NO x Reduction in a 130 t/h Biomass-Fired Circulating Fluid Bed Boiler Using Coupled Ozonation and Wet Absorption Technology

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, O3/NO molar ratio, mixing uniformity, liquid/gas ratio, and O3 residual, were investigated with the industrial real case. The higher O3/NO molar ratio achieved better denitration efficiency, and the O3 residual started to increase once the O3/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 N2O5 formation and O3 decomposition process. In the slurry, NO3 – and SO4 2– were the major byproducts after NO x and SO2 absorption. With the optimization of key parameters, the NO x emission was controlled below 50 mg/Nm3 under 34.8 kg/h O3 dosage.