Vacuum unit carries out both blending and drying
Charles Ross and Son
The Vertical Blender/Dryer (photo) is used to carry out vacuum drying in a wide range of applications for materials that are in either a solid or liquid state, such as powders, granules, pellets, fibers, pastes and slurries. It uses a slow-turning auger screw that gently lifts batch materials upward as it orbits around a conical vessel. Materials carried to the top of the batch cascade slowly back down into regions opposite the moving auger screw. The constant exchange of materials between the heated sidewalls and the center of the cone-shaped unit both blends and dries the contents. The potential loss of fines (often associated with drying and blending operations) is minimized with this design, says the company, because the blending action is thorough but involves very low impact. During the drying cycle hot water or steam is recirculated through the vessel jacket. A particular benefit of this design is that due to the lower processing temperatures made possible by the vacuum environment, there is a reduced risk of creating hot spots on the vessel walls where the product could become overheated. Available in wide array of sizes (from 1 through 500 ft3), this unit does not require a bottom support bearing to keep the screw steady, so discharge is said to be virtually 100% complete. This design concept also simplifies cleaning and maintenance. — Charles Ross and Son Co., Hauppauge, N.Y.