Abstract :
[en] In the context of the energy transition towards a zero-carbon society, amine-based carbon capture has been identified as a transient solution to enable the continued use of fossil fuels while mitigating CO2 emissions. To reduce the penalty associated with carbon capture, exhaust gas recirculation (EGR) is employed to increase the concentration of CO2 in the exhaust gases and to reduce the overall mass flow of these gases. However, operating close to stoichiometric combustion conditions increases CO emissions, which limits the EGR rate and thus the penalty reduction. To overcome this challenge, hydrogen cofiring has been proposed as a promising method to stabilize combustion under near-stoichiometric conditions. However, the impact of hydrogen cofiring as an EGR facilitator has never been tested, and its effects on performance and emissions still require thorough investigations. To fill this gap, experiments are conducted using a 3 kWe micro gas turbine (MTT EnerTwin®), fuelled with pure methane and a blend containing 20% hydrogen. In this study, the effects on emissions are investigated, specifically for NOx, CO, CO2, and O2. The modified setup, designed to allow for higher EGR rates, provides insights on how hydrogen cofiring can stabilize combustion and improve carbon capture efficiency. While the highly diluted conditions encountered in the mGT combustor do not enhance the thermal NOx formation when hydrogen is added, H2 cofiring significantly depletes CO emissions (up to a factor 10). Furthermore, the stabilizing effect of hydrogen on the combustion allows higher EGR rate and exhaust gases more concentrated in CO2 (additional 1.3% compared to pure methane). These findings could be crucial when extrapolating the behaviour of micro gas turbines to industrial-scale systems and evaluating the potential of hydrogen to reduce the overall system penalty of carbon capture technologies.
