Bed layer of the fluidized bed
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What is the relationship between the bed height of a fluidized bed and the gas flow rate? In fluidized bed operations, the powder particles always spread to the next processing stage. Are there any methods that can be used to improve this situation?
If the amount of fluidizing gas is too high, it may carry powder in the fluidizing gas to the downstream area, leading to problems such as blockages in the downstream system. Please check the relevant process conditions: 1. Bed height. If the bed height is too high, there may not be sufficient space and time for the powder to be removed, making it easy for it to be carried downstream by the fluidizing gas. 2. Fluidized gas flow rate and gas velocity. The reasons have been stated earlier.
It depends on the particle size of the powder; it is likely that the separation height of the bed is insufficient, or the design of the cyclone separator does not meet the separation requirements.
When the gas is directed toward the fixed-bed layer and the flow rate increases to a certain level, the bed begins to loosen. As the gas flow rate keeps rising, the bed enters a fluidized state; once the gas flow rate reaches a certain threshold, the density of the bed decreases and the particles in it are carried away. When the bed is flowing properly but a large amount of powder particles are carried away, it is recommended to increase recovery using a cyclone separator.
This kind of situation often occurs in conventional fluidized beds; it is best to use a cyclone separator for separation, and then add a filter at the entrance of the next processing stage to prevent disruptions in that stage. At the same time, the gas velocity can be reduced within a reasonable range.