富氮轻工残渣基于特征水热-热解联用的燃料氮调控机理

Light-industrial biowastes are reported to be a type of typical organic solid wastes with a huge annual amount in China. To realize their clean resource recycling is of great significance to the promotion of national ecological civilization construction. Due to their potential characteristic of excellent fuel quality, thermal utilization would be the most effective and direct technology at current technical level. However, most of them contain high fuel-N content, which would ultimately be converted into NOx pollutants against the environment-friendly process. Obviously, regulatory mechanisms on fuel-N conversion into NOx pollutants is one of the fundamental scientific problems in the clean thermal utilization of light-industrial biowastes. In this research program, experimental and theoretical investigations on regulation of fuel-N conversion during a novel hydrothermal carbonization-pyrolysis combined process were conducted by selecting typical N-rich light-industrial biowastes with different fuel-N characteristic. On the basis of the developed fuel-N conversion mechanisms and the confirmed preferential operating conditions, optimal parameters and inherent laws of active hydrothermal carbonization on enhancing the removal and the stability of fuel-N were firstly elucidated by the quantitative factor analysis of hydrothermal active agents (Acids, Bases). Subsequently, optimal conditions and inherent rules of catalytic pyrolysis on promoting the harmless regulation of NOx precursors were clarified by the quantitative factor analysis of pyrolytic catalytic agents (metal oxides). Afterwards, regulation effects on the removal, the stability and the further harmless conversion of fuel-N via the active hydrothermal carbonization-catalytic pyrolysis combined technique were evaluated. Based on the results obtained above, coupling regulation mechanisms on original fuel-N conversion for thermal utilization of N-rich light-industrial biowastes were established. The research results from this program could provide basic data and theoretical support for the further clean resource utilization of light-industrial biowastes in China.

轻工业生产过程残渣（轻工残渣）是我国一类年产量巨大的典型有机固废，实现其清洁资源化对推进我国生态文明建设具有重要意义。因其优质燃料潜力，热利用是目前最直接有效方式，但绝大多数富含燃料氮，由此带来的NOx排放是制约过程清洁性的关键，有关燃料氮到NOx转化及其调控机制是其清洁热利用资源化的基础科学问题之一。本项目以燃料氮差异和种类代表性的富氮轻工残渣为对象，提出特征水热-热解联用实现燃料氮源端调控的新颖研究思路。在完善转化机理和固定操作条件基础上，通过先后顺序的水热活性剂（酸碱）和热解催化剂（金属氧化物）因素定量研究，分别阐明活性水热强化燃料氮去除及稳定、和催化热解促进NOx前驱物无害化调控的优化条件和作用规律，进而对比评价联用方式对燃料氮去除、稳定及进一步无害转化的调控效果，基于此，建立燃料氮源端耦合调控机理理论。项目研究成果将为我国轻工残渣有机固废的清洁资源化提供基础数据和理论支持。

轻工残渣是轻工业生产过程的剩余物或副产物，年产量巨大、富含氮组分、具有优质燃料属性，清洁高效热利用是目前实现其资源化的最直接有效方式，对推进我国生态文明建设具有重要意义。富氮特征带来的氮污染物排放是制约清洁热利用资源化的关键，有关燃料氮到气相氮污染物的转化及其调控是该领域的基础科学问题之一。.本项目围绕富氮轻工残渣的清洁热利用，研究富氮轻工残渣基于特征热化学转化的燃料氮源端耦合调控的关键科学问题，主要包括：（a）围绕水热与热解的燃料氮迁移演化基本规律和机理；（b）基于燃料氮组分源端调控的分级热化学转化理论与方法。研究成果如下：.（a）解析了富氮轻工残渣的燃料氮官能团结构及其热化学物性规律，明晰了常规水热与热解燃料氮的迁移转化机理。通过解析燃料氮的迁移路径，明确了控制燃料氮转化的关键因素与机制：氮官能团的热稳定性与温度条件。.（b）探究了多类富氮轻工残渣基于单一或耦合热转化手段的燃料氮源端调控潜力。对热解气而言，常规水热+热解、与煤共热解、与褐煤共水热+热解、酸/碱活性水热+催化热解、还原性气氛气化等方式，均能一定程度调控燃料氮到气相氮污染物的转化。其中，碱Ca(OH)2活性水热+金属氧化物Fe2O3催化热解最具优势，可高效实现燃料氮的源端减量和气相氮污染物转化的过程控制，获得低氮高值可燃气（热值提高10-20%，氮污染物：NH3低于25ppmv，HCN低于20ppmv）。.（c）阐明了特征热化学转化实现燃料氮源端耦合调控的机制：活性水热碳化预处理具有对燃料氮组分去除和稳定的能力，进而可调控后续热解阶段气相氮污染物形成路径的强度，催化热解可进一步调控固相燃料氮到气相污染氮组分（NOx前驱物）和无害氮组分（N2）的选择性转化。本项目提出了几类针对含氮污染物源端调控的富氮轻工残渣高效清洁热转化方法，形成了符合低氮污染物排放的分级热转化工艺路线，对我国典型轻工残渣的清洁资源化利用具有重要的实际研究价值和理论指导意义。