Vobis manufactures pilot wiped film evaporator systems (also called agitated thin film evaporators) for high viscosity (to hundreds of thousands of cP), heat sensitive, foaming or fouling applications, for which either high heat transfer or high mass transfer coefficients are required for heat sensitive products. Our systems offer minimal process fluid hold up, short residence time plug flow wiped film evaporation under vacuum conditions.
Our wiped film evaporators use a rotor to create an agitated thin film of the process feed material with a high turnover rate against the interior heat transfer surface wall of the evaporator while the evaporator is operating under positive, neutral or vacuum conditions. This insures that the product basically sees only the vapor equilibrium conditions inside the evaporator until the evaporation transitions from heat transfer to mass transfer. Feed material is tangentially distributed onto the internal wall of the evaporator, and the wiping blades spread this liquid against the heated surface in a rapidly renewed thin film surface with heat on one side and the vacuum conditions on the other side of the film. The residence time of this material in the evaporator is a few seconds before the concentrated bottoms exit the wiped film evaporator. Evaporated volatile components exit the wiped film evaporator and are condensed in a separate chamber (unless extremely high micron level vacuum is required to reduce heating conditions further; for more information regarding this alternative, please see our molecular distillation section).
The separation of the lights from the heavies in our wiped film evaporators is usually accomplished in a single pass in a plug flow manner to minimize product heat exposure. Either a great deal of volatile components can be evaporated, or the rapid surface renewal and large delta T provided by the material being wiped across the heat transfer surface can be used to deliver high heat and mass transfer rates to reduce volatile components to low PPM levels without degrading heat sensitive actives.
Rotor blades are available in a number of different designs depending on the requirements of the application including fixed clearance thin film, hinged wiped film, roller wipers as well as other specialty blade designs.
Vobis pilot wiped film evaporation systems generate scaleable data for the design of required production sized wiped film evaporation systems. These pilot systems can be constructed in the same metallurgies (various SS alloys, hastalloy, duplex steels or titanium) as our production systems, and they have similar vacuum, heating, pumps and controls as our full scale systems; however, pilot systems require substantially smaller feed inputs to allow development work to progress through to generate scale up data. As scale up progresses the WFE pilot system produces products as required for further processing or market development.
Our wiped film evaporation systems are especially appropriate for applications which are:
High viscosity, tens of thousands of cP
Heat sensitive products or actives, often times natural extracts
Normally foaming, which are normally difficult to process
Normally fouling, and which the WFE high surface renewal rate helps to eliminate
Our WFE application experience includes:
Lecithin drying and glycerin recovery and purification
Solvent stripping from foods and polymers
Concentration of sugar solutions to 99.5%
Recycling of solvents from organic chemicals, greases and oils
Removal of solvents and monomers from polymer, both natural and synthetic
Reaction and removal of condensates from polyesters or capralactam from nylon 6
Purification of essential oils
Concentration of enzymes, fruit and vegetable purees, proteins, vitamins, and biological solutions