Columns Scheibel

Fig. 15. Mechanically agitated columns (a) Scheibel column (b) rotating-disk contactor (RDC) (c) asymmetric rotating-disk (ARD) contactor (d) Oldshue-Rushton multiple-mixer column (e) Kuhni column and (f) reciprocating-plate column.

Scale-up and performance of a 1.47-m Scheibel column have been reported (98,154,155), as have detailed description and design criteria for the Scheibel column (156) and scale-up procedures (157). The same stage efficiency can be maintained on scale-up, and total throughput can be increased by three and one-half times at the expense of higher HETS. As of this writing, Scheibel columns up to 2.75 m in diameter are in service. 

As with the design of the other columns described above, the design of a Scheibel column must be based on pilot plant tests and scale-up, The following procedure is recommended ... 

Unhke the RDC and Oldshue-Rusnton columns where the specific throughput of the scaled-up version is the same as the pilot column, it is the characteristic of the Scheibel column that the throughput of the scaled-up column is on the order of 3-5 times greater than that acheived on the pilot column. The reason for this is that the restricted geometry of the 0.075 m diameter column limits throughput these restrictions are removed in the scaled-up columns. 

The scale-up of the Scheibel column is still considered proprietary, and therefore the vendor (Glitsch Process Systems Inc.) should be consulted for the final design. From pilot tests in 0.075-m diameter column, industrial columns up to 3 m in diameter and containing 90 actual stages have been provided. 

Scheelite, 25 349-350 Scheelite sorting, 16 626 Scheibel column, 10 777-778 Scheibler filter, 11 364 Schiff base(s), 21 203, 204, 25 100-101 chelating agents, 5 712t reaction with amino acids, 2 567 reaction with aniline, 2 786 thermochromic materials, 6 622-623 Schiff base chemistry, 24 42 Schiff base (reductive amination) method, for covalent ligand immobilization, 6 396t... 

Mechanical agitation Group E Rotating disc contactor Oldshue-Rushton column Zeihl column Graesser contractor Group F Scheibel column Mixer-settlers... 

To some extent, the Scheibel column may be considered as a centrifugal device, although as coalescence takes place between the layers of mesh packing, in that sense it is a stage-wise contactor, and it has therefore been described in Section 13.6.3. 

Mixer-settlers Scheibel columns Oldshue-Rushton column Rotating disk contractor (ROC) Asymmetric lotating disk extractor (ARC)... 

There are several design variations of the Scheibel column (Fig. 13a). The earlier model consists of alternate compartments agitated with impellers, and the oth-... 

Ppm in feed Cone, factor in extract Porocrft % depletion Scheibel Column % depletion... 

Scheibel Extraction Column The original Scheibel column design consisted of a series of knitted-wire-mesh packed sections... 

The principle of the Scheibel column scale-up procedure is to maintain the same stage efficiency. Therefore, the scaled-up column... 

Kuhni Column Like the Scheibel column, the KUhni column uses shrouded (closed) turbine impellers as mixing elements on a central shaft (Fig. 15-49). Perforated partitions or stator plates extend... 

FIG. 15-48 Scheibel column extractor (third-generation design). (Courtesy of Koch Modular Frocess Systems.)... 

Countercurrent columns with additional kinetic energy input have found a broad range of industrial applications [42-48]. Examples of extraction towers with energy input are pulsed towers, pulsed packed columns and pulsed perforated-plate towers. A number of units with some form of mechanical agitation are also used (Karr column, Scheibel column, Oldshue-Rushton column, Ktihni column, RZE extractor, RDC and ARD extractor, Graesser contactor). 

Other variations of stirred columns which are available include the asymmetric rotating disc (ARD) contactor, the Kuhni column, and two types of Scheibel columns. The rotor of the ARD is located off center, which permits more elaborate baffling for the necessary transport of flows with less backmixing. 

The Kiihni column employs radial flow impellers located between perforated plates for compartmentalization. The first Scheibel column used wire mesh zones to promote coalescence and limit backmixing between turbine-agitated mixing zones. A later Scheibel column used a shrouded radial impeller and multiple ring baffles to direct most of the rotor s energy towards dispersion and away from axial mixing. 

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