In mixing vessels

Oldshue, J. Y, Suspending Solids and Dispersing Gases in Mixing Vessels, Amin Chem. Soc., V. 61, Sept. 1969, p. 79. 

Oldshue, J. Y. and A. T. Gretton, Helical Coil Heat Transfer in Mixing Vessels, Chem. Eng. Prog. 50, 1954, 615. 

Thus, the ratios of the various forces occurring in mixing vessels can be expressed as the above dimensionless groups which, in turn, serve as similarity parameters for scale-up of mixing equipment. It can be shown that the existence of geometric and dynamic similarities also ensures kinematic similarity. 

Biocide should also he added to any water overlay and to water or diluted product left in mixing vessels, storage tanks, pipelines and hoses. 

ZLOKARNIK, M. Adv. Biochem. Eng. 8 (1978) 133. Sorption characteristics for gas-liquid contacting in mixing vessels. 

As a rule, more than two dimensionless numbers will be necessary to describe a physicotechnological problem and therefore they cannot be derived by the method described above. In this case, the easy and transparent matrix calculation introduced by Pawlowski (6) is increasingly used. It will be demonstrated by the following example. It treats an important problem in industrial chemistry and biotechnology because the gas liquid-contact in mixing vessels belongs to frequently used mixing operations (Fig. 2). 

Note The fluid velocity v in pipes—or the superficial gas velocity vq in mixing vessels or in bubble columns—presents a well-known process parameter which combines the fluid throughput q and the diameter of the device D V q/T>. Nevertheless this parameter is not an intermediate quantity. It cannot replace the diameter of the device it is simply another expression for the fluid throughput. Reference The kinematic process numbers like the Reynolds and Froude numbers, which govern the hydrodynamics, necessarily contain the linear dimension of the device. 

Figure 14 Work sheet for the determination of optimum working conditions for the homogenization of liquid mixtures in mixing vessels. Source From Ref 14.

Figure 14 shows this relationship ni=/(Il2) for those stirrer types which exhibit the lowest Hi values within a specific range of II2, i.e., the stirrers requiring the least power in this range. It represents a work sheet for the determination of optimum working conditions for the homogenization of liquid mixtures in mixing vessels. 

Productioa - M. Zlokamik Sorption Characteristics for Gas-Liquid Contacting in Mixing Vessels. 

Earlier studies in mass transfer between the gas-liquid phase reported the volumetric mass-transfer coefficient kLa. Since kLa is the combination of two experimental parameters, mass-transfer coefficient and mterfacial area, it is difficult to identify which parameter is responsible for the change of kLa when we change the operating condition of a fermenter. Calderbank and Moo-Young (1961) separated kta by measuring interfacial area and correlated mass-transfer coefficients in gas-liquid dispersions in mixing vessels, and sieve and sintered plate column, as follows ... 

Calderbank, P. H. and S. J. R. Jones, "Physical Rate Properties in Industrial Fermentation - Part III. Mass Transfer from Fluids to Solid Particles Suspended in Mixing Vessels," Trans. Instn. Chem. Engrs. 39 (1961) 363-... 

The ultimate question is this How do all of these phenomena apply to process design in mixing vessels No one... 

Shear rates normally appearing in mixing vessels are in the range of y = 50-500 s-1, therefore many liquids behave like an Ostwald-de Wade fluid. This explains why the power law is so often used to describe rheological behaviour, see e.g. [37, 38],... 

High Speed Disc dispersion systems. Idealized flow in mixing vessel and typical installations. Reproduced by permission of Dlaf AG from house literature. 

In this work, measurements of the mean velocity and the turbulent fluctuations in the flows generated by the two impellers were confined to the center line of the radial jet since this is the zone where the flow is most strongly influenced by the impeller style. Turbulent flow parameters were determined using a DISA Electronics Laser Anemometer System. As the name implies, this is an optical device that measures the instantaneous velocity at a point. The technique is linear which allows accurate flow measurements at very high turbulence levels such as found in mixing vessels. Since there is no probe, there are no flow disturbances and the measurement is independent of fluid properties. The anemometer used in this work was sensitive to the direction of the instantaneous velocity. 

Computational fluid mixing allows the modeling of flow patterns in mixing vessels and some of the principles on which this is based in current techniques are included. 

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