Laboratory Investigations of Low-Swirl Injectors Operating With Syngases

The low-swirl injector (LSI) is a lean premixed combustion technology that has the potential for adaptation to fuel-flexible gas turbines operating on a variety of fuels. The objective of this study is to gain a fundamental understanding of the effect of syngas on the LSI flame behavior, the emissions and the flowfield characteristics for its adaptation to the combustion turbines in IGCC clean coal power plants. The experiments were conducted in two facilities. Open laboratory flames generated by a full size (6.35 cm) LSI were used to investigate the lean-blow off limits, emissions, and the flowfield characteristics. Verification of syngas operation at elevated temperatures and pressures were performed with a reduced scale (2.54 cm) LSI in a small pressurized combustion channel. The results show that the basic LSI design is amenable to burning syngases with up to 60% H₂. Syngases with high H₂ concentration have lower lean blow-off limits. From PIV measurements, the flowfield similarity behavior and the turbulent flame speeds of syngases flames are consistent with those observed in hydrocarbon and pure or diluted hydrogen flames. The NO_x emissions from syngas flames show log-linear dependency on the adiabatic flame temperature and are comparable to those reported for the gaseous fuels reported previously. Successful firing of the reduced-scale LSI at 330 < T < 446° F and 8 atm verified the operability of this concept at gas turbine conditions.