Impeller slots

Highly viscous polymeric reactions (e.g., the hydrolytic polyamide reaction) are often carried out in a gear-pump reactor (Tadmore and Klein, 1970). This type of reactor is often difficult to operate because the clearance of the gear teeth is increased by wear caused by flow and the reaction process. For smaller viscosity of the melt, a screw reactor or a twin-screw extruder is often used. Sterbecek et al. (1987) used a twin-screw extruder (i.e., Wemer-Pfleiderer extruder ZSK 83) for studying fast ion-catalyzed polymerization (6-caprolactam) in a melt. They indicated that power input and quality of product in such a reactor depends on the slot width between reactor wall and impeller in a twin screw extruder. They provided an optimum design of a twin-screw reactor for a fast ion-catalyzed polymerization in a melt. 

Rotor-stator mixers Slotted ring or impeller, along with slotted stator Either, often continuous 1 < d32 < 50 pm Sparse data for scale-up need extensive testing... 

The Kady mill uses a paste of low viscosity and an impeller rim speed of 8700 ft/min (22). The mill gives little or no shearing action and depends primarily on impact for dispersion. Most of the work is done in the slotted area of the stator. The agglomerates leave the rotor and smash into the stator at high speed where they receive a series of impacts that break up the agglomerates (23). The mill base leaves the stator in a jet stream where some shearing may take place. The mill base should always cover the impeller to achieve the best efficiency and to avoid the introduction of air into the base. The rotor is assisted by two propellers, one of which is above the rotor and the other below. These propellers function as a pump, drawing the batch into the head from the top and the bottom. 

In parallel to each intake cycle, the gas which was in each case taken in before is compressed. This compression is effected by gas flowing backwards into the pump chamber (opening 3). As soon as one impeller opens the intake slot, the second impeller opens in the direction of gas inlet 3 on the exhaust side. The venting gas which is at atmospheric pressure flows into the pump chamber and increases the particle density in the pump chamber to the level of atmospheric pressure. 

Another popular rotor-stator design is the Silverson Machines or Ross type. The rotor is a radial impeller that rotates inside a stationary housing with slots as shown in Figure 8-3a. The rotor moves the fluid radially out of the mixer head through the slots or holes in the stator. Superimposed on the radial flow is a... 

Hydrodynamically, it is expedient to profile impeller shovels in terms of various values of speeds within slot-hole channels. Thus, the gas-dispersed stream can be swing on any necessary angle with the least hydraulic losses (Bussrojd, 1975 and Kutateladze, 1976). 

Thus, if design data of blades of an impeller are set, it is possible to count a gas velocity distribution at a flow its gas-dispersed stream. Knowing speeds of gas in various points of a gas stream, it is possible to define forces of an aerodynamic resistance on which mechanical trajectories of firm corpuscles in slot-hole channels depend. 

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