In a short path evaporator, the rotor cage assembly (top view illustrated below) surrounds an internal condenser and revolves at moderate speeds. Feed enters through a nozzle at the top of the unit and is spread into a thin film on the inside surface of the shell via the rotor blades.
The rotor blades gently agitate the process liquid as it travels down the heated surface in a very short time while vapors are generated on the heating surface. These vapors flow through the rotor cage and entrainment separator before condensing on the internally-located condenser.
The cage-type construction and location of the internal condenser create a short vapor flow path or “short path”, extending the operating pressure capability from 1 mbar to 0.001 mbar compared to a standard thin-film evaporator. Typical heating media temperatures are 300°F to 650°F (149°C to 343°C).
The distillate and the remaining liquid concentrate drain out through separate outlets at the bottom of the unit.
