Thermodynamic Analysis of Gas Turbine Systems Fueled by a CH4/H2 Mixture

Abstract

In the coming years, as a result of changing climate policies and finite fossil fuel resources, energy producers will be compelled to introduce new fuels with lower carbon footprints. One of the solutions is hydrogen, which can be burned or co-fired with methane in energy generation systems. Therefore, this study presents a thermodynamic and emission analysis of a gas turbine fueled by a mixture of CH4 and H2, as well as pure hydrogen. Numerical studies were conducted for the actual operating parameters of the LM6000 gas turbine in both simple and combined cycles. Aspen Hysys and Chemkin-Pro 2023R1 commercial software were used for the calculations. It was demonstrated that with a constant turbine inlet temperature set at 1723 K, the thermal efficiency increased from 39.4% to 40.2% for the gas turbine cycle and from 49% to 49.4% for the combined cycle gas turbine. Nitrogen oxides emissions were calculated using the reactor network, revealing that an increase in H2 content above 20%vol. in the fuel leads to a significant rise in nitric oxides emissions. In the case of pure H2, emissions are more than three times higher than for CH4. The main reason for this increase in emissions was identified as the greater presence of H, O, and OH radicals in the reaction zone, causing an acceleration in the formation of nitric oxides.