Laboratory Investigations of a Low-swirl Injector with H₂ and CH₄ at Gas Turbine Conditions

Laboratory experiments were conducted at gas turbine and atmospheric conditions (0.101 < P₀ < 0.810 MPa, 298 < T₀ < 580 K, and 18 < U₀ < 60 m/s) to characterize the overall behaviors and emissions of the turbulent premixed flames produced by a low-swirl injector (LSI) for gas turbines. The objective was to investigate the effects of hydrogen on the combustion processes for the adaptation to gas turbines in an IGCC power plant. The experiments at high pressures and temperatures showed that the LSI can operate with 100% H₂ at up to ϕ = 0.5 and has a slightly higher flashback tolerance than an idealized high-swirl design. With increasing H₂ fuel concentration, the lifted LSI flame begins to shift closer to the nozzle exit and eventually attaches to the nozzle rim and assumes a different shape at 100% H₂. The STP experiments show the same phenomena. The analysis of velocity data from PIV shows that the stabilization mechanism of the LSI remains unchanged up to 60% H₂. The change in the flame position with increasing H₂ concentration is attributed to the increase in the turbulent flame speed. The NO_x emissions show a log linear dependency on the adiabatic flame temperature and the concentrations are similar to those obtained previously in a LSI prototype developed for natural gas. These results show that the LSI exhibits the same overall behaviors at STP and at gas turbine conditions. Such insight will be useful for scaling the LSI to operate at IGCC conditions.