Combustion Control by Extended EV Burner Fuel Lance

Abstract

Flame stabilization in a swirl-stabilized combustor occurs in an aerodynamically generated recirculation region which is a result of vortex breakdown. The characteristics of the recirculating flow are dependent on the swirl number and on axial pressure gradients. Coupling to downstream pressure pulsations is also possible. In order to fix the position of the recirculation zone, an extended fuel lance was inserted into the burner. An additional benefit of the extended lance was to enable secondary fuel injection directly into the recirculation zone where the flame is stabilized. Tests were conducted with and without secondary fuel injection. The measurements included optimization of the location of the extended lance in the mixing chamber and variation of the amount of secondary fuel injection at different equivalence ratios and output powers. Flow visualizations showed that stabilization of the recirculation zone was achieved. The effect of the extended lance on pressure and heat release oscillations and on emissions of NOx, UHC and CO was investigated. The results were confirmed in high pressure single burner pressure tests and in a full scale land-based test gas-turbine. The lance has been successfully implemented in engines with sufficient stability margins and good operational flexibility. This paper shows the careful development process from lab scale tests to full scale engine tests until the implementation into the field engines.