Flamelet LES of oxy-fuel swirling flames with different O2/CO2 ratios using directly coupled seamless multi-step solid fuel kinetics

Oxy-fuel combustion, in combination with carbon capture technologies, has generated significant interest since it has a high potential for rapid CO2 cutbacks for newly built and retrofitted coal-fired power plants. Although research and development of oxy-fuel combustion technologies have been advancing recently, the combustion of solid fuels in an oxygen-carbon dioxide environment is not yet fully understood. In particular, the oxygen content in the recirculated flue gas is an adjustable parameter in oxy-fuel combustion. This work aims to analyze its impact on the thermo-chemical conversion by applying a recently developed approach for accurately predicting pulverized solid fuel combustion to a range of oxy-fuel swirl flames. The employed modeling framework builds upon a detailed solid fuel kinetic mechanism that seamlessly describes the entire solid conversion process. For the description of the gas phase, a combined flamelet modeling approach with large-eddy simulation is applied. This previously introduced high-fidelity framework (Nicolai et al., 2022) was applied to three operating points in a pilot-scale facility, for which in-reactor data is available. The overall model, combined the available experimental data, is employed for the three operating points with different oxidizer O2/CO2 ratios to give deeper insights into combustion. In particular, the influence of the local oxygen partial pressure on the solid fuel conversion is analyzed in detail.

Automated summary

Oxy-fuel combustion combined with carbon capture technologies has the potential to rapidly reduce CO2 emissions in coal-fired power plants. However, the combustion of solid fuels in an oxygen-carbon dioxide environment is not fully understood. This study aims to analyze the impact of oxygen content on thermo-chemical conversion by applying a recently developed approach to a range of oxy-fuel swirl flames.