Effect of hydrogen addition on the combustion and emission characteristics of methane under gas turbine relevant operating condition

Abstract

The influence of hydrogen addition (0–100%) on the combustion and emission characteristics (NO and CO formation) of laminar-premixed methane flame under gas turbine relevant operating conditions was numerically studied. The PREMIX code of ANSYS CHEMKIN-PRO and the GRI-Mech 3.0 were utilized. The study of the effect of increasing hydrogen content in the methane-hydrogen mixtures on combustion and emissions at T = 298 K, P = 1 atm can provide a reference for our subsequent research on gas turbine conditions (T = 723 K, P = 16.5 atm). The LBV (laminar burning velocity) and AFT (adiabatic flame temperature) with different hydrogen contents (XH2=0–100%) and equivalence ratio (Φ = 0.6–1.4) were investigated. In addition, under gas turbine relevant lean burning conditions (Φ = 0.6, 0.8), the effect of hydrogen addition on the NO and CO emissions were investigated. The rate and sensitivity coefficients of NO/CO production were also examined. The results show that the LBV and AFT increase with the hydrogen content. Both the mole fraction of H, O and OH radicals and the flame temperature were observed to increase with the hydrogen content. Furthermore, the hydrogen addition can significantly increase the NO emissions and on the other hand suppress the CO formation. Reducing the equivalence ratio (from 1.2 to 0.6) can significantly reduce the NO emission. The addition of hydrogen can also increase the combustion stability of methane fuel under fuel-lean conditions. This is a good hint for gas turbine device to reduce NO emissions at fuel-lean side (Φ < 1).