Experimental study on denitrification with microwave induced activated carbon excited plasma jet

doi:10.16085/j.issn.1000-6613.2021-0542

Abstract

Abstract:

Decomposition of NO with microwave plasma has a very high efficiency, but it is difficult to remove NO_x in the presence of oxygen. In order to solve this problem, a new denitration technology using microwave-induced plasma emission jet with the activated carbon and under aerobic condition was put forward. In a microwave tube furnace, the best denitration conditions were obtained by adjusting the diameter and amounts of activated carbon, and microwave power. Then the process mechanism was analyzed in-depth. The effects of initial concentrations of NO and O₂ on denitration by plasma jet were also studied. When nitrogen was used as carrier gas with a flow of 1L/min, the diameter of activated carbon was 2mm, the mass of activated carbon was 15g and the microwave power was 2kW, the plasma jet could be generated quickly and held for a long time. In the experiments with plasma jet, the denitration efficiency of jet plasma was higher than that of lightning plasma. NO was removed in the activated carbon bed zone and plasma jet zone successively. When the concentration of O₂ was less than 4%, the increase of O₂ concentration promoted the removal of NO. When the concentration of O₂ was greater than 4%, the free radicals (·O) and a large amount of CO₂ from excessive oxygen inhibited the removal of NO.

Key words: microwave plasma jet, activated carbon, denitration, reduction, selectivity

摘要：

微波等离子体直接分解NO有极高的效率，但在有氧条件下分解较难。为解决这一问题，本文提出了一种利用微波诱导活性炭激发等离子体射流在有氧条件下脱硝的新技术。利用微波材料学工作站，通过调整激发等离子体参数（活性炭直径、活性炭质量、微波功率）得到了最佳工艺条件，深入分析了等离子体射流形成过程，并将其用于脱硝实验，研究了不同形态等离子体、NO初始浓度和O₂浓度因素对脱硝的影响。结果表明，以1L/min氮气作载气时，在活性炭直径2mm、质量15g、微波功率2kW条件下，可快速产生等离子体射流且持续时间长久。等离子体用于脱硝实验，射流状等离子体脱硝效率高于闪电状等离子体。NO依次在活性炭床层区和等离子体射流区去除。当O₂体积分数小于4%时，O₂浓度的增加对NO的脱除有促进作用；大于4%时，O₂浓度的增加会产生过量的氧自由基（·O）和大量的CO₂，对NO的脱除产生抑制作用。

关键词: 微波等离子体射流, 活性炭, 脱硝, 还原, 选择性

CLC Number:

X701.3

YANG Guangdong, SU Lin, ZOU Zhixue, JIANG Tao. Experimental study on denitrification with microwave induced activated carbon excited plasma jet[J]. Chemical Industry and Engineering Progress, 2022, 41(2): 1054-1062.

杨广东, 苏林, 邹志雪, 姜涛. 微波诱导活性炭激发等离子体射流脱硝实验[J]. 化工进展, 2022, 41(2): 1054-1062.

Figures/Tables 18

References 25

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活性炭直径/mm	活性炭质量/g	微波功率/kW
2，4，6	15	2
2	5~50	2
2	15	1，2，3

活性炭直径/mm	活性炭质量/g	微波功率/kW
2，4，6	15	2
2	5~50	2
2	15	1，2，3

组别	微波功率/kW	活性炭质量/g	NO/mg·m^-3
微波无介质组	2	0	500
闪电状等离子体组	2	15	500
等离子体射流组	2	15	500

组别	微波功率/kW	活性炭质量/g	NO/mg·m^-3
微波无介质组	2	0	500
闪电状等离子体组	2	15	500
等离子体射流组	2	15	500

活性炭/g	功率/kW	NO/mg·m^-3	O₂（体积分数）/%
15	2	500	0
15	2	500，600，700，800	0
15	2	500	2，4，6，8，10