JP4917962B2 - Fresh water generator and fresh water generation method - Google Patents

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 raw seawater have been removed by a nanofiltration membrane device and blended seawater blended with raw seawater are fed to a multi-effect evaporator as treated water and distilled. In this way, condensed water for beverages is generated.
Japanese translation of PCT publication No. 2003-507183

  Scale components such as calcium sulfate contained in the water to be treated supplied to the multi-effect evaporator are reduced in solubility and easily deposited on the surface of the heat transfer tube inside the evaporator. In order to prevent the precipitation of calcium sulfate scale, it is necessary to keep the maximum operating temperature of the evaporator and the concentration rate of the treated water supplied low, and to produce pure water for beverages efficiently. There was a problem that it was difficult to do.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a fresh water generator and a fresh water generation method capable of efficiently generating condensed water while preventing scale precipitation. And

  The above object of the present invention is to generate steam and concentrated water from the water to be treated by supplying the water to be treated to the outer surface of the heat transfer tube through which the steam passes, and the steam is condensed in the heat transfer tube. A plurality of evaporators that generate condensed water, and connected between the plurality of evaporators so that the steam generated by the former evaporator can be led as a heat source into the heat transfer tube of the latter evaporator A fresh water generator comprising a multi-effect evaporator, wherein the plurality of evaporators are grouped into a plurality of evaporator groups from the front side to the rear side, and the scale components contained in the raw water A scale component removing unit that removes at least a portion to generate scale-removed water, and a mixed water obtained by mixing raw water and scale-removed water is treated water, and is disposed on the forefront side of the plurality of evaporators. Of each evaporator in the first evaporator group Each evaporation of the second evaporator group disposed on one low temperature side of the first evaporator group, using mixed water supply means for supplying to the heat pipe and dilution water obtained by mixing concentrated water and mixed water as treated water. This is achieved by a fresh water generator comprising dilution water supply means for supplying to the heat transfer tube of the can.

  Further, in this fresh water generator, the dilution water supply means uses a dilution water obtained by mixing the concentrated water generated in the first evaporator group and the mixed water as a heat transfer tube of each evaporator in the second evaporator group. It is preferable that it is comprised so that it may supply.

  In addition, each evaporator group other than the first evaporator group and the second evaporator group has the first evaporator group and the heat transfer tube of each evaporator constituting the evaporator group, respectively. It is preferable to provide each with concentrated water supply means for supplying concentrated water generated in any of the evaporator groups other than the second evaporator group as treated water.

  Further, the apparatus further comprises means for supplying the concentrated water generated in the first evaporator group to each evaporator in the second evaporator group for flash evaporation, and the dilution water supply means is generated by flash evaporation. Concentrated water, concentrated water generated in the second evaporator group, and dilution water obtained by mixing mixed water are supplied to the heat transfer tubes of the evaporators of the second evaporator group. preferable.

  The scale component removing means is preferably a nanofiltration membrane device.

  Further, the above object of the present invention is to generate steam and concentrated water from the water to be treated by supplying the water to be treated to the outer surface of the heat transfer pipe through which the steam passes, and the steam is generated in the heat transfer pipe. A plurality of evaporators that generate condensed water by condensing are provided, and the plurality of evaporators are connected to each other so that the steam generated in the former evaporator can be led as a heat source into the heat transfer tube of the latter evaporator The plurality of evaporators is a fresh water generation method using a multi-effect evaporator that is grouped into a plurality of evaporator groups from the front side to the rear side, and is included in raw water A scale component removing step for removing scaled water by removing at least part of the scale component, and a mixed water obtained by mixing raw water and scaled water as treated water, and the first stage of the plurality of evaporators Of the first evaporator group arranged on the side A mixed water supply step for supplying heat to the heat transfer tubes of the evaporator, and a second evaporator disposed on one low temperature side of the first evaporator group, with dilution water obtained by mixing concentrated water and mixed water being treated water And a dilution water supply step for supplying to the heat transfer tubes of each evaporator in the group.

  According to the present invention, it is possible to provide a fresh water generator and a fresh water generation method capable of efficiently generating condensed water by high temperature and high concentration operation while preventing scale precipitation.

  Hereinafter, the fresh water generator according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of a fresh water generator according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram illustrating an evaporator that forms the fresh water generator. 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 tank 4 in which raw water such as seawater is stored, a nanofiltration membrane device 5 that removes scale components contained in the raw water, a multi-effect evaporator 2, A driving steam line 10 that guides high temperature driving steam generated in a boiler or the like (not shown) to the evaporator 2, a mixed water supply means 6, a dilution water supply means 7, and a condensing device 8 are provided.

The nanofiltration membrane device 5 is a scale component removing unit that removes at least a part of scale components such as calcium sulfate (CaSO ₄ ) contained in raw water such as seawater stored in the tank 4 to generate descaled water. , Between the tank 4 and the condenser 8. The nanofiltration membrane device 5 mainly has a function of eliminating divalent ions, but a device that specifically eliminates sulfate ions is preferable. This makes it possible to generate scale-removed water from which scale components contained in raw water (in seawater) supplied to the nanofiltration membrane device are removed at a high rate.

  The evaporator 2 is configured by connecting a plurality of evaporators (evaporator 2a to evaporator 2t) in series, and each evaporator has a sealed evaporation chamber 21, indirect, as shown in FIG. A spray heater 23 and a spray nozzle 23 for spraying treated water are provided. The bottom of the evaporation chamber 21 is sprayed from the spray nozzle 23 on the outer surface of the heat transfer tube 221 provided in the indirect heater 22, and a part of the water to be treated is evaporated as a vapor by the heat exchange action of the heat transfer tube 221. The concentrated water storage part 24 in which the subsequent concentrated water is stored is configured. Further, at the bottom of the evaporation chamber 21, a concentrated water introduction part 26 a for introducing concentrated water generated in another evaporator, and a concentrated water stored in the concentrated water storage part 24 are discharged to the outside. And a concentrated water discharge part 26b. In the upper part of the evaporation chamber 21, a steam discharge part 25 a for discharging steam generated on the outer surface of the heat transfer tube 221 by the heat exchange action of the heat transfer tube 221 is provided.

  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 connected to both ends of the plurality of heat transfer tubes 221, respectively. 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 is guided to the second header 223 through the inside of the heat transfer tube 221 disposed at the lowermost portion 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, the vapors in the former evaporators are guided between the evaporators so that the vapor generated in the former evaporator can be guided as a heat source into the heat transfer tube 221 of the latter evaporator. The discharge part 25 a and the steam introduction part 25 b in the latter evaporator are connected via a steam line 25. Further, the concentrated water discharge unit 26b in the preceding evaporator can be guided so as to guide the concentrated water generated in the preceding evaporator and stored in the concentrated water storage unit 24 to the concentrated water storage unit 24 in the next evaporator. The concentrated water inlet 26a in the subsequent evaporator is connected via a concentrated water supply pipe 9126. 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 10 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 or the concentrated water introduction part 26a.

  A steam discharge pipe 51 for introducing steam to the condenser 8 described later is connected to the steam discharge part 25a of the second header 223 of the indirect heater 22 in the final stage evaporator 2p, and the condensed water discharge part 27b. Is connected to a condensed water extraction pipe 53 for discharging condensed water to the outside. In addition, a concentrated water discharge pipe 54 for discharging the stored concentrated water to the outside is connected to the concentrated water discharge portion 26b formed at the bottom of the evaporation chamber 21.

  The plurality of evaporators (evaporator 2a to evaporator 2t) in the evaporator 2 configured as described above are grouped into a plurality of evaporator groups from the front side to the rear side. Specifically, the first evaporator group 3A, the second evaporator group 3B, the third evaporator group 3C, the fourth evaporator group 3D, and the fifth evaporator group 3E are sequentially arranged from the front side of the plurality of evaporators. The evaporator groups 3A to 3E are each configured to include four evaporators. It should be noted that the number of evaporators constituting each of the evaporator groups 3A to 3E can be appropriately changed according to design conditions. Here, since the driving steam is guided to the evaporator 2a arranged on the foremost stage side of the first evaporator group 3A, the operating temperature in each of the evaporator groups 3A to 3E is the highest in the first evaporator group 3A, The operating temperature decreases in the order of the second evaporator group 3B, the third evaporator group 3C, the fourth evaporator group 3D, and the fifth evaporator group 3E. In addition, as for the operating temperature of each evaporator which comprises each evaporator group 3A-3E, respectively, temperature falls as it goes to the back | latter stage side.

  The mixed water supply means 6 includes a plurality of mixed water obtained by mixing the scaled water from which at least a part of the scale component in the raw water is removed in the nanofiltration membrane device 5 and the raw water guided from the tank 4 as treated water. It is a means to supply to the heat exchanger tube of each evaporator of the 1st evaporator group 3A arrange | positioned among the evaporator groups 3A-3E of this. The mixed water supply means 6 includes a mixed water supply pipe 61 connected to the spray nozzles 23 of the respective evaporators 2a to 2d constituting the first evaporator group 3A, and a supply pump (not shown). A part of the mixed water supply pipe 61 is configured to pass through a cooler portion (not shown) provided inside the condensing device 8, and the mixed water passing through the mixed water supply pipe 61 is condensed. It is comprised so that it may act as a refrigerant | coolant for condensing the vapor | steam guide | induced to the apparatus 8. FIG.

  The dilution water supply means 7 uses, as treated water, dilution water obtained by mixing concentrated water and mixed water generated in the second evaporator group 3B arranged on one low temperature side of the first evaporator group 3A. It is a means to supply to the heat exchanger tube of each evaporator 2e-2h of the 2nd evaporator group 3B. More specifically, the dilution water supply means 7 uses the concentrated water stored in the evaporator 2h arranged at the final stage of the second evaporator group 3B as the evaporators 2e to 2h of the second evaporator group 3B. The concentrated water pipe 71 that leads to the spray nozzle 23, and the mixed water that connects the concentrated water pipe 71 and the mixed water supply pipe 61 to a part of the mixed water supplied by the mixed water supply means 6 to the concentrated water pipe 71. A lead-out conduit 72 and a supply pump (not shown) are provided. With such a configuration, the concentration of scale components such as calcium sulfate in the water to be treated supplied to the heat transfer tubes 221 of the respective evaporators 2e to 2h constituting the second evaporator group 3B can be reduced.

  Further, each of the evaporator groups 3C, 3D, and 3E other than the first evaporator group 3A and the second evaporator group 3B is different from the evaporators that constitute the evaporator groups 3C, 3D, and 3E. Concentrated water supply means for supplying concentrated water generated in any of the evaporator groups other than the first evaporator group 3A and the second evaporator group 3B as treated water is provided. In the present embodiment shown in FIG. 1, the concentrated water supply means 9 provided in the third evaporator group 3 </ b> C uses the concentrated water stored in the evaporator 2 l arranged at the final stage of the third evaporator group 3 </ b> C as the third. It is comprised so that it may supply to each evaporator 2i-2l of the evaporator group 3C as to-be-processed water. The concentrated water supply means 9 provided in the fourth evaporator group 3D is configured to supply the concentrated water stored in the evaporator 2p arranged in the final stage of the fourth evaporator group 3D to each evaporator 2m to 4m of the fourth evaporator group 3D. It is configured to supply 2p as treated water. The concentrated water supply means 9 provided in the fifth evaporator group 3E is configured to supply the concentrated water stored in the evaporator 2t arranged in the final stage of the fifth evaporator group 3E to each evaporator 2q to 5q of the fifth evaporator group 3E. It is configured to supply 2t as treated water. Each concentrated water supply means 9 includes a concentrated water supply pipe 91 for introducing concentrated water to the spray nozzles 23 of the respective evaporators constituting each evaporator group 3C, 3D, 3E, and a supply pump (not shown). Yes.

  The condensing device 8 indirectly causes the steam discharged from the steam discharge portion 25a of the evaporator 2t arranged at the most rear side in the multistage effect type evaporator 2 by the mixed water passing through the mixed water supply pipe 61. It is an apparatus that cools and generates condensed water. The generated condensed water is discharged to the outside through the pipe line 52.

  A method for generating condensed water used for, for example, beverages by the fresh water generator 1 configured as described above will be described below. First, driving steam generated by a boiler or the like is supplied to the evaporator 2 through the driving steam line 10. Then, the mixed water of the scale-removed water and the raw water is supplied to the evaporator 2 by the mixed water supply means 6.

  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 in the first evaporator group 3A. The mixed water guided by the mixed water supply means 6 is distributed and supplied to the spray nozzles 23 of the respective evaporators 2a to 2d constituting the first evaporator group 3A, and the outer surface of the heat transfer tube 221 of each of the evaporators 2a to 2d. To be treated as treated water.

  The mixed water sprayed on the outer surface of the heat transfer tube 221 of the first evaporator 2a in the first evaporator group 3A exchanges heat with the driving steam passing through the inside of the heat transfer tube 221, and a part of the water is exchanged. It evaporates and becomes a vapor | steam, and is guide | induced as the heat source to the heat exchanger tube 221 in the evaporator 2b of one back | latter stage side. In addition, the mixed water that has not evaporated on the outer surface of the heat transfer tube 221 becomes concentrated water whose salt concentration and scale component concentration are increased, and flows down along the outer surface of the heat transfer tube 221 to the bottom of the evaporation chamber 21. It is stored and led from the concentrated water discharge part 26b to the evaporator 2b on the next stage side through the concentrated water supply conduit 9126. The driving steam passing through the heat transfer tube 221 is converted into condensed water by heat exchange with the mixed water sprayed on the outer surface of the heat transfer tube 221 and stored in the second header 223 of the indirect heater 22. Then, it is led to the first header 222 of the indirect heater 22 in the one evaporator 2b on the next stage side through the condensed water conduit 27.

  In the evaporator 2b disposed on the one-stage side of the first-stage evaporator 2a in the first evaporator group 3A, the mixed water sprayed from the spray nozzle 23 onto the outer surface of the heat transfer tube 221 and the one-front side Heat exchange is performed between the steam generated in the evaporator 2 a and the steam passing through the heat transfer tube 221 to generate steam and concentrated water, and condensed water is generated in the heat transfer tube 221. The same process is sequentially performed on the other evaporators 2c and 2d constituting the first evaporator group 3A.

  Next, the operation of the second evaporator group 3B will be described. On the outer surface of the heat transfer tube 221 of each of the evaporators 2e to 2h in the second evaporator group 3B, the concentrated water stored in the evaporator 2h disposed on the last stage side of the second evaporator group 3B is mixed with the mixed water Diluted water mixed with the mixed water introduced through the means 33 is sprayed as water to be treated. In the evaporator 2e disposed on the foremost stage side of the second evaporator group 3B, the diluted water sprayed on the heat transfer pipe 221 and the heat transfer pipe generated and generated in the evaporator 2d on the last stage side of the first evaporator group 3A. Heat is exchanged with the steam passing through the interior of 221 to generate steam and concentrated water, and condensed water is generated inside the heat transfer tube 221. In the evaporator 2f disposed on the one-stage side of the first-stage evaporator 2e in the second evaporator group 3B, the dilution water sprayed from the spray nozzle 23 to the outer surface of the heat transfer tube 221 and the one-front side Heat is exchanged between the steam generated in the evaporator 2e and passing through the heat transfer tube 221 to generate steam and concentrated water, and condensed water is generated in the heat transfer tube 221. The same process is sequentially performed on the other evaporators 2g and 2h constituting the second evaporator group 3B.

  On the outer surface of the heat transfer tube 221 of each of the evaporators 2i to 2l in the third evaporator group 3C, concentrated water stored in the evaporator 2l disposed on the last stage side of the third evaporator group 3C is dispersed. In the evaporator 2i disposed on the foremost stage side of the third evaporator group 3C, the concentrated water sprayed on the heat transfer pipe 221 and the heat transfer pipe generated in the last stage evaporator 2h of the second evaporator group 3B. Heat is exchanged with the steam passing through the interior of 221, and steam and concentrated water having a higher salinity concentration are generated, and condensed water is generated inside the heat transfer pipe 221. In the evaporator 2j disposed on the one rear side of the foremost evaporator 2i in the third evaporator group 3C, the concentrated water sprayed from the spray nozzle 23 to the outer surface of the heat transfer tube 221 and the one front side Heat exchange is performed with the steam generated in the evaporator 2i and passing through the heat transfer tube 221 to generate steam and concentrated water. In the heat transfer tube 221, condensed water is generated. The same process is sequentially performed on the other evaporators 2k and 2l constituting the third evaporator group 3C.

  In the fourth and fifth evaporator groups 3D and 3E, the same processing as that of the third evaporator group 3C is performed.

  Condensed water generated in the heat transfer pipes 221 of the respective evaporators 2a to 2t constituting the evaporator 2 is sequentially led to the evaporator on the rear stage side through the condensed water pipe 27, and finally the evaporator 2 Is taken out from the condensed water discharge portion 27b of the evaporator 2t (the evaporator on the last stage side of the fifth evaporator group 3E) arranged on the most rear side through the condensed water discharge conduit 53. Moreover, the vapor | steam produced | generated in the heat exchanger tube 221 surface of the evaporator 2t arrange | positioned in the most back | latter stage side of the evaporator 2 was guide | induced to the condensation apparatus 8 via the vapor | steam extraction conduit 51, and was converted into condensed water. Then, it is taken out via the pipe line 52. The condensed water taken out from the evaporator 2 and the condensed water taken out from the condensing device 8 are then used as drinking water, washing water in various industries such as the electronics industry, and the like.

  A part of the concentrated water stored in the evaporator 2t arranged on the most rear side of the evaporator 2 is discharged to the outside from the concentrated water discharge part 26b via the concentrated water discharge conduit 54.

  According to the fresh water generator 1 according to the present embodiment, the scale component concentration is the highest for each of the evaporators 2a to 2d constituting the first evaporator group 3A having the highest operating temperature and the scales such as calcium sulfate being easily deposited. Since the mixed water is supplied as the water to be treated and the condensed water is obtained by performing the evaporation and condensation treatment, it is ensured that the scale is deposited on the heat transfer tubes 221 of the respective evaporators 2a to 2d. It becomes possible to prevent.

  Moreover, it is comprised so that dilution water with a low scale component density | concentration may be supplied with respect to each evaporator 2e-2h which comprises the 2nd evaporator group 3B whose operating temperature is the next highest after the 1st evaporator group 3A. Therefore, it is also possible to reliably prevent the scale from being deposited on the heat transfer tubes of the respective evaporators 2e to 2h constituting the second evaporator group 3B.

  As described above, it is possible to reliably prevent the scale from depositing on the surface of the heat transfer tube 221 of the evaporator, and as a result, the heat exchange efficiency of the heat transfer tube 221 is avoided from being lowered, and the condensed water for beverages is efficiently used. It becomes possible to manufacture.

  Moreover, since precipitation of scale can be prevented, the temperature of the driving steam supplied to the evaporator 2 is further increased, and each of the evaporators 2a to 2t is driven under a higher operating temperature condition. It becomes possible to drive under, and a large amount of condensed water can be produced efficiently. Furthermore, since the operating temperature in each evaporator 2a-2t can be raised, the vapor specific volume in each evaporator 2a-2t can be reduced, so the volume of each evaporator 2a-2t can be reduced. Thus, the fresh water generator 1 can be reduced in size.

  Moreover, a part of the to-be-processed water evaporatively concentrated in each evaporator 2e-2h which comprises the 2nd evaporator group 3B is the raw | natural water supplied via the mixed water derivation | leading-out pipe 72, and descaling water. Since it is mixed water, the flow rate of the mixed water supplied to each evaporator 2a-2d which comprises the 1st evaporator group 3A is maintained at the flow volume which can be processed most efficiently by each evaporator 2a-2d. In addition, the flow rate of the mixed water subjected to the fresh water treatment in the whole fresh water generator 1 can be increased. As a result, it is possible to efficiently generate condensed water for beverages or the like from a large amount of mixed water.

  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. In the present embodiment, the dilution water supply means 7 uses the dilution water obtained by mixing the concentrated water generated in the second evaporator group 3 </ b> B and the mixed water guided by the mixed water outlet pipe 72 as the second evaporator. For example, as shown in FIG. 3, the concentrated water generated in the first evaporator group and the mixed water outlet pipe 72 are used to supply the heat transfer pipe of each evaporator in the group. It can also comprise so that the dilution water which mixed mixed water may be supplied to the heat exchanger tube of each evaporator 2e-2h of the 2nd evaporator group 3B.

  Moreover, in this embodiment, as shown in FIG. 1, a part of the concentrated water generated and stored in the evaporator groups 3C, 3D, and 3E in which each concentrated water supply means 9 is installed is treated water. Although each concentrated water supply means 9 is comprised so that it may each supply to each evaporator which comprises each evaporator group 3C, 3D, 3E, it is not specifically limited to such a structure. For example, as shown in FIG. 3, each concentrated water supply means 9 includes a group of evaporators 3B, 3B, 3D, 3E disposed on the previous stage of the evaporator groups 3C, 3D, 3E where the concentrated water supply means 9 is installed. A part of the concentrated water generated and stored in the final stage evaporators 2h, 2l, and 2p of 3C and 3D may be supplied to each evaporator.

  Moreover, in this embodiment, although it is comprised so that the dilution water which mixed concentrated water and mixed water may be supplied only to each evaporator 2e-2h which comprises the 2nd evaporator group 3B, Such a configuration is not particularly limited. For example, when there is a possibility that scales such as calcium sulfate may be generated in each of the evaporators 2i to 2l constituting the third evaporator group 3C, the evaporators 2i to 2l constituting the third evaporator group 3C are In contrast, dilution water obtained by mixing concentrated water and mixed water may be supplied.

  Further, in the present embodiment, for example, as shown in FIG. 4, a preheating unit 100 may be provided to heat the mixed water passing through the mixed water supply pipe 61. In FIG. 4, the mixed water is heated by using steam generated in each of the evaporators 2e to 2t constituting the second evaporator group 3B to the fifth evaporator group 3E as a heat source. With such a configuration, the temperature of the mixed water sprayed on the surfaces of the heat transfer tubes 221 of the respective evaporators 2a to 2d of the first evaporator group 3A is efficiently raised, and the heat transfer tubes 221 of the respective evaporators 2a to 2d are heated. The temperature difference from the temperature of the driving steam passing through the inside can be further reduced. As a result, the amount of steam generated inside each of the evaporators 2a to 2d can be increased, and condensed water can be efficiently produced from the mixed water.

  Moreover, in this embodiment, it comprises so that a reverse osmosis membrane apparatus (RO apparatus) may be further provided, and the descaling water produced | generated through the nanofiltration membrane apparatus 5 is supplied water of a reverse osmosis membrane apparatus (RO apparatus). As described above, while producing pure water, RO brine produced by a reverse osmosis membrane device (RO device) is mixed with raw water to produce mixed water, and the first evaporator group using the mixed water as treated water You may make it supply to each evaporator 2a-2d which comprises 3A. Thereby, the water used for drinks etc. can be obtained also from a reverse osmosis membrane apparatus, and it becomes possible to produce water efficiently. Further, if necessary, a mixed liquid obtained by mixing separately nanofiltration membrane-treated water and RO brine is supplied to each of the evaporators 2a to 2d constituting the first evaporator group 3A as treated water. May be.

  Also, in the embodiment shown in FIG. 1, when the pressure of the driving steam passing through the driving steam line 10 is sufficient to compress the steam produced in a suitable evaporator of the evaporator 2, FIG. As shown in FIG. 4, a configuration may be employed in which a vapor recompression ejector 101 is provided in the middle of the drive steam line 10 and a part of the steam generated in the evaporator is guided to the vapor recompression ejector 101. In FIG. 5, a part of the steam generated in the evaporator 2 d disposed on the last stage side of the first evaporator group 3 </ b> A is guided to the steam recompressing ejector 101 via the extraction pipe line 102. is doing. According to such a configuration, the vapor evaporated in the evaporator 2d can be used for heating the other evaporators 2a to 2c arranged on the upstream side of the evaporator 2d, so the number of evaporators is smaller. The desired condensed water (manufactured water) can be obtained. A value obtained by dividing the operating temperature region of the evaporator 2 (corresponding to the difference between the operating temperature of the evaporator 2a arranged on the front stage side and the operating temperature of the evaporator 2t arranged on the last stage side) by the number of evaporators Is the operating temperature difference between adjacent evaporators, so if the number of required evaporators is reduced, the operating temperature difference between adjacent evaporators can be increased accordingly, so mixed water can be used for beverages, etc. The condensed water can be efficiently generated. In addition, the evaporator to which the extraction pipe line 102 is connected can be appropriately changed depending on the design conditions.

  Further, as shown in FIG. 6, a plurality of vapor recompression ejectors 101 and 101 are provided, and the steam generated in the different evaporators 2d and 2h is guided to the respective vapor recompression ejectors 101 and 101, respectively. The driving steam passing through one steam recompression ejector 101 is guided to the heat transfer pipe 211 in the evaporator 2a on the foremost stage side of the first evaporator group 3A, and the driving steam passing through the other steam recompressing ejector 101 is changed to the first. You may comprise so that it may guide in the heat exchanger tube 211 of the evaporator 2d different from the evaporator 2a of the 1st stage of 1 evaporator group 3A.

  Moreover, in this embodiment, in order to prevent soft scales, such as a calcium carbonate, generating in the inside of an evaporator, it may comprise so that a decarboxylation process may be performed by previously adding an acid with respect to mixed water. Good.

  Further, in the present embodiment, the flash evaporation conduit for guiding the concentrated water generated in the first evaporator group 3A to the evaporators 2e to 2h of the second evaporator group 3B, and the second evaporator group 3B Pressure reducing means for depressurizing the inside of each evaporator 2e-2h, and supplying the concentrated water produced in the first evaporator group 3A to each evaporator 2e-2h of the second evaporator group 3B for flash evaporation. It can also be configured as follows. Such a configuration makes it possible to generate condensed water for beverages and the like more efficiently. In addition, when adopting such a configuration, the dilution water supply means 7 uses the concentrated water generated by flash evaporation, the concentrated water generated by the heat exchange action in the heat transfer pipe 211, and the mixed water outlet pipe 72. The diluted water mixed with the mixed water led through the second evaporator group 3B is supplied to the heat transfer tubes of the evaporators 2e to 2h of the second evaporator group 3B.

  Moreover, since the inventors confirmed the effect of the present invention by the solubility product calculation, the results are shown below. When water to be treated having the same properties is used as feed water for a fresh water generator, it can be judged that a liquid feed method capable of obtaining as much condensed water (manufactured water) as possible within a range where scale precipitation does not occur. That is, it can be said that as the concentration rate of the water to be treated supplied to the multi-effect evaporator 2 is increased, more production water can be efficiently obtained. It will be shown below that condensed water (manufactured water) can be efficiently generated by the fresh water generator 2 and the fresh water generation method according to the present invention. First, Table 1 shows typical raw water (untreated seawater), scale-removed water from which a part of scale components has been removed by the nanofiltration membrane device 5 (NF production water), and scale component concentrations of RO brine. Regarding the quality of NF production water in Table 1, an NF membrane (XUS-229323) manufactured by The Dow Chemical Company was used for the nanofiltration membrane device 5, and the NF production produced by the nanofiltration membrane device 5 was used. The concentration of water scale component is shown. Regarding the water quality of RO brine, RO membrane (SW30HRLE-400) manufactured by The Dow Chemical Company is used for the reverse osmosis membrane device (RO device), and the reverse osmosis membrane device (RO device). ) Shows the scale component concentration of the RO brine produced by (1).

混合水供給手段６により第１蒸発缶群３Ａの各蒸発缶２ａ〜２ｄに供給される混合水として、上記表１に示す未処理海水（原水）、ＮＦ製造水、ＲＯブラインを一定の比率で混合した混合水を採用する。具体的には、未処理海水（原水）が５５重量％、ＮＦ製造水が１８重量％、ＲＯブラインが２７重量％とした。このようにして生成された混合水におけるスケール成分濃度を表２に示す。

As the mixed water supplied to each of the evaporators 2a to 2d of the first evaporator group 3A by the mixed water supply means 6, untreated seawater (raw water), NF production water, and RO brine shown in Table 1 above at a certain ratio. Adopt mixed mixed water. Specifically, untreated seawater (raw water) was 55% by weight, NF production water was 18% by weight, and RO brine was 27% by weight. Table 2 shows the scale component concentrations in the mixed water thus produced.

図１に示す構成の造水装置１を用いて、上記表２に示されるスケール成分濃度を有する混合水から一日当り２４０００ｔの凝縮水（製造水）を生成する場合の各蒸発缶における蒸発量及び運転温度（蒸発温度）の条件を表３に示す。表３においては、各蒸発缶群３Ａ〜３Ｅにおける最前段側に配置される蒸発缶２ａ，２ｅ，２ｉ，２ｍ，２ｑの蒸発量及び運転温度（蒸発温度）を代表的に示している。なお、図１に示されるように、加熱蒸気は第一蒸発缶群３Ａの最前段側に配置される蒸発缶２ａに供給され、各蒸発缶内の温度と圧力は、第１蒸発缶群３Ａの最前段における蒸発缶２ａから第５蒸発缶群３Ｅの最後段における蒸発缶２ｔまで順次降下する。各蒸発缶群３Ａ〜３Ｅでは各缶並列に被処理水が給水され、各蒸発缶での蒸発量が同じになるように設定されているので各蒸発缶の伝熱管表面での濃縮水の濃度は同一となる。また、表３に示す各蒸発缶２ａ，２ｅ，２ｉ，２ｍ，２ｑは、各蒸発缶群中、最もスケールの析出しやすい蒸発缶である。

The amount of evaporation in each evaporator when producing 24,000 t of condensed water (manufactured water) per day from the mixed water having the scale component concentration shown in Table 2 above using the fresh water generator 1 having the configuration shown in FIG. Table 3 shows the operating temperature (evaporation temperature) conditions. In Table 3, the evaporation amount and the operating temperature (evaporation temperature) of the evaporators 2a, 2e, 2i, 2m, and 2q arranged on the foremost stage side in each of the evaporator groups 3A to 3E are representatively shown. As shown in FIG. 1, the heated steam is supplied to the evaporator 2a arranged on the foremost stage side of the first evaporator group 3A, and the temperature and pressure in each evaporator can be set to the first evaporator group 3A. The evaporator 2a in the foremost stage of the first to the evaporator 2t in the last stage of the fifth evaporator group 3E is sequentially lowered. In each of the evaporator groups 3A to 3E, the water to be treated is supplied in parallel to each of the cans, and the evaporation amount in each evaporator is set to be the same, so the concentration of concentrated water on the surface of the heat transfer tube of each evaporator Are the same. In addition, each of the evaporators 2a, 2e, 2i, 2m, and 2q shown in Table 3 is the evaporator in which the scale is most easily deposited in each evaporator group.

上記表２に示されるスケール成分濃度を有する混合水を、表３に示す蒸発温度条件及び蒸発量条件にて、造水装置１の濃縮倍率を２として蒸発濃縮処理した場合、及び、濃縮倍率を３として蒸発濃縮処理した場合の溶解度積計算結果を表４に示す。また、造水装置１の濃縮倍率を２とした場合のフロー図を図７に、濃縮倍率を３とした場合のフロー図を図８に示す。なお、今回の溶解度積計算においては、混合水供給手段６から希釈水供給手段７に導かれる混合水の流量を０としている。

When the mixed water having the scale component concentration shown in Table 2 is evaporated and concentrated under the evaporation temperature condition and evaporation amount condition shown in Table 3 with the concentration rate of the fresh water generator 1 being 2, and the concentration rate is Table 4 shows the calculation results of the solubility product when the evaporation concentration treatment is performed as 3. FIG. 7 shows a flow diagram when the concentration rate of the fresh water generator 1 is 2, and FIG. 8 shows a flow diagram when the concentration rate is 3. In this solubility product calculation, the flow rate of the mixed water led from the mixed water supply means 6 to the dilution water supply means 7 is set to zero.

Table 4 shows the value of the maximum concentration (TDS) of the concentrate on the surface of the heat transfer tube in each evaporator, the value of the solubility product due to calcium ions and sulfate ions, and the value of the maximum allowable solubility product. Precipitation of scale occurs when the solubility product value exceeds the maximum allowable solubility product value during operation of the apparatus. Here, the value of the maximum allowable solubility product ([Ca] × [SO ₄ ]) shown in Table 4 is the technical data book (OSW14.16 Page1A, 14.16Page1B) of the Office of Salin Water. Is calculated based on However, this data is obtained by measuring the solubility product limit by dissolving calcium sulfate anhydrous in untreated raw seawater and concentrated seawater, and treating the mixed water of descaled water and raw water (raw seawater) as treated water. However, when compared with the chlorine component concentration, the data from the Office of Salin Water is more stringent, so the solubility product limit Judgment is safe for the sake of convenience, and is rather safer. In order to determine the solubility product limit more accurately, it is possible to use the ionic strength of the water to be treated as a reference.

  Here, the calculation method of the solubility product in Table 4 will be described. Typically, a method of obtaining the solubility product in the evaporator 2a in the first evaporator group 3A when the concentration factor in the fresh water generator is 2 will be shown. First, the flow rate of the mixed water supplied to the evaporator 2a in the first evaporator group 3A is (2000 t / hr) / 4 cans = 500 t / hr from FIG. 7, and the steam flow rate generated in the evaporator 2a is (200 t / hr) / 4 can = 50 t / hr. Therefore, the concentration rate in the evaporator 2a is (500 t / hr) / (500 t / hr−50 t / hr) = 1.111. Therefore, the concentration of concentrated water in the evaporator 2a is 411 × 1.111 = 457 ppm for the calcium component and 1849 × 1.111 = 2405 ppm for the sulfate ion component. Accordingly, the calcium component is 457/40/1000 = 0.0111025 moles / l (40 in the formula is the atomic weight of calcium), and the sulfate ion component is 2054/94/1000 = 0.0213395 moles / l. (94 in the formula is the molecular weight of sulfate ion). Therefore, the solubility product of calcium sulfate is (calcium component) × (sulfate ion component) = 0.0111025 × 0.021395 = 0.000244.

表４に示す結果から、スケール成分が析出しやすい各蒸発缶群３Ａ〜３Ｅの最前側に配置される蒸発缶２ａ，２ｅ，２ｉ，２ｍ，２ｑの全てにおいて、カルシウムイオンと硫酸イオンとの溶解度積の値が、最高許容溶解度積の値よりも小さいことが分かる。つまり、運転最高温度が１２５℃という極めて高温の条件下で造水装置を運転したとしても、蒸発缶の伝熱管表面等にスケールの析出が発生する可能性はなく、本実施形態に係る造水装置によれば、効率よく飲料用等の凝縮水（製造水）を生成することができることが分かる。

From the results shown in Table 4, the solubility of calcium ions and sulfate ions in all of the evaporators 2a, 2e, 2i, 2m, and 2q arranged on the forefront side of each of the evaporator groups 3A to 3E where the scale components easily precipitate. It can be seen that the product value is smaller than the maximum allowable solubility product value. That is, even if the fresh water generator is operated under the extremely high temperature of 125 ° C., there is no possibility of scale deposition on the heat transfer tube surface of the evaporator, and the fresh water according to this embodiment. According to the device, it can be seen that condensed water (manufactured water) for beverages and the like can be efficiently generated.

  For comparison, the solubility product calculation was performed for the case where the mixed water was supplied to each evaporator in the third evaporator group 3C and the case where the mixed water was supplied to each evaporator in the fifth evaporator group 3E. The results are shown in Tables 5 and 6. The concentration ratio in the fresh water generator 1 was 2 and 3. Further, FIG. 9 shows a flow chart when supplying the mixed water to each evaporator of the third evaporator group 3C and setting the concentration ratio of the fresh water generator 1 to 2, and FIG. 9 shows a flowchart when the concentration ratio is 3. As shown in FIG. FIG. 11 shows a flow chart when mixed water is supplied to each evaporator of the fifth evaporator group 3E and the concentration ratio of the fresh water generator 1 is 2, and FIG. 12 shows a flow chart when the concentration ratio is 3. Shown in

表５及び表６に示す結果から、第３、第５蒸発缶群３Ｃ，３Ｅへ混合水を給水する場合において、２倍濃縮及び３倍濃縮のいずれの場合にも、伝熱管表面にスケールの析出が起こるため造水装置における濃縮倍率を２倍以下に抑える必要があり、効率よく飲料用等の凝縮水（製造水）を生成することができないことが分かる。

From the results shown in Table 5 and Table 6, in the case of supplying mixed water to the third and fifth evaporator groups 3C and 3E, in both cases of double concentration and triple concentration, the surface of the heat transfer tube has a scale. Since precipitation occurs, it is necessary to suppress the concentration ratio in the fresh water generator to 2 times or less, and it is understood that condensed water (manufactured water) for beverages and the like cannot be efficiently generated.

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. It is a schematic block diagram which shows the other modification of the fresh water generator shown in FIG. It is a schematic block diagram which shows the further another modification of 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. It is a flowchart in the case of double-concentrating mixed water using the fresh water generator shown in FIG. It is a flowchart in the case of concentrating mixed water 3 times using the fresh water generator shown in FIG. It is a flowchart in the case of supplying mixed water to a 3rd evaporator group, and concentrating mixed water twice. It is a flowchart in the case of supplying mixed water to a 3rd evaporator group, and concentrating mixed water 3 times. It is a flowchart in the case of supplying mixed water to a 5th evaporator group, and concentrating mixed water twice. It is a flowchart in the case of supplying mixed water to a 5th evaporator group, and concentrating mixed water 3 times.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water generator 2 Evaporator 2a-2t Evaporator 3A 1st evaporator group 3B 2nd evaporator group 3C 3rd evaporator group 3D 4th evaporator group 3E 5th evaporator group 4 Tank 5 Scale component removal means ( Nanofiltration membrane device)
6 Mixed water supply means 7 Dilution water supply means 8 Condensing device 9 Concentrated water supply means

Claims (6)

Steam and concentrated water are generated from the water to be treated by supplying the water to be treated to the outer surface of the heat transfer tube through which the steam passes, and condensed water is generated by condensing the steam in the heat transfer tube. A multi-effect evaporation device provided with a plurality of evaporators and connected between the plurality of evaporators so that the steam generated in the former evaporator can be led as a heat source into the heat transfer tube of the latter evaporator A fresh water generator comprising:
The plurality of evaporators are grouped into a plurality of evaporator groups from the front side to the rear side,
Scale component removal means for removing scaled water by removing at least part of the scale components contained in the raw water;
Mixed water supplied to the heat transfer tubes of the respective evaporators of the first evaporator group arranged in the foremost stage among the plurality of evaporator groups, using mixed water obtained by mixing raw water and descaling water as treated water Supply means;
Dilution water supply to be supplied to the heat transfer tubes of the respective evaporators of the second evaporator group disposed on the low temperature side of the first evaporator group using dilution water obtained by mixing concentrated water and mixed water as treated water Fresh water generator comprising means.   The dilution water supply means is configured to supply dilution water obtained by mixing concentrated water generated in the first evaporator group and mixed water to a heat transfer tube of each evaporator in the second evaporator group. The fresh water generator according to claim 1.   Each evaporator group other than the first evaporator group and the second evaporator group has the first evaporator group and the second evaporator with respect to the heat transfer tubes of the evaporators constituting the evaporator group, respectively. The fresh water generating apparatus according to claim 2, further comprising concentrated water supply means for supplying concentrated water generated in any of the evaporator groups other than the evaporator group as treated water. Means for supplying the concentrated water produced in the first evaporator group to each evaporator of the second evaporator group to cause flash evaporation;
The dilution water supply means is configured to supply concentrated water generated by flash evaporation, concentrated water generated in the second evaporator group, and diluted water mixed with mixed water to each evaporator of the second evaporator group. The fresh water generator of Claim 1 comprised so that it may supply to a heat exchanger tube.   The desalinator according to any one of claims 1 to 4, wherein the scale component removing means is a nanofiltration membrane device. Steam and concentrated water are generated from the water to be treated by supplying the water to be treated to the outer surface of the heat transfer tube through which the steam passes, and condensed water is generated by condensing the steam in the heat transfer tube. A plurality of evaporators, connected to each other between the plurality of evaporators so that the steam generated in the former evaporator can be guided as a heat source into the heat transfer tube of the latter evaporator; Is a fresh water generation method using a multi-effect evaporation device grouped into a plurality of evaporator groups from the front side to the rear side,
A scale component removing step for removing scaled water by removing at least part of the scale components contained in the raw water;
Mixed water supplied to the heat transfer tubes of the respective evaporators of the first evaporator group arranged in the foremost stage among the plurality of evaporator groups, using mixed water obtained by mixing raw water and descaling water as treated water A supply step;
Dilution water supply to be supplied to the heat transfer tubes of the respective evaporators of the second evaporator group disposed on the low temperature side of the first evaporator group using dilution water obtained by mixing concentrated water and mixed water as treated water A fresh water generation method comprising a step.

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