Bonotto extractor

FIG. 18-79 Bonotto extractor, [Rickies, Chem, Eng, 72(6), 163 (1965) copif-light 1965 hif McGraw-Hill, Inc., New York. Exceipted with special permission of McGraw-Hill.]... 

Countercurrent action is obtained in the Bonotto extractor of Figure 14.19(d). It has a number of trays arranged in vertical line and provided with scrapers to discharge solids through staggered openings in the trays. The principle of this mode of solid transport... 

Vertical-plate extractor. Exemplified by the Bonotto extractor (Fig. 18-79), this consists of a column divided into cylindrical compartments by equispaced horizontal plates. Each plate has a radial opening staggered 180° from the openings of the plates immediately above and below it, and each is wiped by a rotating radial blade. Alternatively, the plates may be mounted on a coaxial shaft and rotated past stationary blades. The solids, fed to the top plate, thus are caused to fall to each lower plate in succession. The solids fall as a curtain into solvent which flows upward through the tower. They are discharged by a screw conveyor and compactor. Like the Bollman extractor, the Bonotto has been virtually displaced by horizontal belt or tray percolators for the extraction of oil seeds. 

In contrast to the previously described modes of operation, solvent and feed move continuously towards each other in absolute countercurrent extraction. These extractors, e.g. the screw-conveyor extractor, the Bonotto extractor, the Kennedy extractor and extraction batteries with decanter, all move the solid material and are, therefore, mechanically stress objected. For the miscella this requires extended filtration for removing solids. 

In the Bonotto extractor, the extraction tower is equally divided by horizontal plates into cylindrical compartments. Each plate has a radial opening, staggered from the openings of the plates above and below. Each compartment is wiped by a rotating radial blade which allows the feed to enter from the plate above. Therefore, the solid matrix moves from plate to plate from the head of the tower towards the pure solvents at the bottom. At the sump the solids are discharged by a screw-eonveyor. 

In Allis Chalmers, Anderson, and Bonotto extractors.34 solids fell through ascending extract and were intermittently deposited on and swept off circular trays. These extractors are no longer used, probably because effective contacting uccarred only during the descent of the solids and not when they ware on the trays, and because extract turnover and bsckmixing frequently occurred. 

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