以下文章来源于FIE能源前沿期刊 ，作者FIE编辑部

原文信息

NO? and H?S formation in the reductive zone of air-staged combustion of pulverized blended coals

Jinzhi CAI, Dan LI, Denggao CHEN, Zhenshan LI

作者单位：

Key Laboratory for Thermal Sciece and Power Engineering of the Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China

原文链接：

https://link.springer.com/article/10.1007/s11708-020-0804-y

http://journal.hep.com.cn/fie/EN/10.1007/s11708-020-0804-y

中国在经济高速发展的过程中，对电力的需求持续增加，其中60%以上由燃煤锅炉电站提供。为了扩大锅炉适用煤种范围和平衡煤种供求，混煤燃烧技术已被广泛采用。已有的研究结果表明，对于典型的炉外预混掺烧方式，即将不同种煤粉在炉外均匀混合再送入炉中燃烧，混煤的着火点、燃尽特性、积灰和结渣等特性不同于单煤的线性加和，而混煤在空气分级燃烧中的特性仍有待进一步探究。

在锅炉的空气分级燃烧中，NO在还原区被大量还原，而H?S也在还原性气氛中产生，会对锅炉的水冷壁造成严重的腐蚀。在锅炉运行过程中，电站需要通过合理控制过量空气系数、温度和预混比等，促进煤粉的充分燃烧，并在保证NO达标排放的前提下尽量减少H?S的产生以延长锅炉寿命。而指导这一工作的前提，正是准确地把握煤粉燃尽特性和还原型气氛与给定工况的关系。

本次研究中，作者以烟煤与贫煤掺混为例，利用沉降炉实现了不同工况下的稳定的空气分级燃烧，并在还原区沿程采样。实验结果展示了不同温度、掺混比和空气过量系数下还原区的混煤燃尽特性、还原性气氛。通过分析实验结果，作者重点讨论了焦炭气化转化率与CO、H?S和NO气体浓度间的关系。

不同掺混比下的实验结果均显示，在还原区中，焦炭气化转化率与CO浓度成正比。同时，CO与NO的浓度的对数成负线性关系并与H?S浓度成正线性关系。结果证实了焦炭气化转化率、CO浓度、H?S浓度和NO浓度存在着不依赖于掺混比的关系。这为锅炉的减排与腐蚀防护设计提供了指导，也为混煤燃烧的数值模型开发提供了新的思路，即通过准确的单煤焦炭气化机理和气体间的总包反应关系，来预测还原区混煤燃烧情况。

ABSTACT

Low NO? combustion of blended coals is widely used in coal-fired boilers in China to control NO? emission; thus, it is necessary to understand the formation mechanism of NO? and H?S during the combustion of blended coals. This paper focused on the investigation of reductive gases in the formation of NO? and H?S in the reductive zone of blended coals during combustion. Experiments with Zhundong (ZD) and Commercial (GE) coal and their blends with different mixing ratios were conducted in a drop tube furnace at 1200°C–1400°C with an excessive air ratio of 0.6–1.2. The coal conversion and formation characteristics of CO, H?S, and NO? in the fuel-rich zone were carefully studied under different experimental conditions for different blend ratios. Blending ZD into GE was found to increase not only the coal conversion but also the concentrations of CO and H?S as NO reduction accelerated. Both the CO and H?S concentrations inblended coal combustion increase with an increase in the combustion temperature and a decrease in the excessive air ratio. Based on accumulated experimental data, one interesting finding was that NO and H?S from blended coal combustion were almost directly dependent on the CO concentration, and the CO concentration of the blended coal combustion depended on the single char gasification conversion. Thus, CO, NO?, and H?S formation characteristics from blended coal combustion can be well predicted by single char gasification kinetics.

Keywords blended coal combustion, NO? formation, H?S formation, air staged combustion

通讯作者

简介

李振山，工学博士，清华大学副教授、博士生导师。主要研究方向有：气固表面反应与传递、化学链循环过程、污染物超低排放技术。入选2012年教育部新世纪优秀人才支持计划。

Cite this article

Jinzhi CAI,Dan LI,Denggao CHEN, et al. NO? and H?S formation in the reductive zone of air-staged combustion of pulverized blended coals[J]. Front. Energy, 2021, 15(1): 4?13 https://doi.org/10.1007/s11708-020-0804-y

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