Abstract Circulating fluidized beds (CFBs) have been widely used as industrial reactors and the performances rely on the gas-particle contact. In a CFB, particles tend to form dense clusters, sheltering particles from the gas flow. However, in the literature, cluster dimensions and fractions vary up to one order of magnitude, hindering the understanding of CFBs. Recently, it has been found out that different phases were considered as clusters and this circumstance results in the severe variations of cluster properties. In this work, instantaneous solids holdup in a CFB was measured using an optical fiber probe. Then, crest clusters, coalesced particles, trough clusters and dispersed particles were identified in probe signals with the help of images. After that, phases were characterized discriminatively, and phase properties further were validated quantitatively using a high-speed camera. Finally, phases formed by FCC catalysts and glass beads were compared to explore the aggregation mechanism.

中文翻译：

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循环流化床瞬时流动结构的实验研究：相表征与验证

摘要 循环流化床（CFBs）作为工业反应器被广泛使用，其性能依赖于气体-颗粒接触。在 CFB 中，粒子往往会形成密集的簇，从而使粒子远离气流。然而，在文献中，簇的维度和分数变化高达一个数量级，阻碍了对 CFB 的理解。最近，已经发现不同的相被认为是簇，这种情况导致簇特性的严重变化。在这项工作中，使用光纤探头测量 CFB 中的瞬时固体滞留量。然后，借助图像识别探针信号中的波峰簇、聚结颗粒、波谷簇和分散颗粒。之后，对相进行了有区别的表征，使用高速相机进一步定量验证和相位特性。最后，比较了由 FCC 催化剂和玻璃珠形成的相，以探索聚集机制。