Mixer impeller

Figure 5-8A. Dual impeller mixer and drive. Courtesy of Lightnin (formerly Mixing Equipment Co.), a unit of Generai Signai.

Oldshue, J. Y. and F. L. Connelly, Gas-Liquids Contacting with Impeller Mixers, Chem. Eng. Progress, March 1977, p. 85. 

The tanks are nearly tight now. To exclude damaging the covering by homogenizing with an impeller mixer, the tarpaulin can be inflated before mixing. This is dispensible if it is used a hydraulic mixing system. 

Polyvinyl chloride Rigid PVC Plasticized PVC Dry blends Liquid or paste dispersions Intensive high-speed mixers Roll mills or disk Impeller mixers... 

Figure 3. Typical velocity vs. time from a high frequency response probe measuring velocities at a point from an impeller mixer...

Vertical impeller mixers employ a screw-type impeller, which constantly overturns the batch. 

For accuracy, in power number Np calculations, the power of the load on the impeller rather than the mixer motor should be used. Before attempting to use dimensional analysis, one has to measure/estimate power losses for empty bowl or dry stage mixing. Unlike power consumption of the impeller (based on torque measurements), the baseline for motor power consumption does not stay constant and changes significantly with load on the impeller, mixer condition, or motor efficiency. This may present inherent difficulties in using power meters instead of torque. Torque, of course, is directly proportional to power drawn by the impeller (the power number can be determined... 

Motionless mixers are an alternative to rotating impeller mixers. Motionless or static mixers use stationary shaped elements inside pipes or conduits to divide, divert, twist, and recombine flowing material. The dividing, stretching, and recombining processes lead to thinner and thinner striations in viscous materials to achieve uniformity. 

Brucato, A. Magelli, F. Nocentini, M. Rizzuti, L. An application of the network-of-zones model to solids suspension in multiple impeller mixers. Trans. Instn. Chem. Engrs. 1990, 69, Part A, 43-52. 

Espinosa-Solares T., Brito-De La Fuente E., Tecante A., Tanguy P.A., Power consumption of a dual turbine-helical ribbon impeller mixer in ungassed conditions, Chem. Engng. J. 67 (1997), p. 215-219... 

The effect of the mixing mode on the power law index is also shown in Table 3. The polymer chains dissolved in a relatively mild impeller mixer have been mechanically broken the least consequently, these solutions have large [1-n] values. The molecules that have been subjected to severe shearing conditions (380 psi across the orifice) exhibit a Newtonian behavior indicating that the polymer chains have been broken down into short segments. 

Draft tubes. The return flow to an impeller of any type approaches the impeller from all directions, because it is not under the control of solid surfaces. The flow to and from a propeller, for example, is essentially similar to the flow of air to and from a fan operating in a room. In most applications of impeller mixers this is not a limitation, but when the direction and velocity of flow to the suction of the impeller are to be controlled, draft tubes are used, as shown in Fig. 9.6. These devices may be useful when high shear at the impeller itself is desired, as in the manufacture of certain emulsions, or where solid particles that tend to float on the surface of the liquid in the tank are to be dispersed in the liquid. Draft tubes for propellers are mounted around the impeller, and those for turbines are... 

The boundaries between the fields of application of the various types of mixers are not sharp. Impeller mixers of the kind described in Chap. 9 are not often used when the viscosity is more than about 2 kP, especially if the liquid is not newtonian. Kneaders and mixer-extruders work on thick pastes and plastic masses impact wheels are restricted to dry powders. Other mixers, however, can blend liquids, pastes, plastic solids, and powders. 

Figure 6.11. Technological scheme for receipt of alkylsulfates la, lb - tank sulfators with impeller mixers (vr = 0,157-0,44 m ) 4a, 4b - extraction columns of the first stage (Vr = 3,4 m ) 5 - extraction column of the second stage (Vr = 4,7 m ) (scheme a), 1 - tubular turbulent sulfator (Vr = 0,0086 m ) 4 - tubular turbulent extractor of the first stage (vr = 0,003 m ) 5 - tubular turbulent extractor of the second stage (Vr = 0,005 m ) 6 - sediment box (scheme b), 2a-2d - tank reactors-neutralizator with propeller mixers (Vr = 3 m ) . 3 - seoarator.

With high-intensity mixers, plasticizer is not held back all liquid ingredients are charged. Under cooling and agitation, resin and then other solids are added to the mixer vortex in a high-speed impeller mixer, or metered into a sigma blade mixer, at which point vacuum can be applied. 

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