Method and arrangement for washing and cooling at the outlet end of a continuous cellulose digester

Claim 2

IN A METHOD OF LIBERATING CELLULOSIC FIBROUS MATERIAL BY DIGESTION THEREOF WITH A DIGESTING LIQUOR AT A HIGH PRESSURE AND A HIGH TEMPERATUE IN A CONTINUOUS DIGESTER HAVING A FIBROUS MATERIAL OUTLET, THE IMPROVEMENT OF WASHING THE FIBROUS MATERIAL COUNTER-CURRENT TO THE FLOW THEREOF AND IMMEDIATELY BEFORE THE SAME IS DISCHARGED THROUGH THE DIGESTER OUTLET, COMPRISING SUPPLYING COOLING LIQUID TO THE DIGESTER CLOSE TO THE DIGESTER OUTLET, SCREENING OFF THE LIQUID IN THE FIBROUS MATERIAL AND COOLING LIQUID, HEATING SAID SCREENED OFF LIQUIDS EXTERIORLY OF THE DIGESTER, RETURNING THE HEATED LIQUID AS A WASHING LIQUID TO THE DIGESTER AT A GREATER DISTANCE FROM THE DIGESTER OUTLET THAN THE COOLING LIQUID IS SUPPLIED AND HEATING SAID WASHING LIQUID BY EXCHANGING HEAT WITH DIGESTING LIQUID THAT IS DISCHARGED FROM THE DIGESTER PRIOR TO INTRODUCING THE WASHING LIQUID.

Claim 3

IN AN APPARATUS FOR LIBERATING CELLULOSIC FIBROUS MATERIAL BY DIGESTION THEREOF IN A LONGITUDINAL CELLULOSE DIGESTER WITH A DIGESTING LIQUOR AT A HIGH TEMPERATURE AND A HIGH PRESSURE AND ADAPTED SUCH THAT THE FIBROUS MATERIAL WILL BE CONTINUOUSLY FED IN THE LONGITUDINAL DIRECTION OF THE DIGESTER, SAID APPARATUS HAVING A FIBROUS MATERIAL INLET, A DIGESTING LIQUOR INLET AND AN OUTLET FOR DIGESTED FIBROUS MATERIAL, AND SAID APPARATUS INCLUDING MEANS FOR HEATING SAID DIGESTING LIQUOR, THE IMPROVEMENT WHICH COMPRISES PROVIDIDNG SAID APPARATUS WITH A COOLING LIQUID INLET POSITIONED CLOSE TO SAID OUTLET, A SIEVE GIRDLE IN SAID DIGESTER FOR SCREENING OFF SPENT DIGESTING LIQUOR FROM THE FIBROUS MATERIAL, A SIEVE GIRDLE BETWEEN SAID COOLING LIQUID INLET AND SAID SPENT DIGESTING LIQUOR SIEVE GIRDLE FOR SCREENING OFF SAID COOLING LIQUID, A SECOND HEATING DEVICE EXTERIOR OF THE DIGESTER, A CONDUIT CONNECTED TO SAID COOLING LIQUID SIEVE GIRDLE, SAID CONDUIT PASSING THROUGH SAID SECOND HEATING DEVICE AND RETURNING TO THE DIGESTER, AN ORIFICE IN SAID CONDUIT WITHIN SAID DIGESTER BETWEEN SAID COOLING LIQUID INLET AND SAID SPENT DIGESTING LIQUOR SIEVE GIRDLE, SAID APPARATUS BEING ADAPTED SUCH THAT COOLING LIQUID SUPPLIED THROUGH SAID COOLING LIQUID INLET FIRST COOLS THE FIBROUS MATERIAL AND THEN WASHES IT AT A RAISED TEMPERATURE.

Claim 4

IN AN APPARATUS FOR LIBERATING CELLULOSIC FIBROUS MATERIAL BY DIGESTION THEREOF IN A LONGITUDINAL CELLULOSE DIGESTER WITH A DIGESTING LIQUOR AT A HIGH TEMPERATURE AND A HIGH PRESSURE AND ADAPTED SUCH THAT THE FIBROUS MATERIAL WILL BE CONTINUOUSLY FED IN THE LONGITUDINAL DIRECTION OF THE DIGESTER, SAID APPARATUS HAVING A FIBROUS MATERIAL INLET, A DIGESTING LIQUOR INLET AND AN OUTLET FOR DIGESTED FIBROUS MATERIAL, AND SAID APPARATUS INCLUDING MEANS FOR HEATING SAID DIGESTING LIQUOR, THE IMPROVEMENT WHICH COMPRISES PROVIDIDNG SAID APPARATUS WITH A COOLING LIQUID INLET POSITIONED CLOSE TO SAID OUTLET, A SIEVE GIRDLE IN SAID DIGESTER FOR SCREENING OFF SPENT DIGESTING LIQUOR FROM THE FIBROUS MATERIAL, A SIEVE GIRDLE BETWEEN SAID COOLING LIQUID INLET AND SAID SPENT DIGESTING LIQUOR SIEVE GIRDLE FOR SCREENING OFF SAID COOLING LIQUID, A SECOND HEATING DEVICE EXTERIOR OF THE DIGESTER, A CONDUIT CONNECTED TO SAID COOLING LIQUID SIEVE GIRDLE, SAID CONDUIT PASSING THROUGH SAID SECOND HEATING DEVICE AND RETURNING TO THE DIGESTER, AN ORIFICE IN SAID CONDUIT WITHIN SAID DIGESTER BETWEEN SAID COOLING LIQUID INLET AND SAID SPENT DIGESTING LIQUOR SIEVE GIRDLE, SAID APPARATUS BEING ADAPTED SUCH THAT COOLING LIQUID SUPPLIED THROUGH SAID COOLING LIQUID INLET FIRST COOLS THE FIBROUS MATERIAL AND THEN WASHES IT AT A RAISED TEMPERATURE.