Pressure drop fluidized dipleg

As shown above, if the primary or secondary cyclone pressure drop increases, the immersion of the secondary dipleg in the fluidized bed increases, or the solids density in the secondary cyclone dipleg decreases, the solids level in the overflow standpipe (secondary cyclone dipleg) increases. Conversely, if the primary or secondary cyclone pressure drop decreases, the immersion of the secondary cyclone dipleg in the fluidized bed decreases, or the solids density in the secondary cyclone dipleg increases, the solids level in the secondary cyclone dipleg decreases to adjust. 

For external cyclones, people often measure the pressure drop from a point immediately before the cyclone inlet to a point immediately above the cyclone in the gas outlet tube. This measurement does not include the contraction pressure drop as gas flows from the freeboard of the bed into the exit gas line from the fluidized bed. For dipleg seal height calculations, this pressure drop should be taken into account. It is better to measure the total cyclone pressure drop as the difference between the pressure in the freeboard and the pressure in the gas outlet tube. 

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