GB994951A - Process and apparatus for continuous drying of continuous web materials - Google Patents

Abstract

994,951. Drying webs; heating web material. PULP AND PAPER RESEARCH INSTITUTE OF CANADA. July 15, 1963 [Aug. 3, 1962], No. 27901/63. Headings F4G and F4U. In a continuous process for drying web material, e.g. paper, the web is submerged in and supported for passage through a fluidized bed and simultaneously has one side subjected to sub-atmospheric pressure. A web 46, Fig. 1, is dried in a fluidized bed in a chamber 12 by passage about a primary guide roller 35 and then a rotary foraminous roll 28 connected to a vacuum source through a shaft 30 for the removal of vapour from the web, which finally passes around a secondary guide roller 37, a third guide roller 39 mounted between the rollers 35, 37 to provide a nip. The particles of the fluidized bed are heated by heat exchanger tubes 16, 17 and fluidized by gas from a lower plenum chamber 13 which is recirculated through lines 19 having heat exchangers 20. A segment 32 of the interior of the roller 28 is maintained at atmospheric pressure by separation from the remainder of the interior by a fork 33 and seals 34a, 34b. A doctor blade 43 is mounted on roller 39, and combined sealing strips and doctor blades 41, 42 are associated with rollers 35, 28 respectively. In a modification, the fluidized particles are magnetic and a magnetic roller is mounted adjacent a non-magnetic doctor and the roller 28 to remove particles adhering to the web. In another embodiment the roller 28 is replaced by upper and lower solid rollers 50, 51, Fig. 3, and a box 52 therebetween which is divided into two vertical boxes 52a, 52b having perforations 56 which are connectible to the same or dissimilar vacuum sources. A perforated belt 61 passes about the rollers 50, 51 to convey the web through the fluidized bed. In a further embodiment, Figs. 4 to 6 (not shown), a perforated belt is interposed between a portion of a stationary source of sub-atmospheric pressure and the web, which source comprises a box housing belt-supporting rollers. In a final embodiment, Fig. 7 (not shown), the stationary source of sub-atmospheric pressure comprises a chamber having perforated semi-cylindrical base about which the web passes in sliding and supported contact.