Effects of Na/K additives on NO reduction and its promotion mechanism in SNCR process

doi:10.11949/j.issn.0438-1157.20161189

CIESC Journal ›› 2017, Vol. 68 ›› Issue (3): 1178-1184.DOI: 10.11949/j.issn.0438-1157.20161189

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Effects of Na/K additives on NO reduction and its promotion mechanism in SNCR process

SUN Tong¹, LU Ping¹, CAI Jie¹, WU Jiang²

1 School of Energy & Mechanical Engineering, Nanjing Normal University, Nanjing 210042, Jiangsu, China;
2 College of Energy & Mechanical Engineering, Shanghai University of Electric Power, Shanghai 200090, China

Received:2016-08-25 Revised:2016-11-08 Online:2017-03-05 Published:2017-03-05
Contact: 10.11949/j.issn.0438-1157.20161189
Supported by:
supported by the National Natural Science Foundation of China (51476079),Jiangsu Province Prospective Cooperation Research Project of China (BY2015001-01) and Jiangsu Province Major Project of University Natural Science Research of China (15KJA610002).

Na/K添加剂对SNCR脱硝及NO还原机制的影响

孙桐¹, 卢平¹, 蔡杰¹, 吴江²

1 南京师范大学能源与机械工程学院, 江苏南京 210042;
2 上海电力学院能源与机械工程学院, 上海 200090

通讯作者: 卢平,luping@njnu.edu.cn
基金资助:
国家自然科学基金项目（51476079）；江苏省前瞻性联合研究项目（BY2015001-01）；江苏省高校自然科学研究重大项目（15KJA610002）。

Abstract

Abstract:

The effects of Na/K additives (NaOH, Na₂CO₃, NaCl, KOH, K₂CO₃ and KCl) on NO reduction in the selective non-catalytic reduction (SNCR) process were simulated by using Chemkin software based on the established chemical mechanisms of Na-K-C-H-O-N-Cl. The mechanism and routes of Na/K additives on NO reduction in the SNCR process were discussed based on the sensitivity analysis and rate of production (ROP) analysis. The simulated results indicated that NO removal efficiency was almost zero at temperature of 700-800℃ in the SNCR process without Na/K additives. Na/K additives had a significant promotion on NO reduction at temperature lower than 800℃, and had less promotion on NO reduction at temperature higher than 900℃. At temperature of 700℃, NO removal efficiency was 43.86%-60.76% in the SNCR process with Na/K additives. The promotion order of Na/K additives on NO reduction in the SNCR process was NaOH≈Na₂CO₃ > KOH≈K₂CO₃ > KCl > NaCl. However, the concentration of Na/K additives (6.25-25.0 μmol·mol^-1) showed little influence on NO reduction. NO reduction in the SNCR process was performed through NH₂ radicals, which were promoted by OH radicals via respective reaction routes promoted by Na/K additives. The promotion of Na/K additives on NO reduction in the SNCR process was enhanced by alkali metal hydroxides (MOH) via the route of NaOH→NaO₂→Na→NaO→NaOH, but weakened by alkali metal chlorides (MCl) via the route of MCl→M→MCl.

Key words: SNCR, NO reduction, Na/K additives, dynamics simulation

摘要：

基于构建的Na-K-C-H-O-N-Cl化学反应机理模型，采用Chemkin动力学模拟软件，研究Na/K添加剂（NaOH、Na₂CO₃、NaCl、KOH、K₂CO₃和KCl）对选择性非催化还原（SNCR）脱硝性能影响，通过敏感性分析和产率分析，探讨Na/K添加剂对SNCR过程中NO还原的促进机理和路径。模拟结果表明，在温度为700~800℃且无Na/K添加剂条件下，SNCR脱硝效率几乎为零；Na/K添加剂能够显著提高低温区（小于800℃）SNCR脱硝效率，而其对高温区（大于900℃）SNCR脱硝的促进作用不明显。在温度为700℃和Na/K添加剂参与条件下SNCR脱硝效率可达43.86%~60.76%。不同Na/K添加剂对NO还原促进顺序为NaOH≈Na₂CO₃ > KOH≈K₂CO₃ > KCl > NaCl，但同一种Na/K添加剂的浓度变化（6.25~25.0 μmol·mol^-1）对SNCR脱硝效率影响较小。Na/K添加剂通过不同的循环路径产生OH基，进而通过NH2基团促进NO的还原，其中碱金属氢氧化物（MOH）对SNCR脱硝的促进路径为NaOH→NaO₂→Na→NaO→NaOH，碱金属氯化物（MCl）则主要通过MCl→M→MCl削弱Na/K添加剂的促进作用。

关键词: 选择性非催化还原, 脱硝, Na/K添加剂, 动力学模拟

CLC Number:

TK229.6
X701

SUN Tong, LU Ping, CAI Jie, WU Jiang. Effects of Na/K additives on NO reduction and its promotion mechanism in SNCR process[J]. CIESC Journal, 2017, 68(3): 1178-1184.

孙桐, 卢平, 蔡杰, 吴江. Na/K添加剂对SNCR脱硝及NO还原机制的影响[J]. 化工学报, 2017, 68(3): 1178-1184.

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Effects of Na/K additives on NO reduction and its promotion mechanism in SNCR process

Na/K添加剂对SNCR脱硝及NO还原机制的影响

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