基于热解与燃烧反应重构的低NO x 解耦燃烧原理与技术

doi:10.11949/0438-1157.20220716

摘要/Abstract

摘要：

解耦燃烧原理最早于1995年被用于烟煤的低氮无烟燃烧，其通过分离燃料热解与半焦燃烧，打破两反应在传统燃烧方式中的耦合作用，并通过重构热解挥发分与半焦的燃烧反应，实现挥发分完全燃烧的同时有效还原燃烧生成的NO _x。基于此方法的燃烧技术在1997年被定义为“解耦燃烧”。本文围绕固体燃料解耦燃烧高效低氮化原理、燃烧过程反应重构原则和反应过程定向调控关键要素，综合总结近三十年在煤炭与生物质解耦燃烧基础研究、技术开发、民用及工业燃烧典型应用及其实现的燃烧强化效果等方面取得的主要进展。解耦燃烧耦合其他诸如燃料再燃、燃料或空气分级燃烧、流态重构燃烧等先进燃烧技术可以进一步提高燃烧效率，降低空气污染物排放。解耦燃烧技术特别适合高含水燃料，对创新低阶煤和有机废弃物等的高效低氮燃烧新技术具有重要的科学意义和应用价值。

关键词: 解耦燃烧, 低氮燃烧, 炉排炉, 流化床, 煤燃烧, 生物质

Abstract:

Decoupling combustion principle was first introduced to achieve low-NO _x and smokeless combustion of bituminous coal in 1995. By separating fuel pyrolysis from char combustion to break the spatio-temporal coupling of these reactions in traditional combustion, the principle can achieve complete combustion of volatiles and high-efficient NO _x reduction simultaneously through purposely restructuring such reactions. This combustion technology originating essentially from restructuring its involved reactions was formally defined as “decoupling combustion” in 1997. Focusing on the principle of high-efficiency and low-NO _x combustion and general concerns for restructuring the combustion-involved reactions, this article summarizes the major progress made in the last thirty years in fundamental research and technical development of decoupling combustion of coal and biomass as well as the typical applications of the technology for civil and industrial utilizations with proven effectiveness in intensifying combustion and reducing NO _x emission. The decoupling combustion can be combined with other advanced combustion technologies, such as fuel- and air-staged combustion, reburning and combustion based on the theory of fluidization state specification, to further improve combustion efficiency and lower air emissions. The decoupling combustion technology is especially suitable for high water content fuels, and has strong scientific significance and application value for innovative new technologies of high-efficiency and low-NO _x combustion of low-rank coal and organic waste.

Key words: decoupling combustion, low-NO _x combustion, grate boiler, fluidized bed, coal combustion, biomass

中图分类号:

TQ 534

刘新华, 韩振南, 韩健, 梁斌, 张楠, 胡善伟, 白丁荣, 许光文. 基于热解与燃烧反应重构的低NO _x 解耦燃烧原理与技术[J]. 化工学报, 2022, 73(8): 3355-3368.

Xinhua LIU, Zhennan HAN, Jian HAN, Bin LIANG, Nan ZHANG, Shanwei HU, Dingrong BAI, Guangwen XU. Principle and technology of low-NO _x decoupling combustion based on restructuring reactions[J]. CIESC Journal, 2022, 73(8): 3355-3368.

图/表 19

图1 燃料燃烧过程各种反应的发生顺序及反应链

Fig.1 Reaction sequence and chain in fuel combustion process

图2 传统燃烧和解耦燃烧原理

Fig.2 Principles of traditional combustion and decoupling combustion

图3 不同热解产物还原NO能力对比（NO还原效率代表NO还原能力）[25]

Fig.3 NO reduction capabilities of pyrolysis products (NO reduction efficiency represents NO reduction capability) [25]

图4 传统民用炉和解耦燃烧炉的典型结构及原理

Fig.4 Typical structures and principles of traditional and decoupling combustion stoves

图5 基于机器学习的解耦炉结构快速设计与优化[36]

Fig.5 Machine learning-aided prompt design and optimization of decoupling combustion stoves[36]

图6 不同燃烧方式污染物排放对比

Fig.6 Comparison of pollutant emissions in different combustion modes

图7 不同煤炉匹配方式的NMHCs排放因子[33]

Fig.7 NMHCs emission factors of different combustion modes[33]

图8 烟煤型煤与生物质颗粒混烧污染物排放

Fig.8 Emissions from co-firing bituminous briquettes and biomass pellets

图9 传统链条炉和解耦链条炉典型结构及原理

Fig.9 Typical structures and principles of the traditional grate-firing boiler and the decoupling combustion grate-firing boiler

图10 燃料层厚度对污染物排放和解耦燃烧效率的影响

Fig.10 Effect of fuel bed depth on pollutant emission and combustion efficiency in the decoupling combustion grate-firing boiler

图11 热解-燃烧过程匹配对污染物排放和解耦燃烧效率的影响

Fig.11 Effect of pyrolysis-combustion combination on pollutant emission and combustion efficiency in the decoupling combustion grate-firing boiler

图12 解耦链条炉炉膛内的温度和氧气浓度分布

Fig.12 Distributions of temperature and oxygen content in the decoupling combustion grate-firing boiler

图13 不同燃料在解耦链条炉中燃烧时的污染物排放

Fig.13 Pollutant emissions from burning different fuels in the decoupling combustion grate-firing boiler

表1 传统链条炉的解耦燃烧改造效果［44］

Table 1 Improvement of traditional grate-firing boilers by using decoupling combustion technology［44］

Mode of

combustion

NO _x emissions/

(mg/m³)

Outlet oxygen content/% (vol)

LOI of slag/

% (mass)

图14 流化床解耦燃烧技术原理示意图[46]

Fig.14 Principle diagram of fluidized bed decoupling combustion (FBDC) technology[46]

图15 白酒糟1000 t/a流化床解耦燃烧中试装置工艺流程

Fig.15 Process flow diagram of a FBDC pilot treating 1000 t/a distilled spirit lees

图16 白酒糟在不同燃烧模式下的烟气排放特性[47]

Fig.16 Flue gas emissions from burning distilled spirit lees in different combustion modes[47]

图17 年处理量6万吨白酒糟流化床解耦燃烧示范工程照片

Fig.17 Demonstration plant of FBDC with a capability of 60000 t/a distilled spirit lees

图18 白酒糟流化床解耦燃烧示范工程系统典型温度变化及烟气排放特性

Fig.18 Variation of typical temperatures and flue gas emissions in the demonstration plant of FBDC

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