JPS61271081A - Seawater desalination equipment - Google Patents

Abstract

PURPOSE:To obtain the titled seawater desalination apparatus with less consumption of energy and with less problems in the operation by functionally connecting an evaporator, an absorber, a regenerator and a condenser. CONSTITUTION:An evaporator 10 provided with a supply and a discharge port of seawater is separated into a vapor phase part 14 and a liq. phase part 16 by sea level, a salt soln. 22 whose salinity is made higher than that of seawater is charged in an absorber 20, a vapor phase part 24 between a liq. phase part 26 and the vapor phase part 24 both separated by the level of the salt soln. is communicated with the vapor phase part 14 of the evaporator 10. The slat soln. of the absorber 20 is received by the succeeding regenerator 30, a part of water in the salt soln. is vacuum-evaporated, the remaining salt soln. is returned to the absorber 20 and the steam vacuum-evaporated in the regenerator 30 is cooled and condensed by seawater from the evaporator 10 in a condenser 40. Consequently, a seawater desalination apparatus with less energy consumption and with less problems in the operation can be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a seawater desalination device.

[Conventional technology and its problems]

Known methods for desalinating seawater include heating and evaporating seawater under normal pressure or reduced pressure, and using a reverse osmosis membrane. However, the evaporation method consumes a large amount of energy to heat and evaporate seawater, and also requires a large cold source to condense the steam. Although the reverse osmosis membrane method does not require a heat source, it has operational problems such as a reduction in the amount of permeated water due to scale adhesion to the membrane surface, membrane deterioration, and an increase in the salt concentration of the permeated water. 10Kg/
It had to withstand a high pressure of 1 wr" (it had the disadvantage that the construction cost of the equipment was also high).

[Means for solving problems]

The object of the present invention is to solve the above-mentioned problems of the prior art.

An object of the present invention is to provide a seawater desalination device that consumes less energy (and has fewer operational problems).

The present invention includes an evaporator that is equipped with a seawater supply port and a seawater discharge port, and is divided into a gas phase portion and a liquid phase portion by the seawater level, and houses a salt solution prepared at a concentration higher than that of seawater,
an absorber in which a gas phase part of a gas phase part and a liquid phase part divided by the liquid level of the salt solution communicates with the gas phase part of the evaporator; and receiving the salt solution in this absorber; A regenerator is configured to evaporate part of the water in the salt solution under vacuum and return the remaining salt solution to the absorber, and the steam evaporated under vacuum in the regenerator is cooled by seawater from the evaporator. , and a condenser for condensation.

FIG. 1 is a diagram showing the principle of the present invention. Seawater is supplied to the evaporator 10 through a pipe 12, and a gas phase portion 14 and a liquid phase portion 16 are divided by the seawater level. The absorber 20 contains a salt solution 22 prepared to have a salt concentration higher than that of seawater, and a gas phase portion 24 and a liquid phase portion 26 are divided by the liquid level of the salt solution. The gas phase section 24 and the gas phase section 14 of the evaporator 10 communicate with each other through a communication pipe 18. The regenerator 30 includes the absorber 20
The salt solution from the absorber 20 is supplied by line 28 to maintain a vacuum inside the vessel, and the salt solution is returned to the absorber 20 by line 32. The condenser 40 communicates with the regenerator 30 through a communication pipe 34, and seawater from the evaporator 10 is introduced through a pipe 42 to form a cooling coil 44. The condenser 40 also includes a fresh water discharge line 46 .

[For production]

Seawater is supplied to the evaporator 10 from the pipe 12.

Based on the vapor pressure difference with the highly concentrated salt solution 22 accommodated in the absorber 20, a portion of the water in the seawater evaporates, condenses it, and is cooled by taking away the latent heat of vaporization.

The water vapor evaporated in the evaporator 10 passes through a communication pipe 18.

It flows into the absorber 20 and is absorbed by the salt solution 22.

Therefore, the salt solution is diluted and its temperature increases due to latent heat of condensation. The salt solution supplied from the pipe line 28 to the regenerator 30 is cooled under vacuum, with some of the water in the solution evaporating and the latent heat of vaporization being removed. For this reason,
The salt solution returning from the regenerator 30 to the absorber 20 maintains a constant salt concentration and temperature. The water vapor evaporated in the regenerator 30 flows into the condenser 40 through the communication pipe 34, and then flows into the condenser 40.
is cooled by a cooling coil 44 of seawater cooled by
Condenses and produces fresh water.

The heat balance and material balance of the device according to the present invention are modeled and shown in FIG. Figure 2 ignores the amount of heat dissipated from the equipment and the mechanical loss due to feeding the liquid, and the upper row shows the amount of material and the lower row shows the amount of heat using lead lines for the pipes connecting each device. . The amount of heat is shown based on room temperature. As is clear from FIG. 2, the quantity M of seawater supplied to the evaporator 10 can be finally separated into the quantity m of fresh water and the quantity M - m of concentrated seawater. During this time, each device exchanges heat amounts of +Q and -Q as latent heat or sensible heat, respectively, and in principle no external heat source or cold source is required. In Figure 9, R is the amount of salt solution circulated back and forth between the absorber 20 and the regenerator 30, which is determined based on design conditions.

〔Example〕

FIG. 3 shows an example of a system diagram for implementing the present invention. In the figure, parts given the same reference numerals as in FIG. 1 indicate constituent elements having the same meaning as explained in FIG. 1. Evaporator 10
Seawater is continuously sprayed from the pipe 12. Since the evaporation area of seawater increases by the spraying, evaporation in the evaporator 10 is performed efficiently. This evaporator 10 evaporates water.

Concentrated seawater is continuously discharged from the apparatus through the pipe 13. The amount of concentrated seawater discharged is controlled based on, for example, a signal from a liquid level gauge (not shown) so that the water level in the liquid phase portion 16 is constant. The steam evaporated in the evaporator 10 is transferred to the communication pipe 1
8 into the gas phase section 24 of the absorber 20 and is absorbed by the highly concentrated salt solution 22. 9 as high concentration salt solution 22
For example, a saline solution with a salt concentration of 20% is used. Instead of saline, a lithium bromide solution, which is commonly used in absorption refrigeration equipment, may be used. The salt solution diluted by absorption of vapor is sprayed by pump 27 from line 28 to regenerator 30 . After some of the water is evaporated and concentrated, it is sprayed again into the absorber 20 from the line 32 by the pump 31. Since the salt solution is atomized and supplied to each device in this way, the absorption rate and regeneration rate are increased, and the efficiency of the device can be improved. Since the flow rate of the salt solution circulating through the absorber 20 and the regenerator 30 is sufficiently large compared to the amount of water absorbed or evaporated, the concentration and temperature of the salt solution on the outbound and return passes are not significantly different.

In the regenerator 30, the salt solution is slightly concentrated and the temperature is slightly reduced. In the absorber 20, on the contrary, the salt solution is slightly diluted and the temperature rises slightly. For this reason, the salt solution repeats the above changes.

It is always maintained in a constant state in the absorber and regenerator. The regenerator 30 is maintained at room temperature under a vacuum such that water in the sprayed salt solution can efficiently evaporate. The steam evaporated in the regenerator 30 flows into the condenser 40, where it is cooled and condensed into fresh water. Cooling coil 44 of condenser 40
Seawater cooled by evaporation of moisture in the evaporator 10 is used as the cooling fluid. In order to efficiently exchange heat in the condenser 40, the larger the difference between the temperature of the inflowing steam and the temperature of the seawater, which is a source of cold heat, the better. Therefore, the seawater from the evaporator 10 is first sent to the cooling tower 48 by the pump 47, where it is
The recooled seawater is sent to the cooling coil 44 via the pipe 42 by the pump 49. The seawater that has indirectly exchanged heat with the steam in the cooling coil 44 is returned to the evaporator 10 via a pipe 50.

Note that a vacuum pump 51 is attached to the condenser 40. This vacuum pump 51 is used to create a desired degree of vacuum in the regenerator 30 and condenser 40 at the beginning of operation, and after the device is started, the valve 52 is closed to stop the operation. When the device is in operation, the steam evaporated in the regenerator 30 is sequentially condensed in the condenser 40.

The degree of vacuum within the regenerator 30 can be maintained at a desired value.

The degree of vacuum inside the regenerator 30 may decrease due to dissolved oxygen in seawater, etc., so in this case, the vacuum pump 51
operate intermittently. A vacuum gauge may be provided in the regenerator 30 or the condenser 40, and the operation of the vacuum pump 51 may be automatically controlled based on a signal from the vacuum gauge. The fresh water obtained in the condenser 40 is taken out to the outside from a pipe 54 via a pipe 46 (via a water head tank 53). The entire apparatus may be operated in a vacuum system by connecting the vacuum pump 51 and the absorber 20 to the pipe 5.
5 and by opening the valve 56 as necessary, the gas phase portions of the evaporator 10 and absorber 20 are maintained at a desired degree of vacuum. The evaporation action of the evaporator 10 is achieved by creating a vacuum in the gas phase.

The absorption action in the absorber 20 becomes active, and the operating efficiency of the device improves. Evaporator and absorber system.

If a pressure difference of more than a predetermined value occurs between the regenerator and condenser systems, it is automatically detected and both systems have almost the same degree of vacuum, or the evaporator and absorber systems However, it is even more preferable to provide a mechanism for automatically controlling the degree of vacuum to a high degree.

In the embodiment described above, seawater re-cooled in the cooling tower 48 was used as a cold source for the cooling coil 44, but the cooling tower is not essential and may be omitted. Further, instead of the cooling tower, another seawater recooling means may be provided.

Further, as shown in FIG. 4, a steam coil 57 is installed in the liquid phase part of the evaporator 10, and the regenerator
The steam generated may be passed through and condensed.

In other words, in the case of one example.

The steam coil 57 is a condenser, and the evaporator 10 and the condenser are integrated. Seawater in the evaporator 10 is circulated and atomized by a pump 58. In addition, at the outlet of the steam coil 57,
By providing a cooler 59 and exchanging heat with cooling water 60 as necessary.

The steam generated in the regenerator 30 is completely condensed.

〔Effect of the invention〕

As described above, according to the present invention, the energy for operating the device is the power of the pump that supplies seawater or salt solution,
It is powered by a vacuum pump that operates intermittently to maintain an auxiliary cold source and equipment in a vacuum, making it possible to obtain fresh water from seawater with less energy. In addition, because there is no operation at high temperatures or high pressures, and the seawater is discharged from the equipment in a slightly concentrated state, this problem frequently occurs with conventional seawater desalination equipment. There are also fewer problems with scale and other operational problems.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing the principle of the present invention, FIG. 2 is a balance diagram showing a modeled material balance and heat balance of the invention, and FIG. 3 is a system diagram showing an embodiment of the invention. FIG. 4 is an apparatus system diagram showing another embodiment of the present invention. 10... Evaporator 14... Gas phase section 16...
・Liquid phase part 18...Communication pipe 20...Absorber 22...Salt solution 24...Gas phase part
26...Liquid phase section 30...Regenerator 40.
··Condenser. Figure 1 Figure 3

Claims (2)

[Claims] (1) An evaporator equipped with a seawater inlet and a discharge port and divided into a gas phase and a liquid phase by the seawater level, and a salt solution containing a salt solution with a concentration higher than that of seawater. An absorber in which a gas phase part of a liquid phase part and a gas phase part divided by the liquid level of the solution communicates with the gas phase part of the evaporator, and a salt solution in this absorber is received. , a regenerator configured to vacuum evaporate part of the water in the salt solution and return the remaining salt solution to the absorber; A seawater desalination device consisting of a condenser that cools and condenses seawater. (2) Claim 1, characterized in that the condenser is installed inside the evaporator, and the evaporator and condenser are integrated.
The seawater desalination equipment described in Section 1.