Drying and heating of polyamide granules

US5052123A · kind A · utility

Assignee

• BASF SE

Inventors

• Klaus J. Tischendorf · Bad Dürkheim, DE
• Manfred Liebscher · Worms, DE
• Farid Rizk · Schifferstadt, DE
• Franz Zahradnik · Ludwigshafen, DE

Key dates

• Filing date: Jul 3, 1990
• Grant date: Oct 1, 1991
• Expiry date: Jul 3, 2010

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B29B9/16
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

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 favora…