Effects of Co-Firing Biomass and Pulverized Coal on NO Reduction in Cement Precalciner

With increased awareness of the large-scale CO2 emissions from the cement industry, there has been growing focus on greenhouse gas reduction strategies. Among all these strategies, fuel substitution using biomass fuel is extensively used to achieve CO2 zero-emission in cement production. Due to the avoidable high-temperature-generated thermal nitrogen oxides during cement production, research on the impact of biomass application on nitrogen oxide emissions shall be carried out. Three types of biomass fuel and bituminous coal were used to investigate the NO reduction characteristics under different O2 concentrations on experimental benches. It was found that the change in oxygen concentration from 9% to 1% increased the reaction time in the reactor from 555 s to 1425 s, which means the increase in oxygen concentration can lead to shorter reaction time, and correspondingly, the existing time of nitric oxide in the flue gas is also shortened, but the peak value of nitric oxide rises, during the process of O2 concentration changing from 1% to 9%, the peak NO concentration in the flue gas increased from 5.4x10-5 to 1.05x10-4. An increase in O2 concentration greatly reduces the total reduction of NO and the minimum change in NO concentration. The peak NO concentration during the combustion process of corn stalk is 4.56 x10-4, which is approximately 7 times higher than that of coal, and it is caused by the high amount of N in corn stalk. The addition of raw meal has an inhibitory effect on the reduction of NO: after adding raw meal, the effective reduction time of NO by fuel decreased by about 20%, but adding raw meal raises CO2 concentration of fuel gas in the early stage of reaction.