Numerical investigation of temperature distribution in the furnace of a coal fired grate boiler in part load conditions

Łukasz Więckowski, Piotr Krawczyk, Krzysztof Badyda

Abstract


Gas temperature distribution along the grate length in part load conditions is expected to be non-uniform and vary significantly from the nominal. The objective of this work was to simulate the combustion process inside the furnace of a WR-25 coal fired grate boiler at two part load conditions. The results obtained were then compared to on-site temperature profile measurements taken 0.8, 2 and 3.5 meters above the grate level. Numerical analysis was performed using a commercial CFD (computational fluid dynamics) code. Boundary conditions at the grate-freeboard interface were calculated with a black-box type model. Off-design air distribution along the grate was taken into account based on real unit inspection. Model predictions demonstrated a good overall qualitative match with measured temperature profiles, but a quantitative comparison shows a need for improvements in the modeling. It was also shown that more attention needs to be paid to the modeling of soot, as it has a major impact on predicted temperatures.


Keywords


Coal firing; grate boiler; combustion; soot; computational fluid dynamics

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