Higgins contactor

Figure 18.8. Principles of the Higgins contactor (a) Solution pumping (several minutes) (b) Resin movement (3-5 seconds) (c) Solution pumping (several minutes)...

One of the most remarkable units of such a type is the Higgins contactor. The apparatus, in the form of a U, has sections with different diameters and heights. Depending on the process performed the number of sections and valves isolating them can be varied. Both branches of the loop are connected to a piston capable of producing extremes of pressure. 

Figure 27 Scheme for Higgins contactor (a) operating cycie (b) resin movement (c) repeat of operating cycle (1,2) valves (3) piston (4) original solution inlet (5) treated solution output (6) regeneration solution inlet (7) waste output. 

Then valve 2 is shut, valve 1 is opened, the flow of solution is resumed and the piston moves to the left position (Fig. 27c), the exhausted ion exchanger moving to the left branch through a connecting tube and being collected over valve 2. The operations are then repeated. Various designs of Higgins contactors are described in the literature [9,10,43,47, 50,69,70]. 

Continuous contactors operate as intermittently moving packed beds, as illustrated by the Higgins contactor " (Fig. 31), or as fluidized staged (compartmented) columns, as shown in Fig. 32, by the Himsley... 

In the Higgins contactor, the resin is moved hydraulically up through the contacting zone. The movement of resin is intermittent and opposite the direction of solution flow except for the brief period of resin advancement when both flows are cocurrent. This type of operation results in a close approach to steady-state operations within the contactor. 

The major disadvantage of the Higgins contactor is the lifetime of the resin. Estimates range from as high as 30% resin inventory replacement per year due to attrition and breakage of the resin as it passes through the valves.f ... 

One of the earlier attemptst at industrial chromatography used an adaptation ofthe Higgins contactor for the ion exclusion purification of sugar juices. The physical movement of the low cross-linked resin caused attrition as it was moved around the contactor. It was also difficult to maintain the precise control needed on flow rates because ofthe pressure drop changes and volume changes of the resin as it cycled from the mostly water zone to the mostly sugar solution zone. 

Figure 11.79 Higgins contactor, schematic solids shown shaded).

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