Lödige shovel dryers are batch vacuum dryers whose mixing elements are frequency-controlled for ideal adaption to the process. Special rotating mixing elements, installed in a cylindrical drum equipped with a temperature control jacket, create three-dimensional product movement (mechanically generated fluid bed). The resulting contact frequency of the particles with the heat exchange surface results in very short drying times.
Additional advantages of the Druvatherm® vacuum shovel dryer include a maximum heat transfer coefficient, ensuring excellent dryer performance, gentle thermal product treatment in vacuum mode and a multi-phase process with mixing, granulation, drying and cooling. Additionally, intense mixing prevents temperature and moisture gradients within the product, and solvent-recovery is cost-efficient.
In the standard version, the intelligent product movement ensures intense contact of individual product particles with the heated container wall, while guaranteeing very gentle product treatment. Optionally available rotating choppers, installed in the sides of the drum, break down any agglomerated product if a product phase transition is required. Fine particles pulled along by solvent vapours are separated by an installed, pneumatically purged filter and are returned to the drying product bed by the cleaning system.
Mode of operation
The product movement creates intensive contact of the individual product particles with the heated wall of the machine. At the same time, it treats the product as gently as possible. Rotating choppers, installed inside the drum, provide additional dispersion during possible product transition phases and are available as an option. Fine particles in the solvent vapours are collected by a pneumatically cleaned filter mounted on the machine and are returned to the product bed for drying. The vacuum dryer is designed for a multi-phase process. The mixing, granulating, drying and cooling process stages can thus be performed in the same machine, eliminating the need for transferring the product between the individual process stages. This not only avoids product loss but also prevents dust pollution to the environment during transport.