JPH09103763A - Method and apparatus for purification - Google Patents

Abstract

PROBLEM TO BE SOLVED: To refine a solvent from a solution inexpensively and easily.

SOLUTION: This device is provided with a housing 2 having a reservoir 8, a port 4 for feeding and removing a salt bed 9 for the reservoir 8, an inlet port 10 for feeding a liquid to the reservoir 8 and an outlet port 20 for removing steam, a heating means 40 for heating the salt bed 9 in the reservoir 8, and a condensation part 30 for condensing generated water vapor.

COPYRIGHT: (C)1997,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a technique for purifying a solvent from a solution, and more particularly to a technique for obtaining water from an aqueous solution. The present invention can be used, but is not limited to, for desalinating seawater to provide water suitable for drinking.

[0002]

2. Description of the Related Art Obtaining water from an aqueous solution, especially desalination of seawater, is a problem of increasing importance. With the increasing number of tourists to the Primorsky Territory, the demand for drinking water is increasing. In many developing countries, the population is increasing, and it is necessary to supply water of good quality correspondingly, and the demand for water is expanding rapidly. In this regard, it is desired to increase the amount of both drinking water and agricultural water.

Desalination of seawater aims at providing essentially separated salts and residual water, at least residual salts and a fairly dilute salt solution.

In order to achieve the above object, various methods have been adopted. Current desalination technologies include seawater evaporation methods such as multi-purpose distillation, multi-stage flash evaporation, forced circulation vapor compression and the like. Other alternative techniques include freezing seawater and recovering the ice crystals that have formed, and electrolytic dialysis. The purpose of these techniques is generally to reduce the salinity of water to obtain water suitable for drinking.
The salt concentration at that time is generally considered to be about 500 ppm or less.

Various problems are present in the present desalination technology. The thermal evaporation method has problems such as a large amount of investment in the thermal evaporation device and a relatively high energy cost for generating the energy required for evaporation. Moreover, because old evaporators are made of expensive materials, repairs in the field, such as in developing countries, are often impossible, if not impossible. Moreover, due to salt residues or products from its thermal decomposition,
Contamination of the evaporator often causes problems.

In addition to the above, when trying to purify a solvent other than water, it is often necessary to employ an evaporation / distillation process having the same drawbacks as described above. Therefore, there is an increasing demand for alternative purification systems.

The present invention seeks to overcome at least some of the above problems.

[0008]

The purification method of the present invention comprises the steps of supplying a solution to be purified to a hot bed and evaporating the solvent component in the solution while keeping the solid component in the solution on the bed. And then condensing the vapor to provide a purified liquid. Condensation of vapor is also possible by conventional methods. The solution to be purified is often an aqueous solution.

It can be said that the purification method of the present invention particularly relates to a desalination method of an aqueous salt solution. The method comprises supplying a salt aqueous solution to a bed (hereinafter referred to as a salt bed) made of salt in a temperature state sufficient to evaporate water from the salt aqueous solution, collecting the generated steam, and And a step of condensing the water vapor at a place distant from.

In the present invention, when the components in the salt bed are essentially the same as those in the aqueous solution, the salt in the aqueous solution is efficiently recovered and used as a heat transfer medium in the subsequent desalination step. It is effectively reused.

The present invention is most suitable for desalination of an aqueous solution which is seawater.

Since seawater originally contains a large amount of dissolved salts, the desalination technology is not necessarily limited to removing sodium chloride from seawater. In general, seawater contains, in addition to sodium chloride, significant amounts of calcium bicarbonate, calcium sulfate, magnesium sulfate,
And seems to contain magnesium chloride.

Similarly, from the concept of salt beds, the meaning of the term salt is not limited to the substance customarily known as table salt or sodium chloride. The present invention is applicable to many other salts. Generally, hygroscopic salts are used, for example alkali chlorides or alkaline earth chlorides. Aside from theory, it is believed that hygroscopic salts capable of absorbing water behave like high temperature, very thin film evaporators at high temperatures. As described above, the high temperature salt bed composed of the hygroscopic salt particles has a relatively large area, and thus enables efficient evaporation. Therefore, as a hygroscopic salt,
Those containing sodium chloride and magnesium chloride are preferred.

Most preferably, in the hot bed, the major part of the salt is composed in the form of sodium chloride.

In the present invention, the collected water vapor is condensed at a location away from the salt bed, and salt and other mineral components are separated from the solution and remain in the salt bed. When the present invention is applied to seawater collected in a relatively uncontaminated area, it is possible to recover residual salt and use it as natural table salt. Therefore, it is particularly preferred to employ a bed consisting essentially of the salt to be recovered from seawater. In this regard, it is preferred to use a salt bed of sodium chloride. Alternatively, depending on the properties of pollutants and contaminants in seawater, it is also possible to recover the residual salt for industrial use.

Salt beds can be utilized in the present invention over a wide range of temperatures, provided that the temperature allows water to evaporate from the aqueous solution at an appropriate rate. The exact temperature required will depend on the desired rate of reaction and other process conditions.

In the present invention, when carried out at essentially atmospheric pressure, it is usual to feed the aqueous solution to a salt bed at a temperature of at least about 60 ° C.

Of course, at any temperature above freezing, more or less water evaporates from the aqueous solution. However, in view of the economic viability of the present invention, the salt bed would have to be raised to an average temperature of at least about 60 ° C. The appropriate upper limit of salt bed temperature is considered to be determined by economic factors.

The proof is that in a stirred salt bed, a certain amount of water evaporates in about 10 minutes at about 70 ° C.
It evaporates in about 5 minutes at 00 ° C and in about 1.5 minutes at about 120 ° C. The higher the temperature of the salt bed, the faster the evaporation from the material surface, but the production of heat of 100 ° C. or higher inevitably increases the cost. However, temperatures of about 70 ° C. are temperatures that can be obtained from heat sources such as power plants and solar heating that are considered “waste heat”. As a result, in most cases it will be advisable to use a salt bed at a temperature of about 70 ° C. to 100 ° C. Also preferred is a salt bed at a temperature of about 75 ° C to 90 ° C, especially about 80 ° C to 90 ° C.

The salt bed is preferably constituted by anhydrous or dry salts, which are essentially very low water salts. It is also preferable that the salt bed is composed of molten salt. As mentioned above, it is preferred to use dry salt at a relatively low temperature (60 ° C or higher) rather than using extremely hot molten salt.

The present invention also includes the case of stirring the salt bed. This is desirable in that the granular salt is surely fluidized and the spheroidization of the salt is prevented. Stirring of the salt bed is performed by using a stirrer or a stirrer, or rolling or rotating the salt bed.

The present invention provides a device for desalination of an aqueous solution, the device comprising a housing having a reservoir, ports for supplying and removing salt to and from the reservoir, and generally supplying the solution to the reservoir in a spray manner. An inlet port for removing water vapor from the housing, a means for heating the salt in the reservoir to a temperature sufficient to vaporize the solution entering the housing, and an outlet port for the housing And a condenser for condensing the released vapor.

As mentioned above for the description of the invention, sodium chloride and various other salts can be used in the device.

The reservoir is preferably located in the lower part of the device, the location of which is below the inlet port for supplying the aqueous solution, eg seawater, and below the outlet port for the removal of water vapor.

The reservoir has an inner surface that contacts the salt bed,
The inner surface is preferably made of salt or a material resistant to salts. Specifically, it is desirable to use a steel housing that is at least partially coated with a relatively corrosion resistant material such as rubber or polyvinylidene fluoride (PVDF). In the typical construction of the housing, the lining deteriorates to some extent,
The housing is sufficiently close to the reservoir so that it can be repaired if necessary. If necessary,
The coating may be applied only to those areas of the housing that may come into contact with the hot salt bed. The corrosion resistant coating may also prevent the salt bed from increasing in temperature due to the heating means. Therefore, this fact is being taken into account when selecting the appropriate material and degree of coating.

As the inlet port for supplying the aqueous solution to the reservoir, it is effective to use a spray method to diffuse the solution. A preferred inlet port comprises a manifold with two, preferably more than one, spray nozzles spaced apart. Such a spray nozzle
It is desirable to be arranged to supply the aqueous solution to the main part of the reservoir.

When using the apparatus, the rate of supplying the aqueous solution to the reservoir may be determined so that the evaporation of water is performed at an appropriate rate and under a less radical condition. In this regard, the size and number of spray nozzles for supplying the aqueous solution may be selected so that the reaction proceeds at a desired rate.

The housing may include heating means for heating the salt in the reservoir. For the reasons mentioned above, it is desirable that the heating means be capable of raising the temperature of the salt bed to at least 70 ° C. Alternatively, the heating means is capable of raising the temperature of the salt bed to at least the melting temperature of the salt. Examples of heating means include a direct heating type, an indirect heating type, and a solar heat assisting type.

The housing may include the condenser located remote from the reservoir, or the separate portion of the housing may include the condenser.

In this apparatus, the housing is constructed so that salt can be supplied to and removed from the salt bed. In this regard, one port may be provided to serve as both salt supply and removal, or an inlet port and an outlet port may be provided separately.

It is preferred to provide means for stirring the salt bed. This prevents salt from forming into unwanted spheres and lumps and promotes free flow of the particulate material. This means can be realized by a stirrer. Alternatively, the salt may be carried by a moving belt that is agitated as it progresses.

The present apparatus can be constructed so that it can be used in both batch processes and continuous processes.

The present invention has a wide variety of advantages. In particular, the heating-type desalination technology can be adopted at a relatively low temperature of about 70 ° C to 90 ° C. Also, since the device can be operated at a low temperature, there is an advantage that the device can be assembled with a material that is cheaper than the material used in the conventional evaporation device. As mentioned above, synthetic materials such as rubber lined mild steel and PVDF are included as examples of suitable materials for the device. According to the present invention, the pollution problem inherent in the conventional device can be avoided. The reason is that it is not necessary to separate residual salt from the device in order to operate the device efficiently. Rather, in this case, a small amount of residual salt is added to the salt bed to be contained in the heat transfer medium. This is partly due to the lesser degree of contamination, but the maintenance costs have been considerably reduced compared to conventional equipment.

Moreover, because the present invention is carried out at relatively low temperatures, lower grades of fuel can be used as compared to the fuels required by conventional systems and methods. The device is also relatively simple in construction and operates at relatively low temperatures, making it suitable for use in relatively simple conditions in developing countries.

The present invention further provides an apparatus that can be used to purify a solution containing a solvent other than water. In that regard, the present invention is directed to a housing having a reservoir, a port for supplying and removing crystalline material to and from the reservoir, an inlet port for supplying a solution to the reservoir, and a means for removing solvent vapor from the housing. An outlet port, a means for heating the crystalline material in the reservoir to a temperature sufficient to evaporate the solution entering the housing, and a condenser for condensing the vapor emitted from the outlet port of the housing. Concerning what consists of. It is desirable that the crystalline material be able to absorb the solvent, just as the hygroscopic material absorbs water.

[0036]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view of a refining apparatus of this embodiment. The device comprises a housing 2 with a reservoir 8. The housing 2 has a reservoir 8
Has a port 4 for supplying and removing salt. The housing 2 is generally made of steel and has a PVDF lining, at least in the area of the reservoir 8 in contact with the salt. The salt in the reservoir 8 constitutes a salt bed 9. The salt bed 9 may be a mixture of various compounds, but generally most of it is composed of sodium chloride.

The housing 2 comprises an inlet port 10 for supplying seawater (or other solution) to the reservoir 8. The inlet port 10 comprises a manifold 14 having a number of spaced spray nozzles 15. The manifold 14 can supply seawater to the main part of the salt bed 9 by a spray method. A stirrer 18 for stirring the salt bed 9 is also provided in order to prevent the salt from agglomerating.

The heating means for raising the temperature of the salt bed 9 is shown schematically as 40. As described above, various conventional types of heating means can be used. From an economical efficiency point of view, it is desirable to adopt a heat exchange system that utilizes “waste heat” generated from industrial equipment.

In the upper part of the housing 2 there is an outlet port 20 for removing water vapor, which is connected to a condenser, which is indicated schematically by the numeral 30. Various types of conventional equipment may be used to condense the water vapor and for the purposes of the present invention a detailed description may be unnecessary.

The apparatus shown in FIG. 1 may be used for the batch process for periodically collecting water and residual salt. In use, salt is placed in the reservoir 8 to form the salt bed 9 and the heating means 40 raises the temperature of the salt bed 9 to the desired level (typically a value from about 70 ° C to 100 ° C). Let The salt bed 9 is stirred by the stirrer 18.

Subsequently, seawater is supplied to the hot salt bed 9 through the inlet port 10, the manifold 14 and the spray nozzle 15. When the seawater comes into contact with the salt bed 9, the hygroscopic high temperature salt particles absorb the water content of the seawater. It is believed that its mode of absorption is essentially the same as a thin film evaporator. The moisture evaporates and rises to the upper part of the housing 2 and is discharged from the outlet port 20. Then, the water vapor is condensed in the condensing section 3.
Move to 0 and condense in the conventional manner.

Residues of salt and other minerals present in seawater are retained in the salt bed 9. Salt is periodically removed from the salt bed 9 via port 4 and the salt bed 9 level is kept below a desired maximum.

Throughout the whole process of supplying seawater to the salt bed 9,
The hot bed 9 is preferably agitated by an agitator 18 to prevent the formation of lumps within the bed 9.

(Embodiment 2) FIG. 2 is a sectional view of the refining apparatus of this embodiment, and FIG. 3 is a sectional view taken along line III-III of FIG. This device is for use in continuous processes rather than batch processes. The device comprises a housing 102, which is a reservoir 108 for a hot salt bed 109. Here again, heating means 140 for raising the temperature of the salt bed 109 is provided.

In this case, the housing 102 is the drum 10
The drum 103 has a shape of 3 and is supported by rollers 107 on both sides to stir the salt in the salt bed 109. By stirring
Excess salt in housing 102 is reliably drained from port 104. The drum 103 is generally made of steel, and the surface area of the portion of the floor 109 that comes into contact with the condensed salt is provided with a rubber or PVDF lining.

Inside the drum 103, a manifold 114 having substantially the same length as the drum 103 extends. As in the previous case, the manifold 114 has a number of spaced spray nozzles 115. Seawater is provided at one end of the housing 102 with the manifold 11
4 is provided with an inlet port 110. At the other end of the housing 102 is a steam outlet port 12
0 is provided and communicates with the condenser (similar to the first embodiment and not shown).

The illustrated apparatus is operated by activating the heating means 140 to raise the temperature of the salt bed 109 to the desired value. The drum 103 swings on the roller 107 to stir the salt in the salt bed 109. Seawater is supplied to the salt bed 109 via the inlet port 110 and the spray nozzle 115. When the seawater contacts the hot salt bed 109, the water content of the seawater evaporates and is discharged from the housing 102 through the outlet port 120. The hot walls of the drum 103 also help to dissipate water from the salt bed 109. The dry salt then contacts fresh seawater in the cycle. Subsequently, the generated steam is sent to the condenser section separated from the salt bed 109. Salt and other residues separated from seawater
It is held on the salt bed 109. When the level of salt in the salt bed 109 exceeds the desired value, salt is released from port 104.

(Other Embodiments) (1) In Embodiments 1 and 2, the use of desalination of seawater was described, but the purification method and the purification apparatus of the present invention are as follows.
It is not limited to this application, but can be used for purifying a solvent from a solution other than seawater.

(2) As the salt of the salt bed, an inert crystalline material other than sodium chloride can be used.

(3) Means for introducing warm air for fluidizing the salt bed may be provided.

(4) Instead of the stirrer, a moving belt for carrying the salt bed may be provided. This moving belt is set to stir the salt bed as it progresses.

[0053]

According to the invention of claim 1, the solution supplied to the high temperature bed is absorbed by the crystalline material, the solid component in the solution is retained by the crystalline material, and the solvent in the solution evaporates. The evaporated solvent is condensed into a purified solvent. Therefore, it can be obtained inexpensively and easily by purifying the solvent from the solution.

According to the invention of claim 2, water can be obtained by purifying water from an aqueous salt solution.

According to the invention of claim 3, water can be obtained by purifying water from seawater.

According to the invention of claim 4, water can be efficiently evaporated from the high temperature bed, and purified water can be efficiently obtained.

According to the fifth aspect of the present invention, particularly salt in seawater can be efficiently recovered.

According to the invention of claim 6, the economical efficiency can be improved.

According to the inventions of claims 7 to 9, since waste heat can be utilized, economic efficiency can be further improved.

According to the tenth or eleventh aspect of the present invention, the solvent component in the solution can be absorbed and evaporated efficiently, and the purified solvent can be efficiently obtained.

According to the twelfth aspect of the present invention, the crystalline material can be surely fluidized, so that the crystalline material can be prevented from becoming spherical or lumpy, and therefore, the evaporation step can be efficiently performed, Therefore, the purified solvent can be efficiently obtained.

According to the thirteenth aspect of the present invention, the floor can be surely stirred.

According to the fourteenth aspect of the present invention, it is possible to surely stir the floor over the entire area.

According to the fifteenth aspect of the present invention, the water can be efficiently evaporated from the high temperature bed, and the purified water can be efficiently obtained.

According to the sixteenth aspect of the present invention, the solution supplied from the inlet port to the bed of the crystalline material in the reservoir is absorbed by the crystalline material of the bed heated by the heating means, and the solid in the solution is absorbed. The components are retained in the crystalline material, the solvent in the solution evaporates, and the evaporated solvent is discharged from the outlet port and condensed in the condensing section to become a purified solvent. Therefore,
It can be obtained inexpensively and easily by purifying a solvent from a solution.

According to the seventeenth aspect, it is possible to easily supply the aqueous solution and remove the water vapor.

According to the eighteenth aspect of the present invention, the durability of the reservoir and thus the entire apparatus can be improved.

According to the nineteenth aspect of the present invention, the durability of the housing and thus the entire device can be improved.

According to the twentieth aspect of the present invention, the contact efficiency between the solution and the salt can be improved, so that purified water can be efficiently obtained.

According to the twenty-first aspect of the present invention, purified water can be obtained while maintaining good economic efficiency.

According to the twenty-second aspect of the present invention, the size of the device can be reduced.

According to the twenty-third aspect of the invention, it is possible to simplify the structure of the apparatus.

According to the twenty-fourth aspect of the present invention, the crystalline material can be surely fluidized, so that the crystalline material can be prevented from becoming spherical or lumpy, and therefore the solvent can be efficiently evaporated. Therefore, the purified solvent can be efficiently obtained.

According to the twenty-fifth aspect of the invention, it is possible to surely stir the crystalline material.

According to the twenty-sixth aspect of the present invention, it is possible to surely stir the floor over the entire area.

According to the twenty-seventh aspect, the solvent can be efficiently evaporated from the bed, and the purified solvent can be efficiently obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a refining device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a refining device according to a second embodiment of the present invention.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

[Explanation of symbols]

 2,102 Housing 103 Drum 4,104 Port 8,108 Reservoir 9,109 Floor 10,110 Inlet port 14,114 Manifold 15,115 Spray nozzle 18 Stirrer 20,120 Outlet port 30 Condensing part 40,140 Heating means

Claims (27)

[Claims] 1. A purification method obtained by purifying a solvent from a solution, which comprises a temperature condition sufficient to evaporate a solvent component in the solution,
A supply step of supplying a solution to a high-temperature bed made of crystalline material, an evaporation step of evaporating the solvent while keeping the solid components in the supplied solution in the high-temperature bed, a collection step of collecting generated vapor, and a collection step And a condensing step of condensing the vapor at a location apart from the bed. 2. The purification method according to claim 1, wherein the solution is an aqueous solution containing a salt, the solvent is water, and the crystalline material of the high temperature bed is a salt. 3. The purification method according to claim 2, wherein the aqueous solution is seawater. 4. The purification method according to claim 2, wherein the salt of the high temperature bed is a hygroscopic salt which is an alkali chloride or an alkaline earth metal chloride. 5. The purification method according to claim 2, wherein the salt in the high temperature bed is sodium chloride. 6. The purification method according to claim 2, wherein all the steps are performed under atmospheric pressure, and the temperature of the hot bed is at least about 60 ° C. 7. The method of claim 6 wherein the temperature of the hot bed is in the range of about 70 ° C to 100 ° C. 8. The method of claim 7 wherein the temperature of the hot bed is in the range of about 75 ° C to 95 ° C. 9. The method of claim 8 wherein the temperature of the hot bed is in the range of about 80 ° C to 90 ° C. 10. The purification method according to claim 2, wherein the salt of the hot bed is an anhydrous salt or a dry salt. 11. The refining method according to claim 2, wherein the salt in the high temperature bed is a molten salt. 12. The purification method according to any one of claims 1 to 11, which is carried out while stirring the hot bed. 13. The purification method according to claim 12, wherein the stirring is performed by a stirrer or a stirrer. 14. The purification method according to claim 12, wherein the stirring is performed by rolling or rotating a high-temperature bed. 15. The salt of the hot bed is anhydrous salt or dry salt, the hot bed is agitated, and hot air is supplied to the hot bed to fluidize the bed, thereby evaporating water from the aqueous solution. 10. The purification method according to claim 2, wherein the purification is promoted. 16. A purification device obtained by purifying a solvent from a solution, a housing having a reservoir, a port for supplying and removing a bed made of a crystalline material to and from the reservoir, and a solution for supplying the solution to the reservoir. An inlet port for removing vapor from the housing and a heating means for heating the crystalline material in the reservoir to a temperature sufficient to evaporate the solution in the housing, and an outlet port from the housing. And a condensing unit for condensing the vapor discharged through the refining apparatus. 17. The crystalline material is a salt and the reservoir is
17. Purification device according to claim 16, arranged in the lower part of the device, below the inlet port for supplying the aqueous solution and below the outlet port for removing water vapor. 18. The purifier according to claim 17, wherein the reservoir has an inner surface portion for contacting a salt bed, and the inner surface portion is made of a salt-resistant material. 19. The housing is made of steel at least partially coated with a corrosion resistant material such as rubber or polyvinylidene fluoride.
Purification device described. 20. The inlet port comprises a manifold having spray nozzles, the spray nozzles being at least two spaced apart and arranged to supply a solution over a major portion of the reservoir. 20. The purifying device according to claim 17, which is provided. 21. The heating means is capable of raising the temperature of the bed of salt to at least 70 ° C.
21. The purifying apparatus according to any one of 20 to 20. 22. The purifying apparatus according to claim 17, wherein the condensing portion is arranged in the housing at a position apart from the reservoir. 23. The purifying apparatus according to claim 17, wherein the condensing section is arranged in an independent housing separate from the housing having the reservoir. 24. The purifying apparatus according to claim 16, further comprising stirring means for stirring a bed made of a crystalline material. 25. The purifying apparatus according to claim 24, wherein the stirring means is a stirrer or a stirrer. 26. A moving belt for carrying a bed of crystalline material is provided, the moving belt stirring the bed as it advances.
3. The purifying device according to any one of 3 above. 27. A hot air introducing means for fluidizing a bed made of a crystalline material is provided.
The purification apparatus according to any one of 1.