Difference between revisions of "Freeze Dryers"

Until  now most of  the freeze dryers are of the Tray Dryer  type. Despite the  optimal  structure of the individual product particles the  product  layer on the  plates will usually form one piece of hard baked material.  Often the  product has to be crushed after freeze drying, which may  lead to damage  of the product structure. Another disadvantage is the  relatively low  heat  transfer rate due to the dead state of the  material on the plates.  Also the  handling of the product is quite  labor intensive because the  trays have to be  filled and discharged  manually. In this context active freezing came into existent. For this  active freezing process a special kind of dryers were emerged named  Freeze Dryers.

* Freeze Dryer enables to produce at low temperature and low pressure a lump-free, free-flowing, freeze dried product.

* The Freeze Dryer also has a better heat transfer rate due to the continuous mixing of the product, resulting in shortening the drying process.

* The freezing dryer follows such a freezing step that  is simplified because it can be done in  the same vessel  instead of  having a separate freezing unit, which results in  easy  handling of the  product compared to it's predecessor tray dryer equipment.

* The Freeze Dryer can also be used in continuous operation.

* Since the dried product is released from the frozen material during the  drying process, these dry  particles can be collected separate from the  actual dryer.

* Temperature  sensitive materials

* Delicate  structured materials