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Wyeth Laboratories, Paoli, PA
Penicillin

 

Drying problems include air pollution by solvents, product degradation and packaging difficulties due to lumping. Extensive evaluation of different types of dryers narrowed to two contenders: a rotary vacuum unit operating at about 28 to 29 in/Hg and a TURBO-DRYER®. Both recovered solvents satisfactorily and produced an acceptable dried product (0.5% or less volatiles). the TURBO-DRYER® operating cost was less because its chilled-water refrigeration system for condensing solvents cost less than 75% of the cost of the direct-expansion' "Freon" system required for the rotary vacuum unit. The two closed-circuit TURBO-DRYER® purchased are steam heated, stainless steel interior construction, 9.5 ft dia. Large unit is 10 ft high, 18 trays. Smaller unit, 6 ft high, 12 trays. The drying medium is nitrogen at a slight positive internal pressure; make-up rate is 5 scfm max. Oxygen levels are less than 5% by volume. The large unit reduces 30% volatiles to 0.5% at 300 Ib/hr. The smaller unit is used for smaller batches and different grades and reduces 25% volatiles to 0.5% at 150 Ibs/hr. Dried material is free-flowing and non-lumpy. No solvent odors can be detected by operating per-sonnel.

 

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