Chemiluminescence-Based Feedback Control of Equivalence Ratio for a Continuous Combustor

Abstract

Recent pollution requirements and stringent operating conditions for gas-turbine engines have prompted the need for real-time feedback control of combustion processes for power production and propulsion. NO and CO pollutants from gas-turbine engines have been the focus of many researchers for some time. By accurate control of the equivalence ratio (EQR), fluctuations caused by low-frequency air flow rate disturbances may be avoided to maintain desired levels of NO and CO. In this paper, we develop a feedback technique based on CH chemiluminescence for real-time control of EQR in combustion processes. We focus on a continuous combustor for experimental modeling and implementation. An in-depth presentation is given of model development and digital controller design. Experimental step responses and an oxidizer flow rate disturbance test are provided for experimental validation of the EQR controller. The designed controller is successful in providing settling times less than 4.0 s with a maximum overshoot of 11.5 %, while simultaneously compensating for oxidizer flow rate disturbances to within ∼1%. With EQR control, a 153% increase in NO x emissions is prevented in response to a 9% reduction in oxidizer flow rate at a global equivalence ratio near 0.75.