化工学报 ›› 2019, Vol. 70 ›› Issue (8): 3121-3131.DOI: 10.11949/0438-1157.20190111

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燃气锅炉中NO2的生成规律研究

王志宁1,2(),杨协和2,张扬2(),金燕1,张海2,吕俊复2   

  1. 1. 太原理工大学电气与动力工程学院,山西 太原 030024
    2. 清华大学能源与动力工程系, 热科学与动力工程教育部重点实验室,北京 100084
  • 收稿日期:2019-03-05 修回日期:2019-05-13 出版日期:2019-08-05 发布日期:2019-08-05
  • 通讯作者: 张扬
  • 作者简介:王志宁(1990—),男,硕士研究生,13485485840@163.com
  • 基金资助:
    国家自然科学基金项目(51706119)

NO2 formation in natural gas-fired boilers

Zhining WANG1,2(),Xiehe YANG2,Yang ZHANG2(),Yan JIN1,Hai ZHANG2,Junfu LYU2   

  1. 1. College of Electrical and Power Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China
    2. Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
  • Received:2019-03-05 Revised:2019-05-13 Online:2019-08-05 Published:2019-08-05
  • Contact: Yang ZHANG

摘要:

天然气燃烧过程主要污染物是NO和NO2。针对部分燃气锅炉NO2排放较高的情况,开展了中试实验和数值模拟,研究天然气燃烧过程NO2生成规律。结果表明当锅炉采用“燃烧器分级燃烧+烟气再循环”的低氮燃烧策略时,如果燃烧器的伴流风与燃料的混合被推迟,则NO2的生成量较大,最高超过总NO x 生成量的50%,空气和燃料充分混合的条件下NO2生成量较少。NO2在热燃烧产物与冷空气碰撞的交界面上大量生成,NO2生成的温度窗口是800~900 K。NO2主要通过NO与HO2的反应生成,NO2分解后又生成NO,NO2的生成不会显著影响燃烧过程总NO x 的排放。

关键词: 污染, 数值模拟, 天然气, 二氧化氮, 对冲火焰

Abstract:

The main pollutants of natural gas-fired boilers are NO and NO2. The emission data of two natural gas-fired boilers were reported in the present paper and NO2 emission was found to be high. To understand the high NO2 emission in these natural gas-fired boilers, pilot-scale experiments were conducted and detailed chemical kinetic studies were carried out numerically using Chemkin-Pro software. The results showed that the NO2 emission would be high if the low NO x strategy “burner staged-combustion + flue gas recirculation” was applied and the mixing of the co-flow air with the staged fuel was delayed. In this situation, the amount of NO2 emission even exceeded 50% of the amount of the total NO x emission. When the air and fuel were well mixed, NO2 emission was suppressed. NO2 mainly formed near the contact surface of the hot burned product flow and cold air flow. A narrow temperature window, 800—900 K, was found for NO2 formation. The dominating pathway for NO2 formation was the reaction between NO and HO2. When NO2 decomposed, NO formed. Therefore, the formation of NO2 would not significantly affect the total NO x emission of the natural gas-fired boiler.

Key words: pollution, numerical simulation, natural gas, nitrogen dioxide, opposed-flow flame

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