GB597653A - Improvements relating to the drying of continuous webs, and particularly of paper inpaper-making machines - Google Patents

Abstract

597,653. Drying materials in long lengths. CELLULOSE DU PIN. April 27, 1945, No. 10628. Convention date, June 16, 1944. [Class 34 (i)] In drying a continuous web of material, e.g., paper from a paper making machine, the paper is traversed around a cylinder 1 enclosed partly by an air-tight hood 2 into which air at a temperature of about 125'C, from a heater 3 is blown and vapour-saturated air at 80‹C. is withdrawn, through an orifice 4, by a fan 6, this withdrawn air being recirculated through the heater 3 and hood 2 after passage through two heat-exchangers 5a, 5b. In the latter supplied water is converted into steam at temperatures of 60‹C. and 40‹C. respectively, the temperature of the circulating air falling to 60‹C, and this steam is compressed to 90'C. by thermo-compressors 7a, 7b and then injected into other, e.g., pre-drying, cylinders 8 which operate under a light vacuum through a condensate extraction pump 9. Preferably the water supplied to the heat exchangers is the condensate from the drying air. In a modification a number of such cylinders 1 are totally enclosed by a hood having a plurality of hot-air inlet and vapour-saturated air outlet orifices, with the air being exhausted, as before, through heat-exchangers for generating a steam supply to pre-drying cylinders. In addition final drying cylinders are provided, these latter being located in the open and the hot air rising therefrom being collected within an upper open hood and directed to below the pre-drying cylinders.