Agitation baffles

In the case of a packed column, the terms on the right-hand side should each be divided by the voidage, ie, the volume fraction not occupied by the soHd packing (71). In unpacked columns at low values of the sHp velocity approximates the terminal velocity of an isolated drop, but the sHp velocity decreases with holdup and may also be affected by column internals such as agitators, baffle plates, etc. The sHp velocity can generally be represented by (73) ... 

Finally, the reactor vessel has been assumed to be perfectly mixed. Imperfect mixing and a flow pattern created by different types of agitators, baffles, feed locations and other reactor vessel configurations will cause the performance to be below that indicated by perfect mixing. 

Water sodium alcoholate solution "FrederWng" (cast-incoil) agitated, baffled 80... 

Figure 2. Conventional polymerization reactor with top-driven agitator, baffle, and wall-cooling (volumes up to 40 ms)...

O is relatively unchanged when DT/DA is varied from 2 to 7 for turbine- and propeller-agitated baffled systems. 

A.W. Nienow, Suspension of solid paricles in turbine agitated baffled vessels, CES, 23, 1453-1459 (1968). 

Sterilized and introduced to a bioreactor or fermenter, is typically equipped with agitators, baffles, air spargers, and sensing devices for the control of the operating conditions. A pure strain of microorganisms is introduced into the vessel. The number of cells multiplies exponentially after a certain period of lag time and reaches a maximum cell concentration as the medium is depleted. The fermentation is then stopped and the contents are pumped out for the product recovery and purification. This process is operated either by batch or continuous mode. 

Correlation of blending times for miscible liquids in a turbine-agitated baffled vessel. After Norwood and Metznerf )... 

Typical vessel internals are agitators, baffles, and dip tubes. Agitators and dip tubes are covered by fluo-ropolymer by either coating as explained in Spray and Baked Coatings, (Sec. 8.2.3) or by fluoropoly-mer sheets, typically shrink-wrapped PTFE. Baffles... 

Nienow, A.W. (1968). Suspension of Solid Particles in Turbine-Agitated Baffled Vessels, ChemESci. 23, pp. 1453-1459. 

The wide angle observation nozzle shown at the right allows a good view of reactor internals such as agitator, baffles, and movement of reaction mass. This is not possible with a narrow angle view nozzle shown at left (Fig. 6.8). 

Nienow AW. (1969) Dissolution mass transfer in turbine agitated baffled vessels. Can. J. Chem. Eng., 47 248-256. 

Gaskets should be CAF/AR/PTFE of minimum 6 mm thiekness. (Bolted cover facilitates easy maintenance/replacement of agitator, baffles, etc.)... 

With nonproximity agitators, baffles are almost always used to prevent swirl and subsequent vortexing and to increase top-to-bottom motion and turbulence. 

Table 14-3 Heat Transfer Coefficient Correlations for Agitated, Baffled Vessels"... 

For a vessel with axial agitation, baffles, and a liquid height that is about the same as the diameter, the equipment dead time is approximately the turnover time that can be estimated as the liquid mass divided by the summation of the influent, reagent, and recirculation flows plus the agitator pumping rate per Equation 5-3a [Ref. 8.2], While theoretically the dead time is on the average half of the turnover time, in practice it has been found that time delay is actually appreciably larger than the turnover... 

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