Desalination technology is also called desalination technology, which is the process of separating salt and water from seawater.
There are different classification of seawater desalination method, except solvent extraction method and gas hydrate method, most of which have been applied in practice.
The most widely used are flash distillation and reverse osmosis.
The United Nations study on unconventional water sources indicates that during the 35 years from 1950 to 1985, the development of desalination went through three stages, namely the discovery stage, the development stage and the commercialization stage.
During this period, the energy of research and development is mainly concentrated in distillation, freezing, electrodialysis and reverse osmosis.
In the following 10 years, distillation and reverse osmosis law have played a prominent role, forming the main body of the market of modern seawater desalination and brackish water desalination technology.
In these years, the production capacity of seawater desalination plant in the world is distillation, especially the multistage flash method.
However, in 2001-2002, the total production capacity of reverse osmosis devices exceeded the production capacity of any kind of distillation unit, and the reverse osmosis method developed far faster than the distillation method.
So you can think so, since the 50 s, the application of the seawater desalination technology and momentum can be divided into two stages, that is, 2000 years ago is the age of distillation, especially in multi-stage flash method is given priority to, and after 2000 is osmosis membranes, especially of reverse osmosis age [. Although overseas for a variety of seawater desalination technologies for a wide variety of experimental contrast, in the hope of the relative merits of clear, but today the thermal method and membrane technology are each have a wide range of users, shows that the technology is still in development, both have their own technology advantages, applicable conditions and reduce the cost of space.
The development trend of international seawater desalination mainly includes the following aspects :(1) the coexistence of various seawater desalination technologies is complementary and parallel development.
The research and development of multi-stage flash evaporation is the application of new materials, the application of class extraction and other new technologies.
Reverse osmosis desalination research and development of the focus is on the high performance of reverse osmosis membrane, a new pretreatment technology development and the improvement of the traditional pretreatment technology, large high pressure pump and the energy recovery system development and improvement, etc.
These research and development forms the pattern of the coexistence and complementarity of various seawater desalination technologies;
(2) the scale of the project is becoming larger and larger.
The development of social demand and technology has made the international desalination project develop in a large scale and scale.
The scale of desalination plants has grown from a few hundred tons per day to hundreds of thousands of tons per day, and the amount of water produced by a single device has increased rapidly.
(3) the cost is decreasing.
Technical progress, scale more and more construction and running management mechanism innovation gradually reduce the cost of desalination, the desalination of lowest selling price is equivalent to has dropped to nearly 4. 0 yuan/m3;
(4) seawater desalination and resource utilization gradually form the industrial chain.
The combination of seawater desalination project and power plant is becoming a hot spot of international concern by utilizing the waste heat of power plant to recycle fresh water and the comprehensive utilization of brine.