Abstract:

Oxy-fuel combustion with fluidized bed is one of the most promising carbon capture technologies. The oxy-fuel combustion of coal/biomass was simulated in a micro-fluidized bed reactor (inner diameter is 10 mm, combustion temperature is 700-900℃) coupled with an online mass spectrometry, to deeply understand the oxy-fuel combustion behavior. Bituminous coal and rosewood were selected as the samples. The effects of oxygen concentration, combustion temperature and mass ratio of coal to biomass on the combustion characteristics, i.e. the total reaction time, the initial reaction time, CO₂ concentration in flue gas and the generation rate of CO₂ during particle combustion, were investigated. It was found that the increment of oxygen volume fraction lead to an increase of CO₂ yield, the decrease of total reaction time and CO₂ concentration in the flue gas. Increasing the combustion temperature could enhance the enrichment of CO₂, as a result higher CO₂ production by particle combustion and CO₂ concentration in the flue gas were obtained. Higher ratio of biomass advanced the initial reaction time and shortened the total reaction time, which resulted in a decrease of CO₂ concentration in the flue gas and CO₂ production by particle combustion but the rate of CO₂ formation is increased.

Key words: fluidized bed, oxy-fuel combustion, multiphase reaction, fluidizing reaction, CO₂ capture

摘要：

流化床富氧燃烧是具有重要应用前景的燃烧中碳捕集技术。为更深入认识固体燃料的流态化富氧燃烧行为，构建了微型流态化反应-质谱联用实验系统，反应器直径10 mm，燃烧温度700～900℃，探索了基于在线质谱分析的流态化燃烧过程特性表征方法，以烟煤和花梨木为对象，研究了煤、生物质及其混合物在富氧气氛和流态化条件下的燃烧行为，重点考察了氧浓度、燃烧温度、煤与生物质质量比对CO₂谱峰曲线形态、反应总时间、起始反应时刻、烟气中富集CO₂体积分数、颗粒燃烧产生CO₂量、CO₂相对生成率等特性的影响。结果表明，在O₂/CO₂燃烧气氛下，随着氧体积分数增加，燃烧总反应时间缩短，颗粒燃烧产生的CO₂量和生成速率均增加，但烟气中富集的CO₂体积分数减小；提高燃烧温度，缩短了燃烧过程所需的时间，可以促进CO₂的富集，烟气中CO₂浓度、颗粒燃烧产生的CO₂量和生成速率均增加；生物质比例增大，起始反应时间提前，燃烧反应所需总时间减少，烟气中富集的CO₂浓度和颗粒燃烧产生的CO₂均减少，但CO₂生成速率增加。

关键词: 流化床, 富氧燃烧, 多相反应, 流态化反应, 二氧化碳捕集