Mass transfer from fluidized beds

by Yeung, Shuk-wa

Abstract of thesis entitled lii:Iacs transfer from fluidized beds" submitted by Yeung Shuk \ifa for the degree of M. Phil. at the University of Hong KonG in July, 197).

In the present investiGation flow characteristics of

air through b~ds of naphthalene pellets were studied and the maSS transfer coefficient and mass transfer factor wore

determined. Fluidized beds arc used extensively bocause of the high rates of heat transfer and the uniform temperatures within the bod. Heat transfe::.' coefficients are not easy to determine,

but may '00 deduced from the mass transfer measurements by using the Chilton-Colburn analOGY between heat and mass transfer.

AssuminG tho pellet diameter to remain constant during each test run, the flow characteristics of n.ir through fixed

and fluidized beds of naphthalene pellets, ranginG from 1/4 inch to 5/8 inch diameter, were studied. The heat transfer coefficients ,"lere derived from the experimental resul.ts and some new cor--

relat ions bohleen Reynolds numbers and Nussel t numbers were

established.

DurinG each test run, the voidage of and pressure drop across the bed were observed to have affects on mass transfer.

These effects varied according to pellet size. When the resu~~o from diffetentsizes ware compared in a certain Reynolds numj2r range, say, 5000< Dp/)L( 1-?(20000, 3/8 inch and 1/2 inCi:1 diameter

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pellets gave the most reli~blo results, whereas the ~/8 inch diameter ones were affected too much by the void fraction and the wall effect, and the 1/8 inch diameter ones could not be

run in the hiGh Ro-ranGe.

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