| 摘要 |
<p>Prodn. of frozen flakes of liquid film spread on the outer surface of a rotary drum in which a liquefied cryogenic gas, e.g. nitrogen is evapd. as the flakes are doctored from the drum they are transferred through a tunnel to a storage space, and cryogenic vapour exhausted from the evaporator is directed through the tunnel and storage space to mingle with the flakes. Biological and pharmaceutical products may be freeze-dried with high thermal efficiency and economical use of cryogenic liquid. The transfer and storage temp. of the flakes can be kept very low and precisely controlled.</p> |
