Chemical feeder for black liquor recovery systems

Claim 1

IN A SYSTEM FOR RECOVERYING CHEMICAL FROM THE BLACK LIQUOR OF WOOD PULP MILLS,THE COMBINATION OF A BOILER HEATED BY COMBUSTION GASES PRODUCED BY A BURNING OF SAID LIQUOR AND INCLUDING A PASS WHEREIN PRESSURE IS BELOW ATMOSPHERIC VALUE, AN EVAPORATOR FOR CONCENTRATING THE BLACK LIQUOR COMING INTO THE SYSTEM, A SALT CAKE MIXING TANK RECEIVING SAID CONCENTRATED LIQUOR FROM THE EVAPORATOR, A SCREEN POSITIONED IN THE UPPER PORTION OF SAID TANK, FEEDER MEANS FOR DELIVERING INCOMING SALT CAKE UPON THE SCREEN WHEREBY FINE PARTICLES THEREOF WILL PASS THROUGH THE SCREEN WHICH OVERSIZE SAIT LUMPS WILL BE REJECTED BY THE SCREEN, A TROUGH LEADING FROM THE SCREEN TO THE TANK EXTERIOR AND THE ATMOSPHERE AND SERVING TO CARRY SAID REJECTED SALT LUMPS OUT OF THE TANK, TERIOR INTO TWO COMPARTMENTS THE FIRST OF WHICH TERIOR INTO TWO COMPARTMENTS THE FIRST OF WHICH INCLUDES SAID TROUGH PLUS COMMUNICATING SPACE EMBRACING THE FEED SIDE OF THE SCREEN AND THE SECOND OF WHICH INCLUDES ANOTHER PORTION OF THE AFORESAID UPPER TANK INTERIOR THAT IS IN COMMUNICATION WITH THE DISCHARGE SIDE OF SAID SCREEN, AN EXHAUSTER CONDUIT OPENING INTO SAID SCOND COMPARTMENT, AND MEANS CONNECTING SAID CONDUIT WITH SAID BOILER PASS WHEREBY THE AFORESAID SUB-ATMOSPHERIC PRESSURE INTHAT PASS CREATES IN THE CONDUIT AND SECOND COMPARTMENT A SUCTION WHICH DRAWS THROUGH SAID SCREEN FROM THE FEED TO THE DISCHARGE SIDE THEREOF AIR THAT CARRIES AWAY FROM THE SCREEN LIQUOR VAPORS AND SALT DUST WHICH OTHERWISE WOULD CAUSE CLOGGING OF THE SCREEN OPENINGS.