Natural Circulation Evaporator

Evaporation is the process, which involves thermally removing a liquid from a solution, suspension or emulsion. The starting and the end products are in the liquid phase and the end product obtained is in its concentrated from.
Depending on the liquid characteristics to be concentrated, its temperature sensitivity, thermal degradation properties etc different types of evaporators have been designed and are used for variety of applications in different industries. Single stage systems are employed, where the vapour energy of one stage is used as the heating media for the next stage. Further efficiency increase is obtained by using Thermal Vapour Recompression system or Mechanical Vapour Recompression system.

Natural Circulation  Evaporator
 

Natural Circulation Evaporators are vertical evaporators where the evaporation is induced in the tubes, thereby the vapor forcing the liquid to form a thin film along the walls of the tubes.
As thermal energy is used in evaporation and with its increasing cost, it is important to optimize upon the operating costs. Multistage designs help achieve reduced operational costs. Energy is applied to the first stage of the evaporator. Vapor from this stage is reused in the next stage as the heating media. Similalrly, from the second stage, vapors are used as heating media in the third stage and so on. Evaporators upto seven stages are designed, based on the product properties.
For further energy efficiency, Thermal Vapor Recompression system or Mechanical Vapor Recompression systems are used.  

APPLICATIONS OF NATURAL CIRCULATION EVAPORATORs

• Milk concentrate from 8 - 10% upto 45%

• Effluent concentrate before incineration

• Weak liquor low temperature concentration

• Dilute Caustic lye solution concentration

• Herbal extract concentration

• Fruit juice concentration