Experimental analysis of the fluidization process of binary mixtures of solids

Abstract

The simultaneous treatment of dissimilar solids is encountered in a number of processes that exploit f luidization technology (granulation, combustion, pyrolysis, etc.), but a satisfactory description of multicomponent f luidization dynamics is far from being achieved even for the relatively simple case of binary f luidization. This paper discusses the f luidization properties of two-component beds of solids differing either in particle density or diameter. It is shown that although the minimum f luidization velocity of the mixture can be calculated by fully theoretical equations, it has very little meaning if referred to a twocomponent particle system. Experiments on both kinds of mixtures demonstrate that the binary f luidization process occurs within a characteristic velocity range whose boundaries coincide with the “initial” and the “final f luidization velocity” of the particle mixture. Substitution of the conventional concept of umf by these parameters allows us to recognize that the fluidization dynamics of any binary mixture is determined by the initial arrangement of the fixed bed, as well as by the system composition and size or density ratio of its components.