现阶段我国主要的发电方式仍是火力发电,随着“双碳”战略的提出,燃煤电厂的降碳势在必行。氨作为无碳富氢燃料,与煤掺烧能有效降低电厂的碳排放,但由于氨的富氮特性,增加了氨煤混燃过程中NO排放高的风险,因而探究氨煤混燃NO生成特性十分必要。煤粉燃烧可以分为挥发分燃烧和煤焦燃烧两个阶段,当氨掺入后,氨对挥发分燃烧和煤焦燃烧过程中NO排放的影响规律目前尚不明晰,为了探究氨对煤粉不同燃烧阶段NO排放特性的影响,采用高温管式炉系统,研究不同温度(1200℃~1400℃)和不同掺氨比(0%,1%,2%,4%,6%,8%,10%)条件下氨煤耦合燃烧和氨煤分离燃烧对NO排放特性的影响。结果表明:氨煤耦合燃烧与氨煤分离燃烧两种不同燃烧方法下NO生成量均随温度的升高和掺氨比的增加而增加,通过对比发现,分离燃烧中氨耦合挥发分燃烧与氨耦合煤焦燃烧NO生成量均小于氨煤耦合燃烧NO生成量。进一步计算氨煤分离燃烧相对于氨煤耦合燃烧NO变化率,发现分离燃烧NO生成总量整体上低于耦合燃烧NO生成总量,在不掺氨时,分离燃烧相对于耦合燃烧对降低NO排放的效果更显著,降低幅度最高为55%,而随着掺氨比的增加,各工况下分离燃烧对于降低NO排放的程度有所降低,但整体上相较于耦合燃烧,分离燃烧仍有效降低了NO排放。进一步分析不同温度下掺氨比为0%,4%,10%工况条件下,分离燃烧和耦合燃烧中燃料-N到NO的氮转化率变化趋势,发现在不掺氨时,分离燃烧相较于耦合燃烧燃料-N到NO的氮转化率降低显著,而随着氨的掺入,分离燃烧与耦合燃烧的氮转化率差距逐渐缩小,但整体上分离燃烧氮转化率仍然低于耦合燃烧氮转化率。

At present, thermal power generation is still the primary method of electricity production in China. With the proposal of carbon neutrality, it is imperative to reduce carbon emissions in coal-fired power plants. Ammonia, as a carbon-free and hydrogen-rich fuel, can be co-fired with coal to effectively reduce carbon emissions from power plants. However, since the ammonia contains a considerable content of nitrogen, there is an increased risk of high NO emis- sions during ammonia-coal co-combustion. Therefore, it is necessary to explore the mechanism of NO generation for this situation. Coal combustion can be divided into two stages: volatile com- bustion and char combustion. When ammonia is introduced, its impact on NO emissions during these stages is not yet fully understood. In order to explore the influence of ammonia on NO emissions characteristics of coal across different combustion stages, experiments were conducted using a high-temperature tubular furnace system to study the effects of ammonia-coal coupled and separated combustion on NO emission characteristics under various conditions, including temper- atures (1 ℃ ℃) and ammonia blending ratios (0%, 1%, 2%, 4%, 6%, 8%, 10%). The experimental results show that in both ammonia-coal coupled and separated combustion, NO formation increases with the increase temperature and ammonia blending ratio. Comparative anal- ysis indicates that in separated combustion, whether it be ammonia-coupled volatile combustion or ammonia-coupled char combustion, NO formation is lower than in ammonia-coal coupled com- bustion. Further calculations of the NO conversion ratio in separated combustion compared to coupled combustion reveale that the overall NO generation in separated combustion is generally lower than that in coupled combustion. Notably, when no ammonia is added, separated combus- tion shows the most significant reduction in NO emissions compared to coupled combustion, with a maximum reduction ratio of 55%. As the ammonia blending ratio increases, the degree of NO emission reduction in separated combustion decreases under various operating conditions, but separated combustion still achieves lower NO emissions than coupled combustion overall. Further analysis of nitrogen conversion ratios from fuel-N to NO under different temperatures and ammo- nia blending ratios (0%, 4%, and 10%) conditions reveals that without ammonia addition, the conversion ratio from fuel-N to NO in separated combustion decreases significantly compared to coupled combustion. However, with the addition of ammonia, the difference in nitrogen conver- sion ratio between separated combustion and coupled combustion gradually narrows, but overall, the nitrogen conversion ratio in separated combustion is still lower than that in coupled combus- tion.