Vacuum freeze drying method and vacuum freeze drying apparatus

摘要

Problem: the droplet of the raw material liquid is kept frozen without changing the characteristics of the solute and the dispersing property at a short falling distance while maintaining a high speed cooling speed.A vacuum freeze drying method according to an embodiment of the present invention isThe raw material is injected from the injection nozzle in the vacuum vesselIt generates frozen fine particles by self freezing at a height of 1 m or less from an injection nozzle.Is a vacuum freeze drying method having the steps of drying the generated frozen fine particles to produce dry powder;In a state where the vacuum vessel is maintained at a partial pressure of water vapor corresponding to the spontaneous freezing temperature of the source liquidThe raw material liquid is injected from the injection nozzle so that the initial speed of injection of the raw material from the injection nozzle is 6 m / sec or more and 33 m / sec or less.The maximum diameter of the generated frozen fine particles exceeds a predetermined valueOrIf the drop of the raw material liquid is unfrozen,In order to produce frozen fine particles with the maximum diameter below the predetermined valueThe injection flow rate of the raw material liquid from the injection nozzle or the characteristics of the injection nozzle are adjusted.Diagram