The fluid dynamics in the furnaces of large-scale circulating fluidized bed (CFB) boilers are surprisingly little known in contrast to the many laboratory studies made on conditions related to chemical reactors. Two areas are surveyed in the present work: the bottom bed and the upper dilute zone of a furnace. The bottom bed is considered bubbling, but the general opinion is that either it does not exist, or it is turbulent. The flow in the upper furnace is dilute phase transport, judging from regime maps, showing that the state of the flow is outside of the range of fast fluidization. However, this is also not generally accepted. Usually, the regime of fluidization in CFB boilers is said to be fast fluidization. In one work it is considered fast fluidization even though the authors agree that it is different from the general definition. In another investigation it is called entrained flow. Here, the conclusion is that the diversity of opinions should be resolved by further investigations with the aim of defining the conditions for the fluidized flow in furnaces, including the influence of particle size and density, fluidization velocity, gas properties, and effects from the furnace dimensions, if any.

与对化学反应器相关条件进行的许多实验室研究相比，大型循环流化床 (CFB) 锅炉炉膛中的流体动力学令人惊讶地鲜为人知。在目前的工作中调查了两个区域：炉底床和上部稀释区。底床被认为是冒泡的，但普遍的看法是它要么不存在，要么是湍流。上部炉内流动为稀相输运，从流态图来看，表明流动状态在快速流化范围之外。然而，这也未被普遍接受。通常，CFB 锅炉中的流化状态被称为快速流化。在一项工作中，它被认为是快速流化，尽管作者同意它与一般定义不同。在另一项研究中，它被称为夹带流。这里的结论是，意见的多样性应通过进一步调查来解决，目的是确定炉内流化流动的条件，包括粒度和密度的影响、流化速度、气体性质以及来自炉的影响。尺寸，如果有的话。