Vapor-compression desalination (VC) refers to a

distillation Distillation, also classical distillation, is the process of separating the component substances of a liquid mixture of two or more chemically discrete substances; the separation process is realized by way of the selective boiling of the mixt ...

process where the evaporation of

sea A sea is a large body of salt water. There are particular seas and the sea. The sea commonly refers to the ocean, the interconnected body of seawaters that spans most of Earth. Particular seas are either marginal seas, second-order section ...

saline water Saline water (more commonly known as salt water) is water that contains a high concentration of dissolved salts (mainly sodium chloride). On the United States Geological Survey (USGS) salinity scale, saline water is saltier than brackish wat ...

is obtained by the application of heat delivered by compressed vapor.

Overview

Since compression of the vapor increases both the pressure and temperature of the vapor, it is possible to use the

latent heat Latent heat (also known as latent energy or heat of transformation) is energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process—usually a first-order phase transition, like melting or condensation. ...

rejected during condensation to generate additional vapor. The effect of compressing water vapor can be done by two methods. The first method utilizes an ejector system motivated by steam at manometric pressure from an external source in order to recycle vapor from the desalination process. The form is designated ejectocompression or

thermocompression Vapor-compression evaporation is the evaporation method by which a Centrifugal fan, blower, gas compressor, compressor or jet ejector is used to Gas compression, compress, and thus, increase the pressure of the vapor produced. Since the pressure ...

. Using the second method, water vapor is compressed by means of a mechanical device, electrically driven in most cases. This form is designated mechanical vapor compression (MVC). The MVC process comprises two different versions: vapor compression (VC) and vacuum vapor compression (VVC). VC designates those systems in which the evaporation effect takes place at manometric pressure, and VVC the systems in which evaporation takes place at sub-atmospheric pressures (under vacuum). The compression is mechanically powered by something such as a compression turbine. As vapor is generated, it is passed over to a heat exchanging condenser which returns the vapor to water. The resulting fresh water is moved to storage while the heat removed during condensation is transmitted to the remaining feedstock. The VVC process is the more efficient distillation process available in the market today in terms of energy consumption and water recovery ratio. As the system is electrically driven, it is considered a "clean" process, it is highly reliable and simple to operate and maintain.

References

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AN ADVANCED VAPOR-COMPRESSION DESALINATION SYSTEM

Vacuum vapour compression water makers for the oil and gas industry

Vacuum vapour compression water makers

AN ADVANCED MECHANICAL VAPOR COMPRESSION DESALINATION with VVC SYSTEM in desalination and purfying water industry
Evaporators Water desalination

Overview

See also

References