Sequential drying system with isolated closed drying paths

摘要

The sequential drying system comprises a plurality of drying stations each having an upper section arranged in sequence in a tunnel. Material holders which are movable are provided for holding the material to be dried. Moving means move the material holders stepwise from an upper section of one drying station to the upper section of the next drying station through the tunnel. A separate lower section is provided for each drying station for moisture collecting means. Separating means are provided for separating the upper section of the drying stations from each other in the tunnel during the drying intervals between movements of the material holders. The separating means preferably is a vertical panel mounted at one end of a material holder so that it moves with the material holder. The atmosphere in each drying station is recirculated between its upper and lower sections in a closed path. The sequential drying system is especially useful for freeze drying since different temperatures below freezing can be maintained in different drying stations.