关键词: 氨氧化, NO_x, N₂O, 低温燃烧, 一氧化碳, 甲烷, 氢

Abstract: Low-temperature combustion, such as combustion of solid fuels (low-rank coals, biomass etc.) in grate furnaces or fluidized bed combustors, can make NH₃ (fuel-nitrogen) conversion, which is an important source of NO_x and N₂O. To understand deeply on NH₃ oxidation and production of nitrogen oxides in low-temperature combustion process, the effect of combustible gases (CO, CH₄, or H₂) and NO on ammonia oxidation reaction was experimentally investigated in a tubular flow reactor at temperature range 600-1000℃, and the concentrations of NO, NO₂, NH₃, CO, CH₄ and O₂ were monitored continually with online Fourier-transformed infrared gas analyzer (Gasmet DX-4000). The results obtained were analyzed to clarify the chemical reaction mechanism. It was found that trace amounts of CO, CH₄, or H₂ could promote the oxidation of ammonia and enhance the emissions of NO_x and N₂O significantly under the condition of low temperature and oxidizing atmosphere. At equal concentration, the effect of H₂ on ammonia oxidation was the greatest, following was CH₄ and CO. As concentration increase of the combustible gas, the ammonia concentrations in combustion product decreased and approached rapidly zero, while the emissions of NO_x and N₂O increased firstly and then arrived at a stable value. When there was NO in initial gas mixture, oxidation reaction of ammonia could be enhanced too.

Key words: ammonia oxidation, NO_x, N₂O, low-temperature combustion, carbon monoxide, methane, hydrogen