NOx Reduction in a 130 t/h Biomass-Fired Circulating Fluid Bed Boiler Using Coupled Ozonation and Wet Absorption Technology

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Low temperature, high alkali metal, and water content flue gas in biomass boilers restrict the application of traditional NO x treatment technology (i.e., selective noncatalytic reduction and selective catalytic reduction). In this paper, the coupled ozonation and wet absorption technology was used in a 130 t/h biomass circulating fluid bed boiler. Key parameters, that is, O 3 /NO molar ratio, mixing uniformity, liquid/gas ratio, and O 3 residual, were investigated with the industrial real case. The higher O 3 /NO molar ratio achieved better denitration efficiency, and the O 3 residual started to increase once the O 3 /NO molar ratio exceeded 2.1. Mixing uniformity is a key factor for the diffusion of ozone in flue gas, and it would directly influence N 2 O 5 formation and O 3 decomposition process. In the slurry, NO 3 – and SO 4 2– were the major byproducts after NO x and SO 2 absorption. With the optimization of key parameters, the NO x emission was controlled below 50 mg/Nm 3 under 34.8 kg/h O 3 dosage.