Experimental study on ozone denitration of a biomass circulating fluidized bed boiler

In order to reveal the characteristics of reactive molecular ozone denitrification in biomass boilers, a flue gas ozone denitrification test was carried out on a biomass circulating fluidized bed (CFB) boiler using reactive molecular ozone ultra-low emission technology. A flue gas analyzer was used to measure the flue gas components at the positions before the injection of reactive molecular ozone and at the top of the chimney. The emission characteristics of flue gas pollutants before and after denitrification and the effect of ozone dosage on denitration were investigated. The results showed that the boiler load and the initial concentrations of pollutants such as CO and NO_x fluctuated due to the strong random variation of moisture and calorific value of the biomass fuel. The averaged initial concentration of NO_x in the flue gas was 146 mg/m³, while the highest value was 480 mg/m³. The instantaneous concentration of NO_x had a very strong linear correlation with the oxygen content with the regression coefficient R²=0.96. With the increase of ozone dosage, the denitration efficiency increased from 24% at the ozone generator power level of 118 kW to 95% at 250 kW. After the application of reactive molecular ozone denitration technology, the NO_x concentration in the flue gas stayed below 15 mg/m³ with the ozone generator power level of 250 kW, meeting the ultra-low emission standard.