The new high-heat TrueBlend blender from Conair, Cranberrry Township, Pa., allows PET processors to keep recycled and virgin materials separated until just before they are fed to an extruder or molding machine. This is important because, if contamination is discovered in the regrind (a relatively common occurrence), only the regrind stream needs to be cleaned up and production can continue using 100% virgin. Another virtue of separating the streams is that recycled flake does not need to be dried as long as virgin pellets. After 1 hr of crystallization, only 3 hr of desiccant drying are needed. This cuts the energy required to dry the recycled PET by half.
The unique design of the new Conair blenders begins in the material hoppers, which look very much like drying hoppers. They are insulated to minimize heat loss and they have a steep (60°) cone angle at the bottom to encourage flow of material through the hopper. Together with smooth interior walls, this cone design ensures that all material spends the same amount of time in the hopper and prevents heat loss and moisture regain.
All blender components—including load cells, level sensors and air cylinders —stand up to temperatures of 375 F or more. Electronic components are isolated from elevated temperatures to prevent premature failure or generating erroneous data that reduces mixing accuracy. The insulated blenders are available in sizes to 5000 lb/hr. The standard unit includes two hoppers for virgin and regrind, but systems with three, four or more hoppers are available.