PRODUCTION FREEZE-DRYING OF LOW UNITARY FILL VOLUME: OPTIMIZATION OF CYCLES AND OPERATING COSTS.

IN INDUSTRIAL FREEZE-DRYING OF LOW-VOLUME PRODUCTS IN FLASKS, THE FREEZE-DRYING TIME LARGELY DEPENDS ON THE PHYSICAL STRUCTURE OF THE APPARATUS. FOR CONVENTIONAL APPARATUS, THE CYCLE TIME IS LONGER THAN IT WOULD BE IF ONLY FREEZING AND SUBLIMATION WERE CONCERNED ; THE DIFFERENCE IS DUE TO THE COOLING AND HEATING TIMES OF THE SHELVES. A DEVICE WITH < INTERNAL TRANSFER > WAS DEVELOPED TO OPTIMIZE THE CYCLE TIME. IT HAS 2 SETS OF SHELVES IN THE SAME VAT, MAINTAINED AT LOW (FREEZING) TEMPERATURE AND HIGH (SUBLIMATION) TEMPERATURE FOR SEVERAL DAYS. VARIOUS PRODUCTION CYCLES CAN BE REPEATED WITHOUT LOSS OF TIME: AFTER FREEZING THE PRODUCT IS LOADED ON SHELVES AT LOW TEMPERATURE THEN IT IS AUTOMATICALLY TRANSFERRED TO HIGH TEMPERATURE SHELVES,AND FINALLY UNLOADED.