Analysis of the hottest seawater desalination tech

How many methods of seawater desalination do you know

in the early 1960s, multi-stage flash desalination technology came into being, and the modern desalination industry has thus entered an era of rapid development

the large-scale application of seawater desalination technology began in the arid Middle East, but is not limited to this region. Since more than 70% of the world's population lives within 120 kilometers of the sea, seawater desalination technology has been rapidly applied in many countries and regions outside the Middle East for more than 20 years. The latest data shows that by 2003, the world has built and contracted seawater and brackish water desalination plants, with a production capacity of 36million tons of fresh water per day. At present, seawater desalination has spread to 125 countries and regions all over the world, and desalinated water feeds about 5% of the world's population. Seawater desalination, in fact, has become a widely used strategic choice to solve the problem of water shortage in many countries in the world, and its effectiveness and reliability have been more and more widely recognized

reverse osmosis method:

usually known as excess filtration method, is a membrane separation desalination method that was only adopted in 1953. This method uses a semi permeable membrane that only allows the penetration of solvents and does not allow the penetration of solutes to separate seawater from fresh water. Under normal circumstances, fresh water diffuses to the seawater side through the semi permeable membrane, so that the liquid level on the seawater side gradually rises for a long time and stops until a certain height. This process is called infiltration. At this time, the static pressure of the water column above the sea side is called osmotic pressure. If an external pressure greater than the osmotic pressure of seawater is applied to one side of seawater, the pure water in seawater will reverse osmosis into fresh water. The biggest advantage of reverse osmosis is energy saving. Its energy consumption is only 1/2 of that of electrodialysis and 1/401 of that of distillation for permanent reuse. Therefore, since 1974, developed countries such as the United States and Japan have first used the energy difference before and after the pendulum impact sample to confirm the toughness or brittleness of the sample, and then shifted the focus of development to the reverse osmosis method

reverse osmosis seawater desalination technology has developed rapidly, and the engineering cost and operation cost continue to decrease. The main development trends are to reduce the operating pressure of reverse osmosis membrane, improve the recovery rate of reverse osmosis system, cheap and efficient pretreatment technology, and enhance the anti pollution ability of the system

multi stage flash:

the so-called flash refers to the phenomenon that part of the sea water at a certain temperature suddenly evaporates under the condition of a sudden decrease in pressure. Multistage flash seawater desalination is to evaporate the heated seawater in multiple flash chambers with gradually reduced pressure, condense the steam and obtain fresh water. At present, the multi-stage flash evaporation method is still the largest production method in the world, with the most mature technology, high operation safety and flexibility. It is mainly constructed jointly with thermal power plants, suitable for large and super large desalination devices, and is mainly used in Gulf countries. The multi-stage flash technology is mature and reliable. The main development trend is to improve the water production capacity of a single unit, reduce the unit power consumption, and improve the heat transfer efficiency

dew point evaporation method:

dew point evaporation desalination technology is a new method for desalination of brackish water and seawater. It is based on the principle of humidification and dehumidification of carrier gas, and recovers the heat of condensation and dehumidification at the same time. The heat transfer efficiency is controlled by the heat transfer on the mixture side

hydropower cogeneration: Hydropower cogeneration mainly refers to the cogeneration and supply of desalinated water and electricity. Since the cost of seawater desalination largely depends on the cost of electricity and steam consumption, cogeneration can use the steam and electricity of the power plant to provide power for the seawater desalination device, so as to achieve energy efficient utilization and reduce the cost of seawater desalination. The results show that. Most seawater desalination plants abroad are built together with power plants, which is the main construction mode of large-scale seawater desalination projects at present

hot film cogeneration: hot film cogeneration mainly adopts the combination of thermal method and membrane seawater desalination (i.e. med-ro or msf-ro method) to meet different water needs and reduce the cost of seawater desalination. At present, the largest hot film cogeneration desalination plant in the world is the fujaira desalination plant in the United Arab Emirates, with a daily desalination water output of 454000 cubic meters, including 284000 cubic meters per day for MSF and 170000 cubic meters per day for ro. The utility model has the advantages that the investment cost is low, and the seawater intake can be shared. RO and med/msf desalination product water can be mixed in a certain proportion to meet various needs

in addition, other combinations of the above methods are also increasingly valued. In the actual selection, which method is the best is not absolute, but depends on the actual conditions such as scale, energy cost, seawater quality, climatic conditions, technology and safety