15840

agpm X 0.227 = m3/h Source: Schutte and Koerting.

agpm X 0.227 = m3/h Source: Schutte and Koerting.

of eductor. sparger nozzles are normally used for shallow tanks, whereas the following tank mixer described is preferred for deeper vessels.

Figure 10 illustrates a type of eductor called a tank mixer. It is installed under the tank containing the fluid to be agitated. Motive capacities are shown in Table 2. The units are usually custom-designed for a specific entrainment ratio, the required capacity being determined by the quantity of tank fluid, the ratio of mixture desired, and the depth of the tank being agitated.

example 3 It is desired to blend recycled tank fluid into a tank 20 ft (6.1 m) deep in a volume ratio of 1 motive to 1.5 suction. The tank contains 7500 gal (28.4 m3), and it is desired to turn over the tank in 30 min. The motive pump will deliver 60 lb/in2 (4.14 bar) gage at the eductor nozzle. What size mixing eductor is needed?

Solution The 500 gal (28.4 m3) turned over in 30 minutes is equivalent to 250 gpm (56.8 m3/h). Because the motive fluid in this case is recycled from the tank, both motive and suction fluid contribute to the tank turnover. In the ratio of 1.5 suction to 1 motive fluid, the motive quantity required to attain a circulation rate of 250 gpm (56.8 m3/h) is 100 gpm (22.7 m3/h). To select the size, it is necessary to obtain the differential pressure across the nozzle orifice of the eductor. Because the eductor is below the tank, the net driving head is 60 lb/in2 gage - 20/2.31 = 51.35 lb/in2 (4.14 - 6.1/10.2 = 3.54 bar) gage across the nozzle. Enter Table 2 and interpolate between 50 and 60 lb/in2 (3.4 and 4.1 bar) gage. A 1^-in (38-mm) eductor will pass only 73 gpm (16.6 m3/h), whereas a 2-in (51-mm) eductor will pass 129 gpm (29.3 m3/h). The selection would then be a 2-in (51mm) mixing eductor.

spindle proportioning eductobs Another type of mixing eductor is illustrated in Figure 11. Typical applications of this type include mixing hydrocarbons with caustic, oxygen, or copper chloride slurries; producing emulsions; and proportioning liquids in chemical process industries. In critical applications, the regulating spindle is sometimes fitted with a diaphragm operator to achieve close control. Table 3 shows operating pressures and flow rates on several typical applications for units of this type.

sand and mud eductors Figure 12 illustrates a sand and mud eductor used for pumping out wells, pits, tanks, sumps, and similar containers where there is an accumulation of

FIGURE 10 Tank mixing eductor (Schutte and Koerting)

FIGURE 11 Proportioning eductor (Schutte and Koerting)

FIGURE 10 Tank mixing eductor (Schutte and Koerting)

FIGURE 11 Proportioning eductor (Schutte and Koerting)

TABLE 3 Operating pressures and flow ratesâ€”proportioning eductor

Naphtha/ Sour copper kerosene/

Motive liquid/ chloride Hydrocarbon/ Gasoline/ Gasoline/ kerosene suction fluid slurry hydrocarbon slurry water slurry

Pressure, lb/in2 (bar)

gage

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