Abstract:

Refractory brick which is usually used as high-temperature furnace material has high crushing strength and high agglomeration resistance. In this work, a type of high-alumina refractory brick particles were used as support material for Cu-based oxygen carrier preparation. Three samples containing 10%—30% of CuO, denoted as Cu10RefBri, Cu25RefBri and Cu30RefBri, were prepared with successive impregnation method and then subjected to the tests in TGA and fluidized bed reactor under 900—950℃ to explore their characteristics on oxygen release and uptake. The Cu25RefBri sample showed the highest rate of oxygen release in TGA tests (as high as 9×10^-5kgO₂/(s?kgOC)), thus presented a stable O₂ volume fraction of 1.1%. However, as the number of cycles increased , the rate of oxygen release decreased to as low as 2.0×10^-5kgO₂/(s?kgOC), meanwhile the O₂ volume fraction reduced to 0.7%, which is much lower than that for equilibrium case. The main reason for the decrease of oxygen release activity could be the formation of low-reactive crystalline CuAl₂O₄, the concentration of which increased as a function of cycles. Moreover, agglomeration of Cu25RefBri was noticed at a temperature of 950℃ in the fluidized bed reactor.

Key words: chemical looping with oxygen uncoupling, Cu-base oxygen carrier, agglomeration, fluidized bed, deactivated

摘要：

耐火砖常用作高温炉膛材料，具有较高的破碎强度和较强的抗烧结性能。以耐火砖颗粒为惰性载体，采用连续浸渍法制备CuO质量分数为10%～30%的Cu10RefBri、Cu25RefBri和Cu30RefBri氧载体样品，并在热重分析仪（TGA）和批次进料流化床反应器中900～950℃下进行了化学链氧解耦燃烧过程氧载体的释氧-吸氧循环实验测试。结果显示，在上述氧载体样品中Cu25RefBri的释氧速率最高，可达9×10^-5kgO₂/(s?kgOC)，流化床中稳定的O₂体积分数可达1.1%。然而，随着循环次数增加，Cu25RefBri的释氧速率逐渐降低至2.0×10^-5kgO₂/(s?kgOC)，同时流化床尾气中O₂体积分数降低至0.7%，该值远低于对应温度下的平衡O₂浓度值。氧浓度和释氧速率降低的主要原因在于：循环过程氧载体中形成的低释氧活性的CuAl₂O₄尖晶石含量逐渐增加，导致氧载体总体活性下降。此外，在950℃流化床实验过程，还检测到氧载体颗粒的烧结现象。

关键词: 化学链氧解耦, 铜基氧载体, 团聚, 流化床, 失活