A flowing film of a composition of water and a solute over a refrigerated surface, is at such solute concentration and freezing temperature as to de-sublimate or condense the water vapor as ice which is carried away by the film, and subsequently separated from the composition by filtering or centrifuging. A terminal portion of the refrigerated surface is shielded to prevent access of water vapor thereto to effect removal as ice of water that may be absorbed in the film from the vapor, thereby maintaining the film concentration substantially uniform. A salt solution or brine provides an advantageous solute.
A process is provided for freeze-drying medicaments and foodstuffs comprising dissolving the foodstuffs or medicaments in a solvent, introducing the solution formed into a shell comprising a desiccating chamber of a shell-tube freeze-drying device to cause the solution to freeze in a tubular layer, and crushing and comminuting the freeze-dried liquid with a comminuting device to obtain a powder product.
Disclosed is a freeze-drying apparatus for foodstuffs, medicaments, etc., wherein liquid material is directly and distributively poured into upright cylindrical tubes, then, in its isolated state from external atmosphere for perfect sterilization, the liquid material is frozen with uniform thickness onto inner wall surface of the tubes, with further possibility of uniform heating of the freeze-dried layer. The main body of this apparatus is constructed with upright cylindrical tubes for freezing liquid material onto inner surface of tubes and jackets to surround the outer periphery of each of the tubes in a substantially concentric cylindrical shape, within which to circulate heat medium; then, a duct communicating to the vacuum exhaust system is connected to the upper end side of these tubes, while, a recovery chamber provided with valve is connected to the lower end side of tubes; and an inlet port is defined for feeding liquid material into inner cavity of tubes.
