Hygienic drying in a vacuum requires a lot of attributes. The innovative spherical dryer design provides the highest performance according to process control and the latest GMP standards. De Dietrich Process Systems is currently delivering several units in that field.
The lower half of the sphere is removable either by pivoting or dropping. This allows total and full visual along with manual access to the process area. Accessibility, cleanability and fast as well as residue-free discharge are the most important prerequisites for the production of high-quality products. Effective trouble free washing and cleaning (WIP/CIP) is required to maintain the systems in order to meet strict hygienic standards. These conditions are a real challenge to agitated vacuum dryers and are met by the characteristics of the patented top driven Rosenmund Spherical Dryer design.
Superior Mixing with Three Arm Agitator
The spherical dryer achieves a high grade of mixing via a three arm agitator specially designed to conform the spherical wall, states the company. The agitator drive together with the shaft seal is mounted on the upper sphere. For sealing the rotation either gas or liquid lubricated double acting mechanical seals are supplied.
By heating the agitator at a high rational speed, the heat exchange can be increased. A reduced clearance between the body and the agitator improves the heat transfer and prevents wet goods from being baked onto the hub and blades. These are ideal conditions for excellent solid mixing in contact with the heated wall surface which results in short drying times and reproducible drying results. To prevent the formation of agglomerates, a high speed chopper can break up the lumps and assist the removal of moisture from within.
According to the company, at the center and lowest point of the sphere, a dead-space free design of valve allows the product to flow without restriction and the risk of building bulk bridges. With this free passage and a gentle rotating agitator valuable products can be fully discharged without being jammed.
Pack Off System
For the packing of the discharged product the dryer can be supplied with a pack off system. These systems are regularly supplied with a continuous liner to prevent active ingredients being exposed to the ambient. With a weighing scale and a permanent actuated discharge valve the product can be dosed to a preset value. A mill can also be placed between the discharge valve and the pack off system as an integrated part to achieve smaller particle sizes.