JP5089236B2 - 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, condensed water for beverages is obtained by distilling blended seawater, which is obtained by blending raw seawater with scale component-removed seawater from which scale components contained in raw seawater have been removed by a nanofiltration membrane device, using a multi-effect evaporator. Is generated.
Japanese translation of PCT publication No. 2003-507183

  However, in the above-described fresh water generation method, it is impossible to reliably prevent the scale from depositing inside the evaporator, and as a result, the thermal efficiency of the evaporator deteriorates and the condensed water for beverages is efficiently generated. There was a problem that was difficult.

  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 In the fresh water generator, the plurality of evaporators are grouped into a high temperature evaporator group and a low temperature evaporator group from the front stage side to the rear stage side, and sulfate ions which are scale components contained in the raw water Scale component removing means for removing scaled water by removing at least part of the scaled scale water, and descaling water supplied to the heat transfer tubes of the evaporators constituting the high temperature evaporator group using the scaled water as treated water Supply means and raw water As the water is achieved by fresh water generator and a raw water supply means for supplying the heat transfer tube of each evaporator constituting the low-temperature evaporator group.

  Moreover, it is preferable that this fresh water generator includes a high-temperature can group recirculation unit that recirculates a part of the concentrated water generated in the high-temperature evaporator group to the descaled water supply unit.

  Moreover, it is preferable to provide a recirculation means for a low temperature can group that recirculates a part of the concentrated water produced in the low temperature evaporator group to the raw water supply means.

  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 And the plurality of evaporators generate condensed water from the raw water using a fresh water generator grouped into a high temperature evaporator group and a low temperature evaporator group from the front side to the rear side. A scale component removing step for removing scaled water by removing at least part of sulfate ions that are scale components contained in raw water, and using the scaled water as treated water, the high-temperature evaporator group Of each evaporator And removing scale water supply step of supplying to the heat pipe, the raw water as treated water, is achieved by the fresh water generating method and a raw water supply step of supplying to the heat transfer tubes of the evaporator constituting the low-temperature evaporator group.

  According to the present invention, it is possible to provide a fresh water generating apparatus and a fresh water generating method capable of efficiently generating condensed water 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 1 according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram showing an evaporator 20 constituting the fresh water generator 1. Each drawing is partially enlarged or reduced, not the actual size ratio, for easy understanding of the configuration.

  As shown in FIG. 1, a fresh water generator 1 includes a multi-effect evaporator 2, a drive steam line 3 that guides high-temperature drive steam generated in a boiler (not shown) to the evaporator 2, seawater, and the like. The tank 4 in which the raw water is stored, the nanofiltration membrane device 5 that removes the scale components contained in the raw water, the descaled water supply means 6, the raw water supply means 7, and the condensing device 8 are provided.

  The evaporator 2 is configured by connecting a plurality of evaporators 20 in series. As shown in FIG. 2, each evaporator 20 includes a sealed evaporation chamber 21, an indirect heater 22, and treated water. The spray nozzle 23 which sprays is 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. Moreover, in order to discharge | emit the concentrated water stored in the concentrated water introduction part 26a for introducing the concentrated water produced | generated in the other evaporator 20 into the bottom part of the evaporation chamber 21, and the concentrated water storage part 24 outside. The 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 respectively connected to both ends of the plurality of heat transfer tubes 221. The first header 222 includes a steam introduction part 25 b that introduces steam into the heat transfer pipe 221 and a condensed water introduction part 27 a for introducing condensed water generated in the heat transfer pipe 221 of the other evaporator 20. Yes. The 2nd header 223 is provided with the condensed water discharge part 27b which discharges the condensed water (fresh 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 evaporators 20 are connected to each other so that the vapor generated in the preceding evaporator 20 is guided as a heat source into the heat transfer pipe 221 of the evaporator 20 on the next stage. A steam discharge part 25 a in the can 20 and a steam introduction part 25 b in the latter stage evaporator 20 are connected via a steam pipe 25. Further, the concentrated water discharged from the preceding evaporator 20 is guided so that the concentrated water generated in the preceding evaporator 20 and stored in the concentrated water storage section 24 is guided to the concentrated water storage section 24 in the subsequent evaporator 20. The part 26 b and the concentrated water introduction part 26 a in the subsequent evaporator 20 are connected via the concentrated water pipe 26. Further, the condensed water generated in the heat transfer tube 221 in the upstream evaporator 20 and stored in the second header 223 is guided into the first header 222 of the indirect heater 22 in the downstream evaporator 20. In addition, a condensed water discharge part 27 b in the former evaporator 20 and a condensed water introduction part 27 a in the latter evaporator 20 are connected via a condensed water pipe 27.

  In addition, a driving steam line 3 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 20. In the first stage evaporator 20, it is not necessary to provide the condensed water introducing portion 27 a and the concentrated water introducing portion 26 a.

  A steam discharge pipe 81 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 20, and the condensed water discharge part 27b. Is connected to a condensed water outlet conduit 90 for discharging condensed water to the outside. Further, a concentrated water discharge pipe 91 for discharging the stored concentrated water to the outside is connected to the concentrated water discharge part 26 b formed at the bottom of the evaporation chamber 21.

  The plurality of evaporators 20 in the evaporator 2 configured as described above includes a high-temperature evaporator group 2a operated in an environment where the operating temperature is high from the front side to the rear side, and an environment where the operating temperature is relatively low. It is grouped into a low temperature evaporator group 2b operated below. In the configuration shown in FIG. 1, each of the high temperature evaporator group 2 a and the low temperature evaporator group 2 b includes eight evaporators 20. In addition, the number of the evaporators 20 which respectively comprise the high temperature evaporator group 2a and the low temperature evaporator group 2b can be changed suitably with design conditions.

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.

  The descaling water supply means 6 is means for supplying the descaling water from which the scale components in the raw water have been removed in the nanofiltration membrane device 5 to each evaporator 20 constituting the high temperature evaporator group 2a as treated water. The scaled water supply pipe 61 connecting the spray nozzles 23 of the respective evaporators 20 constituting the high temperature evaporator group 2a and the nanofiltration membrane device 5 and a supply pump (not shown) are provided. A part of the scale-removed water supply pipeline 61 is configured to pass through a cooler portion (not shown) provided inside the condensing device 8, and the scale-removed water passing through the scale-removed water supply pipeline 61. However, it is comprised so that it may act as a refrigerant | coolant for condensing the vapor | steam guide | induced to the condensing apparatus 8. FIG.

  The raw water supply means 7 is means for supplying the raw water in the tank 4 to each evaporator 20 constituting the low-temperature evaporator group 2b as treated water, and spraying the evaporators 20 constituting the low-temperature evaporator group 2b. A raw water supply pipe 71 connecting the nozzle 23 and the tank 4 and a supply pump (not shown) are provided. A part of the raw water supply pipe 71 is configured to pass through a cooler portion (not shown) provided inside the condensing device 8, and the raw water passing through the raw water supply pipe 71 is supplied to the condensing device 8. It is comprised so that it may act as a refrigerant | coolant for condensing the vapor | steam guide | induced.

  The condenser 8 is a scale-removed water obtained by removing the scale component from the vapor discharged from the vapor discharge portion 25a of the evaporator 20 arranged on the most downstream side in the multi-stage effect type evaporator 2 by the nanofiltration membrane device 5. And an apparatus for generating condensate by indirectly cooling with raw water guided from the tank 4. The generated condensed water is discharged to the outside through the pipe line 82.

  A method of generating condensed water used for beverages or the like from seawater, for example, by the water producing device 1 configured as described above will be described below. First, drive steam generated by a boiler or the like is supplied to the evaporator 2 through the drive steam line 3. Then, the scaled water from which at least a part of the scale components in the seawater has been removed by the nanofiltration membrane device 5 as the scale component removing means is used as the scaled water supply means 6 for each evaporator that constitutes the high temperature evaporator group 2a. 20 is supplied as treated water, and seawater (raw water) from which scale components have not been removed is supplied as treated water by the raw water supply means 7 to each evaporator 20 constituting the low temperature evaporator group 2b.

  The driving steam supplied to the evaporator 2 is led to the heat transfer tube 221 of the front evaporator 20 in the high temperature evaporator group 2a. The descaling water guided by the descaling water supply means 6 is distributed and supplied to the spray nozzles 23 of the evaporators 20 constituting the high temperature evaporator group 2a, and the outer surface of the heat transfer tube 221 of each evaporator 20 is treated. Sprayed as water. On the other hand, seawater (raw water) guided by the raw water supply means 7 is distributed and supplied to the spray nozzles 23 of the evaporators 20 constituting the low-temperature evaporator group 2b, and the outer surface of the heat transfer tubes 221 of the evaporators 20 is covered. Sprayed as treated water.

  The scale-removed water sprayed on the outer surface of the heat transfer tube 221 of the front-stage evaporator 20 in the high-temperature evaporator group 2a exchanges heat with the driving steam passing through the inside of the heat transfer tube 221, and part of the heat 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 20 of the back | latter stage side. Further, the scale-removed water that has not evaporated on the outer surface of the heat transfer tube 221 becomes concentrated water whose salinity is increased, flows down along the outer surface of the heat transfer tube 221, and is stored at the bottom of the evaporation chamber 21, It is led from the concentrated water discharge part 26b through the concentrated water pipe 26 to the evaporator 20 on the next stage side. In addition, the driving steam passing through the inside of the heat transfer tube 221 is converted into condensed water by heat exchange with the scale-removed 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 evaporator 20 on the one rear stage side through the condensed water pipe 27.

  In the evaporator 20 on the one-stage side of the front-stage evaporator 20 in the high-temperature evaporator group 2a, the descaling water sprayed from the spray nozzle 23 onto the outer surface of the heat transfer tube 221 and the evaporator 20 on the one-front side Heat exchange is performed between the steam generated in the (first stage evaporator) 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. Similar processing is sequentially performed on the other evaporators 20 constituting the high-temperature evaporator group 2a.

  Seawater (raw water) sprayed on the outer surface of the heat transfer tube 221 of the foremost evaporator 20 in the low temperature evaporator group 2 b is generated in the evaporator 20 located on the last stage side of the high temperature evaporator group 2 a and is generated in the heat transfer tube 221. Heat is exchanged with steam passing through the interior. By this heat exchange, a part of the seawater (raw water) is converted into steam, and the remainder becomes concentrated water with an increased salt concentration. Moreover, the vapor | steam which passes the inside of the heat exchanger tube 221 is converted into condensed water. In the evaporator 20 on the one-stage side of the front-stage evaporator 20 in the low-temperature evaporator group 2b, seawater (raw water) sprayed from the spray nozzle 23 to the outer surface of the heat transfer tube 221 and the evaporator on the one-front side 20 (the foremost evaporator 20) is heat-exchanged with 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 The same process is sequentially performed in the other evaporators 20 constituting the low temperature evaporator group 2b.

  Condensed water generated in the heat transfer pipe 221 of each evaporator 20 constituting the evaporator 2 is sequentially led to the evaporator 20 on the rear stage side through the condensed water pipe 27, and finally the evaporator 2 The water is taken out from the condensed water discharge portion 27b of the evaporator 20 arranged on the most rear side through the condensed water discharge conduit 90. Further, the steam generated on the surface of the heat transfer pipe 221 of the evaporator 20 arranged on the most rear side of the evaporator 2 is led to the condenser 8 via the steam outlet pipe 81 and converted into condensed water. Then, it is taken out via the pipe line 82. 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 20 arranged on the most rear side of the evaporator 2 is discharged to the outside from the concentrated water discharge part 26b through the concentrated water discharge conduit 91.

  According to the fresh water generator 1 according to the present embodiment, the nanofiltration membrane device 5 includes each evaporator 20 constituting the high-temperature evaporator group 2a in which the operating temperature is high and the scale is likely to be deposited in seawater. The scale-removed water from which the scale component has been removed at a high rate is supplied as the water to be treated, and evaporative condensation treatment is performed to obtain condensed water. Therefore, the scale is formed in the heat transfer tubes 221 and the like of each evaporator 20. It is possible to reliably prevent the precipitation.

  Moreover, since each evaporator 20 which comprises the low temperature evaporator group 2b is comprised so that seawater may be directly supplied instead of the descaling water from which the scale component was removed by the nanofiltration membrane apparatus 5, The apparatus 1 as a whole can efficiently generate a large amount of condensed water while reducing the operation load of the nanofiltration membrane apparatus 5. The low temperature evaporator group 2b supplied with seawater is operated under low temperature conditions far from the temperature range where scale components such as calcium sulfate are deposited on the surface of the heat transfer tube 221 and the like. It is not.

  As described above, as a result of reliably preventing the scale from being deposited on the surface of the heat transfer tube 221 of the evaporator 20, the heat exchange efficiency of the heat transfer tube 221 can be avoided and condensed water can be removed from raw water such as seawater. It becomes possible to manufacture 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 evaporator 20 can be driven under a higher operating temperature condition, or under a high concentration condition. It becomes possible to drive, and a large amount of condensed water can be produced efficiently.

  About this point, since the inventors confirmed the said effect by solubility product calculation, it demonstrates below. The components of seawater as raw water are 23,000 ppm for the chlorine component, 480 ppm (0.012 mol / L) for the calcium component, and 3200 ppm (0.033 mol / L) for the sulfate ion component. The components of scale-removed water obtained by removing a part of the scale component from the seawater by the nanofiltration membrane device 5 are 20000 ppm for the chlorine component, 180 ppm for the calcium component (0.0045 mol / L, exclusion rate 62.5%), sulfate ion The component is 100 ppm (0.001 mol / L, rejection rate 97%).

  When evaporating and concentrating such descaling water with a concentration factor of 1.6, the solubility product of calcium sulfate is (calcium component) × (sulfate ion component) = 0.445 × 1.6 × 0.001. X 1.6 = 0.000012. On the other hand, when the concentration seawater temperature is 125 ° C. and the chlorine component concentration is 32000 ppm (20000 ppm × 1.6), the solubility product limit of calcium sulfate is based on the relationship between the solubility product limit and the concentration seawater temperature in FIG. , About 0.0003. Here, FIG. 3 is calculated based on the technical data book (OSW14.16 Page1A, 14.16Page1B) of the Office of Salin Water. However, this data is obtained by measuring the solubility product limit by dissolving calcium sulfate anhydrous in untreated raw seawater and concentrated seawater. To apply the scaled water directly as treated water, Although it is impossible, when comparing the chlorine component concentration as a standard, the Office of Salin Water data is more strict than the scaled water, so it is convenient to judge the solubility product limit. It can be said that there is no problem and that it is 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.

  Thus, the solubility product (0.000012) of calcium sulfate when the descaling water is desalinated at a concentration factor of 1.6 is sufficiently lower than the solubility product limit (about 0.0003), and is therefore 125 ° C. Even if high temperature driving steam is supplied to the evaporator 2 and each evaporator 20 is driven, there is no possibility of scale generation. Further, the solubility product limit of calcium sulfate when the concentration seawater temperature is 149 ° C. and the chlorine component concentration is 32000 ppm is about 0.0002 from FIG. 3, and thus has a temperature of 149 ° C. higher than 125 ° C. It can be seen that even when the driving vapor is supplied to the evaporator 2 to drive each evaporator 20, scale deposition does not occur and the evaporator 2 can be driven under a higher temperature condition.

  When the concentration rate is set to 4 and the descaling water is evaporated and concentrated, the solubility product of calcium sulfate is (calcium component) × (sulfate ion component) = 0.004 × 4 × 0.001 × 4 = 0.000072. On the other hand, the solubility product limit of calcium sulfate when the concentration seawater temperature is 125 ° C. and the chlorine component concentration is 80000 ppm (20000 ppm × 4) is approximately from the relationship diagram between the solubility product limit and the concentration seawater temperature in FIG. 0.0007. Here, FIG. 4 is calculated based on the technical data book (OSW14.16 Page1A, 14.16Page1B) of the Office of Salin Water, similarly to FIG.

  Thus, even when the concentration factor is set to 4, the solubility product (0.000072) of calcium sulfate is sufficiently lower than the solubility product limit (about 0.0007), so driving at a high temperature of 125 ° C. It can be seen that even if vapor is supplied to the evaporator 2 and each evaporator 20 is driven, no scale is deposited. Further, the solubility product limit when the concentrated seawater temperature is 149 ° C. and the chlorine component concentration is 80000 ppm is about 0.0005 from FIG. 4, so the concentration factor is set to 4 and is even higher than 125 ° C. 149 It can be seen that even when driving vapor having a temperature of ° C. is supplied to the evaporator 2 and each evaporator 20 is driven, no scale is deposited.

  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, as shown in FIG. 5, the fresh water generator 1 includes a high-temperature can group recirculation means 28 for recirculating a part of the concentrated water generated in the high-temperature evaporator group 2 a to the scale-removed water supply means 6, It is also possible to adopt a configuration including a low-temperature can group recirculation means 29 that recirculates part of the concentrated water produced in the can group 2 b to the raw water supply means 7. The high-temperature can group recirculation means 28 includes a high-temperature can group recirculation pipe 28a that connects the bottom of the evaporator 20 located on the last stage side of the high-temperature evaporator group 2a and the descaling water supply line 61, and a circulation (not shown). With a pump. The low-temperature can group recirculation means 29 includes a low-temperature can group recirculation pipe 29a that connects the bottom of the evaporator 20 located on the last stage side of the low-temperature evaporator group 2b and the raw water supply pipe 71, a circulation pump (not shown), It has. The evaporator 20 to which the high-temperature can group reflux conduit 28a and the low-temperature can group reflux conduit 29a are connected is not particularly limited, and the evaporator 20 to be appropriately connected can be selected depending on design conditions. Further, the connection position between the scale-removed water supply pipe 61 and the raw water supply pipe 71 can be selected as appropriate.

  When such a configuration is adopted, a part of the concentrated water generated in the high-temperature evaporator group 2a is mixed with the descaled water supplied by the descaled water supply means 6 by the high-temperature can group reflux means 28. Since it can be sprayed on the surface of the heat transfer tube 221 of each evaporator 20 constituting the high temperature evaporator group 2a, the amount of descaled water supplied from the nanofiltration membrane device 5 to the high temperature evaporator group 2a is reduced. Can do. Thereby, the operation load of the nanofiltration membrane apparatus 5 can be reduced, and a fresh water treatment can be performed efficiently. Further, since the temperature of the concentrated water generated in the high temperature evaporator group 2a is higher than the temperature of the descaling water supplied to the high temperature evaporator group 2a, the concentrated water is returned to the descaling water supply means 6. By making it, the temperature of the to-be-processed water which the spray nozzle 23 of each evaporator 20 sprays on the heat exchanger tube 221 can be raised. As a result, since the temperature difference between the water to be treated and the steam passing through the heat transfer pipe 221 can be reduced, the amount of steam generated in each evaporator 20 can be increased, and the raw water such as seawater can be efficiently used. Condensed water for beverages and the like can be produced.

  Further, since the low temperature can group reflux means 29 can mix a part of the concentrated water produced in the low temperature evaporator group 2b with the raw water supplied by the raw water supply means 7, the low temperature evaporator group 2b The temperature of the water to be treated sprayed to the heat transfer pipe 221 by the spray nozzle 23 of the constituent evaporator 20 can be increased, the amount of generated steam in each evaporator 20 can be increased, and the condensed water can be efficiently extracted from the raw water. Can be manufactured.

  Further, for example, as shown in FIG. 6, preheating means 95 may be provided so that the scaled water passing through the scaled water supply pipe 61 and the raw water passing through the raw water supply pipe 71 are heated. . In FIG. 6, the plurality of evaporators 20 constituting the high temperature evaporator group 2a are further divided into two groups 2a1 and 2a2 on the front stage side and the rear stage side, and the plurality of evaporators 20 constituting the low temperature evaporator group 2b. Are divided into two groups 2b1 and 2b2 on the front stage side and the rear stage side, and the descaling water supplied to each evaporator 20 of the front stage evaporator group 2a1 of the high temperature evaporator group 2a is the low temperature evaporator group 2b. The steam generated in all the evaporators 20 and the evaporators 20 in the rear-stage evaporator group 2a2 of the high-temperature evaporator group 2a is heated as a heat source. Further, the descaling water supplied to each evaporator 20 of the rear evaporator group 2a2 of the high temperature evaporator group 2a is heated using steam generated in all the evaporators 20 constituting the low temperature evaporator group 2b as a heat source. It is comprised so that. Furthermore, the raw water supplied to each evaporator 20 of the former stage evaporator group 2b1 of the low temperature evaporator group 2b uses steam generated in each evaporator 20 of the lower stage evaporator group 2b2 of the low temperature evaporator group 2b as a heat source. It is comprised so that it may be heated as.

  With such a configuration, the temperature of the descaling water and raw water sprayed on the surface of the heat transfer tube 221 of each evaporator 20 is efficiently raised, and the temperature of the steam passing through the heat transfer tube 221 of each evaporator 20 And the temperature difference can be further reduced. As a result, the amount of steam generated inside each evaporator 20 can be increased, and condensed water can be efficiently produced from raw water.

  Moreover, when the preheating means 95 as shown in FIG. 6 is provided, the temperature of the descaling water supplied to the front stage evaporator group 2a1 of the high temperature evaporator group 2a is the rear stage evaporator group of the high temperature evaporator group 2a. It becomes higher than the temperature of the descaling water supplied to 2a2. In such a case, as shown in FIG. 6, a part of the concentrated water generated in the front-stage evaporator group 2a1 is mixed with the descaled water supplied to each evaporator 20 in the front-stage evaporator group 2a1. In addition, for a plurality of high-temperature can groups, a part of the concentrated water generated in the rear-stage side evaporator group 2a2 is mixed with descaling water supplied to each evaporator 20 of the rear-stage side evaporator group 2a2. It is preferable to provide the reflux means 28. With such a configuration, a temperature difference between the temperature of the water to be treated sprayed on the heat transfer tubes 221 of each evaporator 20 constituting the high temperature evaporator group 2a and the temperature of the steam passing through the inside of each heat transfer tube 221. Therefore, it is possible to reliably increase the amount of generated steam in each evaporator 20 and efficiently produce condensed water for beverages from raw water.

  Similarly, in the low temperature evaporator group 2b, the temperature of the raw water supplied to the upstream evaporator group 2b1 is higher than the temperature of the raw water supplied to the downstream evaporator group 2b2, so the upstream evaporator It is preferable to install the low-temperature can group reflux means 29 so that a part of the concentrated water generated in the group 2b1 is mixed with the raw water supplied to the evaporators 20 of the upstream evaporator group 2b1.

  Further, in this embodiment, the descaling water supply means 6 is configured to include a reverse osmosis membrane device (RO device), and a part of pure water is separated from the descaling water that has passed through the nanofiltration membrane device 5. Then, separated water may be generated, and this separated water may be supplied to each evaporator 20 constituting the high-temperature evaporator group 2a as treated water. Thereby, the water used for drink etc. can be obtained also from a reverse osmosis membrane apparatus, and it becomes possible to perform a fresh water treatment efficiently. In addition, if necessary, a mixed liquid obtained by mixing seawater and separation water separately treated with a nanofiltration membrane may be supplied to each evaporator 20 constituting the high-temperature evaporator group 2a as water to be treated. .

  Further, in this embodiment, when the pressure of the driving steam passing through the driving steam line 3 is sufficient to compress the steam generated in an appropriate evaporator 20 of the evaporator 2, it is shown in FIG. As described above, a configuration may be employed in which the vapor recompression ejector 31 is provided in the middle of the drive steam line 3 and a part of the steam generated in the evaporator 20 is guided to the vapor recompression ejector 31. In FIG. 7, a part of the steam generated in the evaporator 20 arranged on the last stage side of the high temperature evaporator group 2 a is configured to be guided to the steam recompressing ejector 31 through the extraction pipe 32. . According to such a configuration, since the vapor evaporated in the evaporator can be used for heating other evaporators arranged on the upstream side of the evaporator, the desired condensation can be achieved with a smaller number of evaporators. Water (manufactured water) is obtained. The value obtained by dividing the operating temperature range of the evaporator 2 (corresponding to the difference between the operating temperature of the evaporator disposed on the front stage side and the operating temperature of the evaporator disposed on the last stage side) by the number of evaporators is: Since the operating temperature difference between the adjacent evaporators is almost the same, if the number of required evaporators is reduced, the operating temperature difference between the adjacent evaporators can be increased accordingly. The condensed water can be efficiently generated. In addition, the evaporator 20 to which the extraction pipe line 32 is connected can be appropriately changed depending on design conditions.

  Further, as shown in FIG. 8, a plurality of vapor recompression ejectors 31, 31 are provided, and the vapor generated in different evaporators 20 is configured to be guided to each vapor recompression ejector 31, and one vapor recompression is performed. The driving steam passing through the ejector 31 is guided to the evaporator 20 on the front stage side of the high temperature evaporator group 2a, and the driving steam passing through the other steam recompressing ejector 31 is evaporated on the front stage side of the high temperature evaporator group 2a. You may comprise so that it may guide to the evaporation can 20 different from the can 20.

Moreover, in this embodiment, in order to prevent soft scales, such as a calcium carbonate, generating in the inside of the evaporator 20, it is comprised so that a decarboxylation process may be performed by previously adding an acid with respect to raw water, such as seawater. May be. In addition, when the operating temperature of the low temperature evaporator group 2b is low and there is no problem of soft scale generation, it is not necessary to perform a decarboxylation process.

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 graph which shows the relationship between the solubility product limit of calcium sulfate and concentrated seawater temperature in case chlorine component density | concentration is 32000 ppm. It is a graph which shows the relationship between the solubility product limit of calcium sulfate and concentrated seawater temperature in case a chlorine component density | concentration is 80000 ppm. 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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water generator 2 Evaporator 2a High temperature evaporator group 2b Low temperature evaporator group 20 Evaporator 4 Tank 5 Nanofiltration membrane apparatus (scale component removal means)
6 Descaled water supply means 7 Raw water supply means 8 Condensing device

Claims (7)

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, a fresh water generator connected between the plurality of evaporators so as to guide the steam generated in the former evaporator to the inside of the heat transfer tube of the latter evaporator as a heat source,
The plurality of evaporators are grouped into a high temperature evaporator group and a low temperature evaporator group from the front side to the rear side.
Scale component removal means for removing scaled water by removing at least a portion of the sulfate ions that are scale components contained in the raw water;
The descaling water supply means for supplying the descaling water as the water to be treated to the heat transfer tubes of the respective evaporators constituting the high temperature evaporator group,
A fresh water generator comprising: raw water supply means for supplying raw water to the heat transfer tubes of the evaporators constituting the low-temperature evaporator group using raw water as treated water. 2. The structure according to claim 1, wherein the raw water supply unit is connected to a tank that stores raw water, and the scale-removed water supply unit is connected to the scale component removal unit that is directly connected to the tank. Water equipment. The fresh water generator of Claim 1 or 2 provided with the reflux means for high temperature can groups which recirculates a part of concentrated water produced | generated in the said high temperature evaporator group to the said descaling water supply means. The fresh water generator according to any one of claims 1 to 3, further comprising a recirculation unit for a low-temperature can group that recirculates a part of the concentrated water generated in the low-temperature evaporator group to the raw water supply unit. 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 for generating condensed water from raw water using a fresh water generator grouped into a high temperature evaporator group and a low temperature evaporator group from the front stage side to the rear stage side,
A scale component removal step for generating scale-removed water by removing at least part of sulfate ions , which are scale components contained in the raw water,
Descaled water supply step for supplying the scaled water as treated water to the heat transfer tubes of the respective evaporators constituting the high temperature evaporator group,
A raw water supply method comprising: a raw water supply step of supplying raw water as treated water to a heat transfer tube of each evaporator constituting the low temperature evaporator group. The fresh water generation method according to claim 6, wherein the raw water supply step is performed while performing the descaling water supply step.

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