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化学链铁基载氧体磨损特性及机理研究

Study on attrition characteristics and mechanism of chemical looping iron-based oxygen

  • 摘要: 化学链燃烧技术是目前最有前景的CO2捕集技术之一,载氧体是该技术的关键组成部分。铁基载氧体因其来源广泛、价格便宜和环境友好等优点,被认为最具备有工业化应用的潜力,但其存在寿命短、释氧能力弱的问题,磨损是造成该问题的主要原因之一。采用机械混合法制备了煅烧温度为1 300、1 400和1 500 ℃的Fe-Al复合载氧体,分别开展了冷态、热态以及反应态多组流化床磨损试验,分析了煅烧温度对载氧体的磨损和释氧能力的影响,分别研究了氧化反应和还原反应对其磨损的影响,明确了机械碰撞、温度以及化学反应对载氧体磨损的影响程度。研究结果表明:煅烧温度为1 400 ℃的载氧体展现了抗磨损性和循环稳定性能两者之间最佳平衡,基于反应前后载氧体表面的元素分布、晶相分离和微观形貌演变的分析,发现了化学反应中由还原反应引发的载氧体孔容的增加对其磨损和破碎起重要作用,本工作对开发、设计长寿命的复合载氧体有一定的指导作用。

     

    Abstract: Chemical looping combustion technology is one of the most promising CO2 capture technologies at present, and oxygen carrier is a key component of this technology. Iron-based oxygen carriers are considered to have the most potential for industrial application due to their wide source, low price and environmental friendliness. The short lifetime and the weak oxygen transport capacity of oxygen carriers hinder the commercial operation of chemical looping combustion technology. In this paper, Fe-Al composite oxygen carriers with calcination temperature of 1 300 ℃, 1 400 ℃ and 1 500 ℃ were prepared by mechanical mixing method, and several groups of fluidized bed wear tests were carried out in cold, hot and reactive states, respectively, and the calcination temperature was analyzed. The effects of oxidation and reduction reactions on the wear and oxygen release capacity of the oxygen carrier were studied respectively, and the effects of mechanical collision, temperature and chemical reaction on the wear of the oxygen carrier were clarified. The research results show that the oxygen carriers calcined at 1 400 ℃ exhibits the best balance between wear resistance and cycle stability, based on the analysis of element distribution, crystal phase separation and micromorphological evolution on the surface of the oxygen carriers before and after the reactions, and it was found that the increase in the pore volume of oxygen carriers caused by the reduction reaction in the chemical reactions plays an important role in its wear and fragmentation. This work has a certain guiding effect on the development and design of long-life composite oxygen carriers.

     

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