Work

Assisting denitrification and strengthening combustion by using ammonia/coal binary fuel gasification-combustion: Effects of injecting position and air distribution

Year: 2024

Type: article

Abstract: NH3 combustion has drawbacks such as high ignition energy and high NOx emissions, which restrict its large-scale co-combustion in coal-fired unites. In this study, a self-sustaining gasification-combustion experimental system was employed. It was evaluated that denitrification performance and combustion-strengthening capability of gasification-combustion technology on NH3/coal binary fuel. The results of co-firing 20% NH3 in the gasifier indicated that the operating temperature of gasifier can be flexibly controlled within the optimal reaction temperature window of SNCR by adjusting primary air ratio (λ1). Increasing λ1 was beneficial for the conversion and denitrification of NH3 and coal. At λ1 =0.53, the conversion rate of NH3 and N2 reached 86.37% and 83.59%, respectively, with no NOx being detected at gasifier outlet. After entered down fired combustor, increasing λ1 promoted fuel burnout, and reached a level similar to pure coal condition under λ1=0.53. The results of co-firing 20% NH3 in DFC suggested inner secondary air enhanced char burnout, whereas outer secondary air promoted NH3 combustion. Uniform air distribution method balanced the combustion of NH3 and gasified char, and effectively controlled NOx emissions. Moreover, co-firing NH3 in gasifier was more favorable for NOx control, while co-firing NH3 in DFC benefited the burnout of NH3 and coal.

Source: Energy

DOI: 10.1016/j.energy.2024.133609