Humidified exhaust recirculation for efficient combined cycle gas turbines

•Humidification of the recirculated exhaust in Combined Cycle Gas Turbines.•Overall efficiency enhancement even under part load conditions.•Acidic gases removal before stack rejection.

Dwindling fossil fuel reserves require the efficient usage until sustainable alternatives fully replace them. Overall efficiency and output is used to rank the stationary combined cycle gas turbines. Efficient gas turbines require high combustion chamber temperature resulting in NOx generation. Furthermore, low-quality fuel increases the fraction of acidic gases in the exhaust. In this work a novel modification in combined cycle gas turbine cycle is presented, increasing the overall efficiency and decreasing acidic gases production along their capture, before rejection to stack. The modification is implemented on simulated General Electric 9HA.02 turbine using ASPEN HYSYS® v8.6. Applying efficiency and exhaust temperature limit (constraints), bounds the discrepancies in simulated and real gas turbine parameters. A rise of 0.77% in efficiency and a considerable decrease in acidic gases (exhaust) is observed. Different gas turbine operational features pertinent to overall efficiency have been studied. An unprecedented control technique is presented as an addition to the proposed modification to achieve higher efficiencies under part load conditions.