Effect of oxygen concentration on the heterogeneous reduction of NH3/Char/NO in the high temperature reduction zone during ammonia-coal co-combustion

被引：0

作者：

Chen P. ^{[1
]}

Jiang B. ^{[1
]}

Hua C. ^{[1
]}

Wang P. ^{[1
]}

Gu M. ^{[1
]}

Fan J. ^{[2
]}

Wang Y. ^{[3
]}

机构：

[1] School of Energy and Environment, Anhui University of Technology, Maanshan

[2] School of Energy Engineering, Zhejiang University, Hangzhou

[3] State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan

来源：

Meitan Xuebao/Journal of the China Coal Society | 2023年 / 48卷 / 10期

关键词：

ammonia-coal co-combustion; char; micro oxygen; NH[!sub]3[!/sub; NO;

D O I：

10.13225/j.cnki.jccs.2022.1445

中图分类号：

学科分类号：

摘要：

Mixing carbon-free fuel ammonia into pulverized coal boiler can effectively reduce CO2 emissions from power plants, which has attracted more and more attention in recent years. However, ammonia and coal co-combustion increases the path of NOx formation. The study of NO reduction mechanism in high temperature reduction zone of ammonia and coal co-combustion process is particularly critical to achieve a low-nitrogen emission. Considering that the high-temperature reduction zone is not an oxygen free environment, it is necessary to explore the influence mechanism of micro-oxygen in reduction zone on NO reduction by unburned ammonia coupled coal char. In this paper, the influence mechanism of micro-oxygen concentration (0, 0.5%, 1.0%, 1.5% and 2.0%) on NH3/NO homogeneous and NH3/char/NO heterogeneous reduction is studied in a high temperature horizontal tubular furnace. The temperature range is 1 373−1 773 K. The results show that the efficiency of homogeneous reduction of NO by NH3 increases with the temperature increase under high temperature and oxygen-free environment. When the temperature is higher than 1 573 K, the homogeneous reduction of NO by NH3 decreases slightly with the increase of temperature. The optimal reduction temperature of unburned ammonia for NO is 1 573 K. Char significantly improves the efficiency of NO reduction by NH3 at high temperature, and broadens the optimal reduction temperature of NO to 1 673 K. The reduction of NO by char and NH3 is synergistic. Compared with the absence of oxygen, when the temperature is not higher than 1 500 K and the oxygen concentration is within 2.0%, the micro-oxygen promotes the formation of the reduced free radical NH2/NH, which promotes the homogeneous reduction of NO by NH3. Further increasing the temperature is conducive to the oxidation of NH2/NH, so that the homogeneous reduction efficiency of NO by NH3 in the presence of oxygen is lower than that in the absence of oxygen. In the heterogeneous reduction system of NH3/char/NO, when the temperature is not higher than 1 473 K and the oxygen concentration is not higher than 0.5%, the heterogeneous reduction efficiency of NO under micro-oxygen is higher than that without oxygen. With the further increase of oxygen concentration and temperature, the oxidation reaction of NHi with oxidizing radicals such as OH/O is faster than the NO reduction by NHi/char, the reduction efficiency of NO in the NH3/char/NO heterogeneous system decreases. The results indicate that there is an optimal oxygen concentration to promote the reduction of NO by NH3/char in the high temperature reduction zone. © 2023 China Coal Society. All rights reserved.

引用

页码：3912 / 3919

页数：7

共 25 条

[1] WANG Yuguo, TIAN Yu, YANG Shenmin, Et al., Application of advanced control strategy in deep peak shaving generator[J], Automation Application, 2020, 6
[2] ZHOU Shangkun, YANG Wenjun, TAN Houzhang, Et al., Research progress of ammonia combustion[J], Proceedings of the CSEE, 41, 12, pp. 4164-4182, (2021)
[3] CHEN Danan, LI Jun, HUANG Hongyu, Et al., Progress in ammonia combustion and reaction mechanism[J], Chemistry Bulletin, 83, 6, pp. 508-515, (2020)
[4] MASATO Tamura, TAKAHIRO Gotou, HIROKI Ishii, Et al., Experimental investigation of ammonia combustion in a bench scale 1.2 MW-thermal pulverised coal firing furnace[J], Applied Energy, 277, (2020)
[5] SAKIKO Ishihara, ZHANG Juwei, Ito TAKAMASA, Numerical calculation with detailed chemistry on ammonia co-firing in a coal-fired boiler：Effect of ammonia co-firing ratio on NO emissions[J], Fuel, 274, (2020)
[6] ZHANG Juwei, TAKAMASA Ito, HIROKI Ishii, Et al., Numerical investigation on ammonia co-firing in a pulverized coal combustion facility：Effect of ammonia co-firing ratio[J], Fuel, 267, (2020)
[7] MA Lun, FANG Qingyan, ZHANG Cheng, Et al., Numerical simulation of pulverized coal coupled ammonia combustion and NO generation under deep air classification[J], Clean Coal Technology, 28, 5
[8] ZHU Jingji, XU Yishu, XU Jingying, Et al., Effect of co-firing ammonia on coal volatile matter flame characteristics and particulate matter formation behaviours[J], Power Generation Technology, 43, 6, (2022)
[9] CHEN Ping, WANG Ying, WANG Peipei, Et al., Oxidation mechanism of ammonia-N/coal-N during ammonia-coal co-combustion[J], International Journal of Hydrogen Energy, 47, (2022)
[10] CHEN Ping, WANG Ying, WANG Huichun, Et al., Study on molecular mechanism of N oxidation in ammonia-coal co-firing[J], Journal of China Coal Society, 48, 2, pp. 1037-1046, (2023)

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