Freeze Drying Equipment

Figure 11 shows a freeze-drying plant, designed for maximum current demands. The condenser is cooled by liquid nitrogen controllable between — 70°C and — 100°C (Tco); the brine for the shelves is temperature-controlled (Tsh) between + 60°C and — 80°C (cooling by liquid nitrogen); the four-stage pump set can reach about 5 x 10~5 mbar (pe); the vials can be closed shelf by shelf by a hydraulically operated

Figure 11 Freeze-drying plant condenser and shelves cooled with liquid nitrogen. Clean In Place system in chamber and condenser. 1, liquid nitogen inlet to condenser and heat exchanger; 2 nitrogen outlet from the condenser and heat exchanger; 3, heat exchanger for the brine in the shelves; 4, brine to and from the shelves; 5, pressure plate for closing vials; 6, piston rod with bellows; 7, hydraulic piston for 5 and 6; 8, hydraulically operated valve; 9, hydraulic system; 10 and 13, water and steam inlets; 11, pumping system; 12, water outlet. (Courtesy of Steris GmbH, Hurth, Germany.)

Figure 11 Freeze-drying plant condenser and shelves cooled with liquid nitrogen. Clean In Place system in chamber and condenser. 1, liquid nitogen inlet to condenser and heat exchanger; 2 nitrogen outlet from the condenser and heat exchanger; 3, heat exchanger for the brine in the shelves; 4, brine to and from the shelves; 5, pressure plate for closing vials; 6, piston rod with bellows; 7, hydraulic piston for 5 and 6; 8, hydraulically operated valve; 9, hydraulic system; 10 and 13, water and steam inlets; 11, pumping system; 12, water outlet. (Courtesy of Steris GmbH, Hurth, Germany.)

pressure plate; the connection between chamber and condenser is as short as technically possible; the valve between chamber and condenser is operated by a fast hydraulic piston; chamber and condenser can be cleaned by a pressure spray and cleaning system (clean-in-place); chamber, condenser and all components within them can be sterilized by the pressureless Vaporized Hydrogen Peroxide (VHP)® process; loading and unloading of the plant is fully automatic; the documentation and control of the total process from loading to freezing, to drying, to closing of the valves, to venting and unloading can be automatic with no thermocouples in the product; this includes the change from MD to SD, the calculation of the moisture content during SD and the termination of the secondary drying at a specified moisture content.

If no extreme temperatures are required, refrigerant compressors can be used for the condenser down to Tco + — 80°C and for the brine down to Tsh + — 60°C, and a three-stage pump set is sufficient. If steam sterilization is mandatory, the equipment has to be built for pressures up to 2.5 bar and temperatures up to 125°C.

At the other end of the line of freeze-drying equipment laboratory installations are found, of which a typical example is shown in Figure 12. Usually the product is frozen in vials or trays in a separate freezer or in the condenser of the plant and the shelves are only heated. The chamber is often a bell jar, Tco + —45°C, pe + 0.05 mbar. It is not advisable to use this type of plant as a pilot plant for process development, because the product temperature is not sufficiently uniform and cannot be controlled accurately, especially in the low temperature area.

Solar Panel Basics

Solar Panel Basics

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