Biomass-coal reburning: Competitive mechanism of gas-solid product activation coal char

Reburning technology combining coal and biomass can effectively reduce NOx emissions and promote carbon neutrality in coal-fired systems. This work is based on the flat-flame burner test bench that decoupled the process of biomass-coal reburning effect on coal in the initial stage. The changes in surface functional groups and carbon skeleton structure of coal char were analyzed using FTIR, XPS, and Raman detection methods. The char's combustion reactivity and NO reduction ability were analyzed based on the micro-reactive fluidized bed test bench. The results showed that biochar and syngas would react with oxygen in the transport medium, and the resulting reactive species would activate the char. The activated effect of syngas is significantly better than that of biochar. The syngas reacts with oxygen while protecting the unnecessary consumption of the coal particle surface, and the generated active substances are enriched on the surface of the coal char to enhance its reactivity. The disordered structure of char was enhanced, and the number of small aromatic ring clusters increased by about 28%. The total alkane group content on the char surface increased by nearly 140%, and the total oxygen-containing group content decreased by nearly 17.8%. The combustion reactivity of char is increased by nearly 44.6%, and the reduced ability of NO is increased by nearly 23.4%. Theoretically, the reburned pulverized coal is reduced by 23.4%.