Impeller flat blade

When two six-blade open turbines are installed on the same shaft and the spaeing between the two impellers (vertieal distanee between the bottom edges of the two turbines) is at least equal to D, the total power is 1.9 times a single flat-blade impeller. Eor two six-blade pitehed-blade (45°) turbines, the power is about 1.9 times that of a single pitehed-blade impeller. 

Tliese coixelations have been derived for Ruhston turbines, but they can be applied for flat-blade impellers as well (Laakkonen et al., 2005). SI units should be used in these correlations. 

Flower [25], Panda et al. [26], Doran [27]. and Payne et al. [28]. Several kinds of bioreactors, such as the stirred tank bioreactor with hollow paddle and flat blade impellers, the bubble column, the airlift bioreactor with internal and external loops, the rotating drum bioreactor, the stirred-tank with a draft tube, and the mist bioreactor have been attempted for plant cell, tissue and organ cultures (Fig. 1). 

Power Number, Np The power number, Np, sometimes referred to as Po, is a measure of the relative drag of the impeller. Streamline curved blades, like hydrofoils and retreat-curve impellers, have less drag than flat blades consequently, their power numbers are lower than those for flat-blade impellers. Power numbers of some of the more popular impellers are given in Table 9.1. The calculation of power from impeller diameter, speed, and liquid density is given by Equation (9.1). 

To achieve a high stage efficiency (between 90 and 100%) it is necessary to provide fairly vigorous agitation. Based on the work of Skelland and Ramsay (1987), a minimum impeller rate of rotation Qmin is required for complete and uniform dispersion of one liquid into another. For a flat-blade impeller in a baffled vessel of the type discussed above, this minimum rotation rate can be estimated from... 

A correlation of experimental data on Po vs. Re for baffled vessels with six-bladed flat-blade impellers was developed by Laity and Treybal (1957). They found that for Re > 10,000, the power number tends to an asymptotic value of Po = 5.7. 

For the conditions and results of Example 7.7, involving the extraction of benzoic acid from a dilute aqueous solution using toluene as solvent, determine the following when using a six-flat-blade impeller in a closed vessel with baffles and with the raffinate phase dispersed ... 

Radial mixers flat-blade impellers and turbines... 

The foregoing description of the production of forces and of the subsequent power requirements is centred on a single flat blade impeller. If more blades were added, it may at first sight seem that the power would increase in proportion, but this is not so, because the blades are subjected to a diminishing local normal velocity. The wake influence of upstream blades is similar to a sheltering effect and the power increases in proportion to the numbers of blades raised to a power in the range 0.5-0.8. 

Work was also performed with a mixed batch reactor to gain insight into the effects of agitation on batch systems and the possible influence of fluid velocity on hemicellulose removal. For these tests, a 1-L Parr bomb constructed of Carpenter-20 (Parr Instruments, Moline, IL) was fitted with a flat-blade impeller on a one-piece shaft and operated at varying speeds using a Parr DC motor drive (A1750HC, Parr Instruments, Moline, IL) (62),... 

Figure 13-32. Power for impeUers immersed axially in sii e-phase liquids. Curves a, b, d, and e are for vessels with four baffles and with gas-liquid surface, (a) Marine impellers, dj/d = 1/3 (b) flat-blade impeller, w = 0.2d, (d curved-blade turbines (e) pitched-blade turbines. Curves c and g have no baffles, (c) Disk flat-blade turbines with or without a gas-liquid surface, (g) flat-blade turbines in unbaffled covered vessel with no interface and no vortex. Reprinted with permission from Treybal, R. E., Mass-Transfer Operations, McGraw-Hill, New York, 1980, p. 152. Copyright 1980 McGraw-...

The data used to illustrate emulsion polymerization at high Reynolds numbers were those of Ruben (17) 65 35 vinyl chloride-ethyl acrylate copolymers were prepared using a 40-50 60-50 monomer water ratios, 9.2% hydrocarbon sulfonate and 2.3% polyoxyethylated phenol emulsifiers, 0.57% ammonium persulfate initiator, and 0.40% sodium acetate buffer. The polymerizations were carried out in a 2-gallon jacketed stainless steel reactor equipped with a 2-, 3-, or 4-inch flat-blade impeller at pressures less than 110 psi, for 4 hours at 52°, 2 hours at 54°, and 3 hours at 60°. Figure 11 shows... 

Radial flow Flat-blade impeller, disk turbine (Rushton), hollow-blade turbine (Smith)... 

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