JP2008307447A - Fresh water generating apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fresh water generating apparatus and method which can generate fresh water for drinking and the like without discharging highly concentrated salt water generated in an evaporator. <P>SOLUTION: The fresh water generating apparatus 1 comprises the evaporator 2 which generates concentrated salt water and condensed water by evaporating and concentrating sodium chloride-containing water to be treated, and condensing generated steam, a semipermeable membrane permeator 3 which is partitioned by a semipermeable membrane 3a permeating water, and has a concentrated salt water chamber 31 and a dilute water chamber 32 into which the concentrated salt water generated in the evaporator 2 and dilute water having a sodium chloride concentration lower than that of the concentrated salt water are introduced respectively, and a returning means 7 which returns concentrated salt water in the concentrated salt water chamber 31, diluted by water permeating from the dilute water chamber 32 through the semipermeable membrane 3a, to the evaporator 2 as water to be treated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fresh water generator and a fresh water generation method.

Conventionally, for example, a method as disclosed in Patent Document 1 is known as a method for producing drinking water from seawater. In this method, scale component-removed seawater from which scale components contained in seawater have been removed by a nanofiltration membrane device and blended seawater blended with seawater are supplied to the multi-effect evaporator as treated water and evaporated. It produces fresh water for beverages.
Japanese translation of PCT publication No. 2003-507183

  However, according to the above-described fresh water generation method, concentrated salt water concentrated to a high concentration is generated in the process of generating fresh water for drinking from seawater. The produced concentrated salt water is discharged to the sea without being used at all and discarded, but the salt concentration of this concentrated salt water reaches about 2 to 3 times the salt concentration of seawater, so it is discharged. There was a risk that the salinity of the sea area would increase and adversely affect the ecosystem.

  The present invention has been made to solve such a problem, and is capable of producing fresh water for beverages or the like without discharging high-concentration concentrated salt water produced in the evaporator. An object is to provide a water device and a water production method.

  The above-mentioned object of the present invention is partitioned by an evaporator that evaporates and concentrates water to be treated containing sodium chloride and condenses the generated water vapor to produce concentrated salt water and condensed water, and a semipermeable membrane that transmits water. A semipermeable membrane permeator having a concentrated salt water chamber and a dilute water chamber through which the concentrated salt water generated by the evaporator and diluted water having a sodium chloride concentration lower than that of the concentrated salt water are guided, respectively, through the semipermeable membrane This is achieved by a desalinator comprising reflux means for refluxing the concentrated salt water in the concentrated salt water chamber diluted with water permeated from the dilute water chamber to the evaporator as treated water.

  Moreover, in this fresh water generator, it is preferable that the to-be-processed water supplied to the said evaporator is salt solution.

  Moreover, it is preferable that the said reflux means is further provided with the dilution water mixing means in which dilution water is mixed.

  In addition, the above object of the present invention is to provide a concentrated salt water generating step for generating concentrated salt water by supplying water to be treated containing sodium chloride to an evaporator and evaporating and condensing the generated water vapor to generate condensed water. A concentrated salt water chamber and dilute water, which are partitioned by a condensed water generating step and a semipermeable membrane that permeates water and into which the concentrated salt water generated by the evaporation device and diluted water having a lower sodium chloride concentration than the concentrated salt water are guided, respectively. In the semipermeable membrane permeator having a chamber, a diluting step of diluting the concentrated salt water in the concentrated salt water chamber with water permeated from the diluted water chamber through the semipermeable membrane, and the evaporator for diluting the concentrated salt water And a reflux step of refluxing as treated water.

  ADVANTAGE OF THE INVENTION According to this invention, the fresh water generator and fresh water generation method which can produce | generate fresh water for drinks, etc. can be provided, without discharging | emitting the high concentration concentrated salt water produced | generated in an evaporation apparatus outside.

  Hereinafter, the fresh water generator 1 which concerns on this invention is demonstrated with reference to an accompanying drawing. Drawing 1 is a schematic structure figure of fresh water generator 1 concerning one embodiment of the present invention. Each drawing is partially enlarged or reduced, not the actual size ratio, for easy understanding of the configuration.

  As shown in FIG. 1, the fresh water generator 1 includes a multi-effect evaporator 2 and a semipermeable membrane permeator 3.

  The evaporator 2 includes a plurality of evaporators 2 a to 2 d and a condensing unit 29. Several evaporators 2a-2d are connected in series, and each evaporator 2a-2d is the to-be-processed process containing the enclosed evaporation chamber 21, the indirect heater 22, and sodium chloride, as shown in FIG. A spray nozzle 23 for spraying water is provided. Concentrated in the bottom of the evaporation chamber 21 is a portion of the water to be treated sprayed from the spray nozzle 23 to the heat transfer tube 221 so as to store concentrated salt water after evaporating into water vapor by the heat exchange action of the heat transfer tube 221. A salt water storage unit 24 is configured. Moreover, the concentrated salt water discharge part 26a for discharging | emitting the produced | generated concentrated salt water outside is provided in the bottom part of the evaporation chamber 21. As shown in FIG. In the upper part of the evaporation chamber 21, a steam discharge portion 25 a is provided for discharging water vapor generated on the outer surface of the heat transfer tube 221 by the heat exchange action of the heat transfer tube 221 to the outside.

  The indirect heater 22 includes a plurality of heat transfer tubes 221 provided in the evaporation chamber 21, and a first header 222 and a second header 223 respectively connected to both ends of the plurality of heat transfer tubes 221. The first header 222 includes a steam introduction part 25b for introducing steam into the heat transfer pipe 221 and a condensed water introduction part 27a for introducing condensed water generated in the heat transfer pipe 221 of another evaporator. . The 2nd header 223 is provided with the condensed water discharge part 27b which discharges the condensed water produced | generated in the heat exchanger tube 221 by the heat exchange effect | action of the heat exchanger tube 221 outside. Note that the condensed water stored in the first header 222 passes through the heat transfer tube 221 and is guided to the second header 223 when the amount of water exceeds a predetermined amount.

  The spray nozzle 23 is disposed above the indirect heater 22 and is a spray unit that sprays the water to be treated toward the outer surface of the heat transfer tube 221.

  As shown in FIG. 1, between the evaporators 2a to 2d, the vaporization of the preceding stage is performed so that the steam generated by the preceding evaporator can be guided as a heat source into the heat transfer tube 221 of the evaporator on the next stage. A steam discharge part 25 a in the can and a steam introduction part 25 b in the latter stage evaporator are connected via a steam line 25. Further, the concentrated salt water discharge part 26a in the preceding stage evaporator and the subsequent stage so that the concentrated salt water generated in the preceding stage evaporator and stored in the concentrated salt water storage part 24 is guided to the spray nozzle 23 in the latter stage side evaporator. The evaporator spray nozzle 23 is connected via a concentrated salt water transfer pipe 26. In addition, the condensed water generated in the heat transfer tube 221 in the previous stage evaporator and stored in the second header 223 is guided into the first header 222 of the indirect heater 22 in the second stage evaporator, A condensed water discharge part 27 b in the former evaporator and a condensed water introduction part 27 a in the latter evaporator are connected via a condensed water pipe 27.

  In addition, a driving steam line 90 that guides driving steam generated in a boiler or the like is connected to the steam introducing portion 25b of the first header 222 of the indirect heater 22 in the first stage evaporator 2a. In the first stage evaporator 2a, it is not necessary to provide the condensed water introduction part 27a and the concentrated salt water introduction part 26a.

  A condensed water discharge pipe 91 for discharging condensed water to the outside is connected to the condensed water discharge portion 27b in the final stage evaporator 2d. Further, a steam discharge pipe 92 that guides the steam to the condensing part 29 is connected to the steam discharge part 25 a of the second header 223 of the indirect heater 22. The condensing unit 29 is a device that generates condensed water by indirectly cooling the water vapor guided through the steam outlet pipe 92 with cooling water guided from a cooling water supply pipe (not shown). As the cooling water, industrial water cooled by a cooling tower (not shown), cold water (chiller water) cooled by a refrigeration apparatus, or the like can be used.

  As shown in FIG. 1, the semipermeable membrane permeator 3 has an internal space partitioned by a plate-type semipermeable membrane 3a. One space constitutes a concentrated salt water chamber 31, and the other space is a dilute water chamber. 32. The concentrated salt water chamber 31 is a space in which the concentrated salt water generated in the evaporator 2 is supplied via the concentrated salt water supply means 6 described later. The diluted water chamber 32 is a space in which diluted water such as seawater or fresh water having a lower salinity concentration (sodium chloride concentration) than the concentrated salt water guided to the concentrated salt water chamber 31 is supplied via the diluted water supply means 4 described later. . The semipermeable membrane 3a is a membrane having a property of allowing water to permeate, and examples thereof include a polymer membrane such as a cellulose membrane and a polyamide membrane. With such a configuration, the water in the diluted water guided to the dilute water chamber 32 is sucked by the normal osmotic pressure energy of the concentrated salt water in the concentrated salt water chamber 31 and permeates through the semipermeable membrane 3a to be concentrated in the salt water chamber 31. The amount of concentrated salt water can be increased to decrease the salt concentration.

  The fresh water generator 1 further includes a dilution water supply means 4, a dilution water discharge means 5, a concentrated salt water supply means 6, and a reflux means 7. The diluting water supply means 4 generates diluting water such as seawater or fresh water generated in the evaporator 2 and having a lower salinity than the concentrated salt water 31 guided to the concentrated salt water chamber 31 of the semipermeable membrane permeator 3. 3, a diluting water supply pipe 41 through which the diluting water passes, and a pump 42. In addition, a filter, a filter, etc. are attached in the middle of the dilution water supply pipe 41, and it is comprised so that the impurity contained in dilution water may be removed.

  The dilution water discharge means 5 is means for discharging the remaining dilution water in which a part of the water is transmitted to the concentrated salt water chamber 31 side through the semipermeable membrane 3a in the diluted water chamber 32 of the semipermeable membrane permeator 3. The dilution water transfer pipe 51 having one end connected to the diluted water chamber 32, the storage tank 52 connected to the other end of the dilution water transfer pipe 51 and storing dilution water, and stored in the storage tank 52. A discharge pipe 53 for discharging dilution water to the outside and a pump 54 are provided.

  The concentrated salt water supply means 6 is a means for guiding the concentrated salt water generated in the evaporator 2 to the concentrated salt water chamber 31 in the semipermeable membrane permeator 3, and the concentrated salt water discharge part 26a and the semipermeable membrane in the final stage evaporator 2d. A concentrated salt water supply pipe 61 connecting the concentrated salt water chamber 31 in the permeator 3 and a pump 62 are provided.

  The reflux means 7 is means for refluxing the concentrated salt water whose salinity is diluted in the concentrated salt water chamber 31 of the semipermeable membrane permeator 3 as treated water to the evaporator 2, and the concentrated salt water chamber in the semipermeable membrane permeator 3. 31 and a reflux pipe 71 for connecting the spray nozzle 23 in the foremost evaporator 2a, and a pump 72.

  A method for producing condensed water (fresh water) for drinking from seawater by the fresh water generator 1 configured as described above will be described below. First, the reflux means 7 is driven, and the water to be treated previously stored in the concentrated salt water chamber 31 of the semipermeable membrane permeator 3 is supplied to the evaporator 2. Moreover, seawater which is dilution water is supplied to the diluted water chamber 32 of the semipermeable membrane permeator 3. Then, the driving steam generated by a boiler or the like is supplied to the evaporator 2 through the driving steam line 90. Here, a saline solution (sodium chloride aqueous solution) is employed as the water to be stored in the concentrated salt water chamber 31 of the semipermeable membrane permeator 3 in advance. The salt concentration of sodium chloride (sodium chloride concentration) is appropriately changed depending on the salt concentration of seawater supplied to the dilute water chamber 32 of the semipermeable membrane permeator 3. The salt concentration of the concentrated salt water led to the concentrated salt water chamber 31 of the membrane permeator 3 is set to be 3 to 26% (30 g / L to 260 g / L).

  The driving steam supplied to the evaporator 2 is guided to the inside of the heat transfer tube 221 of the evaporator 2a arranged in the foremost stage. The water to be treated (saline solution) guided by the reflux means 7 is supplied to the spray nozzle 23 of the front-stage evaporator 2 a constituting the evaporator 2 and sprayed on the outer surface of the heat transfer tube 221.

  The water to be treated (saline solution) sprayed on the outer surface of the heat transfer tube 221 of the evaporator 2a at the foremost stage exchanges heat with the driving steam passing through the inside of the heat transfer tube 221, and part of the water evaporates. It becomes water vapor. The generated water vapor is led as a heat source to the heat transfer tube 221 in the evaporator 2b on the next stage side. Further, the water to be treated that has not evaporated on the outer surface of the heat transfer tube 221 becomes concentrated salt water whose salt concentration is increased, flows down along the outer surface of the heat transfer tube 221, and is stored in the bottom of the evaporation chamber 21. . The concentrated salt water stored at the bottom is led from the concentrated salt water discharge portion 26a through the concentrated salt water transfer pipe 26 to the spray nozzle 23 of the first evaporator 2b. The driving steam passing through the inside of the heat transfer tube 221 is converted into condensed water (fresh water) by heat exchange with the water to be treated sprayed on the outer surface of the heat transfer tube 221, and the second header of the indirect heater 22. It is stored in 223 and led to the first header 222 of the indirect heater 22 in the evaporator 2b on the next stage side through the condensed water pipe 27.

  In the evaporator 2b disposed on the one-stage side of the first-stage evaporator 2a, the concentrated salt water sprayed from the spray nozzle 23 to the outer surface of the heat transfer tube 221 and the one generated and transmitted in the one-front evaporator 2a. Heat exchange is performed with steam passing through the heat pipe 221 to generate water vapor and concentrated salt water, and condensed water (fresh water) is generated in the heat transfer pipe 221. The other evaporators 2c and 2d constituting the evaporator 2 are also subjected to the same process in order to generate fresh water for beverages and concentrate the water to be treated.

  Condensed water (fresh water) generated in the heat transfer pipes 221 of the respective evaporators 2a to 2d constituting the evaporator 2 is sequentially guided to the subsequent stage side evaporator via the condensed water pipe 27, and finally, The water is taken out from the condensed water discharge part 27b of the evaporator 2d arranged on the most rear side of the evaporator 2 through the condensed water discharge conduit 91. Further, after the water vapor generated on the surface of the heat transfer tube 221 of the evaporator 2d arranged on the most rear side of the evaporator 2 is led to the condensing unit 29 via the vapor extraction pipe 92 and converted into fresh water. , Taken out via the conduit 93. The extracted fresh water is then used as drinking water or cleaning water in various industries such as the electronics industry.

  High-concentration concentrated salt water stored in the evaporator 2 d arranged on the most rear side of the evaporator 2 is guided to the concentrated salt water chamber 31 of the semipermeable membrane permeator 3 by the concentrated salt water supply means 6. Since the seawater having a lower salinity than the concentrated salt water led to the concentrated salt water chamber 31 is supplied to the dilute water chamber 32 via the dilution water supply means 4, due to the osmotic pressure difference between the concentrated salt water and the diluted water, Only the water in the diluted water (in the seawater) permeates the concentrated salt water chamber 31 side through the semipermeable membrane 3a. As a result, the concentrated salt water supplied to the concentrated salt water chamber 31 is diluted and increased, and its salinity concentration decreases. On the other hand, the seawater supplied to the diluted water chamber 32 is stored via the diluting water transfer pipe 51 after a part of the water in the seawater is transmitted to the concentrated saltwater chamber 31 side through the semipermeable membrane 3a. One end is stored in the tank 52, and then, for example, discharged to the sea through the discharge pipe 53. The seawater discharged through the dilution water discharge means 5 is in a state in which the salinity concentration is increased, but the flow rate of the seawater passing through the diluted water chamber 32 of the semipermeable membrane permeator 3 should be adjusted as appropriate. Therefore, the salinity of the discharged seawater is set so that it does not adversely affect the ecosystem of the sea area where the seawater is discharged. The flow rate of the seawater (diluted water) passing through the dilute water chamber 32 may be set so that, for example, 10% to 30% of the seawater is transmitted to the concentrated saltwater chamber 31 through the semipermeable membrane 3a. preferable.

  Concentrated salt water that has been diluted and reduced in salinity is recirculated as treated water to the spray nozzle 23 in the first evaporator 2a by the reflux means 7, and again evaporated and concentrated in the evaporator 2 to produce fresh water for beverages and the like. Is done.

  As described above, according to the fresh water generator 1 according to the present embodiment, the concentrated salt water concentrated in the evaporator 2 is diluted and increased in the semipermeable membrane permeator 3 and then repeatedly reused as treated water in the evaporator 2. Since it is configured so that it can be used, it is possible to produce fresh water for beverages without discharging the concentrated salt water generated in the evaporator 2 to the outside (for example, without discharging it to the sea and discarding it). It becomes possible.

  Further, in the semipermeable membrane permeator 3, only the water in the seawater guided by the dilution water supply means 4 is moved to the concentrated salt water that is returned to the evaporator 2 through the semipermeable membrane 3a, and is contained in the seawater. The scale component such as calcium sulfate does not move into the water to be treated which is refluxed to the evaporator 2. That is, it is possible to maintain that the liquid circulating through the evaporator 2 and the semipermeable membrane permeator 3 is saline. As a result, scales such as calcium sulfate can be reliably prevented from depositing on the surfaces of the heat transfer tubes 221 of the respective evaporators 2a to 2d, so that the heat exchange efficiency of the heat transfer tubes 221 does not decrease, and the fresh water is fed from seawater. Can be manufactured efficiently. Moreover, since precipitation of scale can be prevented, the temperature of the driving steam supplied to the evaporator 2 can be further increased, and each of the evaporators 2a to 2d can be driven under a higher operating temperature condition. A large amount of fresh water can be produced efficiently.

  In addition, as a result of reliably preventing the scale from being deposited on the surface of the heat transfer tube 221 of the evaporators 2a to 2d, a nanofiltration membrane device for removing scale components from seawater in advance, and a chemical for suppressing scale deposition It is not necessary to provide a device for preventing scale deposition such as an addition device and a decarboxylation tower facility, and the water freshening device 1 can be made compact and low in cost. Furthermore, since no acid addition is required, corrosion in the evaporator can be prevented.

  The inventor of the present invention confirmed that the semipermeable membrane permeator 3 can permeate a sufficient amount of water from the dilute water chamber 32 to the concentrated salt water chamber 31 by mass balance calculation. To do.

  First, the salt concentration (sodium chloride concentration) of the concentrated salt water generated in the evaporator 2 and led to the concentrated salt water chamber 31 in the semipermeable membrane permeator 3 was 130 g / L. The osmotic pressure of this concentrated salt water corresponds to about 108 atm. Further, the salt concentration of seawater (diluted water) guided to the dilute water chamber 32 was set to 43 g / L. The salinity of this seawater corresponds to the salinity of seawater in the Middle East region where demand for the fresh water generator 1 is high, and its osmotic pressure is about 31 atm. The osmotic pressure of seawater and the like was calculated by referring to “Reverse Osmosis Method / Ultrafiltration Method I Theory Table A-20” by Haruhiko Oya.

  When 30% of the seawater in the diluted water chamber 32 moves to the concentrated saltwater chamber 31 side through the semipermeable membrane 3a, the outlet portion of the diluted water chamber 32 (connecting portion with the diluted water transfer pipe 51). The seawater concentration is 100 / (100-30) = 1.43 times. That is, in the case of seawater in the Middle East region (salinity concentration = 43 g / L, osmotic pressure = 31 atm), the seawater concentration at the outlet of the dilute water chamber 32 is 60 g / L, and the osmotic pressure corresponds to about 47 atm. . Therefore, the average osmotic pressure of the diluted water chamber 32 is (31 atm + 47 atm) / 2 = 39 atm.

  On the other hand, the concentrated salt water (salt concentration = 130 g / L, osmotic pressure = 108 atm) guided to the concentrated salt water chamber 31 of the semipermeable membrane permeator 3 is diluted with water that has permeated through the semipermeable membrane 3a. The dilution rate varies depending on the flow rate of the concentrated salt water passing through the concentrated salt water chamber 31. The flow rate of the concentrated salt water passing through the concentrated salt water chamber 31 is optimally designed depending on the equipment capacity ratio of the evaporator 2 and the semipermeable membrane permeator 3, but the water to be treated is concentrated 2 to 3 times in the evaporator 2. Therefore, when the flow rate of the concentrated salt water is set on the assumption that the concentrated salt water is diluted twice in the concentrated salt water chamber 31, the outlet portion of the concentrated salt water chamber 31 (connecting portion with the reflux pipe 71). The salinity concentration in is 130 g / L / 2 = 65 g / L (osmotic pressure = 51.5 atm). Therefore, the average osmotic pressure of the concentrated salt water chamber 31 is (108 atm + 51.5 atm) / 2 = 80 atm.

  From the above, the difference in average osmotic pressure between the concentrated salt water chamber 31 and the diluted water chamber 32 in the semipermeable membrane permeator 3 is 80 atm−39 atm = 41 atm, and a sufficient flow rate from the diluted water chamber 32 side to the concentrated salt water chamber 31 side. It can be seen that osmotic water can be supplied. In the above-described material balance calculation, the case where 30% of the seawater in the diluted water chamber 32 moves to the concentrated saltwater chamber 31 side through the semipermeable membrane 3a has been described, but 10% to 20% of the seawater. It is preferable to set the flow rate of the seawater that passes through the dilute water chamber 32 so that the water moves through the semipermeable membrane 3a.

  As mentioned above, although one Embodiment of the fresh water generator 1 which concerns on this invention was described, the specific structure of this invention is not limited to the said embodiment. For example, it is possible to adopt a configuration in which diluted water such as seawater or fresh water is mixed into the concentrated salt water after the dilution increase that the reflux means 7 leads to the evaporator 2. Specifically, as shown in FIG. 3, the reflux means 7 can be configured to include dilution water mixing means 8 that connects the dilution water supply pipe 41 and the reflux pipe 71. The dilution water mixing means 8 includes a dilution water mixing pipe 81 that branches a part of the dilution water guided by the dilution water supply means 4 and leads to the reflux pipe 71 and a flow rate adjusting valve (not shown). With such a configuration, the amount of water to be treated that is evaporated and concentrated in the evaporation device 2 can be increased within a range in which scale deposition can be prevented in the evaporation device 2, so that condensed water (fresh water) for beverages and the like can be used. It becomes possible to manufacture efficiently and in large quantities.

  Moreover, in the said embodiment, although the semipermeable membrane permeation | transmission device 3 by which the inside is divided into the concentrated salt water chamber 31 and the diluted water chamber 32 by the plate-type semipermeable membrane 3a is employ | adopted, especially in such a structure. It is not limited. For example, it is possible to employ the semipermeable membrane permeator 3 in which the inside is partitioned into the concentrated salt water chamber 31 and the dilute water chamber 32 by various semipermeable membranes such as a hollow fiber type, a spiral type, and a tubular type.

  Moreover, in the said description about the method of manufacturing fresh water for drinks etc. from seawater using the fresh water generator 1 which concerns on this embodiment, salt solution is previously accommodated in the concentrated salt water chamber 31 of the semipermeable membrane permeation device 3. Although the structure which starts the drive of the fresh water generator 1 was demonstrated, the seawater from which the scale component was removed beforehand was supplied instead of salt water, and the scale component was removed so that a scale might not precipitate at predetermined heat operation temperature and predetermined salt concentration. The driving of the device 1 may be started. Even in such a configuration, the concentrated seawater concentrated in the evaporator 2 can be reused as treated water in the evaporator 2 after being diluted and increased in the semipermeable membrane permeator 3 and generated in the evaporator 2. It is possible to produce fresh water for drinking, etc., without discharging the concentrated seawater to the sea and discarding it.

  Moreover, in the said embodiment, although the evaporator 2 is a multi-effect type evaporator provided with several evaporators 2a-2d, for example, even if it is a single can type evaporator provided with a single evaporator Good. Further, it may be a multistage flash evaporation type evaporator.

  Moreover, in the said embodiment, the cooling seawater outlet water of the heat | fever discharge | release part (Heat Rejection Section) of the evaporation apparatus 2 can also be used as dilution water led to the semipermeable membrane permeation device 3. Since it is considered that the increase in permeation speed (positive effect) due to the decrease in viscosity is superior to the increase in osmotic pressure due to temperature increase (negative effect), an improvement in performance can be expected.

It is a schematic structure figure showing a fresh water generator concerning one embodiment of the present invention. It is a schematic block diagram which shows the evaporator which comprises the fresh water generator shown in FIG. It is a schematic block diagram which shows the modification of the fresh water generator shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water generator 2 Evaporator 2a-2d Evaporator 3 Semipermeable membrane permeator 3a Semipermeable membrane 31 Concentrated salt water chamber 32 Dilute water chamber

Claims (4)

An evaporator for evaporating and concentrating water to be treated containing sodium chloride, and generating concentrated salt water and condensed water by condensing the generated water vapor; and
Semipermeable membrane permeation having a concentrated salt water chamber and a dilute water chamber, which are partitioned by a semipermeable membrane that permeates water and into which the concentrated salt water generated by the evaporator and diluted water having a sodium chloride concentration lower than that of the concentrated salt water are guided, respectively. And
A fresh water generator comprising reflux means for recirculating the concentrated salt water in the concentrated salt water chamber diluted with water transmitted from the dilute water chamber through the semipermeable membrane to the evaporation device as treated water.   The fresh water generating apparatus according to claim 1, wherein the water to be treated supplied to the evaporation apparatus is a saline solution.   The fresh water generator according to claim 1 or 2, wherein the reflux means further includes dilution water mixing means in which dilution water is mixed. A concentrated salt water generating step for generating concentrated salt water by supplying water to be treated containing sodium chloride to the evaporator and evaporating and concentrating;
A condensed water generation step for generating condensed water by condensing the generated water vapor;
Semipermeable membrane permeation having a concentrated salt water chamber and a dilute water chamber, which are partitioned by a semipermeable membrane that permeates water and into which the concentrated salt water generated by the evaporator and diluted water having a sodium chloride concentration lower than that of the concentrated salt water are guided, respectively. A diluting step of diluting the concentrated salt water in the concentrated salt water chamber with water transmitted from the diluted water chamber through the semipermeable membrane;
A water refining method comprising: a refluxing step of refluxing the diluted concentrated salt water as treated water to the evaporator.

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