What’s a Freeze Dryer/Lyophilizer

Freeze dryers consist of a few sub-systems: refrigeration system, vacuum system, control system, product chamber and condenser. The refrigeration system cools the condenser located in drying chamber. It also cools shelves in the product chamber to freeze the product. The vacuum system consists of one or several vacuum pumps which connected to an airtight condenser and attached product chamber. Control systems vary in complexity and typically include temperature and pressure sensing. Product chamber is typically a larger chamber with  shelves/trays on which the product is dried. The drying chamber is a horizontal cylindrical or rectangular pressure container, containing the condenser, which is installed close to the trays. The products are placed on the trays and heat is supplied through radiation or conduction. The condenser attracts the vapors being sublimed off the product and condenses them back into solid form (ice). The ice condenser can be located inside the drying chamber or in a separate chamber (external condenser) connected to the product chamber by a vapor port.

Batch freeze dryers are popular in market, with capacities ranging from 10 kg to 2000 kg per batch are common.

Drying Chamber

• Freeze drying chamber is the largest part of a freeze dryer. A Pressure Container that enable create vacuum environment.
• Typically, there are several plates installed in drying chamber, to allow products placing.

Ice Condenser

• Vapors that come out from products will flow to ice condenser.
• Inside of ice condenser, a group of coils are arranged and cooled by compressor system. When the vapors hit sub-cooled coils, they will be condensed on coils surface, as ice type.

Vacuum Pump

• Create and maitain drying chamber vacuum pressure, guarantee the sublimate continuously.

Compressors

• Refrigeration system offers cooling energy to ice condenser, for vapors condensing. As well, it cools shelves, for product pre-freezing.

Heating and Fluid Circulating

• Deliver cooling energy for raw product freezing, and later deliver heating energy for sublimation and drying.

Control System

• A modern freeze drying machine use PLC based controller box, couple with a touch screen or PC software, to control and monitor the freeze dry system.