The difference between fluidized bed and moving bed

Fluidized bed: A fluid flows upward through a bed of fine particles (in a tower); when the flow rate is low, the fluid simply passes through the gaps between the stationary particles, and in this case the bed is referred to as a fixed bed； As the flow rate increases, the particles move apart from each other, and a small number of particles can be seen vibrating and moving within a certain range; this is known as an expanded bed ； When the velocity increases further to the point where all particles are just suspended in the upward-flowing gas or liquid, this stage represents the starting point of a fluidized bed. Simply put, the phenomenon in which solid particles exhibit behavior similar to that of a fluid under the influence of a fluid is called fluidization. A fluidized bed is a device in which fluidization occurs. A moving bed ion exchange resin is an ion exchange device in which the resin flows periodically between exchangers, regenerators, and cleaning towers.

The fluidized bed catalyst remains fluidized without escaping the reactor； The moving-bed catalyst exits the reactor along with the reaction products, and is conveyed to the top of the reactor via a lifting device to re-enter it.

The answer upstairs is a bit far-fetched. . Does the catalyst in the fluidized bed not leave the reactor? ? So, is catalytic cracking considered a fluidized bed reactor? How can the catalyst enter the regenerator for regeneration without leaving the reactor?

It’s a bit far-fetched; our production uses a fluidized bed, and the catalyst is discharged along with the material

In a fluidized bed, gas (or liquid) blows the solid particles, keeping them in a suspended or flowing state; mixing is relatively intense； In a moving bed, the solid particles move downward simultaneously; there is little relative motion between the particles, and backmixing is minimal. Therefore, a moving bed can be considered as a moving fixed bed.

Narrow sense fluidized bed: The particles move around chaotically within the bed, with the operating flow rate lying between the settling velocity and the carrying velocity. Broadly defined fluidized beds: include narrowly defined fluidized beds and gas-fluidized beds; the latter refer to reactors in which the operating flow velocity is greater than the carrying velocity, causing the solid catalyst or particles resulting from the reaction to be carried away by the fluid. In fact, in typical fluidized-bed uncatalyzed reactors, such as those used for the roasting of pyrite, due to the wide particle size distribution of the solid materials, it is inevitable that some solid particles are carried away by the furnace gases; they are only essentially separated at the boiler and cyclone units. A small amount of fine dust then needs to be separated during subsequent wet purification processes. Can this type of bed be classified as a narrow sense fluidized bed? ? ? Moving bed: In short, both the fluid and the solid move slowly, usually in opposite directions; typical examples are coal ball furnaces and rotary kilns. It’s just my humble opinion; please forgive me if it’s imperfect. :lol

The answers are getting more and more classic, haha