Following the selection of internals for a 109mm diameter fluidized bed

four kinds of internals were evaluated for a 360mm diameter fluidized bed on the basis of the oxidation of o-xylene to phthalic anhydride. The yield of phthalic anhydride was chosen as the test index. The results obtained were essentially the same as those for the previous smaller bed

i.e.

the lower baffles were the best

the perforated plate slightly inferior

and the vertical tubes the least ideal. But

when vertical tubes were used in combination with horizontal plates

equivalent effects were noted with plate-type baffles having smaller spacings. Regression equations showed that fluidized beds equipped with vertical tubes were less sensitive to temperature and gas velocity

implying that the flow patterns were not the same as those for horizontal internals.