Thermodynamic Analysis of New Combination of Supercharged Boiler Cycle and Heat Recovery Cycle for Power Generation

Abstract

The aim of this paper is to study the performance of a new combination of supercharged boiler–gas turbine cycle, which is expected to reduce the cooling air in the combustor and heat recovery cycle, from a thermodynamic point of view. Two designs of this cycle were adopted and the influences of various operating parameters, such as compressor pressure ratio, ambient temperature, inlet gas temperature of gas turbine, percentage of excess air, and number of feedwater heaters, were studied. Three techniques were applied to increase the overall cycle efficiency: first, increasing the mean temperature of heat supplied by increasing the inlet gas temperature of the gas turbine; second, decreasing the mean temperature of heat rejected through a heat recovery cycle; and third, reducing the percentage of excess air in the supercharged boiler. A performance comparison between the adopted cycles and a conventional heat recovery cycle was made. The results show that there is an improvement in overall cycle efficiency of about 8.5–9.5 percent with the first design of the adopted cycle over the conventional heat recovery cycle, while an improvement of overall cycle efficiency of about 1.0–5.5 percent is obtained for the second design.