Development of High Turbulence BGR Ultra-low NOx Combustor for Liquid Fueled Micro Gas turbine

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Micro gas turbine system is now received much attention for a local energy plant. As for the viewpoint of fuel, an energy plant using liquid fuel is desirable because of safety and smooth fuel supply even id the emergency situation such as earthquake. Also combustion emission from energy plant should be minimized for daily use of the plant. Ultra low Nox combustor with liquid kerosene fuel is developed as a micro gas turbine combustor for this purpose. The developed combustor has a unique flow system that is called upward swirl flow. This flow can form the upward reverse flow with burned gas re-circulation and is effective for flame stabilization with high turbulence. Also it is effective to attain a low Nox combustion by the effect of BGR. The main results obtained here are as follows. (1) Longer length of primary combustion zone results the undesirable combustion such as CO and Nox increases and low stability of flame. (2) The effect of vane angle of the swirl generator is not so much, however HC and CO emissions increase when the swirl generator is eliminated. (3) Air guide vane set at the bottom end of primary combustion zone shows the strong effect on the flame stabilization. For flame stabilization, enough height of vane is needed. Also an enough size of throat diameter at the outlet of primary combustion zone is needed for flame stabilization. (4) An optimization among the size of primary combustion zone, swirl generator, air guide vane and outlet throat results the enough emission performance of the combustor. Nox emission index less than 0.8 g/ (kg-fuel) and CO emission index less than 10 g/ (kg-fuel) can be attained under the primary excess air ratio of 1.5 〜 1.6