RDC extractor

FIG. 15-39 Rotating-disk (RDC) extractor, (Couitesy of Glitsch Frocess Systems Inc.)... 

Vaporizer/Heater 2 Reactor 3 Gas separator 4 RDC-extractor 5 Saturation column 6 Phase-separation vessel... 

The Oldshue-Rushton (Mixco) extractor is similar in construction to the RDC in the fact that it is a relativelv open design, consisting of a series of compartments separated by horizontal stator baffles. The major difference from the RDC is that the height/diameter ratio of the compartments is greater, each compartment is fitted with vertical baffles, and the mixing is accomplished by means of a turbine impeller rather than a disc. 

FIG. 23"37 Equipment for liquid/liquid reactions, a) Batch stirred sulfonator. (h) Raining bucket (RTL S A, London), (c) Spray tower with Loth phases dispersed. (d) Two-section packed tower with light phase dispersed, (e) Sieve tray tower with light phase dispersed, (f ) Rotating disk contactor (RDC) (Escher B V, Holland). (g) Oldshue-Rushton extractor (Mixing Equipment Co. ). 

FIG. 23-38 Efficiency and capacity range of small-diameter extractors, 50 to 150 mm diameter. Acetone extracted from water with toluene as the disperse phase, V /V = 1.5. Code AC = agitated cell PPC = pulsed packed column PST = pulsed sieve tray RDC = rotating disk contactor PC = packed column MS = mixer-settler ST = sieve tray. (Stichlmair, Chem. Ing. Tech. 52(3), 253-255 [1980]). 

A wide variety of extraction column forms are used in solvent extraction applications and many of these, such as rotary-disc contactors (RDC), Oldshue-Rushton columns, and sieve-plate column extractors, have rather distinct compartments and a geometry, which lends itself to an analysis of column performance in terms of a stagewise model. As the compositions of the phases do not come to equilibrium at any stage, however, the behaviour of the column is therefore basically differential in nature. 

Figure 11 Agitated extractors. Left to right RDC, Karr, Oldshue-Rushton, Scheibel, Kuhni extraction columns. 

Figure 6.23 Effect of Interfacial Tension on NETS for the RDC and RPC Extractors (Source Reference 6.31 with permission).

The RDC has a moderate throughput typically in the range of 20 to 35 mV(h m ) [500 to 850 gal/(h ft )j, and it can be turned down to 20 to 35 percent of the design rate. However, the relatively open arrangement leads to some bacWixing and results in only moderate mass-transfer performance. As a consequence, some RDC columns are being replaced by more efficient extractor designs. The RDC can be... 

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). 

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