Size and distance between orifices

Geldart (1985) mentions some generalizations that can be made about the size and distance between orifices of the distributors:

  1. Distributors with orifices smaller than 1 mm in diameter are very expensive, but they are commercially available;
  2. 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;
  3. The porous distributors form smaller bubbles, without formation of dead zones near the distributor, and have the advantage of solids do not settle down.
  4. 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: