Short Path Distillation – The Technology
For thermal separation of thermal sensitive compounds via distillation, part of the product to be treated is evaporated using heat, and condensed separately. Many organic substances, e.g. vitamins, flavoring agents or pharmaceutical intermediates, however, become damaged even at low temperatures, e.g. due to thermal decomposition, polymerization and side reactions which have a negative influence on the quality of the end product. There is an increasing loss of quality caused by high temperature and duration of thermal stress. By means of extreme reduction of operating pressure and special design, the evaporation temperature and duration of thermal stress on a product can be reduced considerably and the quality is significantly improved.
Short Path Distillators
The UIC Short Path Distillators normally operate within a pressure range of 0.001 to 1 mbar.
The product to be treated flows along the inside wall of the evaporator as a liquid film from the supply point to the discharge point. The residence time in the apparatus is very short. Thus thermal stress is minimal. We have developed a unique wiper system for the operation inside the evaporator which ensures an even distribution of liquid on the evaporator surface and ideal mixing of the product which flows downwards. This means that volatile substances are continuously brought to the film surface and evaporate more efficiently. Heating of the evaporator is made via heat transfer medium, e.g. thermal oil or steam.
A special feature of this apparatus is the condensation of vapors on the internally positioned condenser. The ‘short path’ of the vapor phase to the condenser results in only little pressure loss, meaning that extremely low pressures can be achieved. Therefore, in Short Path Distillators, in comparison to Thin Film Evaporators, distillation can take place at considerably lower temperatures. This process is most gentle for the product.