化工学报 ›› 2015, Vol. 66 ›› Issue (12): 5079-5087.DOI: 10.11949/j.issn.0438-1157.20151166

• 能源和环境工程 • 上一篇    下一篇

富氧燃烧方式下煤中砷的挥发行为

刘慧敏1, 王春波1, 黄星智1, 张月1, 孙鑫2   

  1. 1 华北电力大学能源动力与机械工程学院, 河北 保定 071003;
    2 华北理工大学冶金与能源学院, 河北 唐山 063009
  • 收稿日期:2015-07-21 修回日期:2015-09-09 出版日期:2015-12-05 发布日期:2015-12-05
  • 通讯作者: 刘慧敏
  • 基金资助:

    国家高技术研究发展计划项目(2013AA065404);中央高校基本科研业务费专项资金资助(2015XS115)。

Volatilization of arsenic in coal during oxy-fuel combustion

LIU Huimin1, WANG Chunbo1, HUANG Xingzhi1, ZHANG Yue1, SUN Xin2   

  1. 1 Department of Energy Power&Mechanical Engineering, North China Electric Power University, Baoding 071003, Hebei, China;
    2 College of Metallurgy and Energy, North China University of Science and Technology, Tangshan 063009, Hebei, China
  • Received:2015-07-21 Revised:2015-09-09 Online:2015-12-05 Published:2015-12-05
  • Supported by:

    supported by the National High Technology Research and Development Program of China (2013AA065404) and the Fundamental Research Funds for the Central Universities (2015XS115).

摘要:

选取SJS烟煤,利用高温管式炉模拟富氧燃烧,在600~1400℃温度范围内研究了O2浓度、CO2浓度及温度对砷挥发的影响,并进行了空气燃烧模式下的对比实验。对不同工况下的灰样进行FTIR表征并结合化学热力学软件模拟进行分析,结果表明:富氧气氛和空气气氛下煤中砷的挥发比例均随温度升高不断增大,并在低温区间(<900℃)和高温区间(>900℃)分别出现了砷的剧烈失重,但O2浓度和CO2浓度影响了不同气氛下砷的具体挥发行为。低温下(<900℃)O2浓度是影响砷挥发的主要因素,O2浓度越高,砷的挥发比例越大;相同O2浓度下,CO2浓度越高,砷的挥发比例越低,CO2的存在抑制了煤中砷的挥发。高温下(>900℃)CO2浓度是影响砷挥发的主要因素,富氧气氛下高CO2浓度对热量的阻碍导致相同条件下砷酸盐发生分解需要更高的温度,因此富氧气氛下砷的挥发较空气模式滞后;此外CO2在煤颗粒表面形成还原性气氛,高价态砷化合物向不稳定的低价态砷化合物转变,低价态砷化合物的快速分解导致高温下富氧气氛中砷的挥发速率较常规空气模式快。

关键词: 富氧燃烧, 砷挥发, 温度, O2浓度, CO2浓度

Abstract:

Arsenic volatilization characteristics of SJS bituminous coal were carried out on the high-temperature tube furnace from 600℃ to 1400℃ at different oxy-fuel atmospheres. Combined with FTIR analysis and thermodynamic analysis, and taking air condition into consideration, the effects of O2, CO2 and temperature on arsenic volatilization were studied. Results showed that the releasing proportion of arsenic increased with increasing temperature both in oxy-fuel and air combustion. Two arsenic mass loss peaks were observed at <900℃ and > 900℃ stages, separately. At temperature lower than 900℃ oxygen content was the major fact. The more O2 ratio, the larger volatile proportion of arsenic. But at the same O2 ratio condition, the higher CO2 concentration brought down the emission of arsenic and thus the volatile proportion was decreased. At temperature higher than 900℃ the content of carbon dioxide was the major fact, The higher CO2 concentration in oxy-fuel atmosphere hindered heat transfer, and thus higher temperature was needed for the decomposition of arsenates under the same conditions, which led to the delay of the intensive emission of arsenic compared to air condition. Besides, high CO2 content in oxy-fuel condition resulted in the reductive atmosphere around coal particles, which caused arsenic compounds with high chemical valence being reduced to compounds with lower chemical valence, while the arsenic compounds with lower chemical valence were unstable and their fast decomposition led to the higher mass loss rate of arsenic in oxy-fuel condition than to the air condition.

Key words: oxy-fuel combustion, arsenic volatilization, temperature, O2 concentration, CO2 concentration

中图分类号: