Side-entering agitators

Axial-tlow impellers rnav also be mounted near the bottom of the cylindrical wall of a cssel as shown in Fig, 18-10, Such side-entering agitators are used to blend low- iscositv fluids [<(), Pa-s (100 cP)] or to keep slowly settling sediment suspended in tanks as large as some 4000 rn (1(P gal). Mixing of paper pulp i.s often carried out by sideentering propellers. 

Side-Entering Impellers For vessels greater than 4 m (1000 gal), a side-entering propeller agitator (Fig. 18-9) mav be more economical than a top-mounted impeller on a centered vertical shaft. 

Side-entering agitators are used for blending low viscosity liquids in large tanks, where it is impractical to use conventional agitators supported from the top of the tank see Oldshue et al. (1956). 

For vessels greater than 38 m (10,000 gal), the economic attractiveness of side-entering impellers increases. For vessels larger than 380 m (100,000 gal), units may be as large as 56 kW (75 hp), and two or even three may be installed in one tank. For the suspension of slow-settling particles or the maintenance of uniformity in a viscous slurry of small particles, the diameter and rotational speed of a sideentering agitator must be selected on the basis of model tests or experience with similar operations. 

Figure 6.4b is an example of a side-entering configuration. It should be clear that swirls and vortices would also be avoided in this kind of configuration. Figure 6.4c shows the agitator mounted at the center of the vessel with four baffles installed on the vessel wall. The swirl may initially form close to the center. As this swirl... 

BLENDING OF MISCIBLE LIQUIDS. Miscible liquids are blended in relatively small process vessels by propellers or turbine impellers, usually centrally mounted, and in large storage and waste-treatment tanks by side-entering propellers or jet mixers. In a process vessel all the liquid is usually well agitated and blending is... 

Three-blade propeller agitator. There are several types of agitators commonly used. A common type, shown in Fig. 3.4-1, is a three-bladed marine-type propeller similar to the propeller blade used in driving boats. The propeller can be a side-entering type in a tank or be clamped on the side of an open-vessel in an off-center position. These propellers turn at high speeds of 400 to 1750 rpm (revolutions per minute) and are used for liquids of low viscosity. The flow pattern in a baffled tank with a propeller positioned on the center of the tank is shown in Fig. 3.4-1. This type of flow pattern is called axial flow since the fluid flows axially down the center axis or propeller shaft and up on the sides of the tank as shown. 

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