GB898671A - Improvements in or relating to the heat treatment of filaments, fibres, threads, films and sheet material - Google Patents

Abstract

898,671. Fluidized beds for heating sheet or filamentary materials. BRITISH RAYON RESEARCH ASSOCIATION. April 30, 1959 [May 6, 1958], No. 14426/58. Class 64(2) Filamentary or sheet material 22 is passed vertically by rollers 29 down from a bed of ballotini (100-1000 microns) fluidized in a container 12 by air passed up through a succession of throats 17, 20 and heated by tubes, Figs. 3, 4 (not shown), in the container 12 and containing steam or electric heaters. To impede the horizontal movement of the ballotini, there are horizontal baffles arranged louvre-fashion as in Specification 848,676 adjacent the material 22 in the bed. If sheet material or a row of filaments is to be heated, the throats and the chambers 14 between them are in the form of slots but if a single filament is heated they are of circular section. The throats 17 get successively narrower in the downward direction except for the lowest throat 20 which is at least as wide as the top throat 17. The lowest of the throats 17 is adjustable, one side of the chambers 14 on either side of the throat being formed by a damper 26 with flexible extensions 27. This throat is closed when the container 12 is being filled with ballotini and is opened when the fluidizing air is turned on. It closes automatically when the air is turned off. Air for fluidizing is introduced to each of two headers 23 through a pipe 24 and as in Specification 848,677 is passed to the throat 20 up through each of two slits 25 flanking an outlet 21 for the material 22. Instead of there being slits 25, formed as in Specification 848,677, extra fluidizing gas may be introduced into the chambers 14. An air box A is formed below the headers 23 by the two halves of the airfeed and roller assembly and is sealed by the rollers 29 and seals S. The material may be passed upwardly through one part of a fluidized bed and downwardly through another part of similarly through two beds, Fig. 4 (not' shown), or a succession of beds. The Provisional Specification describes also apparatus in which one of the upper throats is closable and in which gas diverted through or past the material outlet as in Specification 848,677 need not be the fluidizing gas. Specifications 773,598, 800,091, 814,526 and 838,784 also are referred to.