The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 01, 1991
Filed:
Jul. 03, 1990
Klaus J Tischendorf, Weisenheim, DE;
Manfred Liebscher, Worms, DE;
Farid Rizk, Neuhofen, DE;
Franz Zahradnik, Ludwigshafen, DE;
BASF Aktiengesellschaft, Ludwigshafen, DE;
Abstract
Polyamide granules are dried and heated by feeding a suspension of granules in water into a sieve (1), where the bulk of the water is removed, and then into a tower dryer (10), where they are deposited in bed form and then freed of the remaining water while moving in plug flow under the force of gravity with a counter-current inert gas stream at from 70.degree. to 200.degree. C. The tower dryer possesses an inlet at the top (11) and outlet at the bottom (34) for the granules and also feed lines (20, 22, 31) for the inert gas. To achieve a uniform degree of drying of the granules, the inert gas is divided on entry into the tower dryer at a point between the drying zone and the heating zone into a stream which flows radially inward into the bed of granules on the one hand and a stream which flows radially inward and outward on the other. In this way the inert gas is distributed particularly uniformly and the granules are dryable in a very short drying zone down to a water content of 0.0001 kg of water/kg of polymer. The lower, conically tapered area of the tower dryer--bin 30--ensures a uniform rate of descent of the granules and hence a uniform solid-phase condensation with a favorable molecular weight distribution. The tower dryer (10) is followed by a fluidized bed cooler (41) in which the granules are cooled with air to <50.degree. C.