PAPER PLANT - METHOD AND APPARATUS FOR PRODUCING PULP FROM CELLULOSIC FIBROUS RAW MATERIALS AND RECOVERING CHEMICALS AND ENERGY FROM PULP LIQUORS

摘要

The invention includes a treatment apparatus (10) for treating fibrouscellulosic raw material suitable for use in a paper making plant comprisingextracting means for extracting contrary material from the raw material,crushing means for crushing the raw material to remove nodes therefrom andsplitting means for splitting the crushed raw material lengthways. A co-rotating twin screw conveyor (12) is used to pulp the crushed material, theconveyor being divided up into a plurality of zones, means for insertingtreatment materials into at least one zone and means for controlling thetemperature and/or pressure of all of the zones. The black liquor effluentproduced in the pulping process is treated in an apparatus (14) comprising anevaporator for concentrating the liquor to 30-70 % solids, a processing vesselfor treating the concentrated liquor at a temperature of between 300-650 ~C,and a closed conveyor for transporting the concentrated liquor from theevaporator to the processing vessel in excess of 90 ~C. The invention alsoincludes the method involved in using the above apparatus.