Melt crystallization Kureha purifier

Brodie crystallizer-purifier, 545, 547 Kureha purifier, 545,547 multistage, 543 MWB process, 543,545 Phillips process, 544-546 Schilaknecnt column, 543,544,546 TNO bouncing ball process 545.547 Melt purification. See Melt crystallization Membranes, 631,632,641 applications, 632 cellulose acetate, 635 equipment configurations, 632 gas permeation,633,644 hollow fiber, 632,633,641,643 performance, 646 Permasep, 641 olate and frame, 638 Prism, 633,643 properties, 635,636 structures, 632 tubular, 638,639 types, 635, 636... 

Kureha Double-Screw Purifier [Fig. 16.16). This unit employs a double screw with intermeshing blades that express the liquid from the crystal mass as it is conveyed upward. The melt is formed at the top, washes the rising crystals countercurrently, and leaves as residue at the bottom. A commercial unit has an effective height of 2.6 m and a cross section of 0.31 m2. When recovering 99.97% p-dichlorbenzene from an 87% feed, the capacity is 7000 metric tons/yr. The feed stock comes from a tank crystallizer and filter. Data on other eutectic systems are shown, and also on separation of naphthalene and thiophene that form a solid solution a purity of 99.87% naphthalene is obtained in this equipment. 

A fourth process is the Brennan-Koppers crystal purifier (Brennan 1982). The apparatus has wall filters like the Phillips column and a melter at the top like the Kureha process. The crystals move up due to the movement of the liquid. The crystal bed is held compact with a rotating top plate, which is called a harvester. Some crystals at the top of the bed are collected (scraped off) and some openings thereafter permit these crystals to enter the melting zone at an adjustable rate. Some of the remolten liquid flows back through the harvester and washes the crystals in the bed. The residue leaves the apparatus by the filters. Details are given in the patent cited above. 

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