EXHAUST GAS RECIRCULATION AT ELEVATED PRESSURE USING A FLOX® COMBUSTOR

To reduce CO2 emissions from the combustion of fossil and alternative fuels, carbon capture technologies present a promising approach. But the efficiency of the capture process depends on the CO2 concentration in the exhaust gas which is relatively low for gas turbine power plants. Exhaust gas recirculation (EGR) is a promising approach to increase the CO2 concentration in the exhaust gas stream and thus reduce the energy losses. In this study a FLOX (R) combustor was used to investigate the influence of EGR on the combustion process of natural gas at elevated pressure. The combustor stabilizes the flame without use of swirl, by creating a strong recirculation through high momentum injection of the fresh gas into the combustion chamber. This enables the establishment of a distributed combustion zone, which promises advantages for the use of gas mixtures with low reactivity like those occurring in EGR processes. At a pressure of 5 bar it was possible to increase the CO2 concentration in the exhaust gas up to 7 vol%, which is already enough to realize an efficient CO2 capture process. At 10 bar the CO2 concentration could be increased to 9 vol%. The changes in flame stabilization due to pressure increase and different EGR rates are investigated by. OH*-chemiluminescence imaging and discussed. The contribution of auto-ignition and flame propagation to flame stabilization is estimated by a kinetic model calculation.