JPH10216702A - Fresh water making method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and inexpensively produce fresh water by reducing energy consumption to a large extent. SOLUTION: Raw water 1 is allowed to pass through a distillation tank 2 and the distillation tank 2 is reduced in pressure to generate steam which is, in turn, condensed by a chiller 7 to recover fresh water. At this time, raw water 1 is passed through the multistage distillation tank 2 and the vacuum pump 9 arranged in the respective distillation tanks 2 are driven to reduce the pressure in the distillation tanks 2 to generate steam which is, in turn, condensed and recovered by the chiller 7 or raw water heated by a heat exchange means is introduced into the distillation tank 2 and energy required in the reduction of pressure is supplied from a solar cell 6 or a solar hot water device may be utilized as the heat exchange means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for obtaining inexpensive fresh water from turbid water such as seawater or muddy water.

[0002]

2. Description of the Related Art Conventionally, in ships and deserts, seawater is evaporated and the distilled water is used for domestic water such as drinking water and desert greening using a water retention agent. The conventional fresh water production equipment used for this purpose is to burn sea oil at normal temperature by burning oil, cool and recover the steam generated by this, and obtain fresh water directly from sea water by ion exchange resin or reverse osmosis membrane. is there.

[0003]

In the former method, a large amount of heat energy is required to heat seawater to obtain steam, and the heat energy is relied on oil combustion. Therefore, where fresh water is originally required for desert greening, an enormous amount of carbon dioxide is discharged in order to produce it. Also,
The cost is also very high, and fresh water is more expensive than gasoline in the Middle East.

[0004] In the latter method, the exchange frequency of the ion-exchange resin becomes extremely high due to the extremely high ion concentration in seawater, which increases the cost. As a result, as in the former method, fresh water becomes higher than gasoline. Inviting the current situation.

[0005]

[Means for Solving the Problems] In response to the current situation,
An object of the present invention is to produce fresh water efficiently and inexpensively by greatly reducing energy consumption. The above-mentioned problem can be solved by allowing the raw water to pass through the distillation tank, depressurizing the distillation tank to generate the above-mentioned water, and condensing this by a chiller to recover fresh water. Here, the raw water is passed through the multi-stage distillation tanks, and the vacuum pumps installed in the respective distillation tanks are driven to reduce the pressure in the distillation tanks to generate steam. Or in the distillation tank,
A method may be adopted in which the raw water heated by the heat exchange means is introduced and the energy required for decompression is supplied from a solar cell, or a solar water heater may be used as the heat exchange means.

Next, the operation of the present invention will be described. For example, seawater boils at 100 ° C. at a standard atmospheric pressure of 760 torr and becomes steam. On the other hand, under reduced pressure, the pressure causes a boiling point drop, and the lower the pressure, the lower the boiling point. Therefore, when heated water is introduced into a distillation tank which is closed to some extent, and the pressure is reduced by a vacuum pump or the like, the water can be boiled with an extremely small amount of energy. On the other hand, in order to maintain a certain amount of processing, the distillation tank must be set as large as possible.However, when the distillation tank is large, the vacuum pump used for decompression must be large. Is also taken into account. By adopting such a configuration, it is possible to use an inexpensive and highly versatile vacuum pump. By the operation of the present invention, the energy required for generating steam can be significantly reduced as compared with the conventional combustion method under the atmospheric pressure.

Seawater moves in a distillation tank separated by a partition wall, and the final distillation tank is in a state where seawater is most concentrated. However, by returning seawater that has been concentrated to some extent to the sea through a drain pipe without collecting salt, it is possible to prevent the drain pipe from being clogged with precipitated salt. By driving a vacuum pump arranged in each of the separated distillation tanks, seawater can be efficiently boiled and steam can be generated. Therefore, the higher the temperature of the seawater supplied to the distillation tank, the smaller the vacuum pump can be. That is, if the seawater is heated to around its boiling point of 100 ° C. by some means, it will boil at the atmospheric pressure of 760 torr. On the other hand, in desert areas such as the Middle and Near East, it is a common phenomenon that accumulated water in drums reaches about 70 ° C. to 80 ° C. during daytime when the temperature rises. In such a case, use a vacuum pump for 200
By reducing the pressure to about 300 torr, seawater can easily boil to obtain fresh water.

[0008] In Japan, the number of areas suffering from water shortages in summer has recently increased, but this phenomenon is not merely a phenomenon observed only in urban areas but occurs everywhere in Kyushu and Shikoku. Even in Japan, the accumulated water in the drum can easily reach a temperature of 30 ° C. or more in summer, so that by reducing the pressure to about 40 torr, the boiling point is reached and fresh water can be obtained.

In general, a vacuum pump requires some drive energy for initial evacuation as long as the container is kept sufficiently sealed. However, in a steady state, sufficient energy is required to maintain the degree of vacuum. is there. Here, when the seawater introduced into the distillation tank boils, the heat of vaporization is taken away, so that the temperature of the seawater decreases somewhat. When the temperature is lowered, the boiling point is not maintained at the same degree of vacuum. Therefore, for example, new heated seawater only to compensate for the temperature reduction may be supplied. Therefore, the supply amount of seawater to the distillation tank and the capacity of the vacuum pump may be appropriately set so as to achieve the above balance. Due to such a configuration, the amount of energy required for running is small. Compared with the conventional method of increasing the temperature of seawater to the boiling point (100 ° C.) of normal pressure (atmospheric pressure), the energy is extremely small. Thus, steam can be generated efficiently.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows an embodiment for realizing the present invention. 1 is seawater, 2
Is a distillation tank (the number of tanks is n) separated by a plurality of partition walls, which pumps seawater 1 from a mainstream seawater suction pipe 3 by a pump 4 and serves as a tributary heat exchange panel serving as a heat exchange means using the principle of a solar water heater. It is introduced into the distillation tank 2 through the section 5. The seawater 1 is heated by the solar heat in the tributary heat exchange panel 5, and in Japan, the temperature is raised to about 30 ° C. in summer and to about 70 ° C. in regions such as the Middle and Near East.
Will be introduced within. Reference numeral 6 denotes a solar cell array for driving a vacuum pump, which is arranged on the roof of the distillation tank 2 in the illustrated example. Reference numeral 7 denotes a cooling chiller device, and a chiller tube 8 is arranged near the upper ceiling in the distillation tank 2.

Seawater slowly moves in the distillation tank 2 from the left side to the right side tank in the drawing. The inside of the distillation tank 2 separated by each partition is kept in a reduced pressure state by a vacuum pump 9 driven by electric power from a solar cell array.
Vapor of fresh water distilled under reduced pressure is condensed in the cooling chiller device 7 and is recovered as fresh water by a large number of toys 10 arranged above the distillation tank 2. The residual liquid in which the salt is concentrated in the distillation tank 2 is supplied to the tributary drain pipe 1 directly connected to the final tank.
1 and returned to the sea as drainage through the mainstream drainage pipe 12. Reference numeral 13 denotes an electric control box containing a battery for storing power from the solar cell array 6. In this embodiment, it is installed in the desert 14, but this can be carried out on a ship sailing on the ocean. Also, as shown in this example, a plurality of freshwater production units A of the example shown can be connected to one mainstream seawater suction pipe 3 and one mainstream drainage pipe 12.

Here, the principle of producing fresh water from seawater by distillation will be described again in detail. Although the vapor pressure characteristics of seawater and general water are strictly different, it does not matter much without citing the vapor pressure characteristics of seawater composed of various complex composition systems in various places. Therefore, the principle of the present invention can be explained as follows by the vapor pressure characteristics of water shown in FIG. In FIG. 2, if the seawater is heated to 100 ° C., it boils at 760 torr, which is a normal pressure of 1 atm, and is evaporated and vaporized to obtain fresh water. However, in tropical regions such as the Middle East, the seawater that is pumped is heated to around 70 ° C. in a short time by irradiation with sunlight. Therefore, it can be boiled at about 250 torr at point A in the figure. On the other hand, in Japan in summer, the temperature of the pumping water is about 30 ° C., and the water boils at point B of 45 torr.

In the embodiment of the present invention, all of the electric components such as a pump and a vacuum pump, and sensors (not shown) such as a temperature sensor and a liquid level sensor are driven by solar cells. The electric energy is converted into electric energy by the solar cell array 6 and stored in the battery housed in the electric control box 13. The seawater 1 is pumped by the pump 4 and is heated by the irradiation of sunlight while slowly flowing through the tributary heat exchange panel 5. The heated seawater slowly moves inside the distillation tank 2 from left to right. The vacuum pump 9 installed in each distillation tank 2 partitioned by the partition wall maintains the pressure in the space of the distillation tank 2 at a vacuum degree according to the vapor pressure characteristic of FIG. Steam is generated in the space of the tank 2. Since the cooling chiller tube 8 is provided at the upper portion, the steam condenses at the upper portion to become fresh water.
The fresh water is received by a plurality of toys 10 arranged in multiple stages, collected in a storage tank, and used for drinking water, living water, or desert greening.

Since a plurality of vacuum pumps P1, P2,... Pn are arranged, the distillation tank 2 divided by each partition is provided.
Fresh water is extracted from the inside, but the salt in the seawater that flows in from the left is concentrated as it goes to the right. The seawater in the final tank is quickly returned to the sea by the tributary drainage pipe 11 and the mainstream drainage pipe 12 to avoid problems such as clogging of the pipe due to salt. However, when salt formation is performed, the concentrated seawater may be boiled down in another container.

[0015]

According to the present invention as described above,
Since fresh water is produced by efficiently generating steam by reducing the pressure, the cost can be significantly reduced as compared with the conventional heating method. This is because much less energy is required for depressurization than generating steam by oil combustion under normal pressure. In addition, by keeping the distillation tank separated by a plurality of partition walls in a reduced pressure state with a vacuum pump using a solar cell, fresh water can be obtained extremely inexpensively and without discharging carbon dioxide gas. Using this method, a mobile desalination ship equipped with this device can be built on board to deal with the water shortage in summer, to easily produce drinking water and living water for ships required for navigation, and Has a wide variety of uses and uses, such as contributing to greening of the desert.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a fresh water producing apparatus for realizing the present invention.

FIG. 2 is an explanatory diagram of vapor pressure characteristics of water.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 seawater 2 distillation tank 3 mainstream seawater suction pipe 4 pump 5 tributary heat exchange panel section 6 solar cell array 7 cooling chiller device 8 chiller tube 9 vacuum pump 10 toy 11 tributary drainage pipe 12 mainstream drainage pipe 13 electric control box 14 desert A fresh water Production unit

Claims (4)

[Claims] Claims: 1. A feed water is passed through a distillation tank.
A fresh water production method in which the distillation tank is depressurized to generate steam, which is condensed by a chiller to recover fresh water. 2. The raw water is passed through a multi-stage distillation tank, and a vacuum pump installed in each distillation tank is driven to reduce the pressure in the distillation tank to generate steam, which is condensed and recovered by a chiller. The fresh water production method according to claim 1, wherein fresh water is obtained by heating. 3. The fresh water production method according to claim 1, wherein the raw water heated by the heat exchange means is introduced into the distillation tank, and energy required for decompression is supplied from the solar cell. 4. The method for producing fresh water according to claim 3, wherein a solar water heater is used as the heat exchange means.