Control of Emissions and Pulsations in a Premix Combustor using Fuel Staging

Extremum seeking control was applied to modify the fuel distribution of a premixed atmospheric swirl stabilized gas combustor to suppress combustion instabilities without increasing NOx emissions. The overall fuel flow was split into one premixed and two secondary injections. Dierent injection repartitions were tested and the best configuration regarding instability suppression was selected for closed loop control. Two dierent types of extremum seeking controllers were implemented and tested on symmetric and asymmetric secondary fuel injections at dierent operating points of the combustion chamber. To increase the controller speed, a fast NOx sensor based on chemiluminescence was implemented. The controller was able to suppress the instability of two operating points of the combustion system within a few minutes, mainly limited by the response time of the fuel flow sensors. The control scheme was also able to maintain the combustion stable during transients.