Abstract: In a freeze-drying method, liquid substances to be dried are sprayed into a stream of cold gas, usually air, at ambient pressure creating a collection of small frozen particles that are metered through a vacuum lock into a vacuumized vertical tower having heated walls and, as the particles fall through the vacuum in the tower to its bottom, radiant heat from the tower walls causes the ice contained in the particles to sublime. The resulting sublimed vapor is removed from the tower by low temperature condensation while the dried particles are collected at the bottom and transferred through another vacuum lock into a container. The operation is continuous and fast, providing significant advantages compared to prior known freeze-drying operations.

Abstract: Spray-freeze-drying systems and methods are disclosed for converting a wide variety of liquid substances into dry powder that may be reconstituted into the original substance by addition of water or other liquid that had been removed therefrom. Such systems and methods involve repetitive cycles of four operational steps, i.e., freezing, drying, defrosting and resetting and are characterized by: spraying the liquid substance downwardly in a vessel while surrounding the spray with a downward flow of process gas during the freezing step and by utilizing a heat pump for energy recapture to increase efficiency of operation.