Continuous freeze-drying apparatus

Claim 1

A DRIER COMPRISING, IN COMBINATION, A SHELL DEFINING A GAS-TIGHT ENCLOSURE, MEANS FOR EVACUATING THE INTERIOR OF THE SHELL TO MAINTAIN A VACUUM THEREIN, AN ELONGATED DRYING TUBE OF POLYGONAL CROSS-SECTION WITHIN SAID SHELL AND HAVING A FEED END AND A DISCHARGE END, THE SAID DRYING TUBE BEING MOUNTED AT A SLOPE FROM THE HORIZONTAL SO THAT THE DISCHARGE END IS LOWER THAN THE FEED END, SAID DRYING TUBE PROVIDING THE MEANS FOR CONVEYING MATERIAL THERETHROUGH WITH A TUMBLING ACTION WHILE EXPOSING IT TO HEAT AND VACUUM, MEANS FOR ROTATING THE DRYING TUBE, MEANS FOR HEATING THE DRYING TUBE, A FEED SCREW MOUNTED ADJACENT TO THE FEED END OF THE DRYING TUBE AND OPERATIVE BY THE ROTATION OF THE DRYING TUBE TO FEED MATERIAL THEREINTO AT A PREDETERMINED RATE, A PERFORATED TUBE CONNECTED COAXIALLY TO THE DISCHARGE END OF THE DRYING TUBE FOR RECEIVING MATERIAL DISCHARGED FROM THE DRYING TUBE AND FOR EXPOSING SAID MATERIAL TO VACUUM AND TO A LESSER DEGREE OF HEAT THAN IT WOULD BE IF RETAINED IN SAID DRYING TUBE, A DISCHARGE SCREW MOUNTED IN SAID PERFORATED TUBE AND HAVING A DIRECTION OF TWIST OPPOSITE TO THAT OF THE AFORESAID FEED SCREW, SAID DISCHARGE SCREW ACTING AS A WEIR TO RESTRICT DISCHARGE OF MATERIAL FROM SAID PERFORATED TUBE AND TO MAINTAIN A BED OF MATERIAL OF PREDETERMINED DEPTH THROUGHOUT THE LENGTH OF THE DRYING TUBE AND THE PERFORATED TUBE, AND MEANS FOR REMOVING PRODUCT DISCHARGED PAST SAID DISCHARGE SCREW.