The fluidization process of binary mixtures of solids: Development of the approach based on the fluidization velocity interval

• Published in: Powder technology 2008-07, Vol.185 (2), p.97-108
• Main Authors: Formisani, B., Girimonte, R., Longo, T.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bed voidage; Chemical engineering; Exact sciences and technology; Fluidization; Miscellaneous; Mixing; Segregation; Solid mixtures; Solid-solid systems
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2007.10.003

The main characteristic of the fluidization process of particulate mixtures is the interaction between bed suspension and segregation–remixing dynamics of their components. On addressing the fluidization properties of binary beds of solids differing either in particle density or diameter, the paper shows how interpretations based on definition of a minimum fluidization velocity of the mixture can lead to erroneous conclusions about the influence played by system variables on their behaviour. An alternative method of investigation is followed which takes into consideration the existence of a finite velocity interval, bounded by the “initial” and “final fluidization velocity” of the mixture, along which the whole process of fluidization has place. The results of a wide series of experiments demonstrate that this alternative approach allows recognizing the independent variables of binary fluidization; they also highlight the differences of behaviour between density- and size-segregating beds. On illustrating the fluidization properties of two-solid beds undergoing segregation either by component density or size, the paper discusses the misleading significance of mixture u mf and shows how the approach based on the fluidization velocity interval of the mixture, bounded by its “initial” and “final fluidization velocity”, constitutes a sounder criterion of analysis of system behavior. [Display omitted]