WO2007053059A1

WO2007053059A1 - Sea-water desalting device

Info

Publication number: WO2007053059A1
Application number: PCT/RU2006/000529
Authority: WO
Inventors: Victor Alexandrovich Chernysh; Sergey Victorovich Chaykin; Andrey Yulievich Afanasiev; Alexander Borisovich Krusiyan
Original assignee: Victor Alexandrovich Chernysh; Sergey Victorovich Chaykin; Andrey Yulievich Afanasiev; Alexander Borisovich Krusiyan
Priority date: 2005-10-31
Filing date: 2006-10-12
Publication date: 2007-05-10
Also published as: RU2005133496A; RU2309125C2

Abstract

The invention relates to sea-water desalting devices and can be used for producing fresh water for agriculture, industry and municipal services. Water-tight tanks (1, 2) are lifted at a height of approximately 10.5 m. Said tanks are provided with three pipelines: the supply (7), drain (8) and distilled water (9) pipelines whose lower ends are arranged below the level of water to be desalted. The supply pipeline (7) is provided with a pump (12) which incorporated therein and permanently supplies new portions of water to the tank (1). Plates (26) are arranged inside the tank (1) above a water mirror at a small angle with respect to the horizon, wherein the inclination of the next plate is directed oppositely to the previous plate inclination. A system (21) for irrigating by cold fresh water is used in the other rank (2) for vapour condensation. The irrigation fresh water is cooled by a cooler, whose coolant-containing pipeline (19) is positioned below the water level in the second tank.

Description

A device for desalination of sea water.

The field of technology.

The invention relates to devices for desalination of sea water and can find application in the design and manufacture of desalination plants for fresh water for agriculture, industry and utilities.

The prior art.

There are several ways to obtain fresh water: evaporation, electrodialysis, and reverse osmosis [1, 2]. All these methods are quite complex and energy intensive.

The removal of salts from water to a limit close to their content in distilled water (several mg / l) is called desalination, and the removal of salts to concentrations acceptable for drinking water (up to 1 g / l) is called desalination.

Desalination of water by electrodialysis or reverse osmosis is characterized by significantly lower energy costs compared to traditional distillation. In electrodialysis, selective, ion-exchange membranes are used.

In reverse osmosis, semipermeable membranes that allow water molecules to pass through but retain dissolved mineral and organic substances.

Electricity consumption per 1 m ^{3 of} water desalted by electrodialysis is at least 30 kWh, and reverse osmosis is at least 15 kWh.

By electrodialysis, water can be desalted by 90%, reverse osmosis - by 98%.

In reverse osmosis plants, the working pressure reaches 5-10 MPa (50 - 100 atmospheres).

As you can see, the desalination of water by electrodialysis or reverse osmosis is associated with significant energy costs, the manufacture of quite complex and expensive desalination plants, constant monitoring of their performance, repair, replacement of membranes with a limited service life, etc.

There is also a method for distillation of sea water, based on the law of decreasing the boiling point of water with decreasing pressure above its surface [3, 6].

If you reduce the pressure above the surface of the water, intensive evaporation will begin even at a temperature close to the freezing temperature. The evaporation rate depends on the temperature of the water and the pressure difference between the pressure above its surface and the pressure of saturated vapors at a given temperature. When the pressure above the surface of the water is equal to the pressure of saturated water vapor at a given

SUBSTITUTE SHEET (RULE 26) temperature, boiling will stop. If continuously formed water vapor is formed, the boiling process will continue. This can be achieved in two ways: by pumping out the vapors with a vacuum pump followed by their condensation outside the zone of reduced pressure or by condensation of the vapor and removal of condensate from the zone of reduced pressure. As a third option, a combination of these methods is used [4, 5].

The disadvantages of these methods are the complexity and high cost of desalination plant equipment, low productivity and high cost of fresh water.

The invention [7] is the closest analogue of the claimed method (prototype).

This patent describes a system for continuous distillation under reduced pressure, having two pressurized tanks connected by a steam line, an injection pipe, on which there is a pump for continuously supplying desalinated water to the tank, and a pipe for distilled water, as well as a device for heating and condensing vapors water, which is a refrigerator, the pipeline with a heated refrigerant which is below the water level in the first tank and gives it its heat, and the pipeline with a cooled refrigerant It is higher than the water level in the second tank and serves to condense water vapor, which flows into the pipeline for distilled water, and from it into the tank for distilled water.

The first disadvantage of the device is the high energy costs of creating a vacuum above the surface of the water, and, therefore, the high cost of desalinated water.

The second disadvantage of this device is the low specific productivity of the desalination plant, since the rate of water evaporation is directly proportional to the area of the water mirror in the desalination tank. To obtain acceptable performance of the desalination plant, the manufacture of a large-diameter sealed tank is required.

The third disadvantage of this device is the low rate of condensation of water vapor in the pipeline with cold refrigerant. Condensation of water vapor occurs on the surface of cold water or on the surface of a pipeline with cold refrigerant. Due to the large surface tension of the water, droplets cannot begin to slide off the pipeline until they reach a certain size. As a result

SUBSTITUTE SHEET (RULE 26) This pipeline is covered with a significant layer of water, preventing the transfer of heat from steam to the cold pipeline.

The elimination of these disadvantages is as follows.

In order not to waste energy creating a vacuum in the tank, the Torricelli principle is used (an inverted U-shaped tube filled with water, the ends of which are lowered into the water). In this case, a reduced pressure is created in the upper part of the tube. When the length of the ends of each tube is more than 10 meters in its upper part, the water breaks, and a pressure equal to the pressure of saturated water vapor at a given temperature is established above the surface.

The sealed tank is raised to a height of approximately 10.5 meters. It has three pipelines: discharge, drain and for distilled water, the lower ends of which are below the level of desalinated water. A pump is installed on the discharge pipe, which constantly supplies fresh water to the tank, and from it the water flows by gravity back to the sea via a drain pipe. Water, under its own weight, tends to go down, but atmospheric pressure counteracts it, so the water level will drop to about 10 meters above the level of desalinated water. Above the water, a reduced pressure forms in the tank and its intense evaporation occurs.

To increase the open area of water on which evaporation occurs, plates with a slight slope relative to the horizontal position are installed inside the first tank above the water mirror, the slope of the subsequent plate having the opposite direction to the previous one. Desalinated water continuously flows from the tank onto the top plate. Water flows from the upper plate to a lower installed plate, changes the flow direction to the opposite, again flows to a lower installed plate, changes the flow direction and so on to the water level in the tank. Thus, the evaporated area of water increases tenfold. With a small tank diameter, a large evaporation area can be obtained.

The third disadvantage is eliminated as follows. The condensation rate is directly proportional to the contact area of the vapor with a cold surface. Since the area of pipelines with refrigerant is limited by the internal volume of the upper part of the desalination plant, an increase in the rate of condensation of water vapor is possible only on the surface of cold water, which is sprayed inside the upper part of the desalination plant. A drop of water, falling, captures the vapor and condenses it on itself. By increasing the amount of irrigation, you can repeatedly increase the amount of condensed water. Near the tanks is a refrigerator with two

SUBSTITUTE SHEET (RULE 26) pipelines with cold and heated refrigerants that are located inside the tanks.

A pipeline with a heated refrigerant is below the water level in the first tank and gives it its heat, and a pipe with a cooled refrigerant is below the water level in the second tank and cools it. Chilled water is pumped into the irrigation nozzles.

Brief Description of the Drawings

The invention is illustrated by two figures.

In FIG. 1 shows a desalination plant, an indoor unit, FIG. 2 shows another embodiment of a desalination plant.

The desalination plant device for the implementation of the proposed method consists of two sealed tanks 1 and 2, mounted on a stand 3, interconnected by a steam line 4. The upper parts of the tanks are above the maximum level of the water column 5 (the level of the water column in the tube, the sealed end of which is located above, and the open end is lowered into the water) relative to the level of desalinated water 6 (sea level).

Tank 1 has two pipelines: injection 7 for sea water and drain 8 for brine. Tank 2 also has two pipelines: for draining distilled water 9 and forcing for fresh water 10. The lower ends of all pipelines are located below the level of desalinated water. The injection pipeline for sea water 7 is equipped with an intake with a filter 11 and a pump 12. The injection pipeline for fresh water 10 is equipped with a shut-off device (valve) 13 and a pump 14.

The lower end of the drain pipe 8 is equipped with a locking device (valve) 15, opening or closing it.

The pipeline for distilled water 9 contains a locking device (valve) 16.

For heating desalinated water and condensation of steam, a refrigerator 17 is located next to tanks 1 and 2.

From the refrigerator 17 to the tank 1 there is a pipeline with heated refrigerant 18, which is below the water level in the tank and heats it, and to the tank 2 there is a pipeline with cooled refrigerant 19. The pipeline with cooled refrigerant 19 serves to cool distilled water, which is pumped 20 enters the nozzles 21 of the irrigation system of the tank 2.

From above, tanks 1 and 2 have non-return valves 22, which open when pressure increases in them and closes when pressure drops below atmospheric pressure and tank fullness sensors 23. These sensors indicate that the tanks are full with water. Inside

SUBSTITUTE SHEET (RULE 26) tank 1 there is a sensor for the lower limit level of water 24. The height of the lower limit level of water 25 is selected so that the pipeline with the heated refrigerant 18 is always below the water level in the tank, that is, completely closed by water.

A number of plates 26 are mounted above the water mirror, one above the other, with a slight slope relative to the horizontal position, with the slope of the subsequent one having the opposite direction to the previous one. Desalinated water is continuously supplied to the upper plate through a pipe 27, which is taken from the same tank 1 and is pumped into it. Water flows from the upper plate to a lower installed plate, changes the flow direction to the opposite, again flows to a lower installed plate, changes the flow direction and so on to the water level in the tank.

A valve 29 is installed on the steam line 4 from the side of the tank 1. The steam through the steam line 4 enters the tank 2 and enters the zone of the irrigation system with drops of cold distilled water. Cold drops fall down and capture water vapor, condensing them on yourself. Condensed distilled water flows through a conduit 9 down to a distilled water inlet basin 30. Since the outlet of the conduit 9 from the tank 2 is located above the conduit with cold refrigerant 19, the water always closes this conduit.

Embodiments of the invention.

The principle of operation of the desalination plant is to create a reduced pressure above the surface of the water, which leads to its boiling, intense vaporization and subsequent condensation of water vapor in a special receiver. Water vapor condenses and discharges into a distilled water pool 30.

In order not to waste energy on creating a vacuum in the tank, the principle of an inverted U-shaped tube filled with water, the ends of which are lowered into water, is used. Water tends to flow out of the tube, but atmospheric pressure counteracts it. In this case, a reduced pressure is created in the upper part of the tube. With a tube longer than 10 meters in the upper part, the water breaks, and a pressure equal to the pressure of saturated water vapor at a given temperature is set above the surface. Desalinated water is pumped into the tank 1 with the tap of the drain line 15. The valve 29 on the steam line 4 is closed. At the same time, fresh water is pumped into tank 2. Air dissolved in water, released from it under reduced pressure and accumulated inside the tanks, leaves through check valves 22 located in the upper parts of tanks 1 and 2. When tanks 1 and 2 are full and water starts to pour out of them through check valves, at the same time signals from

SUBSTITUTE SHEET (RULE 26) the gauges of the completeness of the tanks 23 open the taps 15 of the drain pipe and the pipeline for distilled water 16.

The refrigerator 17 is turned on, designed to cool distilled water and simultaneously heat desalinated water. The pipeline with the heated refrigerant 18 is below the level of desalinated water in the tank 1 and gives it its heat, and the pipeline with the cooled refrigerant 19 enters the tank 2 with distilled water and cools it. Cooled distilled water, using a pump 20, enters the nozzles 21 of the irrigation system of the tank 2, leaving them, it is divided into drops, which, falling down, captures water vapor, condenses them on itself and flows down the pipe 9 into the receiving pool for distilled water 30.

If you do not provide a continuous supply of fresh water to tank 1, then the salt concentration in it will increase until the salt completely precipitates. This can lead to loss of operation of the desalination plant. To prevent an increase in salt concentration above a predetermined limit, fresh desalinated water is continuously supplied to the tank 1 through the pipe 7 by the pump 12. The brine with a high concentration of salt by gravity through the drain pipe 8 is continuously removed from the tank 1.

Since dissolved air is always present in water, it will come out of the water and accumulate above the surface of the water. This is especially intense under reduced pressure. As the air escapes, the water level in the tanks will drop. When the water level drops to the pipeline with heated refrigerant 18, the capacity of the installation will begin to decrease, since the heat transfer of desalinated water will begin to decrease, and part of the heat will be transferred to the steam, reducing the efficiency of the refrigerator.

To prevent stopping the distillation, periodically remove accumulated air.

This is achieved by the fact that when lowering the water level in the tank to the maximum set level 25, the sensor of the lower limit water level 24 generates a signal by which the taps in the drain pipe 8 and the pipe for distilled water 9 are closed, and the valve 13 on the discharge pipe for fresh water 10 opens. Water through the discharge pipe 7 continues to fill the tank 1 with water and air accumulated above the surface of the water is squeezed out through the check valve 22 into the atmosphere. At the same time, the pump for fresh water 14. The water fills the tank 2 and the air accumulated above the surface of the water is squeezed out through the check valve 22 into the atmosphere.

SUBSTITUTE SHEET (RULE 26) To prevent mixing of fresh and salt water, when filling the tanks, a valve 29 is used through the steam line 4, which closes when the air is extruded.

When water begins to pour out of the tanks through the non-return valves 22, the tank fullness sensors 23 generate a signal that opens the valve 15 on the drain pipe 8 and the valve 16 on the distilled water pipe 9, the fresh water pump 14 is turned off and the discharge pipe tap 13 is closed. The check valves of the tanks 22 are closed, the water level drops, a lower pressure is again created above the water surface, and the distillation process resumes.

The second embodiment of the desalination plant is that the plates 27, designed to increase the area of the water mirror, are installed in the form of a helical surface and water flows down them.

The third embodiment of the desalination plant is that the nozzles of the irrigation system are rotated relative to the axis of the tank so that the axis of the nozzles form a single-cavity rotation hyperboloid.

Information sources:

1. Chemical encyclopedia. In 5 volumes - M.: Soviet Encyclopedia, 1988.

2. Physical encyclopedia. In 5 volumes - M.: Soviet Encyclopedia, 1988.

3. Matveev A.N. Molecular Physics: Textbook. manual for universities. - M .: Higher school, 1981.-400 s, ill.

4. Russian patent JNb 2142912, class C02F 1/04.

5. Patent of Russia N ° 2206510, class C02F 1/04.

6. Russian patent JN ° 2087421, class C02F 1/14.

7. US patent US 4880504, class B01DЗ / 10.

SUBSTITUTE SHEET (RULE 26)

Claims

Claim.

1. A device for desalination of sea water containing two sealed tanks connected by a steam line, the first tank has a discharge pipe equipped with a pump for continuously supplying desalinated water to the tank, the second tank has a pipe for distilled water, while the tanks are connected to a device for heating water and condensation its vapor, which is a refrigerator, the pipeline with a heated refrigerant which is below the water level in the first tank and gives it its heat, and the pipeline with refrigerated refrigerant is in a second tank, characterized in that the tanks are installed at a height of not less than the maximum column height of the water barometer above the level of desalinated water, to increase the area of the water mirror from which evaporation takes place, plates are installed on which the desalinated water is continuously poured, in the second tank an irrigation system with nozzles into which distilled water is colder than steam, which is cooled by a pipeline with a cold refrigerant located below the level of distilled water, One of the nozzles, the water is divided into drops, which, falling down, capture water vapor and condense them on itself, each tank has check valves and tank fullness sensors located in the upper part of the tanks and the first tank has a lower limit water level sensor, and a cover is installed on the steam line.

2. The device according to claim 1, characterized in that the plates are staggered one above the other, with a slight slope relative to the horizontal position, the slope of the subsequent plate having the opposite direction to the previous one, desalinated water is continuously pouring onto the upper plate and flowing down it falls onto the next plate, changes the direction of the current to the opposite, falls onto the next plate again changes the direction of the current to the opposite and so on to the water level in the tank.

3. The device according to claim 1, characterized in that the plates intended to increase the area of the water mirror are installed in the form of a helical surface and water flows down them.

4. The device according to p. 1, characterized in that the nozzles of the irrigation system are installed at an angle to the axis of the tank, they, twisting the flows of falling drops of water in the second tank, increase the volume of trapped and condensed steam.

SUBSTITUTE SHEET (RULE 26)

5. The device according to claim 1, characterized in that the refrigerator switches off at the signal of the lower limit water level sensor, the taps on the drain pipe of the first tank and the distilled water pipe of the second tank are closed, while the discharge pipes continue to fill the tanks with water, squeezing air accumulated above the surface of the water through the non-return valves to the atmosphere, until the sensors of the tank are triggered, upon the signal of which taps are opened on the drain pipe and the pipe for distilled water , the tank check valves are closed and the distillation process is resumed, and the lid installed on the steam line to prevent mixing of the desalinated water of the first tank and the fresh water of the second tank is closed when a signal from the lower limit water level sensor is received and opens when the water level drops below the steam line.

SUBSTITUTE SHEET (RULE 26)