ES362198A1 - Method and equipment for drying web material - Google Patents

Abstract

An apparatus for drying a web (e.g. paper) carried on a foraminous support comprises at least one drying unit comprising a pressure box adjacent one face of the web and having openings in a wall thereof for applying hot air jets in excess of 8000/min. to the web and a suction box adjacent the opposite face of the web for exhausting air forced through the web, the openings having a total cross-sectional area less than 10% of the area of the web portion being dried by the unit. The pressure box wall having the openings may be a reticulated member formed of sintered metal particles. In the drying unit of Fig. 1 the web 13 is supported on a perforated support and passed between a pressure box 11 which has elongated nozzle openings formed by spaced channel members 23 and which is connected to pump 27 and heater 28, and a vacuum box 12 connected to pump 31, the upper surface of the vacuum box being formed by spaced bars 17. In Fig. 4 a paper furnish is supplied by header 34 to Fourdrinier wire 33 and the formed web 13 is dried by suction devices 36, drying units 37, 38 and 48 which are similar to the unit of Fig. 1, and steam heated drying cylinder 49. In units 37 the web may be subjected to unheated or heated air jets. The heated exhaust air from unit 38 may be used in unit 37. In Fig. the drying unit comprises an air jet hood 69 surrounding a perforated drum 55, the inside portion of which between the baffles 67 is subjected to suction. In Fig. 7 a paper web is subjected to five drying units 83-87 similar to that in Fig. 5. Units 83, 87 also include separate high vacuum chambers 88. Unit 87 is provided with two drying air vacuum chambers 92, 93 and two pressure chambers 94, 95 in the hood.