Heterogeneous flow, slurry

Figure 2-48. Critical velocity characteristics depend on whether slurry is heterogeneous or homogeneous. By permission, Deramme-laere, R. H. and Wasp, E. J., Fluid Flow, Slurry Systems and Pipelines, Encyclopedia of Chemical Processing and Design, J. McKetta, Ed., M. Dekker, vol. 22,1985 [25].

Figure 2-51. Friction factor correlation for slurry flow in heterogeneous flow regime. By permission, Turian, R. M. and Yuan, T. F., Flow of Slurries in Pipelines, A/.Ch.E. Journal, vol. 23, 1977, p. 232-243.

Suppose that the reaction takes place in a slurry bubble column and that it is desirable to work in the heterogeneous flow regime. Moreover, assume that the liquid is batch and well mixed and the flow of the gas approximates the ideal plug flow. 

Flow behavior of slurry flow in horizontal pipelines depends on many factors, including flow rate pipe shape, characteristic length, and orientation physical properties of the carrier fluid and particle size, density, and concentration. Two extremes of slurry behavior, homogeneous and heterogeneous flow, occur as a result of particular interactions of these factors as reported by Satchwell et al. (2) and Wasp et al. (3). 

The other extreme of slurry behavior in a horizontal pipe, heterogeneous flow, is characterized by a pronounced variation in the local solids concentration with position in the pipe. The particle settling velocity in this case is high. This implies that the density of the solid particles is higher than the working fluid, for example, sand-water slurry... 

Figure 12.21 Hydrodynamic model of a slurry bubble column reactor in the heterogeneous flow regime [82]. (Source van der Laan [82]. Reproduced with permission of Elsevier.)...

What are the chief distinguishing characteristics of homogeneous flow and heterogeneous flow in slurries ... 

Slurry flows that have some form of segregation or separation of solids in layers are called heterogeneous flows, whereas the slurries themselves are called settling slurries. 

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