Freeze drying system

Claim 1

A FREEZE DRYING SYSTEM COMPRISING A PLURALITY OF LOW PRESSURE DRYING CHAMBERS, HOLLOW COOLING ELEMENTS IN SAID CHAMBERS, SAID COOLING ELEMENTS HAVING REFRIGERATION INLETS AND OUTLETS, A REFRIGERATION UNIT COMPRISING A COMPRESSOR AND A CONDENSER, A SET OF NORMAL REFRIGERATION LINES FOR CONNECTING THE REFRIGERATION INLETS OF SAID COOLING ELEMENTS FOR RECEIVING REFRIGERANT FROM SAID CONDENSER, AND FOR CONNECTING THE REFRIGERATION OUTLETS OF SAID COOLING ELEMENTS TO THE INLET OF SAID COMPRESSOR; A SET OF DEFROST LINES FOR CONNECTING THE REFRIGERATION INLETS AND OUTLETS OF SAID HOLLOW COOLING ELEMENTS BETWEEN THE OUTLET OF SAID COMPRESSOR AND THE INLET OF SAID CONDENSER; VALVE MEANS IN SAID SETS OF LNORMAL REFRIGERATION LINES AND IN SAID DEFROST LINES, SAID VALVE MEANS BEING SET FOR CONNECTING THE HOLLOW COOLING ELEMENTS OF CERTIN OF SAID DRYING CHAMBERS INTO SAID REFRIGERATION LINES BETWEENS THE CONDENSER OUTLET AND THE COMPRESSOR INLET FOR DRYING; SAID VALVE MEANS ALSO BEING SET FOR CONNECTING THE HOLLOW COOLING ELEMENTS OF ONE OF SAID DRYING CHAMBERS INTO SAID DEFROST LINES AND BETWEEN THE OUTLET OF SAID COMPRESSOR AND THE INLET OF SAID CONDENSER FOR DEFROSTING; THE RESULTING CIRCUIT BEING SUCH THAT THE OUTLET OF SAID COMPRESSOR, THE DRYING CHAMBER BEING DEFROSTED, THE CONDENSER, THE DRYING CHAMBERS BEING REFRIGERATED, AND THE INLET OF SAID COMPRESSOR ARE ALL CONNECTED IN SERIES, AND IN THE SEQUENCE NAMED, THE COOLING ELEMENTS OF THE DRYING CHAMBER BEING DEFROSTED PROVIDING THE SOLE PASSAGEWAY FRO REFRIGERANT THAT PASSES THROUGH THE CONDENSER AND FOR REFRIGERANT THAT PASSES THROUGH SAID CERTIAN DRYING CHAMBERS FRO DRYING; MEANS FOR MAINTAINING SAID CERTAIN DRYING CHAMBERS AT SUBATMOSPHERIC KPRESSURE, MEANS FOR LOADING THE FROZEN PRODUCT INTO SAID CERTAIN DRYING CHAMBER, AND MEANS FOR HEATING THE FROZEN PRODUCT IN THE LATTER DRYING CHAMBERS.