Process of and apparatus for the continuous manufacture of cellulose or hemicellulose from cellulosic fibrous materials

Claim 1

IN A CONTINUOUS PROCESS OF CHEMICALLY DIGESTING FIBROUS CELLULOSIC MATERIAL TO YIELD CELLULOSE AND HEMICELLULOSE, SAID DIGESTION PROCESS BEING CARRIED OUT AT A TEMPERATURE EXCEEDING 100*C. AND UNDER PRESSURE IN A CLOSED VERTICAL CHAMBER WHEREIN DIGESTION AS WELL AS SUBSEQUENT WASHING OF THE DIGESTED CELLULOSIC MATERIAL ARE EFFECTED, THE STEPS WHICH COMPRISE REACTING AN INTIMATE MIXTURE OF FIBROUS CELLULOSIC MATERIAL CONCURRENTLY WITH THE DIGESTING LIQUID IN THE UPPER PART OF SAID CHAMBER, WASHING THE DIGESTED CELLULOSIC MATERIAL COUNTERCURRENTLY IN THE LOWER PART OF SAID CHAMBER, AND WITHDRAWING THE SPENT DIGESTING LIQUID OBTAINED IN THE UPPER PART OF THE CHAMBER FROM THE CONTINUOUSLY SUPPLIED DIGESTIN LIQUID, AND THE WASH WATER CONTINUOUSLY SUPPLIED TO THE LOWER PART OF SAID CHAMBER, IN ADJACENT ZONES IN A PORTION OF THE CHAMBER BETWEEN THE DIGESTING ZONE AND THE WASHING ZONE IN THE SAME RATIO IN WHICH THEY ARE SUPPLIED, THEREBY FORMING A SUBSTANTIALLY STAGNANT MIXTURE OF SPENT DIGESTING LIQUID AND USED WASH WATER IN THE INTERMEDIATE ZONE BETWEEN THE DISCHARGE OUTLETS OF SPENT DIGESTING LIQUID AND USED WASH WATER, SAID STAGNANT MIXTURE OF SPENT DIGESTING LIQUID AND USED WASH WATER FORMING A SEPARATING LAYER BETWEEN THE TEMPERATURE OF THE DIGESTION ZONE AND THE TEMPERATURE OF THE WASHING ZONE, THE DISGESTED CELLULOSIC MATERIAL TRAVELING THROUGH SAID INTERMEDIATE ZONE FROM THE DIGESTION ZONE TO THE WASHING ZONE.