氨为一种理想的无碳燃料,通过氨煤混燃替代和降低燃煤发电中部分煤炭燃料是实现碳减排的有效措施,但氨煤混燃会生成额外的NO,其中氧体积分数变化对燃烧时NO的生成具有显著影响。利用高温管式炉研究了不同温度(1000℃~1500℃)、不同掺氨比(0%~20%)下氧体积分数对氨煤混燃时NO生成特性的影响。结果表明:当过量空气系数(α)从1.1增加至1.2时,纯煤粉燃烧条件下,氧体积分数的增加促进了燃料-N到NO的转化;1100℃与1300℃下,氧体积分数的增加抑制了氨煤混燃过程燃料-N到NO的转化;1500℃下,氧体积分数的增加促进了氨煤混燃过程燃料-N到NO的转化,且掺氨比和温度是氧体积分数增加时燃料-N转化为NO的氮转化率变化的重要影响因素。氧体积分数的增加利于系统氧化性自由基生成,从而促进了NH2→HNO→NO,NH2→H2NO→HNO→NO以及NCO与O,O2自由基等氧化的进行,促进了混燃过程中NO生成。

Ammonia is an ideal carbon-free fuel, and co-firing ammonia with coal in coal- fired power generation is an effective measure to achieve carbon reduction.  However, the co- combustion of ammonia and coal has the risk of high NO  emission, in which the oxygen volume frac‐ tion has a significant effect on the formation of NO during co-combustion.  The impact of oxygen  volume fraction on NO formation characteristics during ammonia-coal co-combustion at different tem‐ peratures (1 000 ℃−1 500 ℃) and ammonia co-firing ratio (0% −20%) was investigated using a  high-temperature tubular furnace.  The results show that when the excess air coefficient (α) increases  from 1. 1 to 1. 2, the increase in oxygen volume fraction promotes the conversion of fuel-N to NO for  pure coal combustion condition; however, at temperatures of 1 100 ℃ and 1 300 ℃, the increase in  oxygen volume fraction inhibits the conversion of fuel -N to NO during ammonia-coal co- combustion; at 1 500 ℃, the conversion rate of fuel-N to NO increases with the increase of oxygen  volume fraction, the ammonia co-firing ratio and temperature are important factors influencing the  variation of fuel-N conversion rate with increasing oxygen volume fraction.  The increase in oxygen  volume fraction facilitates the formation of oxidative free radicals, promoting the oxidation processes  NH →HNO→NO, NH →H NO→HNO→NO, as well as the oxidation of NCO byfree radicals like  O and O , thereby enhancing the generation of NO during the co-firing process.