2100.     LEVA, M., GRUMMER, M., WEINTRAUB, M. AND POLLCHIK, M.  Introduction to Fluidization.  I.  Chem. Eng. Progress, vol. 44, No. 7, 1948, pp. 511-520.

        Counterflow and cogravity flow of air, CO₂, and He through beds composed of round and sharp sand have been investigated.  Countergravity flow does not differ from cogravity flow as long as no bed expansion is experienced.  Correlations have been developed that permit the prediction of the fluid velocity necessary to expand a bed of sand under countergravity flow conditions.  Correlations include a shape factor, and typical photographs of the various sizes and shapes of sands are presented to permit comparison of any new materials with those tested.  In this way, it is believed the approximate shape factor of new and similar materials may be determined satisfactorily.  The equations presented apply also to mixed sizes of sands, provided the effective diameter of the mixture is evaluated, according to the rule suggested.  The most-complex mixture investigated was composed of 5 individual components.   It is believed that the correlations apply also with good results to more-complex mixtures.  Describes typical fluidization phenomena in 2.5- and 4-in. tubes.