GB806554A - Improvements in the treatment of fibrous materials in the production of cellulose or semi-cellulose - Google Patents

Abstract

<PICT:0806554/IV (a)/1> <PICT:0806554/IV (a)/2> <PICT:0806554/IV (a)/3> In the production of cellulose or hemicellulose, fibrous materials are impregnated with a digesting liquor in vacuo and, after being freed from excess liquor, are heated and digested in an atmosphere of steam. As shown in Fig. 1, a chamber 1 connected to vacuum pump 6 has two downwardly-extending pipes 2, 3 dipping into containers 4, 5 respectively, for the digesting liquor. Fibrous material fed to the apparatus through funnel 8, pipe 7, and chamber 9 rises up the liquid column 17 and falls to the top of liquid column 18, whence it is transferred by screw conveyer 10 to container 5, to be subsequently removed by conveyer belt 25, on which the excess liquor drains away. Addition of fresh liquor to column 17 assists the elevation of fibrous material, and conveyers may be provided in pipes 2 and 7, for the same purpose. In Fig. 2 a conveyer with rotating stirrers 29 moves material discharged from pipe 3 to conveyers 26, 27 positioned to deal with floating and sinking material. Strainer 30 prevents floating material from surfacing. Fig. 3 shows a suitable digester, wherein fibrous material is conveyed to the top of pressure chamber 31 and introduced from funnel 33 by rotary feeder 32 driven by motor 34. Steam under pressure is injected through conduit 35, and worm 37 driven by motor 38, and stirrer 40 driven by motor 41, discharge the cooked product through opening 39.