GB537828A - Improvements in or relating to method of and apparatus for heating and drying - Google Patents

Abstract

537,828. Drying boards; heating gases. CELOTEX CORPORATION. Jan. 3, 1940, No. 200. Convention date, Jan. 16, 2939. [Classes 34 (ii) and 64 (i)] Boards and the like, especially heat-insulating sheets made from a mixture of wood and bagasse fibres, are dried by air or superheated stream, e.g. at 700‹F., which is circulated through the drier and through an air heater 40 where it is heated from 350‹F. to 700‹F. by combustion products or hot gas which has been tampered, e.g. from 3300‹F. to 1200‹F. Flue gas for the air heater is tempered by waste gas from the heater, which may also be led through a duct 47 to a tubular economizer 17 of a steam plant 10, preferably, after use in tempering. The boards may be 150-250 feet long or shorter and move at about 3 m.p.h. on racks on conveyers 66 in tiers. Combustion products from a furnace 30 pass a thermo-statically controlled damper 35 to a mixing chamber 34 and are tempered by fresh air or by waste gases from the air heater admitted by a duct 39 and pass over the air or steam heater 40. This heated air or steam passes by a duct 53 to the end 54 of the drying chamber where the boards enter and is re-circulated from the other end through passages 57 at the sides of the drying chamber to the air heater by a fan 48 through ducts 62. 50. Baffles 63, 65 distribute drying gas or steam in the drying chamber, excess pressure being relieved by a vent 69.