JP2011005428A - Desalination apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a desalination apparatus which can be manufactured inexpensively, is less in energy loss than heretofore, and can efficiently obtain distilled water from raw water such as seawater and contaminated water.SOLUTION: In the desalination apparatus, the inside of an evaporation can 2a is divided to the upper and lower directions via a heat conduction plate 22 so as to form two distillation chambers 20a, 20b, a heating means 3 of heating raw water W1 fed to the lower distillation chamber 20a is provided, the upper distillation chamber 20b is provided with a cooling means 4 condensing water vapor in the distillation chamber 20b, further, water vapor generated in the lower distillation chamber 20a is condensed at the lower face of the heat conduction plate 22 composing the ceiling face of the lower distillation chamber 20a so as to be recovered, and further, heat of condensation generated by the condensation of the water vapor is made to conduct to the raw water W1 received on the upper heat conduction plate 20b via the heat conduction plate 22.

Description

  The present invention relates to a desalination apparatus for obtaining fresh water from raw water such as seawater, salt-containing water, and industrial wastewater by a distillation method.

  In response to the problem of depletion of water resources, interest in desalination technology is increasing worldwide. Currently, the desalination method that has become the mainstream in the industry is the so-called evaporation method in which condensed water, that is, distilled water, is obtained by condensing the generated water by evaporating the raw water using a heat source, and the raw water is pressurized through a reverse osmosis membrane. There is a so-called membrane filtration method that obtains fresh water desalted by filtration with a slag. Among the evaporation methods, the so-called multiple effect vacuum distillation method (MED), which decompresses the inside of the vessel and multiplexes the distillation chamber, can directly use the energy of solar heat, and efficiently uses fresh water using a heat source such as a heat pump. In recent years, it has been actively studied (see Patent Document 1 and Non-Patent Document 1).

By the way, as an index of energy efficiency in multi-effect vacuum distillation, there is a coefficient of performance of distillation (hereinafter referred to as “COPD”).
That is, COPD can be obtained by the following formula (1), and is 2 at maximum in the case of double effect (two evaporators).

（式（１）中、Lは蒸発潜熱 [kJ・kg^-1] 、ΣM_outは蒸留水量 [kg]、ΣQ_inは供給熱量 [kJ]をあらわす。）

(In formula (1), L represents the latent heat of vaporization [kJ · kg ^-1 ], ΣM _out represents the amount of distilled water [kg], and ΣQ _in represents the amount of heat supplied [kJ].)

  However, in order to achieve high energy efficiency using a shell-and-tube heat exchanger such as Non-Patent Document 1 and Patent Document 1, the entire length of the tube is increased and expensive titanium is used for the tube. Therefore, the apparatus becomes complicated and there is a problem in the manufacturing cost of the apparatus.

Japanese Patent No. 3698730

K. Uda et al., 1994 ASME / JSME / JSES International Solar Energy Conf, ASME Book, No.00837, 513-519 (1994)

  In view of the above circumstances, the present invention provides a desalination apparatus that can be produced at a lower cost than conventional ones, has less energy loss, and can efficiently obtain distilled water from raw water such as seawater or contaminated water. The purpose is to provide.

  In order to achieve the above object, a desalination apparatus according to the present invention comprises two or more distillation chambers, supplies raw water into each distillation chamber and reduces the pressure in a reduced pressure state by heating means. While heating to evaporate the water in the raw water, the heat of condensation released by the condensation of water vapor generated in the other distillation chamber is used as a heating source for the raw water provided in the distillation chamber other than the one distillation chamber. A heating device that heats raw water supplied to the lowermost distillation chamber by forming a plurality of distillation chambers by partitioning the inside of the evaporator vertically through a heat transfer plate. The uppermost distillation chamber is provided with a cooling means for condensing the water vapor in the distillation chamber, and the water vapor generated in the lower distillation chamber is condensed on the lower surface of the heat transfer plate constituting the ceiling surface of the lower distillation chamber. And collect It is characterized in that condensation heat generated by the condensation of water vapor was so transferred to the raw water received on the upper heat transfer plate through the heat transfer plate.

In the present invention, the material of the evaporator is not particularly limited, but it is preferable that the heat insulation is as high as possible so that the inside of the distillation chamber is not affected by the external atmosphere, and the weight and cost of the apparatus are reduced. Then, resin is preferable.
The resin forming the evaporator is not particularly limited, and examples thereof include vinyl chloride resin, polyethylene, polypropylene, ABS resin, polyester resin, polyurethane resin, foams thereof, fiber reinforced bodies, and composites thereof. A metal material may be combined as a reinforcing material.

The material of the heat transfer plate is preferably a material having high thermal conductivity, such as copper, aluminum, silver, and alloys thereof. Copper is preferable in consideration of cost and thermal conductivity.
The heat transfer plate is not particularly limited, but its lower surface is preferably inclined with respect to the horizontal plane. That is, the condensed water condensed on the lower surface of the heat transfer plate due to the inclination flows downstream along the lower surface of the heat transfer plate. And the condensed water can be easily recovered by providing a receiver of the condensed water on the downstream side.

The heat transfer plate may be corrugated or curved in order to increase the heat transfer area.
The heat transfer plate may be roughened to increase the heat transfer area or to promote boiling of raw water received on the upper surface of the heat transfer plate.

Moreover, it is preferable that the lower surface of the heat transfer plate is made hydrophilic. That is, if the condensed water droplets cover the lower surface of the heat transfer plate, the condensation heat generated by the condensation is less likely to be transferred to the raw water in the upper distillation chamber received by the upper surface of the heat transfer plate. Therefore, the condensed surface becomes hydrophilic so that water droplets generated by condensation immediately flow down from the lower surface of the heat transfer plate.
The method for hydrophilizing the heat transfer plate is not particularly limited as long as the metal plate can be hydrophilized. For example, corona treatment, plasma treatment, laser irradiation, electron beam irradiation, chemical treatment (etching), coating ( Inorganic hydrophilic treatment agent, organic hydrophilic treatment agent, photocatalyst paint) and the like.

In addition, it is preferable that the lower surface of a heat exchanger plate inclines with respect to a horizontal surface. That is, it is possible to prevent water droplets generated by condensation from flowing along the lower surface of the heat transfer plate to the downstream side of the inclination due to the inclination, and the condensed water droplets covering the lower surface of the heat transfer plate. Moreover, since the condensed water droplets are collected on the downstream side of the inclination, it is easy to collect the condensed water.
The method of inclining the lower surface of the heat transfer plate is not particularly limited, and the method of inclining the evaporator itself, as the heat transfer plate, the lower surface has an inclined structure (for example, a curved surface that gradually decreases from the center toward the peripheral wall, etc. And a method of partitioning the inside of the evaporator with the heat transfer plate in a state where the heat transfer plate is inclined.

The upper surface of the heat transfer plate is preferably subjected to water repellent treatment. That is, when the upper surface of the heat transfer plate is subjected to water repellent treatment, boiling of raw water on the upper surface of the heat transfer plate occurs actively, and water vapor can be generated more efficiently.
The method for the water repellent treatment is not particularly limited, and examples thereof include fluorine treatment, organosilicon compound treatment, and electron beam irradiation.

Although the desalination apparatus of the present invention is not particularly limited, a trap that prevents raw water droplets generated by boiling of raw water between the raw water reservoirs of each distillation chamber and the heat transfer plate from mixing into the condensed water is provided. It is preferable to provide it.
The structure of the trap is not particularly limited as long as the raw water droplets containing impurities can be prevented from being mixed into the condensed water, but water vapor can efficiently reach the heat transfer plate and efficiently recover water droplets condensed on the heat transfer plate. Therefore, for example, it is preferable to have a structure that has a vent hole at the center and has an upward convex convex umbrella shape, and the trap upper surface serves as a condensate receiving portion.

If the hole diameter is too large, droplets condensed on the heat transfer plate may return to the raw water again. If it is too small, water vapor generated from the raw water moves to the heat transfer plate side. To inhibit that. However, since the optimum diameter varies depending on the diameter of the evaporator and the inclination angle of the umbrella shape of the trap, the optimum diameter is appropriately determined empirically.
Further, when the gap between the trap vent and the surface of the raw water is narrow and there is a possibility that the splash of the raw water may be mixed into the condensed water, a demister may be further provided in the trap vent portion. .

In the desalination apparatus of the present invention, each distillation chamber is depressurized, but the pressure in the distillation chamber is not particularly limited, but non-condensable gas is exhausted, and the saturated vapor pressure of water is about 5 kPa. The pressure is preferably reduced to
In the desalination apparatus of the present invention, the raw water in the lowermost distillation chamber is heated by a heating means. Although it does not specifically limit as a heat source of this heating means, For example, an electric heater, solar heat, waste heat, a heat pump, etc. are mentioned, Solar energy, waste heat, and a heat pump are preferable when energy cost is considered.
Incidentally, in the case of a heat pump, if the heating side is arranged in the lower distillation chamber and the cooling side is arranged in the upper distillation chamber, there is no need to separately provide a cooling device.

As described above, the desalination apparatus according to the present invention has a simple structure in which a plurality of distillation chambers are simply formed by partitioning the inside of the evaporator in the vertical direction via a heat transfer plate. Can be manufactured.
Then, the water vapor generated in the lower distillation chamber is condensed and recovered on the lower surface of the heat transfer plate constituting the ceiling surface of the lower distillation chamber, and the condensation heat released by the condensation of the water vapor passes through the heat transfer plate. Since the heat is transferred to the raw water received on the upper heat transfer plate, the heat of condensation is efficiently transferred to the raw water in the distillation chamber directly above, and the raw water can be distilled with low energy consumption and high efficiency.

It is a figure showing typically one embodiment of a desalinator concerning the present invention. It is a figure showing typically one embodiment of a desalinator concerning the present invention. 4 is a graph showing the evaporation yield measured in Test Example 1 in comparison. 4 is a graph showing COPD obtained by comparison with the evaporation yield measured in Test Example 1. 6 is a graph showing the evaporation yield measured in Test Example 2 in comparison. 6 is a graph showing COPD obtained by comparison with the evaporation yield measured in Test Example 2. 10 is a graph showing COPD calculated from the evaporation yield measured in Test Example 3 in comparison.

Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof.
FIG. 1 shows one embodiment of a desalination apparatus according to the present invention.
As shown in FIG. 1, the desalination apparatus 1 a includes an evaporator 2 a, a heating unit 3, a cooling unit 4, and a decompression unit 5.

The evaporator 2a has a cylindrical synthetic resin body 21 whose upper and lower sides are closed by a top plate 21a and a bottom plate 21b, and the inside thereof is partitioned by a heat transfer plate 22 into a distillation chamber 20a and a distillation chamber 20b. ing.
The heat transfer plate 22 is made of a high heat conductive material such as copper. The upper and lower surfaces are roughened, the upper surface is water-repellent, and the lower surface is hydrophilized.
The distillation chambers 20 a and 20 b are divided into upper and lower portions by a trap 23.

The trap 23 is not particularly limited. For example, the trap 23 is formed of a synthetic resin such as polyvinyl chloride, polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, and the like. It has a substantially umbrella shape that gradually decreases toward the part.
A demister 24 is provided in the vent hole 23 a of the trap 23.
The demister 24 includes a demister main body 24a and a baffle plate 24b.
The demister main body 24a has a cylindrical shape having substantially the same diameter as the vent hole 23a formed from a metal net.
The mesh size of the demister main body 24a is set to a size that allows water vapor to pass smoothly and prevents raw water droplets from passing.
The baffle plate 24b blocks the lower end of the cylinder of the demister main body 24a, and prevents the splash of the raw water W1 generated by the boiling of the raw water W1 from entering the demister main body 24a.
In addition, it may not be provided when there is no possibility that the splash of the raw water is mixed into the condensed water, for example, because the gap between the trap vent and the surface of the raw water is wide.

The raw water supply pipe 7a and the drain pipe 7b are connected to the peripheral wall below the trap 23 of each distillation chamber 20a, 20b.
Although not shown, the raw water supply pipe 7a is connected to the raw water tank, and supplies raw water W1 such as seawater or polluted water from the raw water tank into the distillation chambers 20a and 20b.
The drain pipe 7b discharges the concentrated water concentrated by distillation and the solids contained in the concentrated water from the distillation chambers 20a and 20b.

The heating means 3 includes a heat exchange pipe 31 provided along the bottom of the lowermost distillation chamber 20a and a heat medium supply means (not shown) for supplying a heat medium to the heat exchange pipe. Yes.
The heat exchanging pipe 31 is made of a metal material having excellent corrosion resistance such as stainless steel, and is provided so as to meander along the bottom of the distillation chamber 20a or spirally.

The cooling means 4 includes a cooling pipe 41 provided along the ceiling of the uppermost distillation chamber (in this embodiment, the second-stage distillation chamber) 20b, and a chiller unit that circulates refrigerant through the cooling pipe 41 ( (Not shown).
The cooling pipe 41 is made of a metal material having excellent corrosion resistance, such as stainless steel, and is provided so as to meander along the ceiling of the distillation chamber 20b or spirally.

The decompression means 5 includes a vacuum pump 5a and a suction pipe 5b.
The suction pipe 5 b is branched into two branch pipes 51 and 51.
One branch pipe 51 faces the lowest part of the trap 23 of the lower distillation chamber 20a, and one end thereof is connected to the distillation chamber 20a.
The other branch pipe 51 faces the lowest part of the trap 23 of the upper distillation chamber 20b, and one end thereof is connected to the distillation chamber 20b.

The two branch pipes 51 are separated via a condensed water reservoir 51a provided in the middle between the upstream side (distillation chambers 20a and 20b side) and the downstream side (vacuum pump 5a side), The condensed water W2 collected on the trap 23 of the distillation chambers 20a and 20b is sucked from the distillation chambers 20a and 20b and collected in the condensed water reservoir 51a. It passes through the upper space of the container 51a and is evacuated to the vacuum pump 5a side.
In FIG. 1, 6 is a pressure gauge.

Next, the principle of the desalination method of the raw water W1 using the desalination apparatus 1a will be described in detail.
In the desalination method of the raw water W1 using the desalination apparatus 1a, first, the raw water W1 is supplied into the distillation chambers 20a and 20b through the raw water supply pipe 7a to a predetermined level.
Then, the vacuum pump 5a is operated so that the non-condensable gas is exhausted in each of the distillation chambers 20a and 20b, and the pressure is reduced until the saturated vapor pressure near the environmental temperature of water of about 5 kPa is reached.
At the same time, the raw water W1 in the lower distillation chamber 20a is heated by the heating means 3. By this heating, the non-condensable gas is exhausted in the distillation chamber 20a and the pressure is reduced to the saturated vapor pressure in the vicinity of the environmental temperature of water of about 5 kPa. Therefore, the raw water W1 in the distillation chamber 20a is near the environmental temperature and a small temperature. Boiling easily occurs due to the difference, and water in the raw water W1 in the distillation chamber 20a evaporates as water vapor.
In the distillation chamber 20a, the evaporated water vapor passes through a vent hole 23a provided in the center of the trap 23 via the demister 24 as shown by an arrow in FIG. 1, and in the space above the trap 23 in the distillation chamber 20a. It diffuses and contacts the entire lower surface of the heat transfer plate 22.
The water vapor contacting the lower surface of the heat transfer plate 22 condenses on the lower surface of the heat transfer plate 22. Then, the condensed water W2 is received on the upper surface of the trap 23, and accumulates on a portion along the inner wall surface of the evaporator 2a due to the inclination of the trap 23.
The condensed water W2 collected on the upper surface of the trap 23 is sucked into the condensed water reservoir 51a via the branch pipe 51 and stored.

On the other hand, the condensation heat is generated by the condensation of water vapor, and this condensation heat is transferred to the raw water W1 in the upper distillation chamber 20b received on the upper surface of the heat transfer plate 22 via the heat transfer plate 22.
The raw water W1 on the upper distillation chamber 20b side is heated by the condensation heat transmitted through the heat transfer plate 22, and like the raw water W1 in the lower distillation chamber 20a, the raw water W1 is easily boiled near the environmental temperature and with a small temperature difference. The water in the raw water W1 evaporates as water vapor.
The water vapor generated in the upper distillation chamber 20b in this way passes through a vent hole 23a provided in the center of the trap 23 via the demister 24 as shown by an arrow in FIG. 1, and flows into the trap 23 of the distillation chamber 20b. It diffuses in the upper space and is cooled and condensed by the cooling means 4. Then, the condensed water W2 is received on the upper surface of the trap 23, and accumulates on a portion along the inner wall surface of the evaporator 2a due to the inclination of the trap 23.
The condensed water W2 collected on the upper surface of the trap 23 is sucked into the condensed water reservoir 51a via the branch pipe 51 and stored.

Since the desalination apparatus 1a has a simple structure in which the inside of the evaporator 2a is simply partitioned in the vertical direction by the heat transfer plate 22 as described above, it can be manufactured at low cost.
In addition, the heat of condensation generated by the condensation of water vapor generated in the lower distillation chamber 20a is immediately used for heating the raw water W1 in the upper distillation chamber 20b via the heat transfer plate 22, so that energy efficiency is good.
Further, the non-condensable gas is exhausted and the saturated steam pressure of water of about 5 kPa is reduced, and the raw water W1 in the distillation chamber 20a is easily boiled near the environmental temperature and with a small temperature difference. There is no problem that the evaporator 2a undergoes thermal deformation even if it is made of a heat-sensitive synthetic resin.
In addition, since the evaporator 2a is made of synthetic resin, it has lower thermal conductivity than metal materials, can suppress heat loss to the environment and sensible heat loss due to temperature rise, and reduce the overall weight of the device. Can be planned.

FIG. 2 shows a second embodiment of the desalination apparatus according to the present invention.
As shown in FIG. 2, the desalination apparatus 1b includes an evaporator 2b that is partitioned into three evaporation chambers 20c to 20e via two heat transfer plates 22, and a heating means is provided in the lowermost evaporation chamber 20c. 3, the cooling means 4 is provided in the uppermost evaporation chamber 20 e, the heating means 3 and the cooling means 4 are not provided in the middle evaporation chamber 20 d, and the evaporator 2 b is provided on the bottom plate 21 b of the evaporator 2 b. A spacer 8 is provided below, and the lower surface of the heat transfer plate 22 is held so as to have a downward gradient of about 5 degrees in one direction with respect to the horizontal plane (in this embodiment, leftward in FIG. 2). Except that, it is the same as the desalination apparatus 1a.

  Since the desalination apparatus 1b is held so that the lower surface of the heat transfer plate 22 has a downward slope of about 5 degrees in one direction with respect to the horizontal plane as described above, the lower surface of the heat transfer plate 22 The condensed condensed water W <b> 2 immediately flows in the downward direction along the lower surface of the heat transfer plate 22. Accordingly, the water vapor is always stably condensed on the lower surface of the heat transfer plate 22.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the heat exchanger is provided in the lowermost distillation chamber as the heating means, but the bottom of the lowermost distillation chamber is used as the heat transfer plate, and the heat transfer plate and the bottom of the evaporator are used. A space that can be filled with a heating medium may be provided between and a heating medium may be circulated in the space for heating. Further, three or more distillation chambers may be provided.

Hereinafter, specific examples of the present invention will be described in detail.
[Production of test unit]
Except for not providing the demister 24, the test apparatus of the desalination apparatus is provided with two upper and lower distillation chambers 20a and 20b having the same shape as the desalination apparatus 1a shown in FIG. A to J were prepared.

(Test unit A)
[Evaporator 2a]
Material: Transparent vinyl chloride resin Shape and size: Cylindrical shape with a wall thickness of 10 mm, an inner diameter of 400 mm, and a height of 500 mm from the upper surface of the bottom plate 21b to the lower surface of the top plate 21a [Heat transfer plate 22]
Material: Copper flat plate Size: Heat transfer area 0.13 m ² , Wall thickness 0.5 mm
Partition position: Height position of 200 mm from the upper surface of the bottom plate of the evaporator 2a [Trap 23 of the lower distillation chamber 20a]
Material: Polyvinyl chloride Tilt angle: 10 °
Vent diameter: 100mm inside diameter
Lowermost height position: 100 mm height position from the upper surface of the bottom plate 21b of the evaporator 2a [trap 23 of the upper distillation chamber 20b]
Material: Polyvinyl chloride Tilt angle: 10 °
Vent diameter: 100mm inside diameter
Lowermost height position: 100 mm height position from the heat transfer plate 22 [Heating means 3]
Electric heater with maximum output of 3kW [Cooling means 4]
Cooler with heat transfer area of 0.12 m ² and cooling water circulation rate of 2.3 L / min

(Test unit B)
The test unit A was the same as the heat transfer plate 22 except that a flat copper plate whose bottom surface (surface on the lower distillation chamber 20a side) was ground with a No. 150 sandpaper and was roughened was used.

(Test unit C)
As the heat transfer plate 22, the lower surface (surface on the lower distillation chamber 20 a side) is polished by sanding with No. 150 sandpaper, and after the surface is roughened, water repellent wax (Kyowa Kogyo Co., Ltd. No. Permaluxe Super Compound) was the same as test unit A except that a flat copper plate coated with an appropriate amount so as to completely cover the surface was used.

(Test unit D)
As a heat transfer plate 22, a water-repellent wax / water-repellent wax (trade name Permaluxe Super Compound) of Kyowa Kogyo Co., Ltd. is applied to the lower surface (the surface on the lower distillation chamber 20 a side) in an appropriate amount so as to completely cover the surface. The test unit A was the same as the test unit A except that a copper plate was used.

(Test unit E)
As the heat transfer plate 22, a flat copper plate coated with an appropriate amount of hydrophilic wax (trade name WATER · X of Nishinodo Co., Ltd.) on the lower surface (the surface on the lower distillation chamber 20 a side) was used so as to completely cover the surface. Except for the above, the test unit A was the same as the test unit A.

(Test unit F)
As the heat transfer plate 22, the lower surface (surface on the lower distillation chamber 20 a side) is roughened by polishing with No. 150 sandpaper, and after the roughening, hydrophilic wax (trade name of Nishinodo Co., Ltd.) is further formed on the lower surface. WATER.X) was the same as test unit A except that an appropriate amount of flat copper plate was used to completely cover the surface.

(Test unit G)
The test unit A was the same as the heat transfer plate 22 except that a flat copper plate whose upper surface (surface on the upper distillation chamber 20b side) was polished with a No. 150 sandpaper and roughened was used.

(Test unit H)
As the heat transfer plate 22, a flat copper plate coated with an appropriate amount of water-repellent wax (Kyowa Kogyo Co., Ltd. trade name Permaluxe Super Compound) on the upper surface (the surface on the upper distillation chamber 20b side) is used. Except that, it was the same as test unit A.

(Test unit I)
As the heat transfer plate 22, the upper surface (the surface on the upper distillation chamber 20 b side) is polished by sanding with No. 150 sandpaper, and after the surface is roughened, water repellent wax (Kyowa Kogyo Co., Ltd. No. Permaluxe Super Compound) was the same as test unit A except that a flat copper plate coated with an appropriate amount so as to completely cover the surface was used.

(Test unit J)
As the heat transfer plate 22, the lower surface (surface on the lower distillation chamber 20 a side) is roughened by polishing with No. 150 sandpaper, and after the roughening, hydrophilic wax (trade name of Nishinodo Co., Ltd.) is further formed on the lower surface. Apply an appropriate amount of WATER · X) so that the surface is completely covered, and the upper surface (the surface on the upper distillation chamber 20b side) is polished with sandpaper No. 150 and roughened. Thereafter, the same procedure as in Test Unit A was performed, except that a flat copper plate coated with an appropriate amount of water-repellent wax (trade name Permaluxe Super Compound, manufactured by Kyowa Kogyo Co., Ltd.) on the upper surface was applied to completely cover the surface.

(Test Example 1)
For each of the test units A to F, 5 L of tap water as raw water is injected into the lower distillation chamber 20a, and 8 L of tap water as raw water is injected into the upper distillation chamber 20b, and the vacuum pump 5a is operated to operate each of the test units A to F. After reducing the inside of the distillation chambers 20a and 20b to the saturated vapor pressure of water, the raw water in the lower distillation chamber 20a is heated using the electric heater adjusted to 500 W output using a slidac and the cooler is operated. After confirming that the temperature of each part became constant, collection of condensed water was started, and after 1 hour, the test unit was stopped and the test for measuring the distillation yield (condensed water yield) was performed three times.
And while comparing each distillation yield calculated | required in the said Experimental example 1 and showing in FIG. 3, COPD calculated | required from each distillation yield was compared and shown in FIG.
3 and 4, normal is test unit A, file is test unit B, file + water repellent wax is test unit C, water repellent wax is test unit D, hydrophilic wax is test unit E, file + hydrophilic wax. Represents each test unit F.
3 and 4 that the desalination apparatus of the present invention has a high COPD value and high energy efficiency.
In addition, it is well understood that the energy efficiency can be improved by roughening or hydrophilizing the lower surface of the heat transfer plate, and a stable improvement in energy efficiency can be seen by combining the roughening and hydrophilization.
Furthermore, when the state of the lower surface side (condensation side) of the heat transfer plate 22 of each test unit B to F was visually observed from the outside of the evaporator 2a, the roughened test unit B, the hydrophilized test unit E, The test unit F, which was roughened and hydrophilized, had a film condensation aspect on the lower surface, and the condensed water fell smoothly and the condensation was promoted. On the other hand, the lower surfaces of the water-repellent test units C and D were droplet condensation. Originally, the drop condensation is characterized in that the condensed water W2 on the lower surface of the heat transfer plate 22 is wiped off when the water droplet is detached, and the lower surface of the heat transfer plate 22 is exposed. They remained stagnant in the place where they occurred and were not seen to leave very much.
From this, it is considered that the lower surface of the heat transfer plate 22 is preferably roughened, hydrophilized, or roughened and hydrophilized.

(Test Example 2)
For each of the test units A and G to I, 5 L of tap water as raw water is injected into the lower distillation chamber 20a, and 8 L of tap water as raw water is injected into the upper distillation chamber 20b. After operating and depressurizing each distillation chamber 20a, 20b to the saturated vapor pressure of water, the raw water in the lower distillation chamber 20a is heated using the electric heater adjusted to an output of 500 W using a slidac, Start the cooler and confirm that the temperature of each part has become constant, start collecting condensed water, stop the test unit one hour later, and measure the distillation yield (condensed water end) three times each It was.
Then, the respective distillation yields obtained in the test example 2 were compared and shown in FIG. 5, and the COPD obtained from each distillation yield was compared and shown in FIG.
5 and 6, normal represents the test unit A, file represents the test unit G, water repellent wax represents the test unit H, and file + water repellent wax represents the test unit I.
5 and 6 that the desalination apparatus of the present invention has a high COPD value and high energy efficiency.
In addition, it can be seen that if the upper surface of the heat transfer plate is roughened or water repellent, the energy efficiency is improved, and if the surface roughening and water repellent are used in combination, stable energy efficiency is improved.
Furthermore, about each test unit of said test unit GI, when the state of the upper surface side (boiling side) of the heat-transfer plate 22 of each test unit was observed visually from the outer side of the evaporator 2a, the test roughened In the case of unit G, although the number of bubbles immediately after the start of boiling was small, bubbles were generated from many places on the surface compared to others when the steady state was reached. In addition, in the case of the test unit H with water repellency, the amount of bubbles generated was larger than immediately after the start of boiling compared to the others. However, when the raw water temperature reaches a steady state, the places where boiling occurs are limited. In the case of the test unit I having a roughened surface and water repellency, the above two characteristics appeared and boiling occurred actively.
From this, it is considered that the upper surface of the heat transfer plate 22 is preferably roughened and water repellent.

(Test Example 3)
For each of the test units A and J, tap water 5L as raw water is injected into the lower distillation chamber 20a, and tap water 8L as raw water is injected into the upper distillation chamber 20b, and the vacuum pump 5a is operated. After reducing the inside of each distillation chamber 20a, 20b to the saturated vapor pressure of water, the raw water in the lower distillation chamber 20a is changed using the electric heater by changing the output in increments of 100W from 300W to 1000W using a slidac. Test to start distillation, collect condensed water after confirming that the temperature of each part became constant, and stop the test unit after 1 hour and measure the distillation yield (condensed water end) Went to each.
Then, COPD was calculated based on the obtained distillation yield, and the result is shown in FIG. In FIG. 7, “non-treated surface” represents the test unit A, and “tated surface” represents the test unit J.
As shown in FIG. 7, in the system to which a heat amount of 900 W is applied, not only the test unit J but also the test unit A can be obtained with considerably high energy efficiency. It can be seen that a high energy efficiency of 86 and a COPD of 100% efficiency is almost close to the maximum value of 2. For test unit J, the distillation yield was about 2.7 L / h in the system to which a heat of 900 W was applied, and the distillation yield was improved by 33% compared to test unit A.
Further, in the system to which the heat amount of 900 W of the test unit J was added, the temperature of the cooling water at the inlet of the cooler, the temperature of the cooling water at the outlet of the cooler, the raw water temperature of the lower distillation chamber 20a, the steam temperature of the lower distillation chamber 20a, the upper distillation When the temperature change from the test start to the end of each of the raw water temperature of the chamber 20b, the water vapor temperature of the upper distillation chamber 20b, the lower surface temperature of the heat transfer plate 22, and the upper surface temperature of the heat transfer plate 22 was examined, The maximum temperature difference between the raw water temperature in the lower distillation chamber 20a and the cooling water in the cooler cooler is only about 20 ° C., and it can be determined that highly efficient distillation was performed with a relatively small temperature difference.

  Although the desalination apparatus concerning this invention is not specifically limited, For example, it can be used for desalination of well water contaminated by desalination of seawater etc. or arsenic.

1a, 1b Desalination devices 2a, 2b Evaporators 20a, 20b, 20c, 20d, 20e Distillation chamber 22 Heat transfer plate 23 Trap 23a Vent 24 Demister 3 Heating means 4 Cooling means 5 Decompression means W1 Raw water W2 Condensed water

Claims (8)

Two or more distillation chambers are provided, and raw water is supplied to each distillation chamber and the pressure is reduced, and the raw water in one distillation chamber is heated by heating means to evaporate the water in the raw water. A desalination apparatus that uses the heat of condensation emitted by condensation of water vapor generated in another distillation chamber as a heating source of raw water provided in a distillation chamber other than the chamber,
A plurality of distillation chambers are formed by partitioning the inside of the evaporator vertically with a heat transfer plate, and heating means for heating the raw water supplied to the lowermost distillation chamber is provided. In addition to providing a cooling means for condensing the water vapor in the distillation chamber, the water vapor generated in the lower distillation chamber is condensed and recovered on the lower surface of the heat transfer plate constituting the ceiling surface of the lower distillation chamber. The desalination apparatus characterized in that the generated condensation heat is transmitted to the raw water received on the upper heat transfer plate via the heat transfer plate.   The desalination apparatus according to claim 1, wherein the evaporator is formed of a resin.   The desalination apparatus of Claim 1 or Claim 2 in which the lower surface of a heat exchanger plate inclines with respect to a horizontal surface.   The desalination apparatus according to any one of claims 1 to 3, wherein at least one of the upper and lower surfaces of the heat transfer plate is roughened.   The desalination apparatus in any one of Claims 1-4 by which the lower surface of the heat exchanger plate was hydrophilically processed.   The desalination apparatus according to any one of claims 1 to 5, wherein an upper surface of the heat transfer plate is subjected to water repellent treatment.   The desalination apparatus in any one of Claims 1-6 with which the trap which prevents that the raw | natural water splash which generate | occur | produces by boiling of raw | natural water mixes in condensed water is provided in the distillation chamber.   The desalination apparatus according to claim 7, wherein the trap has a substantially umbrella shape having a vent hole in the center and is convex upward, and the trap upper surface serves as a condensate receiving portion.

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