Oxyfuel combustion of biomass is a promising alternative to coal combustion in order to achieve climate-neutral combustion with reduced emissions in large-scale power plants. In contrast to combustion in air, the oxidizer in oxyfuel combustion mainly consists of oxygen and carbon dioxide (CO2). The primary goal of oxyfuel combustion is to increase the proportion of CO2 in the combustion exhaust gas in order to enable the use of carbon capture sequestration (CCS). However, the increased proportion of CO2 in the oxidizer stream leads to significant changes in the basic combustion chemistry and transport processes. Understanding gas phase chemistry under oxyfuel atmosphere and developing the appropriate reaction kinetic models are essential to establish the design and operation of advanced biomass combustion systems under oxyfuel conditions. The aim of this project, which is integrated in the Transregio Collaborative Research Center TRR / SFB129 "Oxyflame", is to understand the basic kinetics of the combustion of gas phase biomass under oxyfuel conditions. For this purpose, the experiments are carried out on an idealized flame configuration, the counterflow burner. The experimental boundary conditions in the counterflow burner configuration are very well characterized and reproducible. Therefore, countercurrent burner flames are ideal for basic experiments and for validating numerical models.

In order to examine the combustion processes in detail, species measurements are carried out using a time-of-flight molecular mass spectrometer. The use of a molecular beam enables not only the detection of stable species but also the determination of unstable flame species. The species in the flame are not only of fundamental importance in the conversion of the fuel, but also play a decisive role in the formation of pollutants. Based on the experimental data, novel reaction mechanisms are developed that describe the complex chemical processes in the flame. These chemical models are then used in simulations to predict large-scale fuel batch and emissions generation within biomass combustion systems under oxyfuel conditions.