List Introduces Process Sublimators

N/Aany%> (Acton, Mass.) has introduced several new thermal processing systems for chemical/pharmaceutical products. Among these are a sublimation unit ideal for purifying salicylates, anthraquinones, chlorides, and metal organic compounds used to make fine chemicals and drug intermediates.

In the List process, raw product is fed into the heated sublimator by means of a feed lock system. Pure product vaporizes under vacuum and condenses as a free-flowing solid in the closed List DiscoTherm B desublimator. From here it is discharged by a specially designed vacuum lock system. The sublimator operates semi-continuously under vacuum without carrier gas. After several filling cycles the accumulated impurities are discharged from the sublimator.

View Figure 1

Advantages include automated semi-continuous operation, compact closed system (no carrier gas), high product purity and yield, and no product degradation.

Bench Scale Processors
The other products of note are two new bench-scale processors: the single-shaft DiscoTherm B 2.5 Batch and CRP 2.5 Batch units, designed for laboratory applications involving processing of viscous, sticky, pasty and crust-forming products.

Applications include:

• Polymerization/polycondensation reactions
• Reactions in solid, liquid and viscous phases without solvents
• Direct solvent recovery from polymer solutions
• Melting, drying, crystallization and evaporation

For example, in solvent recovery mode the processors work by continuously evaporating distillation residues. Vaporized solvents are recovered by condensation; the remaining non-toxic waste typically is a free-flowing powder with residual solvent contents below 0.5 percent.

View Figure 2

For more information, contact Jane Whelihan,
Senior Marketing Administrator, List, Inc.,
42 Nagog Park, Acton, MA 01720. Tel: 508-635-9521.

By Angelo DePalma