In response to the narrow temperature window and low denitration efficiency of the selective non-catalytic reduction (SNCR) technology at low temperatures

this paper investigates the characteristics of the ammonium bicarbonate denitration reaction and selects sodium salts as additives for denitration efficiency enhancement experiments in a tubular furnace. Based on the Chemkin-Pro software

the yield and sensitivity analysis of key free radicals are carried out

and the low-temperature enhancement mechanism of sodium carbonate and sodium acetate on the SNCR technology is explored with the experimental results. The results show that adding sodium salts at a low temperature of 750℃ can improve denitration efficiency to varying degrees at different ammonia-to-nitrogen molar ratios (normalized stoichiometric ratio

NSR)

and the reductant utilization reaches its peak at NSR=1.7. Adding 50 μmol/mol of Na2CO3 and CH3COONa to the reaction system at NSR of 1.7 reduces the lower limit of the denitration temperature window to 785 and 776℃

respectively

and the average low-temperature denitration rate increases from 12.5% to 42.57% and 44.25%

respectively. CH3COONa shows a more pronounced improvement in low-temperature denitration performance. Simulation analysis indicates that after adding CH3COONa

·NH2 and ·OH radicals exhibit two “generation peaks

” with sodium and acetate ions jointly enhancing low-temperature SNCR efficiency. In contrast

Na2CO3 only strengthens the formation pathway of the intermediate radical NNH under the influence of sodium ions

thereby accelerating its reduction with NO; thus

its improvement on low-temperature denitration performance is less significant than that of CH3COONa.