Vertical internals

Vertical internals do not affect entrainment in small-particle beds, but may increase entrainment in large-particle beds. 

The uniformity and contact efficiency of a fluid bed can be improved by immersion of a surface within the bed (G15,15, V12). Ikeda has defined a generalized equivalent diameter, considering that the commercial reactors have not only vertical internals but also horizontal baffles. Figure 24 indi-... 

For the interfacial shear-controlled flows, annular film flow pattern is established, and the tube orientation is irrelevant. Consequently, the correlations for annular condensation in horizontal tubes can be applied for vertical internal downward flows as well—see Table 17.25. 

Figure 3. Boundary-element model of a vertical hydrofracture propagating through ten layers of different stiffnesses. Horizontal arrows indicate the hydrofracture s fluid overpressure of 6 MPa in the lowermost layer J. Crosses indicate the fastening of the model in the lower comers. The opening displacement is exaggerated. Three vertical internal springs (through layers 1. H and G) allow the hydrofracture tip to propagate up to the bottom of the soft layer F, which makes the tip wide and blunt, dissipates most of the fracture-tip tensile stress (contours of Tj in megapascals), and may arrest the hydrofracture.

Figure 6 Vertical internals used in the iron reduction process. 1 - vertical tube 2 - crosspiece. 

It has been suggested that a combination of horizontal and vertical internals has an important effect on improving fluidization quality. Thus various kinds of insert bodies come into being, such as pagoda-shaped bodies by Jin et al. (1982), ridge-shaped bodies by Jin et al. (1986b), inverse cones by Zheng et al. (1990), half oval bluff-bodies by Gan et al. (1990), and spiral flow plates by Li (1997). 

Jin Y, Yu ZQ, Shen JZ, Zhang, L. Pagoda-type of vertical internal baffles in gas fluidized beds. Int Chem Eng 20 191 196, 1980. 

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