RAY™ batch freeze dryer
RAY™ batch freeze dryer

The RAY™ batch freeze drying plant is designed for production in small-medium volumes of products like coffee/tea, fruit/berries/vegetables, meat/seafood, soup blocks, rice dishes, etc.

Freeze drying is the drying of an already frozen product in a vacuum below the triple point. The vacuum allows the ice to turn directly into vapour without first passing through the water stage, in a sublimation process, and this preserves the product's original shape, colour, taste, and nutrients.

The RAY™ freeze drying plant:

The RAY™ batch freeze drying plant is a cabinet - usually made of stainless steel - with a door for loading and unloading of the product to be freeze dried.

Inside the cabinet are a number of heating plates made of anodized aluminum. Hot water is circulated through the system to ensure efficient heat transfer by radiation to the product that is to be freeze dried. The water temperature can be regulated during the freeze drying process in order to achieve optimal evaporation laps and avoid overheating of the products.


The product is placed onto a wagon hanging on trolleys in a pre-weighed amount or by volume in frozen form. By correctly loading the cabinet, the product trays are placed between the heating plates for optimal heat transfer by radiation. Direct contact between the product trap and the heat plates must be avoided as heat can damage the product. The vapor condenser module made of stainless steel is build into the cabinet. Liquid NH3 is circulated in a pipe on which the sublimated water vapor will condense.

For the smaller RAY™ (2, 45, and 50) cabinets the condenser is flushed with warm water at the end of each freeze drying circle. The ice will melt within 10 minutes.

The larger RAY™ (75, 100, and 125) cabinets are equipped with a duplex vapor condenser for Continuous De-Icing (CDI). When one of the vapor condensers has to be de-iced (typically after one hour operations), the section is sealed off while the other takes over the condensation function.

To melt the accumulated ice, water vapor (vacuum steam) at 25 degrees C is led into the room. The water vapor will now condense on the cold icy surface of the condenser and thus melt the ice. In order to restore the de-iced condenser to operating conditions, any remaining vapor in the condenser chamber must be condensed by cooling it down until operating temperature and vacuum is reached. A direct switch-over when the next de-icing cycle is needed can now be done without loss of operating vacuum.

The CDI system is fully automatic. It ensures:

  • A maximum ice build up to 5 millimeter resulting in a negligible temperature drop over the ice and a low energy consumption
  • Constant condenser temperature
  • High freeze drying capacity/m2 of tray surface
  • Short time from one change to another
  • Continuous de-icing

Freeze drying of bacteria, enzymes and other sensitive products  
The RAY™ freeze drying plant is also available in a fully sanitary design: the Ray™-S for freeze drying of bacteria, enzymes, and similar sensitive products.

Pilot freeze drying plants
The RAY™ is also available in a pilot plant size RAY™-1 for product development.

Complete instant coffee process line with a RAY™ batch freeze dryer.
Complete instant coffee process line with a RAY™ batch freeze dryer.

To view the details, download the flowsheet drawing as a PDF below.