Solid-liquid mixing agitated reactors

Multiphase Mixing and Solid-Liquid Mixing in Agitated Reactors... 

In previous sections, we examined the design parameters for gas-liquid, gas-solid, liquid-liquid, gas-liquid-solid, biological polymerization, and special types of mechanically agitated reactors. In this section we present a brief review on available techniques for the measurement of various mixing and transport parameters for a mechanically agitated vessel. Both physical and chemical techniques are examined. 

Tlie requirement for mechanical agitation can be avoided by using a fluidized bed reactor. In this type of reactor, the agitation and mixing are achieved by means of the moving liquid that carries the solids through the reactor or mixes with the particle phase. Thus, high heat and mass transfer rates are assured. 

Bubble slurry column reactors (BSCR) and mechanically stirred slurry reactors (MSSR) are particular types of slurry catalytic reactors (Fig. 5.3-1), where the fine particles of solid catalyst are suspended in the liquid phase by a gas dispersed in the form of bubbles or by the agitator. The mixing of the slurry phase (solid and liquid) is also due to the gas flow. BSCR may be operated in batch or continuous modes. In contrast, MSSR are operated batchwise with gas recirculation. 

The pulsating three-phase reactor has been examined only at the laboratory level. The pulsation gives good mixing and l)eat- and mass-transfer characteristics in the column. The first three types of gas-liquid-suspended-solid reactor are the most commonly used in practice. Schematic diagrams for these reactors are shown in Fig. l-3fn), (b), and (c), respectively. The agitated and nonagitated slurry... 

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