NOx 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 NOx 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 N2O5 formation and O-3 decomposition process. In the slurry, NO3- and SO42- were the major byproducts after NOx and SO2 absorption. With the optimization of key parameters, the NOx emission was controlled below 50 mg/Nm(3) under 34.8 kg/h O-3 dosage.