Thermodynamic simulation and economic analysis of combined cycle with inlet air cooling and fuel pre-heating: Performance enhancement and emission reduction

Abstract

Gas-steam combined cycle power plant (CCPP) performance suffers from sensitivity to ambient condition, higher fuel consumption rate and greenhouse gas emission. Several solutions were adapted to resolve one or two problems with expense of other. In this study, a hybrid process for compressor inlet air cooling (CIAC) and fuel pre-heating (FPH) is proposed to enhance the CCPP performance with simultaneous reduction in fuel consumption and emission. Three simulation cases have been presented for CCPP design and off-design mode of operation at a site-specific condition. The result shows that, compared to conventional cases the influence of CIAC and FPH leads to capacity increment of 10.7% to 12.7 % with load variation from 40% to 100%. The associated overall efficiency enhancement is 2.2 – 0.58% when ambient air temperature Ta cooled from 35 °C to 15 °C operating at site condition Ta = 35 °C, RH = 65%. The sensitivity analysis is performed based on monthly mean weather data. The rate of fuel consumption and CO2 emitted are considered per unit of power generated. The CO2 emitted is maximum at low Ta in the range of 26 – 28 °C and lower RH. The CCPP at its full-load, for an operating period of 24 h the fuel consumption will reduce approximately to 12226 kg and this will lead to saving in operating cost of 4307 dollars per day.