Conversion of suspension fuel droplets in the flame zone of an entrained flow gasifier

The High-pressure Entrained Flow Gasification (EFG) process can play an important role in future production chains with a closed carbon cycle because of its ability to generate a high-quality syngas from waste-based fuels, e.g., pyrolysis oils and suspensions derived from biomass and mixed plastic wastes. This work aims to improve the understanding of the conversion processes in the EFG flame zone for suspension fuels by applying a well-defined model suspension (monoethylene glycol and beech-wood char) in a combined experimental and numerical approach. A 2-Phase Free Jet Model is used to numerically investigate the reacting fuel spray and to perform a sensitivity study on suspension droplet conversion models. Modeled flame structures are validated by OH-LIF experiments at an atmospheric EFG. Results show that the flame structure for the suspension fuel is mainly determined by entrainment of syngas into the oxidizer jet and liquid fuel evaporation, whereas solid reactions are shown to play a minor role. Different suspension droplet conversion models are compared in a sensitivity study, showing a strong impact of the modeling approach on the amount of liquid fuel evaporation, which in turn influences flame structure. The insights of the study serve as a valuable basis for further research elucidating the coupled transport and reaction phenomena in the EFG flame, in particular the formation and conversion of intermediate solid products.