Seawater desalination: operating principle

We all know that a man is two-thirds water. And if without food our body can last about a month, then without water, at best, only a week (sometimes much less). A person needs to consume enough fresh water every day to avoid problems with health. The desalter of sea water and the mechanism of its functioning - the topic is more than relevant.

Industrial cleaning

Active population growth directly influenced the number of fresh water sources on our planet. As a result, there was a shortage of it, which pushed people to search for various ways of making drinking water "manually". The only way out was the possibility of desalination of salty sea water, not suitable for drinking.

The source for desalination was the World Ocean. Sea waters undergo numerous cleaning steps, as a result of which the liquid gets rid of excess amounts of different salts. The use of specialized installations comes to the rescue.

The use of sea water desalters makes it possible to successfully bring it to the drinking state. Desalination of water on an industrial scale is done in many ways. Most of these methods are based on the use of overall energy-intensive facilities. These are specialized filters and distillers. Consider the main types of desalination of water in large volumes.

Methods of purification

In our world, only a few technologies have been developed that make it possible to convert sea water into a flowing one. One of them is the use of chemical reagents. This method implies the use of special chemical compounds for desalination of liquids. When in contact with salt water, a reaction occurs, resulting in the formation of insoluble chemical compounds.

After completion of the reaction, it remains only to remove the resulting precipitate by filtration. This method is not used in everyday life, and is rarely used for desalination of water in industry.

This method has significant disadvantages. Firstly, a considerable amount of chemical substances is required for desalination, and secondly, the process takes a long time and, thirdly, it is not cheap.

Method of reverse osmosis

This method has long established itself, nowadays it is actively used in industry. It uses special cleaning membranes. They are made of semipermeable material. For example, from polyamide or cellulose.

A liquid with an excessive amount of salts is passed through these membranes under a certain pressure. As a consequence, the liquid particles pass through a microscopic grid, on the surface of which larger particles of various impurities settle. Due to this method, it is possible to obtain a rather large volume of desalinated water.

Principle of operation of a seawater desalter

The desalter of sea water is a device that allows you to remove the salts dissolved in it from the liquid. After passing this procedure, purified water is obtained. It can be used not only in everyday life, but also as good drinking water.

The peculiarity of the device design is convenient and practical in operation. But fresh does not mean pure. After all, in it, in one way or another, various components are saved. Their density directly depends on the use of the water obtained. For example, ships require completely different types of water:

• Drinking - only for cooking and drinking;
• Water for personal hygiene and deck washing;
• Water for steam generators, otherwise it is called nutrient;
• Water for technical purposes (used as engine coolant);
• distilled water.

For all these species, different ship desalters of seawater are used.
All methods fall into two categories:

1. Distillation - a desalination plant that works by the principle of distillation, heats and evaporates seawater. Then the steam is "caught" and brought to the desired temperature.
2. Filtration - the principle of reverse osmosis. Salt water is desalinated without transition from one aggregate state to another.

His work is based on "leveling" the concentration of dissolved impurities. Extremely high pressure allows us to "squeeze out" unnecessary particles of salts.

Interesting fact

The world's largest seawater desalter is located in Hadera (Israel). By its scale, this unit resembles almost the whole plant. Every year it desalts about thirty-three billion gallons of sea water.

This covers two-thirds of the country's total demand. After all, as is known, in Israel the acute issue is the lack of drinking water. This seawater desalter operates, like most desalination plants, according to the principle of reverse osmosis, under the influence of which the waters of the Mediterranean Sea are not subjected to heat treatment.

Solar water desalter

Recently, on the shelves of the store, unique desalination plants have appeared, interacting with solar energy. Inside the device, sea water is poured, from the resulting solar heat it turns into steam, condenses on the walls of the shell, and settles in the lower part of the receiver.

The design of the installation is completely hermetic, it can create a greenhouse effect and does not allow evaporation from outside the desalter. Accordingly, as a result of this pure water is saved more. At the end of this process, simply unscrew the plug and drain the purified water into a vessel.

Vacuum desalter of sea water

This type of desalination is used in the marine fleet. It utilizes the heat of the liquid, which cools the main and auxiliary diesels. Clean water, heated to about sixty degrees Celsius, at the inlet comes through the pipes of the heating battery. At the outlet, the water temperature drops to about fifty-five degrees Celsius.

The vacuum distiller allows for an hour to get about eight hundred liters of distilled water. This type of distiller can cover almost all the needs of fresh water without the extra costs for fuel energy and after-sales service. The device is fully automated. Since the temperature of evaporation is low enough, the water desalter can work without cleaning for six to twelve months.

Instrument maintenance

Maintenance of the device should be carried out every week, every month and once a quarter.

Once a week, an external examination of the device is required. It is also worth checking the correct operation of the pumping seals and the rarely used valves. Eliminate loosely adheres and all kinds of leaks in the joints. Once a month, over a weekly inspection, it is necessary to clean the screen of the seawater filter and lubricate the bearings of the pumps. Once a quarter the flowmeter is checked, replacement of protectors on pipes, brine and pumps is carried out. Purify the spray holes of the annular tube of the evaporator, replace the stuffing boxes at the pumps.

Repair work

The repair process involves cleaning the salt water heater and evaporator-condenser with their subsequent crimping and placing the defective tubes.

It is necessary to open the liquid heater, clean the filters from the pipes and the pipes themselves from various debris and formed scale. Also it is necessary to disassemble the flowmeter in order to clean it from dirt and rust. If the pump bearings are worn, they must be replaced. In addition, it is recommended to clean the surfaces of shells in contact with seawater.

Seawater desalination for yachts

The presence of a seawater desalination system on board a small vessel is comfortable and safe. A manual seawater desalter allows you to save your budget because there is no need to replenish the stocks of clean drinking water.

On average, in an hour such a desalter, designed for small ships, handles hundreds of liters of salt water, turning it into a clean drinking water.

Some models of desalinators for yachts have the function of remote control, which greatly facilitates the control of the process. Such installations are suitable for use on both sailing and motor yachts. Spare parts of ship desalination plants, directly in contact with sea water, are made of substances not affected by corrosion. The outer structure is most often made of stainless steel.

Portable device for water purification

More recently, researchers have announced a new original device, created specifically to divide sea water into drinking and salted water. The lion's share of desalination plants is based on reverse osmosis technology, while consuming a large amount of electricity. The disadvantages of this method of desalination can also be attributed to the inefficiency of working with small volumes.

A new invention - a portable seawater desalter is based on the technology of polarization of ion concentration. The nano-sized channel is filled with liquid, an electric current is connected, which creates an electric field. Due to this, water is divided into two parallel streams. In one of them, ions of salts fall, while in the other stream pure fresh water turns out.

The creators plan to bring to mind a new device that will be powered by an alkaline battery. The planned rate of desalination is about fifteen liters per hour. The invention is promised to be launched into the masses in the next two years.

How to make a desalter of sea water with your own hands?

Water can be made clean and without the use of industrial devices. Make a manual desalination is not difficult. To do this, you need a saucepan with a tight fitting lid.

This method of water desalination is based on the entire known physical phenomenon - condensation. Pour into the pan sea water, close the lid and boil. The steam accumulated under the lid is clean condensate. All water impurities have a large mass, so they settle on the bottom of the pan, and the H ₂ O particles condense in the form of steam.

This method allows to desalinate the liquid with a large amount of loss of pure water. Therefore, the design should be slightly improved. To do this, you need to make a small hole in the pan cover, insert a flexible hose (tube) into it, cover the pan with a lid. The other end of the hose is directed to the next pan (any capacity) and be sure to cover the top with a moistened towel. This will help the steam stay warm.

We put sea water on the fire and boil it. We wait until all the water "goes" to another pan. This will be freshened drinking water. All salts, as well as various impurities will remain in the same pan. Here is a simple, made by hand desalter of sea water will help to get clean drinking water.

Another way to desalinate salty water is to freeze it. The fact is that the freezing temperature of sea water and fresh water is somewhat different. To freeze the salt it takes a temperature lower than for freezing fresh. The resultant ice is desalinated water, which may well be suitable for drinking.

A desalter of sea water is definitely a necessary thing, but only for industrial scale. At home it is possible to transform sea water into drinking water with the help of simple tricks with which we have met today. So now you can not worry about the fact that in an emergency situation, a lack of water can grow into a serious problem.