technologies are compared and evaluated for improving the power and efficiency of a combined cycle power plant (CCPP) using liquid natural gas (LNG). The three technologies are applied to the CCPP and compared quantitatively: (i) Gas turbine intake cooling system; (ii) wet cycle (steam injection); and (iii) turbine cooling air precooling. In the gas turbine intake cooling system, an electric chiller and evaporative cooler are used for cooling the inlet temperature. The high-pressure steam header exit flow is used for injection to a combustor in the wet cycle. To simulate the turbine cooling air system, the intermediate pressure steam outlet flow is employed to cool down the bleed air extracted from compressor. The comparative results indicate that the wet cycle shows best performance in the all selected technology. The results for both the inlet air cooling and turbine cooling air precooling technologies show decreased thermal efficiency of CCPP. However, when the wet cycle applied to the system with 5 % steam injection, the power and thermal efficiency of CCPP are improved 1.37 %, respectively.