Liquid fuel evaporation under entrained flow gasification conditions – Insights for burner development

This study investigates the evaporation of a liquid surrogate fuel in the burner near region of an atmospheric pressure Entrained Flow Gasification (EFG) unit. Fuel evaporation is compared for two twin-fluid atomizer nozzles with different gas exit area under identical gas and liquid mass flow. PDA and Fuel-Tracer LIF are used to measure droplet size, droplet velocity and fuel spray distribution under reacting conditions for both cases while OH-LIF is used to measure the flame structure. A 2-Phase Free Jet Model (2-Ph-FJM) is applied in a sensitivity study on the influence of gas momentum flow, spray angle and droplet size on fuel evaporation in the high temperature oxidation zone. The impact of the liquid evaporation model is investigated by comparing two model approaches. Model results are used to interpret the experimental data and to derive an understanding of the fuel conversion processes in the investigated flame. A major portion of fuel was found to evaporate outside the flame boundaries in both investigated cases. Data indicates a strong impact of droplet residence time and spray parameters on the amount of fuel evaporation within the EFG flame. ... mehrThe 2-Ph-FJM shows the capability to identify beneficial and detrimental parameter spaces for fuel evaporation in the flame. With further understanding of by-product formation under EFG conditions, the detailed experimental data and the insights gained from the numerical study are a useful basis for further development of EFG burners and to define boundary conditions for CFD reactor simulations.