在“双碳”战略目标驱动下,煤炭高效清洁利用技术革新已成为能源领域的重要研究方向。煤粉纯化−燃烧耦合技术作为新型热转化工艺,其核心在于通过预纯化过程实现燃料氮的高效脱除,为后续燃烧环节的NOx源头控制提供新路径。为探究反应温度对煤粉纯化反应氮析出与转化特性的影响,基于高温热化学转化机理,在自行搭建的1700℃四温区滴管炉试验台上,设置不同温度条件进行纯化反应。结果表明:反应温度从900℃提升至1300℃,煤气中H2和CO占比大幅度增加,煤气产率和煤气组分均有所增加;各组分转化率有所增加,N元素向气相的转化率从48.26%跃升至83.14%,相当一部分焦炭N在高温时发生转化,仅有16.86%燃料N残留在固相焦炭N中,这部分氮将是后续燃烧过程中NOx的主要来源。当温度达到1000℃时,燃料N向N2的转化率超过50%,且温度升高能进一步提高还原成N2的比例,同时转化为NH3和HCN的比例也有所增加,而促进燃烧前燃料N的析出并还原成N2是煤燃烧NOx减排的关键所在。另一方面,神木烟煤经过纯化反应,比表面积和孔容积大幅增加,最高分别增加为原煤的66.3倍和10.5倍,平均孔径有所减小,燃料碳架稳定性下降,反应活性位点增加,燃料燃烧特性有所改善,且随温度升高这种改善作用进一步提升,可见纯化反应有利于后续燃料的清洁高效燃烧。

Under the background of “ carbon peaking and carbon neutrality” ,the innovation of efficient and clean coal utilizationtechnologies has become a significant research direction in the energy sector. The coal purification-combustion coupling technology,as anovel thermal conversion process,focuses on the efficient removal of fuel nitrogen through a pre-purification process,offering a newpathway for the source control of NOx in subsequent combustion stages. To investigate the influence of reaction temperature on thenitrogen release and transformation characteristics during coal purification,experiments were conducted at varying temperatures on aself-constructed 1700 ℃ four-temperature zone drop-tube furnace,based on high-temperature thermochemical conversion mechanisms.The results indicate that as the reaction temperature increased from 900 ℃ to 1300 ℃,the proportions of H2 and CO in the coal gassignificantly increased,along with the gas yield and composition. The conversion rates of various components also increased,with theconversion rate of nitrogen to the gas phase jumping from 48.26% to 83.14%. A considerable portion of coke nitrogen was transformed athigh temperatures,leaving only 16.86% of fuel nitrogen in the solid phase coke,which would be the primary source of NOx in subsequent combustion processes. When the temperature reached 1000 ℃,the conversion rate of fuel nitrogen to N2 exceeded 50%,and highertemperatures further increased the proportion reduced to N2,while also increasing the proportions converted to NH3 and HCN.Promoting the release and reduction of fuel nitrogen to N2 before combustion is crucial for NOx emission reduction in coal combustion.On the other hand,after the purification reaction,the specific surface area and pore volume of Shenmu bituminous coal significantlyincreased,up to 66.3 times and 10.5 times that of the raw coal,respectively,with a decrease in average pore diameter. The stability of thefuel carbon framework decreased,and the number of reactive sites increased,improving the combustion characteristics of the fuel. Thisimprovement was further enhanced with increasing temperature,demonstrating that the purification reaction is beneficial for thesubsequent clean and efficient combustion of the fuel.