Oxyfuel Combustion of Biogenic Low Calorific Value Gases

Oxyfuel combustion describes the combustion of a fuel with pure oxygen. Idealized, the exhaust gas consists only of CO2 and H2O. A high-purity CO2 point source can be created by condensing water. The technology is therefore very suitable for CCUS. One possibility for moderating the combustion chamber temperature in oxyfuel combustion is the injection of liquid water. In this paper, the influence of water injection on the flue gas composition and emissions during oxyfuel combustion of a biogas-like CH4-CO2 mixture is analyzed. The experimental investigations are carried out on an oxyfuel plant of around 50 kW with downstream flue gas cooling for water vapor separation and flue gas recirculation. In addition, the combustion process is modeled using CFD. A CO2 content of 93-94.8 vol.% is achieved in the experimental tests. The injection of water proves to be a very efficient cooling strategy for the combustion chamber. The numerical simulation shows that the CO burnout is boosted by the injection of liquid water. In the next steps, an adsorption column for flue gas drying will be installed and the oxyfuel system will be coupled with a pyrolysis reactor.