Adsorption equipment fluidized beds

Continuous fluidized bed equipment has been utilized for gas adsorption, but usually attrition losses of comparatively expensive adsorbents have been prohibitive and the loss of efficiency because of axial mixing has been a serious handicap. Drying equipment such as those of Figure 9.13 presumably can be operated in reverse to recover valuable substances from a vapor phase, and the forward mode applied for regeneration in associated equipment. Other possibly suitable fluidized bed configurations are those of the reactors of Figures 17.32(a), (c), and (d). 

Because the ion-exchange process is very similar to the adsorption process, the equipment is also similar. Ion exchange occurs in batch tanks, stirred tanks, fixed-bed columns, fluidized-bed columns, and moving-bed processes. The most common process is a fixed-bed column (Figure 8.6), which can be operated in a cocurrent or countercurrent fashion. 

Class 1 equipment are also called column-type equipment. Under this category, there are the various multiphase contactors. Gas-liquid contactors include bubble columns, packed bubble columns, internal-loop and external-loop air-lift reactors, sectionalized bubble columns, plate columns, and others. Solid-fluid (liquid or gas) contactors include static mixers, fixed beds, expanded beds, fluidized beds, transport reactors or contactors, and so forth. For instance, fixed-bed geometry is used in unit operations such as ion exchange, adsorptive and chromatographic separations, and drying and in catalytic reactors. Liquid-liquid contactors include spray columns, packed extraction... 

Atmospheric freeze-drying of several foods, including mushrooms and carrots, was investigated in a fluidized bed of finely divided adsorbent that combined adsorption and fluidization, achieving improved heat and mass transfer and shorter drying time than vacuum drying [50,51]. Products could be dried economically using very simple equipment. 

The procedure for the scale-up of an expanded-bed-adsorption process is relatively straightforward and the principles are similar to those used for a packed-bed process. It is important that the length of the laboratory column be equal to the pilot-plant column. If the pilot-plant equipment is not specifically designed for expanded-bed-adsorption procedures, it should be modified as described in the previous section on laboratory equipment. To verify that the expanded-bed flow patterns are similar for the lab and pilot-plant columns, pulse tests using NaCl solution should be carried out. The adsorbent used, whole-broth-solvent ratio, bed height, and linear velocity, should not be changed on scale-up. The volumetric flow should be increased m proportion to the mcrease in the cross-sectional area of the two columns. Thus, the superficial velocity will be maintained and the adsorption and the fluidization properties will be constant. 

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