Continuous upflow digester

Claim 1

IN CONTINUOUS PULPING APPARATUS COMPRISING A GENERALLY UPRIGHT PRESSURIZED ELONGATED REACTION VESSEL OF GENERALLY UNIFORM CIRCULAR CROSS-SECTIONAL AREA FOR DIGESTING WOOD CHIPS, AND MEANS FOR FEEDING SUBSTANTIALLY CONTINUOUSLY A WOOD CHIP-LIQUID MIXTURE INTO THE LOWER END OF SAID REACTION VESSEL TO MAINTAIN A COMPACTED MASS OF WOOD CHIPS WITHIN AN ELONGATED ZONE IN THE CENTRAL AND OPPOSITE UPPER END PORTIONS THEREOF AND ADVANCING THE WOOD CHIPS UPWARDLY THROUGH SAID ZONE AT A RATE SUBSTANTIALLY INDEPENDENT OF THE MOVEMENT OF LIQUID IN SAID VESSEL TO TREAT SAID WOOD CHIPS, THAT IMPROVEMENT CONSISTING OF DISCHARGING MEANS FOR DISCHARGING TREATED WOOD CHIPS FROM SAID PRESSURIZED REACTION VESSEL, SAID DISCHARGING MEANS INCLUDING AN UPRIGHT PRESSURIZED PULP RECEIVER VESSEL HAVING A CROSS-SECTIONAL AREA LESS THAN THAT OF SAID REACTION VESSEL IN A RATIO OF 10-50 TO 1, AND IN FREE PRESSURE COMMUNICATION WITH SAID REACTION VESSEL, SAID PULP RECEIVER VESSEL HAVING A BOTTOM SURFACE WITH A BLADED AGITATOR ROTATABLY MOUNTED CLOSELY ADJACENT TO SAID SURFACE AND GENERALLY CENTRALLY THEREOF ON A CENTRAL SHAFT TO WIPE SAID SURFACE, SAID BOTTOM HAVING A DISCHARGE ORIFICE THROUGH SAID SURFACE AND A FLUID INLET THROUGH SAID BOTTOM ADJACENT TO SAID DISCHARGE ORIFICE AT A POSITION SPACED THEREFROM, MEANS FOR ROTATING SAID AGITATOR TO WIPE SAID SURFACE ACROSS ITS AREA, VALVE MEANS FOR CONTROLLING THE OPENING OF SAID ORIFICE, VALVE MEANS FOR CONTROLLING THE OPENING OF SAID ORIFICE, VALVE MEANS CONTROLLING THE FLOW OF SAID PRESSURIZED FLUID THROUGH SAID INLET, MEANS SENSING THE UPPER LEVEL OF WOOD CHIPS IN SAID RECEIVER VESSEL, CONVEYANCE MEANS LOCATED ABOVE SAID UPPER LEVEL OF WOOD CHIPS FOR MOVING DRAINED WOOD CHIPS FROM SAID REACTION VESSEL TO SAID PULP RECEIVER VESSEL FOR COLLECTION THEREIN OF SUBTANTIALLY DRAINED, TREATED WOOD CHIPS, AND MEANS RESPONSIVE TO SAID LEVEL SENSING MEANS CONTROLLING SAID VALVE MEANS FOR CONTROLLING THE OPENING OF SAID DISCHARGE TO CONTROL SAID UPPER LEVEL OF ORIFICE WOOD CHIPS FOR CONTINUOUS DISCHARGE OF SAID CHIPS THROUGH SAID ORIFICE WHILE PROVIDING A FLOW OF PRESSUIRIZED FLUID TO AID SAID DISCHARGE.