Systems & Modules

The SMS thin film evaporator type HYVAP serves the increasing demand of the pharmaceutical industry for continuous concentration of heat sensitive, viscous and fouling products. Hygienic design for the pharmaceutical industry The HYVAP is a horizontal thin film evaporator that allows easy access and inspection of the interior and controlled and reliable CIP cleaning. The technology of the HYVAP combines the proven advantages of our conventional horizontal thin film evaporators DKH with the following new features: • Cantilever rotor design • Comfortable rotor extraction • No bearing in product space • Mechanical seal in hygienic design • Electro-polished surfaces • Sight glasses for inspection during operation The new HYVAP DZH offers the hygienic design that meets current GMP requirements. The evaporator sizes range from 0.1 m2 for laboratory to 2.0 m2 for industrial applications. LP steam as well as hot water can be applied as heating media.

For the thermal separation of a mixture a thin film is produced at the heated wall of a cylindrical or conical evaporator. A distribution ring on the rotor distributes the liquid evenly across the periphery. Then, the blades fitted at the rotor spread the liquid as a thin film of min. 0.5 mm over the heat transfer surface. The model concept for the flow in the thin film evaporator assumes that prior to each rotor blade a bow wave is formed. In the gap between the rotor blade and the heating surface, fluid is supplied from the bow wave of a highly turbulent area with intense heat and mass transport. This results in a good heat transfer performance even with viscous products. In addition, the formation of deposits is avoided and the intensive mixing also protects temperature-sensitive products from overheating.

The falling film principle requires an even distribution of the feed liquid. To achieve this distrubution one or more distribution trays are located in the top head of the evaporator over the complete tube sheet. Our proven distribution system makes sure that the inner surface of each individual tube is properly wetted. The liquid film moves down the tubes by gravity force. Heat applied through the tube wall effects boiling-off the light fraction from the film. The picture shows a co-current operating evaporator with vapour and liquid leaving the bottom of the evaporator into the separator vessel.

The wet product fed through the inlet nozzle is picked up by the rotor blades, applied on the hot wall and simultaneously conveyed towards the outlet nozzle at the opposite end of the body. The generated vapours are streaming counter-currently to the product flow and are leaving the dryer close to the feed nozzle. Evaporating and conveying capacity are adapted by the right rotor blade arrangement. Entrained particles from the dry zone are removed in the wet zone. Moisture levels of less than 1 % can be achieved. The residence time of the product is typically between 5 and 15 minutes. The outstanding heat transfer rate for hot solid products enables cooling of large amounts of solids in a compact machine compared to usually used cooling screws and without cooling air.In product melting like the melting of urea, the particles are heated up and molten inside the dryer. The melt can be mixed with other liquid and solid additives to improve the properties of the final products.