Falling Films Evaporators
PSTM’s falling film evaporator (FFE) is a form of vertically oriented shell and tube (S&T) heat exchanger used to separate two or more liquids with different boiling points.
PSTM’s Falling Film Evaporators are specially designed to treat the temperature-sensitive products which having low viscosity and low tendency for fouling. The use of vacuum and the short residence time along the heated surface are two essential parameters in preventing secondary reactions and preserving organoleptic properties.
Main benefits
• High heat transfer coefficients
• Short residence time on the heated tube surface
• Low pressure drop
• Suitable for operation under deep vacuum
• High evaporation ratios
• Low susceptibility for fouling
• Single pass or with recirculation
• Process vapours and liquid flow co-currently or counter-currently
Main applications
• Especially for low viscous products
• Suited for products with low fouling tendency
• Chemical industry
• Petrochemical industry
• Polymer industry
Forced Circulation Evaporator
PSTM’s Forced Circulation Evaporator comprises a heat exchanger, a separator and a circulation pump.
The Liquid is circulated through Calandria by means of a circulation pump, where it is superheated by steam at an elevated pressure, higher than its normal boiling pressure. By entering the separator, the pressure of liquid rapidly reduced, resulting in some of the liquid being flashed or boiled off.
Main Advantages:
(i) There is a rapid movement of liquid due to the high heat transfer coefficient.
(ii) The liquid entering the circulation evaporator boils in the separator and not on a heating surface hence minimizing fouling.
(iii) Salting, scaling, and fouling are not possible due to forced circulation.
(iv) These evaporators are suitable for thermolabile substances because of rapid evaporation.
(v) It is suitable for viscous preparation because a pumping mechanism is used.
(vi) These evaporators are also used for liquids with high solids content.
(vii) Circulation evaporators are fairly compact and are easy to clean and operate.
Application: -
(i) Forced circulation evaporator is used to concentrate thermolabile substance solutions.
(ii) It is used for the concentration of insulin and liver extracts.
(iii) It is well suited for crystallizing operations where crystals are to be suspended at all times.
(iv) These evaporators are used in the production of salt, corn steep water, and calcium carbonate.
