METHOD FOR CONTINUOUS DIGESTION OF FIBROUS MATERIAL Russian patent published in 1999 - IPC

FIELD: cellulose production technology. SUBSTANCE: this relates to continuous isothermic digestion of cellulose under higher pressure and increased temperature of fibrous material in vertical digesting kettle. According to method, delivery of fibrous material and digestion liquor is effected into upper part of digesting kettle 1. Used liquor is branched out from at least one annular sorter 1D of digesting kettle. This sorter is positioned between top and bottom of digesting kettle. Fibrous material is branched out from lower part 1C of digesting kettle. Installed in digesting kettle 1 is additional annular sorter 2. Lower part of this additional sorter is located at less than 5 m distance from upper part of lowest annular sorter 1B of digesting kettle. In result, temperature in all operating digesting zones of kettle can be actually maintained at same level. Application of aforesaid method allows for improving quality of cellulose including its whiteness without resorting to bleaching by means of chlorine-bearing bleaching agents. EFFECT: higher efficiency. 6 cl, 3 dwg