| 摘要 |
The invention relates to a process for producing pulp, from raw lignocellulosic material based on annual or perennial plants, or residues of such plants. The process comprises impregnating said raw material with an aqueous soda solution such that the weight proportion of soda is substantially comprises between 3.5 % and 10 % based on the dry material and that the weight ratio of hydration of the cellulosic material after impregnation is at least equal to 40 %, and subjecting the lignocellulosic material thus impregnated to vapocracking which consists in pressurising said material under saturated vapour conditions and producing a sudden expansion through a direct passage valve. The solid fraction which forms the pulp is then separated from the aqueous phase and the hydrosoluble products. The process yields good quality pulps characterized particularly by a braking length higher than 5500 meters, and having a high lignine ratio (KAPPA index comprises between 60 and 65).
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