Role of Fuel Injection Scheme in a High Intensity Combustor

Abstract

Fuel injection at two locations in a combustor using premixed, partially pre-mixed and non-premixed schemes has been explored for improved distributed combustion. The effect of dual location fuel injection to the combustor is examined and the results compared from single fuel injection. Focus of dual and single injection scheme was on enhancing reaction zone uniformity in the combustor. A cylindrical combustor at a combustion intensity of 36MW/m3.atm and heat load of 6.25 kW was used. Three different schemes of dual location fuel injection with different proportions of fuel injected from each injector were investigated using methane as the fuel. The role of fuel distribution between the two injection ports using constant air flow rate to the combustor at room temperature was examined on reaction zone distribution and pollutants emission. Three different equivalence ratios of 0.6, 0.7 and 0.8 were examined with different fuel distributions between the two injectors to the combustor at a constant overall thermal load. The results showed lower emission with dual location fuel injection as compared to single location. Dual location fuel injection showed 48% NO reduction with 90% of the total fuel from injector 1 while only 13% reduction was achieved with 80% of the fuel injection from this location. . OH* Chemiluminescene intensity distribution within the combustor showed that under favorable fuel injection condition, the reaction zone shifted downstream to allow longer fuel mixture preparation time prior to ignition. The longer mixing time resulted in improved mixture preparation and lower emissions. The OH* Chemiluminescene intensity distribution with fuel introduced through two injectors showed improved OH* distribution in the combustor. Improved mixture preparation enhanced reaction distribution in the combustor and lower emission.