燃料后燃特性对带绝热分离器的循环流化床锅炉氮氧化物排放影响

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燃料后燃特性对带绝热分离器的循环流化床锅炉氮氧化物排放影响

王庆旋¹，杨秀娟²，李云妹³，冯巩²，黄中^3*

1．华电淄博热电有限公司，山东省淄博市 255054；2.清华大学山西清洁能源研究院，山西省太原市 030032；3．清华大学能源与动力工程系，北京市海淀区 100084

基金资助:
国家重点研发计划项目(2022YFB4100301)；北京市杰出青年科学基金项目(JQ23010)；华能集团总部科技项目(HNKJ23-H71)

Effect of Fuel Post-Combustion Characteristics on Nitrogen Oxides Emissions in Circulating Fluidized Bed Boilers With an Adiabatic Separator

WANG Qingxuan¹, YANG Xiujuan², LI Yunmei³, FENG Gong², HUANG Zhong^3*

1.Huadian Zibo Thermal Power Co., Ltd., Zibo 255054, Shandong Province, China; 2. Shanxi Research Institute for Clean Energy, Tsinghua University, Taiyuan 030032, Shanxi Province, China; 3. Department of Energy and Power Engineering, Tsinghua University, Haidian District, Beijing 100084, China

Supported by:
National Key R&D Program of China (2022YFB4100301); Beijing Outstanding Young Scientists Fund Project (JQ23010); Huaneng Group Headquarters Science and Technology Project (HNKJ23-H71

摘要/Abstract

摘要： 【目的】针对某国产带绝热分离器的循环流化床锅炉燃用贫煤时面临的氮氧化物(NOx)排放控制难题，研究了燃料后燃特性对NOx排放影响。【方法】通过使用烟温探针和加装水冷取样装置的烟气分析仪，对分离器入口、出口的烟气温度及成分进行了测试。【结果】受锅炉燃料挥发分较低、绝热分离器结构设计、炉内燃烧组织等因素影响，在分离器内部出现了明显的后燃现象，导致分离器出口的烟气温度升高，升温幅度最高可达约62 ℃；同时，出口烟气中的O2含量下降，CO浓度上升；在未进行选择性非催化还原(selective non-catalytic reduction，SNCR)脱硝的情况下，随着后燃现象的出现，烟气中的NOx浓度增加，同一分离器入口、出口的NOx质量浓度差最高可达33 mg/m³。通过更换高挥发分煤种、优化炉内燃烧可以消除分离器内部出现的后燃现象。【结论】锅炉燃用低挥发分煤种时，可通过优化粒度分布、调整配风等措施，延长燃料在炉内的停留时间，减少后燃现象；可通过增设分离器出口烟道喷枪，提高SNCR出力和脱硝效率。研究结果对提升循环流化床锅炉运行环保性和经济性具有指导作用。

关键词: 循环流化床, 锅炉, 清洁燃烧, 非催化还原(SNCR), 脱硝, 煤电机组, 超低排放, 氮氧化物, 绝热分离器

Abstract: [Objectives] To address the challenges of nitrogen oxide (NOx) emission control in a domestic circulating fluidized bed boiler burning lean coal with an adiabatic separator, this study investigates the influence of post-combustion characteristics of fuel on NOx emissions. [Methods] Measurements of flue gas temperature and composition at both inlet and outlet of the separator are conducted using a flue gas temperature probe and a gas analyzer equipped with water-cooled sampling devices. [Results] Significant post-combustion phenomena are observed within the separator due to three main factors: the low volatile content of boiler fuel, the structural design of adiabatic separator, and the combustion configuration in the furnace. This post-combustion leads to a flue gas temperature increase of up to about 62 ℃ at the separator outlet, along with reduced O2 levels and elevated CO concentrations. Without selective non-catalytic reduction (SNCR) denitrification, NOx concentration in the flue gas rises due to post-combustion phenomenon, with a maximum mass concentration difference of 33 mg/m³ between the separator inlet and outlet. Switching to high-volatility coal or optimizing in-furnace combustion can effectively eliminate post-combustion within the separator. [Conclusions] For circulating fluidized bed boilers burning low-volatility coal, extending fuel residence time through optimized particle size distribution and air distribution adjustments can mitigate post-combustion. The SNCR capacity and denitration efficiency can be improved by installing additional injection lances at the separator outlet flue. These findings provide practical guidance for improving the environmental and economic performance of circulating fluidized bed boiler operation.

Key words: circulating fluidized bed, boiler, clean combustion, selective non-catalytic reduction (SNCR), denitration, coal-fired power unit, ultra-low emissions, nitrogen oxides, adiabatic separator

王庆旋, 杨秀娟, 李云妹, 冯巩, 黄中. 燃料后燃特性对带绝热分离器的循环流化床锅炉氮氧化物排放影响[J]. 发电技术.

WANG Qingxuan, YANG Xiujuan, LI Yunmei, FENG Gong, HUANG Zhong. Effect of Fuel Post-Combustion Characteristics on Nitrogen Oxides Emissions in Circulating Fluidized Bed Boilers With an Adiabatic Separator[J]. Power Generation Technology.

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