Hildebrandt extractor

FIG. 1S-SO Hildebrandt extractor. McCabe, Smith, and Harriett, Unit Operations of Chemical Engineering, 5th ed., p. 616. Copyright 1993 by McGraw-Hill, Ine., New York. Used with permissien by McGraw-Hill Book Company.)... 

The Hildebrandt extractor consists of a U-shaped screw conveyer with a separated helix in each of the downward, horizontal, and upward sections. Solids are fed to one leg and fresh solvent is fed to the other to give countercurrent flow. In a Dorr classifier, soUd is introduced near the bottom of a sloping tank and is gradually moved up by means of a rake. The solvent enters at the top and flows in the opposite direction of the sohd and passes under a baffle before finally being discharged over a weir. A number of these units can be connected in series to give countercurrent flow. 

Moving-bed leaching equipment (a) BoIIman extractor (b) Hildebrandt extractor. 

The Hildebrandt extractor operates according to the dipping principle, immersion extractor, body contains two vertical and one horizontal screw, countercurrent flow of solvent and solids. While the solids pass through the unit they are compacted by the screws extract phase is discharged via rod cages. 

The Hildebrandt extractor in Fig. 12.8-2b consists of three screw conveyors arranged in a U shape. The solids are charged at the top right, conveyed downward, across the bottom, and then up the other leg. The solvent flows countercurrently. 

Immersion-type extractors have been made continuous through the inclusion of screw conveyors to transport the soHds. The Hildebrandt immersion extractor (18) employs a sequence of separate screw conveyors to move soHds through three parts of a U-shaped extraction vessel. The helix surface is perforated so that solvent can pass through the unit in the direction countercurrent to the flow of soHds. The screw conveyors rotate at different speeds so that the soHds are compacted as they travel toward the discharge end of the unit. Alternative designs using fewer screws are also available. 

The Hildebrandt total-immersion extractor is shown schematically in Fig. 18-80. The hehx surface is perforated so that solvent can pass through countercurrently. The screws are so designed to compact... 

The first domestic crushing of soybean occurred in Seattle, Washington, in 1910, using seed imported from Manchuria.152 Domestically produced soybean was crushed at cottonseed oil mills in the South and linseed (flaxseed) oil mills in the Midwest during the 1910-1920 era.152,156 The first commercially successful domestic soybean solvent continuous extraction plants were installed by Archer Daniels Midland Company (ADM) and the Glidden Company in Chicago in 1934, both using 100 tpd Hildebrandt U-tube extractors and commercial hexane as solvent. They also were equipped to produce phosphatides.153... 

BoUmann basket conveyor extractor Hildebrandt screw convQfor extractor ... 

Figure 12.8-2. Equipment for moving-bed leaching [a) Bollman bucket-type extractor, (b) Hildebrandt screw-conveyor extractor.

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