Experimental characterization of an industrial burner operated with simulated EGR

The implementation of Exhaust Gas Recirculation (EGR) in gas turbines can become an interesting opportunity to enhance the coupling between natural gas fuelled GT power plants and Carbon Capture and Storage (CCS) systems. In fact, as the CO2 content of the incoming flow increases, performance of CCS units improves in terms of efficiency and compactness. As a drawback, the oxygen content available for the combustion reaction decreases, making the combustion process challenging in terms of flame stability and therefore engine operability. This work presents the results of an experimental campaign investigating the behaviour of an industrial burner operated with simulated EGR. For the investigation EGR is recreated by diluting standard air with CO2. The burner is operated at ambient pressure in a single sector optical test rig with tubular quartz liner, using natural gas as fuel. The effect of fuel split between premix and pilot line was investigated along with the lack of oxygen caused by EGR. OH* chemiluminescence imaging was employed to study flame topology, and exhaust gas analysis was performed. Emission measurements showed significant NOx reduction, but at the same time as expected CO levels increased remarkably under EGR-like conditions. Additionally, CO2 addition is found to trigger thermoacoustic instabilities in certain conditions, limiting the EGR operability window.