| US 7,540,884 B2 | ||
| Method for performing the purifying separation of crystals out their suspension in a mother liquor | ||
| Ulrich Hammon, Mannheim (Germany); Dieter Baumann, Frankenthal (Germany); Joerg Heilek, Bammental (Germany); Klaus Joachim Mueller-Engel, Stutensee (Germany); and Bernd Eck, Viernheim (Germany) | ||
| Assigned to BASF Aktiengesellschaft, Ludwigshafen (Germany) | ||
| Appl. No. 10/494,721 PCT Filed Nov. 08, 2002, PCT No. PCT/EP02/12497 § 371(c)(1), (2), (4) Date May 06, 2004, PCT Pub. No. WO03/041832, PCT Pub. Date May 22, 2003. |
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| Claims priority of application No. 101 56 016 (DE), filed on Nov. 15, 2001; and application No. 102 23 058 (DE), filed on May 24, 2002. | ||
| Prior Publication US 2004/0256319 A1, Dec. 23, 2004 | ||
| Int. Cl. B01D 9/00 (2006.01) | ||
| U.S. Cl. 23—295R [23/296; 62/532; 62/540; 62/542; 62/544; 210/774; 422/245.1; 422/252; 562/598; 562/600; 585/812] | 6 Claims |
| 1. A process for purifying removal of crystals from their suspension in mother liquor, in which
the suspension is fed to a washing column which has a wall which encloses a process chamber, and which wall on its side facing
away from the process chamber contacts a first contact area and on its side facing towards the process chamber contacts a
second contact area,
mother liquor from the suspension fed into the process chamber is passed out of the process chamber while holding back the
crystals and forming a crystal bed in the process chamber,
the crystal bed is conveyed within the process chamber, at least one force other than gravity acts in the process chamber
in the conveying direction of the crystal bed and conveys the crystal bed within the process chamber,
pure melt comprising molten crystals which have been purifyingly removed by the process claimed is conducted in the process
chamber in countercurrent to the crystal bed in such a manner that a washing front forms in the crystal bed which divides
the crystal bed into a mother liquor zone and a pure melt zone,
wherein
the wall is a metal wall which, on its side facing away from the process chamber, is heated at least along the length of the
pure melt zone, such that the temperature of the first contact area of said length of the metal wall on its side facing away
from the process chamber is higher than the temperature of the second contact area of said length of the metal wall on its
side facing toward the process chamber, so that a heat flux flows from the outside of the process chamber through the wall
to the inside of the process chamber, and wherein realization of heating comprises encasing the washing column and maintaining
a gas in the casing at a temperature above the pure melt temperature.
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