氧气对秸秆热解氮迁移与转化的影响

以秸秆为原料,在两段式固定床反应器上模拟层燃工况进行热解实验,研究了氧气对热解过程中燃料氮迁移与转化的影响。通过对焦油中含氮化合物种类与含量的GC-MS分析,提出了热解过程中燃料氮转化的反应路径,并分析了氧气的影响。与惰性气氛下相比,氧气的引入降低了焦油与焦炭的产率,从而降低了焦油与焦炭中氮的分配比,增加了气体组分中氮的分配比。以蛋白质和氨基酸作为燃料氮的禀赋形态,其在热解过程中发生一系列一次反应,生成酰胺、胺类等初级焦油产物。初级焦油发生二次反应,进一步生成腈类及含氮杂环化合物等二级焦油产物。有氧条件下,焦油中酰胺、胺类等初级焦油成分的含量显著降低,腈类及含氮杂环化合物等二级焦油成分的含量升高。

Influence of oxygen on nitrogen distribution and transformation during straw pyrolysis

To study influence of oxygen on distribution and transformation of fuel-N, pyrolysis experiments of straw were conducted in a two stage fixed bed reactor simulating the run conditions of grate firing. The conversion pathway of fuel-N was depicted by studying types and content of N-containing compounds in tar by GC-MS, and effect of oxygen was analyzed. Compared with inert atmosphere, tar and char yields decrease with introduction of oxygen, which leads to a decrease of N-distribution in tar and char and increase in gas fractions. Protein and amino acids are the main N-containing components in fuel, which initially go through a series of primary reactions, producing primary tar components like amides and amines. Then the primary tar goes through secondary reactions to yield secondary tar components including nitriles and N-heterocyclic compounds. In the presence of oxygen, content of primary tar components like amides and amines decrease significantly, and secondary tar components like nitriles and N-heterocyclic compounds increase.