JP2004000887A - Seawater desalting method, seawater concentrating method and apparatus, desalted deep seawater and concentrated deep seawater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method which adjusts the amount of a solute contained corresponding to the use of obtained fresh water or concentrated seawater when fresh water or concentrated seawater obtained from deep seawater is utilized for various commodities and performs the efficient desalting and concentration of seawater at normal pressures, and also to provide an apparatus therefor. <P>SOLUTION: Seawater sampled from deep sea is injected in the vacuum chamber of a vacuum tank wherein a steam chamber is provided around the vacuum chamber through a heat transfer wall and steam overheated to a boiling temperature or higher by high frequency heating under atmospheric pressure is supplied to the steam chamber to heat seawater in the vacuum chamber. Thereby, moisture in seawater is evaporated and condensed to obtain fresh water. Further, concentrated seawater remaining in the vacuum chamber is taken out and, if necessary, moisture of concentrated seawater is further evapolated to obtain salt. Moisture of seawater can be separated in a short time. The content of a solute in distilled water is increased when the vacuum degree of the vacuum chamber is raised, and reduced when lowered. By utlizing such operation, a ratio of a mineral component in the obtained fresh water or concentrated seawater can be changed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is particularly suitable for utilizing seawater (deep water) collected from the deep sea as a raw material or additive of products such as foods, beverages, seasonings, cosmetics, etc. The present invention relates to a method and an apparatus, and to a desalinated deep water and a concentrated deep water (including salt) obtained by the method, which are characterized by heated steam serving as a heat source when evaporating seawater moisture to desalinate or concentrate. Some of the above methods and apparatus and products.
[0002]
[Prior art]
It has been practiced since ancient times to evaporate and condense water in seawater to make it desalinated and to further heat the remaining concentrated seawater to obtain salt. The use of steam for heating the liquid is also a commonly used technique. In the case of steam heating, unless the temperature of the heating steam is somewhat higher than the boiling temperature of the liquid to be heated, rapid heat transfer cannot be expected, and efficient processing cannot be performed. In the evaporation of water in seawater by steam heating, it is necessary to make the temperature of the heating steam higher than the boiling point of water, so pressurized pressure steam is used. Therefore, a heating vessel, a boiler for generating steam, or the like is a pressure vessel, and it is necessary to consider strength and airtightness.
[0003]
Further, since deep water collected from the deep sea contains a mineral component different from ordinary seawater, drinking water, cosmetics, and the like using mineral-containing water obtained by desalinating or reducing the salt are commercialized. Conventionally, as a method for desalinating or concentrating deep water, an ion exchange method (JP-A-2001-212864), a refrigeration method (JP-A-2001-129542), an electrolysis method (JP-A-2000-23646), and reverse osmosis. (Japanese Patent Laid-Open No. 2000-354864) and the like have been proposed.
[0004]
[Problems to be solved by the invention]
The present invention relates to the use of freshwater or concentrated seawater or salt obtained from deep water for various products, the proportion of solutes (salts or minerals) contained in the freshwater or concentrated seawater depending on the intended use. It is an object of the present invention to provide a method and an apparatus capable of adjusting the water content and efficiently performing desalination and concentration or salt production at normal pressure, and to provide desalinated deep water and concentrated deep water obtained by the method.
[0005]
[Means for Solving the Problems]
The seawater desalination method according to the invention of claim 1 of the present application that solves the above-mentioned problem is characterized in that seawater is supplied to the decompression chamber of the decompression tank 1 provided with a steam chamber 14 around the decompression chamber 13 with a heat transfer wall 11 interposed therebetween. Injecting seawater collected especially from the deep sea, supplying normal-pressure steam superheated to a boiling temperature or higher by high-frequency heating to the steam chamber, heating the seawater in the decompression chamber and evaporating the water in the seawater. This is condensed to obtain fresh water.
[0006]
The method for concentrating seawater according to the invention of claim 5 of the present application is to obtain concentrated seawater remaining in the decompression chamber after the step of evaporating water by heating the seawater in the decompression chamber 13. In addition, the salt producing method according to the invention of claim 10 is to further evaporate the water content of the concentrated seawater to obtain a salt.
[0007]
In the method for concentrating seawater according to the invention of claim 6 of the present application, seawater desalinated by the ion exchange method or the method of claim 1, 2 or 3 is preferably stored in the decompression chamber 13, and particularly preferably the method described above. Inject deep water desalinated in the above, supply steam at normal pressure superheated to a boiling temperature or higher by high frequency heating to the steam chamber, heat the desalinated seawater in the decompression chamber to remove the water in the desalinated seawater. Is evaporated to obtain concentrated desalinated seawater remaining in the decompression chamber.
[0008]
As a means for obtaining superheated normal-pressure steam, a method of spraying water on air passing through a high-frequency coil and a method of passing saturated steam generated by a boiler through a steam pipe around which the high-frequency coil is wound are preferred in practice.
[0009]
Further, the seawater concentrating apparatus of the present invention used for carrying out the above-mentioned concentrating method has a heat transfer wall 11 having a large number of folds 10 in a direction parallel to the rotation center axis to form a surrounding steam chamber 14 and a decompression chamber 13 inside thereof. The partitioned rotary drum 1, the seawater inlet 23 opening to the decompression chamber 13 via the rotary joint 19L, the vacuum suction port 22 opening to the decompression chamber via the rotary joint 18L, and the rotary joints 18R and 19R. A heating steam supply port and a discharge port 39 and 40 that open to the steam chamber 14 via the heating chamber 14, and a high-frequency coil 32 provided in a steam supply pipe 30 connected to the heating steam supply port.
[0010]
Further, in the seawater desalination apparatus of the present invention used for carrying out the desalination method, a condenser 26 is connected to a vacuum suction port 22 of the concentrator through a vacuum pump 25.
[0011]
In the present invention, since the deep water is evaporated in a vacuum environment using superheated steam heated to a saturation temperature or higher as a heat source, water in seawater can be separated in a short time, and by condensing this steam, a trace amount of water can be separated. Fresh water containing the components and concentrated seawater remaining in the decompression chamber can be obtained. When the degree of vacuum in the decompression chamber 13 is increased, the compound boiled violently and various compounds contained in the deep water were caught in the steam, so that the contamination of the solute into the distilled water increased. The solute retention rate increases. Utilizing this, by setting the degree of vacuum in the decompression chamber, it is possible to change the ratio of the trace components in the obtained fresh water and concentrated seawater, and to use the desalinated deep water and concentrated deep water suitable for the application. Obtainable.
[0012]
In the present invention, superheated steam induction-heated by a high-frequency coil is used as a heat source for heating deep water. As is well known, water does not rise above its boiling temperature (about 100 ° C.) at normal pressure (atmospheric pressure). In order to obtain higher temperature steam in order to increase the processing speed, the steam chamber needs to be pressurized. On the other hand, according to the method of obtaining superheated steam by high-frequency heating, superheated steam of 200 ° C. or more can be obtained even at normal pressure, and when water molecules pass through an electromagnetic field, electrons are excited to generate intermolecular and intermolecular molecules. A phenomenon in which the bonding is loosened occurs, and the molecules become finer, so that the heat conductivity is improved. That is, instead of using saturated steam at normal pressure as heating steam, by using superheated steam heated by high frequency, the heat transfer rate is improved due to a large temperature difference, and the steam molecules are subdivided. The synergistic effect with the improvement of the heat transfer coefficient is obtained, and the processing can be performed more quickly.
[0013]
A method for obtaining superheated steam is to pass saturated steam obtained by a boiler through a metal tube around which a high-frequency coil is wound, and receive heat from a heated tube wall to obtain superheated steam. By using a non-conductive tube such as a glass tube or a ceramic tube around which a high-frequency coil is wound as a tube through which the saturated water vapor passes, it is possible to obtain superheated steam with higher efficiency and higher heat conductivity.
[0014]
Furthermore, by adopting a method in which water sprayed into the air is passed through a non-conductive tube around which a high-frequency coil is wound to perform high-frequency heating, superheated steam can be obtained quickly with a simple device, and the cost of the device can be reduced. Can be inexpensive.
[0015]
By making the heat transfer wall 11 between the decompression chamber 13 and the steam chamber 14 a heat transfer wall having the fold 10 in the axial direction of the rotary drum, the heat transfer rate can be improved by increasing the heat transfer area. The concentrated seawater remaining in the decompression chamber can be taken out by vacuum suction. The concentrated seawater taken out is put in a heating vessel and reheated by an appropriate heat source, whereby water can be further evaporated to obtain a salt.
[0016]
The supply of deep water into the decompression chamber 13 is performed using the negative pressure of the decompression chamber. The water evaporated in the decompression chamber 13 is guided from the vacuum suction port 22 to the vacuum pump 25, and is condensed by the condenser 26 to become fresh water. The steam may be heated by a high-frequency coil and then condensed for desalination.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic diagram showing an embodiment of the seawater desalination apparatus of the present invention. The rotating drum 1 serving as a processing container is cylindrical and has support flanges 2 on both outer peripheral portions thereof. By supporting two circumferential portions of each support flange with support rollers 4 on the base 3, It is supported so as to be freely rotatable around a horizontal axis. A ring-shaped sprocket 5 is fixed to the center of the outer periphery of the rotating drum 1, and the sprocket and a sprocket attached to an output shaft of a motor 6 are connected by a chain 7 to drive the rotating drum 1.
[0018]
The rotating drum 1 is provided with an opening / closing door 8 in which transparent glass is fitted at several locations on the outer periphery. Inside the outer peripheral wall 9 of the rotary drum, a heat transfer wall 11 having a large number of axial folds 10 formed by bending into a deep waveform as shown in FIG. 2 has both ends of the end plates 12L, 12R of the rotary drum. The inside of the rotary drum 1 is partitioned into a decompression chamber 13 inside the heat transfer wall 11 and a steam chamber 14 outside.
[0019]
Double pipes 15L, 15R are fixed to the centers of the end plates 12L, 12R on both sides of the rotary drum 1, respectively, and end portions of the inner pipes 16L, 16R and the outer pipes 17L, 17R of each double pipe are respectively rotated. The joints 18L, 19L, 18R, 19R are connected. The base end of the inner tube 16L of the double tube on the left side in FIG. 1 is a vacuum suction port 22 that protrudes and opens into the decompression chamber 13, and the base end of the outer tube 17L is a ring-shaped on the inner surface of the end plate 12L. The seawater inlet 23 is open to the outside. The vacuum suction port 22 is connected to a vacuum pump 25 via a rotary joint 18L and a vacuum pipe 24, and a condenser 26 is connected to a discharge side of the vacuum pump 25. The seawater inlet 23 is connected to a seawater tank 28 via a rotary joint 19L and a seawater pipe 27. An opening / closing valve 29 is provided in the seawater pipe 27.
[0020]
In FIG. 1, the inner pipe 16L of the double pipe on the left side of the rotary drum 1 in the drawing is connected to a vacuum pump 25 to form a steam passage, and the outer pipe 17L is connected to a seawater tank 28 to form a seawater passage. The 16L may be connected to the seawater tank 28 to form a seawater passage, and the outer pipe 17L may be connected to the vacuum pump 25 to form a steam passage. Considering that the steam flow rate is larger than the seawater flow rate, the latter structure is rather preferable.
[0021]
The rotary joint 18R of the inner pipe 16R of the double pipe on the right side in FIG. 1 is connected to a steam supply pipe 30 made of ceramics. A high-frequency heater 31 is provided in the steam supply pipe 30, and a high-frequency coil 32 wound around the supply pipe is connected to a high-frequency power supply 33. A water spraying device 34 for spraying water into the steam supply pipe 30 is provided on the near side of the high-frequency heater 31 (upstream of the steam flow), and a pushing fan 35 is further provided on the upstream side thereof. . A steam discharge pipe 36 is connected to the rotary joint 19R of the outer pipe 17R of the double pipe on the right side in FIG. The inner pipe 16R and the outer pipe 17R are opened at the ends of the steam chamber 14 as supply ports 39 and discharge ports 40 via connecting pipes 37 and 38 in the radial direction.
[0022]
Next, a method for desalinating deep water using the above-described apparatus will be described. Deep water collected from the deep sea is supplied to a seawater tank 28. The vacuum pump 25 and the condenser 26 are operated to evacuate the decompression chamber 13. Further, the pushing fan 35 is operated to supply a high-frequency current to the coil 32 of the high-frequency heater 31 to spray water from the water spray device 34. The sprayed water is heated by high frequency and flows into the steam chamber 14 together with the air by the pushing fan 35.
[0023]
By providing a high-frequency heater having a sufficient capacity, the spray water is heated to about 200 ° C. at normal pressure. When the on-off valve 29 is opened in this state, deep water in the seawater tank is sucked into the decompression chamber 13 by vacuum pressure. When an appropriate amount is sucked, the on-off valve 29 is closed, and the rotating drum 1 is continuously rotated. The moisture of the deep water in the decompression chamber 13 is heated and evaporated by the heat transfer wall 11 heated by the superheated steam in the steam chamber 14, sucked by the vacuum pump 25, and condensed by the condenser 26. The on-off valve 29 is opened and closed as necessary so as to replenish the evaporated water, and the deep water is supplied into the decompression chamber 13. When the seawater tank 28 becomes empty and the deep water in the decompression chamber 13 is concentrated, the apparatus is stopped.
[0024]
Since various compounds dissolved in the deep water remain concentrated in the decompression chamber, the opening / closing door 8 is opened and vacuum suction is performed to collect. The collected concentrated deep water is appropriately diluted and used as a raw material for a seasoning, a health food, and a liquid for adding a lotion. Further, the obtained concentrated deep water is put into a heating vessel, and further heated with a gas stove or the like to evaporate the water to obtain a salt. The obtained salt is used as a raw material for seasonings. The distilled water condensed by the condenser 26 is used as a raw material for soft drinks, lotion, and the like as desalinated deep water.
[0025]
By injecting the desalinated seawater or the desalinated deep water obtained by the ion exchange method or the method of the above embodiment into the seawater tank 28 and performing the above operation, the seawater can be further concentrated in the decompression chamber 13 and the desalinated seawater can be obtained. In addition, the mineral concentration in the desalinated deep water can be increased. The concentrated seawater or concentrated deep water obtained by this method is used as a raw material for soft drinks, lotion, etc. as desalinated seawater or deep water containing a high concentration of minerals.
[0026]
FIG. 3 is a diagram showing another apparatus for obtaining superheated steam used in the method of the present invention. The apparatus shown in FIG. 3 includes a boiler 41 for obtaining saturated steam and a superheater 42 for the obtained saturated steam. The boiler 41 has a high-frequency coil 44 wound around a metal can 43 at intervals. When water is put into the can 43 and a high-frequency current is applied to the coil 44, the heat of the induction-heated can wall is transferred to the water in the can and boiled to generate saturated steam. The superheater 42 has a high-frequency coil 45 wound around a ceramic steam supply pipe 30 through which saturated steam passes. The saturated steam generated in the boiler 41 is induction-heated by the high-frequency coil 45 while passing through the steam supply pipe 30, and is supplied to the steam chamber as superheated steam.
[0027]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention demonstrated above, the solute component in the fresh water obtained by evaporating and condensing deep water and the remaining concentrated seawater can be adjusted, and the desalination deep layer which changed the mineral content according to the application Water and concentrated deep water are easily obtained. In addition, by using high-frequency heated superheated steam as a heating means for distilling or condensing deep water, it is possible to perform rapid processing by improving heat transfer efficiency and to provide a compact processing apparatus at low cost. This makes it possible to effect low-cost and efficient desalination or concentration treatment at individual food processing plants or cosmetic factories.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional side view showing an embodiment of a desalination / concentration apparatus. FIG. 2 is a vertical cross-sectional view of a rotating drum of the apparatus of FIG. 1. FIG. 3 shows another example of a superheated steam generator. Typical cross-sectional side view [Description of symbols]
DESCRIPTION OF SYMBOLS 1 Rotary drum 10 Fold 11 Heat transfer wall 13 Decompression room 14 Steam room 18L Rotary joint 18R Rotary joint 19L Rotary joint 19R Rotary joint 22 Vacuum suction port 23 Seawater injection port 30 Steam supply pipe 32 High frequency coil 39 Steam supply port 40 Vent

Claims (13)

Seawater is injected into the decompression chamber of the decompression tank (1) provided with the steam chamber (14) around the decompression chamber (13) via the heat transfer wall (11), and the steam chamber is heated to a boiling temperature or higher by high frequency heating. A seawater in the decompression chamber is heated to evaporate water in the seawater and condensed to obtain freshwater, thereby obtaining freshwater. The seawater desalination method according to claim 1, wherein water is sprayed on air passing through the high-frequency coil to obtain the superheated normal-pressure steam. The seawater desalination method according to claim 1, wherein the superheated normal-pressure steam is obtained by passing saturated steam generated by the boiler through a steam pipe around which a high-frequency coil is wound. 4. A desalinated deep water obtained by desalinating the deep water by the method of claim 1, 2 or 3. Seawater is injected into the decompression chamber of the decompression tank (1) provided with the steam chamber (14) around the decompression chamber (13) via the heat transfer wall (11), and the steam chamber is heated to a boiling temperature or higher by high frequency heating. A method for concentrating seawater, comprising supplying superheated normal-pressure steam to seawater in the decompression chamber and evaporating water in the seawater to obtain concentrated seawater remaining in the decompression chamber. . The method according to claim 1, wherein the depressurizing chamber of the depressurizing tank (1) provided with a steam chamber (14) around the depressurizing chamber (13) via a heat transfer wall (11) is an ion exchange method or a method according to claim 1. Injecting seawater desalinated in, supplying steam at normal pressure superheated to a boiling temperature or higher by high frequency heating to the steam chamber, heating the desalinated seawater in the decompression chamber to remove the water in the desalinated seawater. A method for concentrating seawater, comprising evaporating to obtain concentrated desalinated seawater remaining in the decompression chamber. The seawater enrichment method according to claim 5 or 6, wherein water is sprayed on air passing through the high-frequency coil to obtain the superheated normal-pressure steam. The method for concentrating seawater according to claim 5 or 6, wherein the superheated normal-pressure steam is obtained by passing saturated steam generated by the boiler through a steam pipe around which a high-frequency coil is wound. Concentrated deep water obtained by concentrating deep water by the method of claim 5, 6, 7, or 8. 9. A method for producing a salt, characterized by further evaporating the water content of the concentrated seawater obtained by the method according to claim 5, 7 or 8 to obtain a salt. A salt obtained by salting deep water by the method of claim 10. A rotary drum (1) partitioned into a surrounding steam chamber (14) and a decompression chamber (13) inside by a heat transfer wall (11) having a number of folds (10) in a direction parallel to the rotation center axis; A seawater inlet (23) opening to the decompression chamber (13) via a rotary joint (19L), a vacuum suction port (22) opening to the decompression chamber via a rotary joint (18L), and a rotary joint ( 18R, 19R) through a supply port and a discharge port (39, 40) for superheated steam that opens into the steam chamber (14), and a high-frequency coil (30) provided in a steam supply pipe (30) connected to the supply port for superheated steam. 32) A seawater concentrating device comprising: A rotary drum (1) partitioned into a surrounding steam chamber (14) and a decompression chamber (13) inside by a heat transfer wall (11) having a number of folds (10) in a direction parallel to the rotation center axis; A seawater inlet (23) opening to the decompression chamber (13) via a rotary joint (19L), a vacuum suction port (22) opening to the decompression chamber via a rotary joint (18L), and a rotary joint ( 18R, 19R), a supply port and a discharge port (39, 40) of the superheated steam which open to the steam chamber (14), and a condenser (22) connected to a vacuum suction port (22) via a vacuum pump (25). 26) and a desalination apparatus for seawater, comprising: a high-frequency coil (32) provided in a steam supply pipe (30) connected to a supply port of superheated steam.

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