Thermo-economic analysis of a heat recovery steam generator combined cycle

A significant amount of energy gets lost through the exhaust of simple gas turbine plants, more often than not, this energy can be used to run another power cycle or a combined heat and power setup, leading to an increase in the overall efficiency of the plant, reduce air pollution and energy wastage. In this study, a retrofitted performance analysis of incorporating a steam power cycle to the existing gas turbine cycle in Delta IV power station is carried out, the analysis is carried out using first law of thermodynamics and energy cost comparison to describe the effect of combining both cycles on power output, thermal efficiency and energy cost. Operating data were obtained from existing gas thermal plant in Ughelli (Delta IV) and steam thermal plant in Lagos (Egbin). Preliminary assessment shows that power output increases by a further 51.5MW, thus raising the overall combined efficiency to 41.85%. Analysis on cost savings accruable from incorporating a heat recovery steam generation was also done and significant savings in cost was obtained.Keywords: combined cycle, HSRG, gas turbine, steam turbine, energy cos