Freeboard Combustion and NOx Modeling of a 6x6 Fluidized Bed Combustor

This paper presents an analysis of combustion and NO pollutant formation in the freeboard of the EPRI/Babcock & Wilcox Company (B&W) 6' x 6' Atmospheric Fluidized Bed Combustor (AFBC). The objective was to apply a multidimensional model to determine if such a model could ultimately be applied to scale up staged combustion to larger AFBC units. It was found that Lagrangian particle transport models can predict elutriation of small particles from the bed. Exit flue gas temperatures were well predicted but intermediate freeboard gas temperatures were underpredicted. An existing NO model underpredicted reaction rates for fuel NO production and reduction. Additional experimental data are required to validate the computer code before combustion and NO analyses can be used for scale-up.