低温燃烧下NH3的氧化特性

NH₃的气相氧化是低温燃烧过程中NO_x（NO和NO₂）与N₂O的重要来源，为了深入认识其反应规律，在管式流动反应器系统中进行了实验研究。重点考察了挥发分中的可燃气（CO、CH₄或H₂）和NO对NH₃氧化及氮氧化物排放的影响规律，并根据化学反应机理对实验结果进行了分析。研究结果表明，低温氧化性气氛下微量的可燃气就能够显著促进NH₃的氧化，并使NO_x和N₂O的生成量大幅度升高。当可燃气体浓度相同时，H₂对NH₃氧化的影响最大，CO的影响最小，CH₄对NH₃氧化的影响略大于CO。随着可燃气体浓度的升高，其对NH₃氧化与氮氧化物生成的影响先逐渐增加，然后趋于稳定。反应初始气体中存在NO时，也会加速NH₃的氧化。

Characteristics of ammonia oxidation in low-temperature combustion

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.