The Flash Reactor and Flash Drier are the technologically most advanced production of VRV for chemical reactions and thermal drying. The principle of the thin-layer, horizontal axis centrifugal equipment is further exploited in its under  vacuum application, improving the heat exchange, with consequent increase of the evaporative capacity, as well as production yield and quality. This execution, which is innovative in many respects, is suitable especially for chemical-pharmaceuticals, fine chemicals and foodstuff and also for heat sensitive or difficult-to-handle products, and has been successfully used, for instance, for:

• stripping solvent from heat-sensitive products, where temperatures of 80-100°C cannot be exceeded
• evaporating substances which can form explosive mixtures
• drying products subject to atmospheric oxidation
• recovering toxical or expensive solvents
• processing powder products without any entrainment losses

The plant is continuous and is equipped with under-vacuum feeding devices for uniform and constant feeding of wet powders, pastes, thick suspensions and liquids. The product continuous discharge is based on a programmed cyclic sealed system, with the possibility of taking samples for analysis and controls. Each component is designed and manufactured for maximum safety in environmental impact and to facilitate and speed up cleaning and decontaminating operations.

The plant is considerably energy-saving: the rotor high tip speed, combined with the minimum distance of the blades from the stator, create optimal conditions for the product distribution in a thin, dynamic film, which is renewed continuously and quickly. These conditions assure the maximum exchange coefficient and, therefore, higher ther mal flows than those possible in other systems.
                                
Operative conditions
Vacuum degree: up to 20-30 mbar (absolute)
Rotor tip speed: over 30 m/sec
Heat transfer: indirect
Maximum temperature: up to 320°C
Temperature control: possible at different levels

Main results achieved
In the under-vacuum "Flash" plant it was possible to treat a wide range of products, like for instance:

• chemical and pharmaceutical bulks both with high and low solvent content, obtaining a dried product with solvent percentages much lower than 1% by weight
• suspensions of heat-sensitive dyestuff, which cannot be dried at atmospheric pressure because a highly plastic phase develops during treatment, obtaining products which already meet specifications as regards residual moisture and physical state
• surfactants in aqueous phase at different concentrations. In this case, it was possible to dry twice as much product in the time unit as in the atmospheric drier, to the same moisture percentage, and keeping feeding rate and exchange surface the same as in the atmospheric  drier.
• products of various origin and composition, which were dried at low temperature to keep 100% of their activity and organoleptic characteristics.