A Closed System for Continuous Freeze-Drying of Liquid Material by the Use of Vertical Tubes(Papers presented at the 34th Annual Meeting, April 1988, Tokyo)

Abstract

Up to now, development of non-tray system freeze-dryers has been tried in many cases, but did not still reach the practical level for stable production, mainly due to the product loss in operation (or dried product remains inside the equipment in the form of dispersion or in adhesion) as pointed out by Lorentzen. Having restudied the methods by Mason and Seffinga, author has succeeded in developing a closed system for continuous freeze-drying of liquid materials by the means that an ice-lining is first placed on the inner (or outer) surface of a vertical tube and then frozen layer of liquid material is formed on the lining. Such ice lining is proved to be much effective not only in preventing dry product remains from being adhered to the tube surface, but also in eliminating the formation of isolated ice crystals and impermeable surface layer which impede drying.