Geldart (1985) mentions some generalizations that can be made about the size and distance between orifices of the distributors:
- Distributors with orifices smaller than 1 mm in diameter are very expensive, but they are commercially available;
- If the orifices are larger than 5dp, it occurs deposition of solids in the region of gas homogenization. For this reason it is used a screen (mesh) on the distributor or it is used distributors such as caps or tuyere with horizontal orifices;
- The porous distributors form smaller bubbles, without formation of dead zones near the distributor, and have the advantage of solids do not settle down.
- IV. If the total number of orifices of the distributor exceeds 1000 orifices/m2, a few inches above the distributor, the size of the bubbles formed are the same as a porous distributor. However, if Nor is too small, problems of jet penetration and movement of the particle may occur.
Qureshi and Creasy (1979) present a criterion for estimating the spacing of the orifices in a distributor, based on the fraction open area, defined by equation 6.
In accordance with the arrangement chosen for the orifices, the spacing between the orifices, Lor,is given by Equations 7 and 8:
For quadratic arrangement :
For an equilateral triangular arrangement: