Mixing vortex depth

In the case of more or less axially mounted stirrers in vessels without baffles, the liquid is set in rotation, and generates a liquid vortex. As long as the vortex is not so deep that gas can be entrained by the stirrer, the vortex depth has no influence either on the stirrer power or on the mixing process. Naturally, the power number Ne and the mixing number nO depend upon whether the stirred tank is provided with baffles or not (see Fig. 1.36 and 3.3). 

Rieger F., Ditl P., Novak V., Vortex depth in mixed unbaffled vessels, Chem. Eng. Sci. 34 (1979), p. 397-403... 

For turbine agitators, impeller to tank diameter ratios of up to about 0.6 are used, with the depth of liquid equal to the tank diameter. Baffles are normally used, to improve the mixing and reduce problems from vortex formation. Anchor agitators are used with close clearance between the blades and vessel wall, anchor to tank diameter ratios of... 

For liquid-liquid mixtures, the calculations of mixing time and power (or Newton) number outlined above are valid for unbaffled vessels only as long as the vortex created by the stirrer does not reach the stirrer head. Otherwise, gas entrainment occurs and the physical properties of the system change. The depth of the liquid-gas interface at the vessel axis with respect to static liquid surface level, HL, can be related to the Froude and Galileo numbers. Some of the reported relationships are summarized in Table XIV. The value of H, at which the vortex reaches the upper impeller blades level can be expressed as... 

It is a little difficult to explain the success of the three-layer strategy. I suspect that the middle fluid plus the injected layer forms a broader initial line start by turbulent mixing than a density gradient restricted to within a small depth of the surfiice of the vortex of the spin fluid. Within this turbulent mixed zone the operative concentration of solids may be considerably less than that in the injected suspension. The writ-... 

Researches on studying of separation properties were spent on metal dual-lead vortex tube Z)=125-2.5mm with a diameter on a thread of 175mm with a variable depth of thread from 10 to 25mmwatercolumn of cutting of 8.5, a conditional outlet angle of gas a =78°. Superposition of ultrasonic vibrations for clearing of a gas mix was spent with the following fasted frequency 18.5 21.6 22.1 23.5 kc. The best results are had at frequency of ultrasoimd 21.6 kc. 

---