Model Based Control of Emissions and Pulsations in a Premixed Combustor Using Fuel Staging

Abstract

A mixing model of a swirl inducing premixed burner is derived from non-reacting investigation and used to control the fuel staging of the burner to ensure stability and low NOx emissions. The convective time delays, critical for the combustor stability, are obtained after identification of a step response of the outlet concentration with a one dimensional mixing model. The steady mixing is used to evaluate quantitatively the mixing quality which correlates with NOx emissions. Time delays as well as scalar unmixedness criteria derived from those measurements are used to predict the combustor stability and NOx emissions maps for different injection configurations at one operating point. The resulting model is used to extend an Extremum Seeking Controller, which adjusts the fuel repartition to reduce the pressure pulsations and NOx emissions.