JP2007203138A - Production device and production method for sodium hypochlorite aqueous solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently produce a sodium hypochlorite aqueous solution with a relatively high concentration by the electrolysis of a sodium chloride aqueous solution. <P>SOLUTION: The sodium hypochlorite aqueous solution production device is provided with: a vertical type cylindrical vessel 170 capable of storing a sodium chloride aqueous solution; and an electrode group 180 including an anode and cathodes. The electrode group 180 is arranged at the lower part of the vessel 170. When the sodium chloride aqueous solution is stored in the inside of the vessel 170, and electric power is supplied to the electrode group 180, the sodium chloride aqueous solution is electrolyzed, and the sodium hypochlorite aqueous solution is produced. The sodium hypochlorite aqueous solution accumulates in the upper part of the vessel 170 since its specific gravity is lower than that of the sodium chloride aqueous solution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus and method for producing an aqueous sodium hypochlorite solution, and more particularly to an apparatus and method for producing an aqueous sodium hypochlorite solution by electrolysis of an aqueous sodium chloride solution.

  In commercial buildings, industrial plants, and the like, cooling water for cooling a cooling load device such as a heat exchanger is circulated and used while cooling in a cooling tower from the viewpoint of saving water. The cooling tower can be generally classified into two types, an open type cooling tower and a closed type cooling tower.

  The open-type cooling tower has an opening at the top and a circulating water reservoir for cooling the cooling load device at the bottom, a cylindrical main body having a vent on the side, and a vent in the main body. A fan for generating an air flow in the main body so that outside air passes through the opening, a supply path for supplying circulating water from the reservoir to the cooling load device, and the circulating water supplied to the cooling load device And a recovery route for recovering to. The terminal part of the collection path is disposed below the fan in the main body, and has a water spout for sprinkling circulating water toward the storage part.

  In such an open-type cooling tower, circulating water is supplied from the reservoir of the main body to the cooling load device through the supply path, and this circulating water cools the cooling load device. The circulating water that has cooled the cooling load device flows through the recovery path, and is sprinkled from the water spout to the reservoir in the main body. At this time, the sprinkled circulating water is cooled by touching the air flow generated by the fan, that is, the outside air passing from the vent hole of the main body to the opening. The cooled circulating water is stored in the storage unit and supplied to the cooling load device through the supply path. Therefore, in this cooling tower, the circulating water stored in the storage part circulates between the main body and the cooling load device through the supply path and the recovery path.

  On the other hand, the hermetic cooling tower has a cylindrical main body having an opening at the top and a sprinkling water reservoir at the bottom, and a vent on the side, and outside air passes from the vent to the opening in the main body. A fan for generating an air flow in the main body, a circulation path for circulating circulating water for cooling the cooling load device between the main body and the cooling load device, and a terminal extending from the storage portion The part is provided with a moving path of sprinkling water disposed below the fan in the main body. The terminal part of a movement path | route has a water spout for sprinkling spray water toward a storage part.

  In such a closed cooling tower, the cooling load device is cooled by circulating water circulating through the circulation path. On the other hand, the spray water stored in the storage part of the main body flows through the movement path, and is sprayed from the water spout to the storage part in the main body. At this time, the sprayed water sprayed is cooled by touching the airflow generated by the fan, that is, the outside air passing from the vent hole of the main body to the opening. The cooled spray water comes into contact with the circulation path and cools the circulation path. Thereby, the circulating water circulating through the circulation path is cooled. The sprayed water that has cooled the circulation path is stored in the storage section, and continuously sprayed from the sprinkling port through the moving path. Therefore, the spray water is circulated through the movement path.

  As described above, since the circulating water in the open cooling tower and the spray water in the closed cooling tower are used in a circulating manner, algae breed. Algae that have propagated in circulating water or spray water (hereinafter sometimes referred to as “cooling water” collectively) adhere to the pipes of various routes or clog the water spouts, making the cooling water smooth. It may impede circulation and impair the operation efficiency of the cooling tower. Moreover, when algae adheres to the cooling water path | route of a cooling load apparatus, there exists a possibility of inhibiting a heat exchange performance. Furthermore, algal metabolites and the like adhering to the pipes and the like serve as a nutrient source for Legionella, and thus can promote the reproduction of Legionella. And since Legionella genus bacteria propagated in cooling water partly flows into the atmosphere together with the airflow, there is a risk that it will diffuse into the atmosphere together with these cooling waters. For this reason, in the cooling tower, hypochlorite ions are present in the cooling water to suppress the growth of algae. In this case, hypochlorous acid ions also have an effect of suppressing the growth of general bacteria, and therefore can suppress the growth of bacteria.

  As a method for causing hypochlorite ions to exist in the cooling water, a method of electrolyzing a part of the circulating cooling water is known (Patent Documents 1 to 3). However, this method focuses on the fact that raw water such as tap water and industrial water used as cooling water contains a very small amount of chloride ions, so it is limited to the concentration of hypochlorite ions obtained by electrolysis of cooling water. In many cases, the growth of algae and fungi cannot be sufficiently suppressed.

  On the other hand, for the purpose of producing a sodium hypochlorite aqueous solution capable of supplying hypochlorite ions to cooling water, Patent Document 4 discloses a dilute saline solution obtained by diluting a high-concentration saline solution ( An electrolysis apparatus for electrolyzing (dilute sodium chloride aqueous solution) is disclosed. This electrolysis apparatus includes a cylindrical tank (container) for storing dilute sodium chloride aqueous solution, a cathode disposed on the inner surface of the tank, and a columnar anode disposed in the vertical direction in the center of the tank. It is mainly equipped with. In this electrolysis apparatus, when electric power is supplied between the anode and the cathode, the stored dilute sodium chloride aqueous solution is electrolyzed to produce a sodium hypochlorite aqueous solution.

  However, since the sodium hypochlorite aqueous solution has a specific gravity smaller than that of the diluted sodium chloride aqueous solution, it tends to move to the upper part of the tank and accumulate. As a result, in the tank during the electrolysis, a two-layered structure is formed with a lower layer of dilute sodium chloride aqueous solution and an upper layer of sodium hypochlorite aqueous solution, and the cathode and anode located in this upper layer are electrolyzed of the dilute sodium chloride aqueous solution. It becomes difficult to get involved in. That is, in both the cathode and the anode, the area contributing to the electrolysis of the dilute sodium chloride aqueous solution (effective electrode area) decreases as the production of sodium hypochlorite proceeds. Therefore, this electrolysis apparatus has a limit in increasing the concentration of the sodium hypochlorite aqueous solution because the electrolysis efficiency of the dilute sodium chloride aqueous solution decreases as the sodium hypochlorite aqueous solution is generated.

JP 2001-62457 A JP 2003-285064 A JP 2003-285068 A JP 2005-206929 A

  An object of the present invention is to enable efficient production of a relatively high concentration aqueous sodium hypochlorite solution by electrolysis of an aqueous sodium chloride solution.

  The apparatus for producing a sodium hypochlorite aqueous solution according to the present invention is for producing a sodium hypochlorite aqueous solution by electrolysis of a sodium chloride aqueous solution, and is a cylindrical vertical container capable of storing a sodium chloride aqueous solution. And an electrode group including an anode and a cathode for electrolyzing the sodium chloride aqueous solution, and the electrode group is disposed at the lower part of the vertical container.

  In this manufacturing apparatus, when a sodium chloride aqueous solution is stored in a vertical container and electric power is supplied to the electrode group, the sodium chloride aqueous solution is electrolyzed and sodium hypochlorite is generated. The produced sodium hypochlorite is in the form of an aqueous solution dissolved in a sodium chloride aqueous solution, but this sodium hypochlorite aqueous solution has a lower specific gravity than the sodium chloride aqueous solution and moves to the upper part of the vertical container. Accumulate. As a result, with the generation of sodium hypochlorite, two layers of the upper layer of the sodium hypochlorite aqueous solution and the lower layer of the sodium chloride aqueous solution proceed in the vertical container. However, even if such double-layering proceeds, the electrode group is disposed at the lower part of the vertical container, so that the entire electrode group can be involved in the electrolysis of the underlying sodium chloride aqueous solution. That is, in the electrode group, the area (effective electrode area) that contributes to the electrolysis of the aqueous sodium chloride solution is unlikely to decrease. Therefore, even if the production of the sodium hypochlorite aqueous solution progresses, this production apparatus can efficiently electrolyze the lower layer sodium chloride aqueous solution and continue the production of sodium hypochlorite. The sodium hypochlorite aqueous solution concentration in the upper layer can be gradually increased to produce a relatively high concentration sodium hypochlorite aqueous solution.

  In this manufacturing apparatus, the vertical container has, for example, a sodium chloride aqueous solution replenishment path and a dilution water supply path for diluting the sodium chloride aqueous solution at the lower end, and the manufactured sodium hypochlorite aqueous solution Has a discharge path for discharging the water at the upper end.

  In this case, when the sodium chloride aqueous solution is supplied to the vertical container from the supply path and the dilution water is supplied from the supply path, a sodium chloride aqueous solution having an appropriate concentration is prepared in the vertical container. And the sodium hypochlorite aqueous solution produced | generated by electrolysis of this sodium chloride aqueous solution moves to the upper part of a vertical container, and accumulates as above-mentioned. Therefore, when diluting water is newly supplied from the supply path to the vertical container, the sodium hypochlorite aqueous solution accumulated in the upper part of the vertical container is pushed out to the discharge path by the newly supplied diluting water, and the vertical container is It is discharged out of the mold container.

  The method for producing a sodium hypochlorite aqueous solution according to the present invention is a method for producing a sodium hypochlorite aqueous solution by electrolysis of a sodium chloride aqueous solution, and the sodium chloride aqueous solution is stored in a cylindrical vertical container. And a step of disposing an electrode group including an anode and a cathode under the vertical container and supplying electric power to the electrode group.

  In this manufacturing method, when a sodium chloride aqueous solution is stored in a vertical container and electric power is supplied to the electrode group, the sodium chloride aqueous solution is electrolyzed and sodium hypochlorite is generated. The produced sodium hypochlorite is in the form of an aqueous solution dissolved in a sodium chloride aqueous solution, but this sodium hypochlorite aqueous solution has a lower specific gravity than the sodium chloride aqueous solution and moves to the upper part of the vertical container. Accumulate. As a result, with the generation of sodium hypochlorite, two layers of the upper layer of the sodium hypochlorite aqueous solution and the lower layer of the sodium chloride aqueous solution proceed in the vertical container. However, even if such double-layering progresses, the electrode group is arranged at the lower part of the vertical container, and therefore the entire electrode group can be involved in the electrolysis of the lower sodium chloride aqueous solution. That is, in the electrode group, the area (effective electrode area) that contributes to the electrolysis of the aqueous sodium chloride solution is unlikely to decrease. Therefore, even if the production of the sodium hypochlorite aqueous solution proceeds, this production method can efficiently electrolyze the lower layer sodium chloride aqueous solution and continue the production of sodium hypochlorite. The sodium hypochlorite aqueous solution concentration in the upper layer can be gradually increased to produce a relatively high concentration sodium hypochlorite aqueous solution.

In this manufacturing method, for example, 1-3% concentration of aqueous sodium chloride solution, the power supplied to the electrode group at ^{0.2~0.5mV / mm 2 0.5~1.0mA / mm 2} , the electrode assembly The time for supplying power is preferably set to 3 to 6 hours. In this case, an aqueous sodium hypochlorite solution having a concentration of about 6,000 ± 3,000 mg / liter can be obtained at the upper part of the vertical container.

  In the apparatus for producing a sodium hypochlorite aqueous solution according to the present invention, the electrode group is arranged at the lower part of the vertical container, and therefore, a relatively high concentration hypochlorous acid is obtained by electrolysis of the sodium chloride aqueous solution stored in the vertical container. An aqueous sodium chlorate solution can be produced efficiently.

  In the method for producing a sodium hypochlorite aqueous solution according to the present invention, a sodium chloride aqueous solution is stored in a vertical container, and power is supplied to an electrode group disposed at the lower part of the vertical container. A relatively high concentration sodium hypochlorite aqueous solution can be efficiently produced by electrolysis of the stored sodium chloride aqueous solution.

1st form With reference to FIG. 1, the cooling water circulation system using the manufacturing apparatus of the sodium hypochlorite aqueous solution which concerns on this invention is demonstrated. In FIG. 1, the cooling water circulation system 100 mainly includes a cooling tower 110 including a water supply device 120 and a sodium hypochlorite aqueous solution manufacturing device 160 and a cooling load device 130.

  The cooling tower 110 is an open-type cooling tower that supplies circulating water for cooling the cooling load device 130, and includes a cylindrical main body 140 having an opening 141 at the top. The main body 140 is provided with a louver 142 on the side surface for introducing outside air, and has a storage part 143 for storing circulating water at the bottom. A fan 144 is horizontally disposed in the opening 141 of the main body 140. The fan 144 is rotatable so that outside air flows from the louver 142 into the main body 140, and is rotated by a motor 145. A motor 145 that rotationally drives the fan 144 is connected to the inverter 146. The inverter 146 changes the power frequency supplied to the motor 145 steplessly to change the rotational speed of the motor 145 and adjust the rotational speed of the fan 144.

  A cooling water supply path 149 extends from the storage portion 143 of the main body 140 toward the cooling load device 130. The supply path 149 has a water pump 150. The water supply pump 150 is for continuously sending the circulating water stored in the storage unit 143 of the cooling tower 110 to the cooling load device 130.

  In addition, a cooling water recovery path 151 is disposed horizontally in the upper part of the main body 140 and below the fan 144. The end portion of the recovery path 151 has a large number of nozzles 152 (an example of a sprinkling port) for sprinkling circulating water toward the bottom of the main body 140 in the main body 140. In addition, the other end of the recovery path 151 extends toward the cooling load device 130.

  The water supply apparatus 120 is for supplying circulating water to the cooling tower 110, and mainly includes a raw water supply path 121, a water softener 122, and a water supply path 123. One end of the raw water supply path 121 is connected to a raw water supply source (not shown) such as tap water or industrial water, and supplies the raw water to the water softener 122. The raw water supply path 121 has a first valve 124 for controlling the amount of raw water supplied to the water softener 122. The water softener 122 is for obtaining soft water by removing hardness from raw water by an ion exchange method using saturated saline. Specifically, the water softener 122 includes a saturated saline tank 122a and an ion exchange resin (not shown), and determines the hardness of calcium ions and magnesium ions contained in the raw water from the raw water supply path 121. It is intended to soften raw water by ion exchange with sodium ions derived from saturated saline. The water supply path 123 is for supplying the soft water obtained by the water softener 122 to the storage unit 143 of the cooling tower 110.

  The sodium hypochlorite aqueous solution manufacturing apparatus 160 is for supplying the sodium hypochlorite aqueous solution to the circulating water stored in the storage unit 143. As shown in FIG. It mainly includes an electrode group 180 disposed in 170. The container 170 is for storing a saline solution (sodium chloride aqueous solution) therein, and is formed in a vertical cylindrical shape. The bottom of the container 170 extends from the saturated saline tank 122 a of the water softener 122, a saturated saline replenishment path 171 (an example of a replenishment path) having a second valve 171 a, and a third branch extending from the water supply path 123. A soft water supply path 172 (an example of a supply path) having a valve 172a is in communication. Further, a drain path 173 having a fourth valve 173 a for discharging saline solution or the like stored in the container 170 extends from the bottom of the container 170. Further, a first sensor 174 for determining the water level in the container 170 is disposed near the bottom in the container 170.

  On the other hand, an air passage 175 having a fifth valve 175 a for venting between the inside and outside of the container 170 and a sodium hypochlorite aqueous solution generated in the container 170 are stored in the cooling tower 110 at the upper end of the container 170. A supply path 176 (an example of a discharge path) having a sixth valve 176a for supplying to the section 143 is provided. A second sensor 177 for determining the water level in the container 170 is disposed near the upper end portion in the container 170.

  The electrode group 180 is a lower part in the container 170 (preferably a position of 1/3 or less of the height inside the container 170, and more preferably a position of 1/5 or less of the same height) above the first sensor 174. As shown in FIG. 3 (III-III cross-sectional view of FIG. 2), it has three plate-like electrodes arranged in parallel. One of them is an anode 181 formed using a material such as platinum. The other two sheets are cathodes 182a and 182b formed using a material such as titanium, and these are arranged with the anode 181 interposed therebetween. Here, both sides of the anode 181 are effective electrode surfaces. On the other hand, the cathodes 182a and 182b are effective electrode surfaces only on one side facing the anode 181. A constant current / constant voltage device 190 is connected to such an electrode group 180.

  The cooling load device 130 is a variety of devices such as heat exchangers that require cooling with circulating water, such as turbo chillers and absorption chillers for various chemical plants, air conditioning coolers for buildings, and cold water production machines for food factories. Or a vacuum cooler or the like, and has a required cooling water flow path (not shown). The cooling water flow path has a cooling water introduction part 131 and a cooling water discharge part 132. The end of the supply path 149 is connected to the cooling water introduction part 131. In addition, the other end of the recovery path 151 is connected to the cooling water discharge unit 132. As a result, the cooling water flow path forms a circulation path for circulating circulating water between the main body 140 of the cooling tower 110 and the cooling load device 130 together with the supply path 149 and the recovery path 151.

  The above-described cooling water circulation system 100 includes a control device 195 for controlling the operation thereof. The control device 195 is usually a computer device, the first valve 124, the valves 171a, 172a, 173a, 175a, 176a of the sodium hypochlorite aqueous solution production device 160, the sensors 174, 177 and the constant current / constant voltage. The device 190 and the inverter 146 are in communication.

Next, the operation of the cooling water circulation system 100 will be described while referring to a method for producing a sodium hypochlorite aqueous solution by the sodium hypochlorite aqueous solution production apparatus 160.
First, in the cooling tower 110, the motor 145 is operated by the inverter 146, and the fan 144 is rotated. As a result, outside air flows into the main body 140 through the louver 142 as indicated by arrows in the figure. This outside air passes through the inside of the main body 140 and is discharged from the opening 141 to the outside.

  Further, when raw water is supplied from the raw water supply path 121 to the water softener 122 by operating the first valve 124, the raw water is softened by removing the hardness in the water softener 122. The soft water is supplied from the water softener 122 to the storage unit 143 of the cooling tower 110 through the water supply path 123 and stored.

  The soft water stored in the storage unit 143 is supplied to the cooling load device 130 as circulating water for cooling the cooling load device 130. Here, the soft water (hereinafter referred to as “circulated water”) in the storage section 143 is continuously supplied to the cooling water introduction section 131 of the cooling load device 130 through the supply path 149 by the operation of the water pump 150. The circulating water supplied to the cooling water introduction unit 131 passes through the cooling water flow path of the cooling load device 130 to cool the cooling load device 130 and is discharged from the cooling water discharge unit 132 to the recovery path 151.

  The circulating water discharged to the recovery path 151 is sprinkled from the nozzle 152 in the main body 140 of the cooling tower 110, falls in the main body 140 as shown by a dotted line in the figure, and returns to the storage unit 143. At this time, the circulating water falling in the main body 140 is cooled by touching the outside air flowing into the main body 140 by the rotation of the fan 144. The circulating water cooled and returned to the storage unit 143 is supplied again to the cooling load device 130 through the supply path 149 and returns to the storage unit 143 through the recovery path 151. Therefore, the circulating water stored in the storage unit 143 is used as cooling water for cooling the cooling load device 130 by circulating through the supply path 149, the cooling water flow path of the cooling load device 130, and the recovery path 151 during the operation of the cooling tower 110. Function.

  In the cooling tower 110 as described above, the cooling capacity of the circulating water sprayed from the recovery path 151 is determined by the rotational speed of the fan 144. In other words, when the fan 144 is rotated at a high speed, the amount of outside air flowing into the main body 140 from the louver 142 increases, so that the cooling capacity of the circulating water in the cooling tower 110 increases. Conversely, when the fan 144 is rotated at a low speed, the amount of outside air flowing from the louver 142 into the main body 140 is reduced, so that the cooling capacity of the circulating water in the cooling tower 110 is weakened. Therefore, when it is necessary to cool the circulating water more strongly, for example, in summer when the temperature is high, it is advantageous to rotate the fan 144 at a high speed. On the other hand, when it is not necessary to cool the circulating water strongly, it is advantageous to rotate the fan 144 at a low speed from the viewpoint of energy saving even in the winter or summer when the temperature is low, for example, at night.

  In the operation of the cooling tower 110 as described above, in parallel with the circulation of the circulating water as described above, the sodium hypochlorite aqueous solution manufacturing apparatus 160 manufactures the sodium hypochlorite aqueous solution, and this sodium hypochlorite. The aqueous solution is injected into the circulating water stored in the storage unit 143.

  Here, first, the fifth valve 175a is kept open. And the 2nd valve | bulb 171a is open | released and a saturated salt solution is replenished in the container 170 from the saturated salt solution tank 122a. Then, when the saturated saline is stored in the container 170 and the water level reaches the position of the first sensor 174, the second valve 171a is closed and the supply of the saturated saline is stopped. Next, the third valve 172 a is opened, and soft water from the water supply path 123 is supplied into the container 170. Then, when the water level in the container 170 reaches the position of the second sensor 177, the third valve 172a is closed and the supply of soft water is stopped. Thereby, in the container 170, the salt solution (dilute salt solution) diluted with soft water will be in the state stored (saline production | generation process).

  Incidentally, the concentration of the saline solution produced by diluting the saturated saline solution is usually preferably set to about 1 to 3% by weight. This concentration of saline can be obtained by adjusting the mounting positions of the first sensor 174 and the second sensor 177 in consideration of the capacity of the container 170.

Next, the constant current / constant voltage device 190 is operated to supply power to the electrode group 180. Here, it is usually preferable to apply a current of 0.5 to 1.0 mA / mm ² at 0.2 to 0.5 mV / mm ² . Thereby, the salt solution stored in the container 170 is electrolyzed, and sodium hypochlorite (NaClO) is generated by the following reaction (electrolysis step).

  The sodium hypochlorite thus produced is in an aqueous solution state dissolved in an ionic state in saline, but this sodium hypochlorite aqueous solution has a lower specific gravity than the saline, so And accumulate in the upper part of the container 170. As a result, with the generation of sodium hypochlorite, in the container 170, the two layers of the upper layer by the sodium hypochlorite aqueous solution and the lower layer by the saline solution proceed. However, even if such two-layering progresses, the electrode group 180 is arranged at the lower part of the container 170, and therefore is not easily affected by the upper sodium hypochlorite aqueous solution, and the whole thereof is the lower salt. Can participate in water electrolysis. That is, in the electrode group 180, the area (effective electrode area) that contributes to the electrolysis of the saline solution is unlikely to decrease. As a result, the sodium hypochlorite aqueous solution in the upper layer gradually increases in sodium hypochlorite concentration due to sodium hypochlorite generated by electrolysis of the lower layer saline solution, and usually 3 to 6 hours from the start of electrolysis. Among them, a sodium hypochlorite aqueous solution having a relatively high concentration of about 6,000 ± 3,000 mg / liter is obtained.

  Next, after closing the fifth valve 175a, the third valve 172a and the sixth valve 176a are set to the open state. Thereby, soft water from the water supply path 123 is continuously supplied into the container 170, and the sodium hypochlorite aqueous solution generated in the container 170 is pushed out into the supply path 176 by the supply pressure, and the cooling tower 110 It is supplied to the reservoir 143 at a time (injection process).

  Next, after a predetermined time has elapsed, the third valve 172a and the sixth valve 176a are closed, and the cleaning process of the container 170 is performed. Here, the fifth valve 175a is kept open. When the fourth valve 173a is opened, the sodium hypochlorite aqueous solution or soft water remaining in the container 170 is discharged. Next, when the fourth valve 173a is closed and the third valve 172a is opened, the container 170 is replenished with soft water and washed with this soft water. The soft water that has washed the inside of the container 170 is discharged when the third valve 172a is closed and the fourth valve 173a is opened.

  In this cooling water circulation system 100, the production of the sodium hypochlorite aqueous solution by the sodium hypochlorite aqueous solution production apparatus 160 is periodically repeated, and the following is generated for the circulating water stored in the storage unit 143 of the cooling tower 110. An aqueous sodium chlorite solution can be injected intermittently at regular intervals.

  If the sodium hypochlorite aqueous solution is intermittently injected into the circulating water, the free residual chlorine concentration of the cooling water increases rapidly and then gradually decreases. Therefore, circulating water repeatedly produces such a change in free residual chlorine concentration at regular intervals. This suppresses the growth of algae and fungi in the circulating water. As a result, the cooling tower 110 maintains a smooth circulation of the circulating water, makes it difficult for the cooling efficiency of the cooling load device 130 to decrease, and as a secondary effect of suppressing the growth of algae, Legionella spp. Because of the suppression of the propagation of Legionella, it is difficult for the Legionella spp. To spread to the environment.

  Furthermore, in this cooling tower 110, since circulating water is soft water, the production | generation of the scale which impairs the heat exchange efficiency in the cooling load apparatus 130 can be effectively suppressed collectively.

2nd form With reference to FIG. 4, the other cooling water circulation system using the manufacturing apparatus of the sodium hypochlorite aqueous solution which concerns on this invention is demonstrated. In the figure, the cooling water circulation system 200 mainly includes a cooling tower 210 having a water supply device 220 and a sodium hypochlorite aqueous solution manufacturing device 270 and a cooling load device 230.

  The cooling tower 210 is a hermetic cooling tower that supplies circulating water for cooling the cooling load device 230, and includes a cylindrical main body 240 having an opening 241 in the upper part, a circulating path 250 for circulating water, and A spray water moving path 260 for cooling the circulating water is mainly provided.

  The main body 240 is provided with a louver 242 for introducing outside air on the side surface, and has a storage part 243 for storing sprayed water for cooling the circulating water at the bottom. A fan 244 is horizontally disposed in the opening 241 of the main body 240. The fan 244 is rotatable so that outside air flows from the louver 242 into the main body 240, and is rotated by a motor 245. A motor 245 that rotationally drives the fan 244 is connected to the inverter 246. The inverter 246 is for changing the power frequency supplied to the motor 245 in a stepless manner to change the rotational speed of the motor 245 and adjusting the rotational speed of the fan 244.

  The circulation path 250 is for circulating circulating water for cooling the cooling load device 230 between the main body 240 and the cooling load device 230, and is filled with circulating water. The circulation path 250 meanders in the main body 240 to ensure a contact area with the spray water, and both end portions extend to the cooling load device 230. Furthermore, the circulation path 250 has a first pump 251 for circulating the cooling water.

  The moving path 260 extends from the storage portion 243 to the outside of the main body 240, and the end portion is horizontally disposed in the main body 240 below the fan 244. Moreover, the terminal part of the movement path 260 has many nozzles 261 (an example of a water spray port) for sprinkling spray water toward the bottom part of the main body 240. Further, the moving path 260 includes a second pump 262 for supplying the sprayed water stored in the storage unit 243 to the nozzle 261.

  The water supply apparatus 220 is for supplying spray water to the cooling tower 210, and is configured in the same manner as the water supply apparatus 120 described in the first embodiment (in FIG. 4, in the same part as FIG. 1). Are marked with the same sign).

  The sodium hypochlorite aqueous solution manufacturing apparatus 270 is for injecting the sodium hypochlorite aqueous solution into the sprayed water stored in the storage unit 243. The sodium hypochlorite described in the first embodiment It is comprised similarly to the aqueous solution manufacturing apparatus 160 (In FIG. 4, the same code | symbol is attached | subjected to FIG. 1 and the same part).

  The cooling load device 230 is various devices that require cooling with circulating water, is the same as the cooling load device 130 in the first embodiment, and has a required cooling water flow path (not shown). The cooling water flow path has a cooling water introduction part 231 and a cooling water discharge part 232. Then, one end of the circulation path 250 is connected to the cooling water introduction part 231. Further, the other end of the circulation path 250 is connected to the cooling water discharge unit 232.

  The above-described cooling water circulation system 200 includes a control device 295 for controlling the operation thereof. The control device 295 is usually a computer device, each valve of the water supply device 220 and the sodium hypochlorite aqueous solution manufacturing device 270, and each sensor of the sodium hypochlorite aqueous solution manufacturing device 270 (the first sensor 174 and FIG. 2). The second sensor 177), the constant current / constant voltage device (constant current / constant voltage device 190 in FIG. 2), the inverter 246, and the like are in communication.

Next, an operation method of the cooling tower 210 in the cooling water circulation system 200 will be described.
First, in the cooling tower 210, the motor 245 is operated by the inverter 246, and the fan 244 is rotated. As a result, the outside air flows into the main body 240 through the louver 242 as indicated by arrows in the figure. This outside air passes through the inside of the main body 240 and is discharged from the opening 241 to the outside.

  In addition, when the first pump 251 is operated in the circulation path 250, the circulating water circulates in the circulation path 250. This circulating water flows through the cooling water flow path of the cooling load device 230 and cools the cooling load device 230.

  Further, when raw water is supplied from the raw water supply path 121 to the water softener 122 by operating the first valve 124, the raw water is softened by removing the hardness in the water softener 122. The soft water is supplied from the water softener 122 to the storage unit 243 of the cooling tower 210 through the water supply path 123 and stored.

  The soft water stored in the storage unit 243 is continuously supplied into the movement path 260 by the operation of the second pump 262 as spray water for cooling the circulating water circulating in the circulation path 250. Then, the spray water supplied into the movement path 260 is sprinkled from the nozzle 261 in the main body 240, falls in the main body 240 as shown by a dotted line in the figure, and returns to the storage unit 243. At this time, the spray water falling in the main body 240 is cooled by touching the outside air flowing into the main body 240 by the rotation of the fan 244. The cooled sprayed water comes into contact with the circulation path 250 and cools the circulation path 250 and the circulation water circulating in the circulation path 250. The sprayed water that has returned to the storage unit 243 is sprayed from the nozzle 261 again through the movement path 260 and returns to the storage unit 243. Therefore, the sprayed water stored in the storage unit 243 circulates through the movement path 260 during the operation of the cooling tower 210.

  In the cooling tower 210 as described above, the cooling capacity of the circulating water by the spray water is determined by the rotational speed of the fan 244. That is, when the fan 244 is rotated at a high speed, the amount of outside air flowing into the main body 240 from the louver 242 increases, so that the spray water is strongly cooled, and the cooling capacity of the circulating water by the spray water is enhanced. On the other hand, when the fan 244 is rotated at a low speed, the amount of outside air flowing into the main body 240 from the louver 242 is reduced, and the cooling capacity of the circulating water by the spray water is weakened. Therefore, it is advantageous to rotate the fan 244 at a high speed when the circulating water needs to be cooled more strongly (that is, when the spray water needs to be cooled more strongly), for example, in summer when the temperature is high. is there. On the other hand, when it is not necessary to cool the circulating water strongly (that is, when it is not necessary to cool the sprayed water strongly), for example, in the winter or summer when the temperature is low, the fan is used from the viewpoint of energy saving at night. It is advantageous to rotate 244 at a low speed.

  In the operation of the cooling tower 210 as described above, the production of the sodium hypochlorite aqueous solution by the sodium hypochlorite aqueous solution production apparatus 270 is periodically repeated in parallel with the circulation of the sprayed water as described above. A sodium chlorite aqueous solution is intermittently injected into the spray water stored in the storage unit 243 of the cooling tower 210. Here, the manufacturing method of the sodium hypochlorite aqueous solution by the sodium hypochlorite aqueous solution manufacturing apparatus 270 and the method of injecting the sodium hypochlorite aqueous solution into the spray water are the same as in the first embodiment.

  If the sodium hypochlorite aqueous solution is intermittently injected into the spray water under the above-described conditions, the concentration of free residual chlorine in the spray water increases rapidly and then gradually decreases. Therefore, the sprayed water repeatedly undergoes such a change in free residual chlorine concentration every certain time. This suppresses the growth of algae and fungi in the sprayed water. As a result, the cooling tower 210 maintains a smooth circulation of the spray water, makes it difficult for the cooling efficiency of the cooling load device 230 to decrease, and as a secondary effect of suppressing the growth of algae, Legionella spp. Because of the suppression of the propagation of Legionella, it is difficult for the Legionella spp. To spread to the environment.

  Furthermore, in this cooling tower 210, since spray water is soft water, the production | generation of the scale in the movement path | route 260 grade | etc., Can be suppressed effectively.

Other Embodiments In the sodium hypochlorite aqueous solution manufacturing apparatuses 160 and 270 according to the above-described embodiments, the electrode group 180 including three plate-like electrodes arranged in parallel is used. As long as it includes an anode and a cathode, other forms can be used. For example, the electrode group may have an anode and a cathode arranged in a concentric ring shape. In this case, the electrode group is installed horizontally at the lower part in the container 170.

The sodium hypochlorite aqueous solution manufacturing apparatus 160 described in the above embodiment was made as a prototype. Here, the container 170 was set to have an inner diameter of 110 mm, a height of 580 mm, and a capacity of 5.5 liters. Inside this container 170, the electrode group 180 was arranged at a position 110 mm high from the bottom. In the electrode group 180, one anode 181 (size = 50 mm × 130 mm × 2 mm, effective electrode area (total area on both surfaces) = 13,000 mm ² ) formed using platinum and titanium is formed. Two cathodes 182a and 182b (size = 50 mm × 130 mm × 2 mm, effective electrode area (one-sided area) = 6,500 mm ^{2, respectively} ) were used.

5.5 L of a predetermined concentration of saline solution (sodium chloride aqueous solution) is stored in the container 170, and electric power of 0.38 mV / mm ² and 0.54 mA / mm ² is supplied to the electrode group 180 to supply the saline solution. Electrolyzed for 6 hours. And 250 milliliters of sodium hypochlorite aqueous solution which collected by this at the upper part in the container 170 was extract | collected, and the free residual chlorine concentration was measured by the factory drainage test method prescribed | regulated to JISK0102 (1998). The results are shown in Table 1.

  According to Table 1, it can be seen that a relatively high concentration sodium hypochlorite aqueous solution suitable for application to circulating water and spray water of a cooling tower is obtained from a salt solution having a concentration of 1 to 3% by weight. .

BRIEF DESCRIPTION OF THE DRAWINGS Schematic of the cooling water circulation system using one form of the manufacturing apparatus of the sodium hypochlorite aqueous solution which concerns on this invention. The cross-sectional schematic of the manufacturing apparatus of the sodium hypochlorite aqueous solution which concerns on the said one form. III-III cross-sectional schematic of FIG. Schematic of the other cooling water circulation system using one form of the manufacturing apparatus of the sodium hypochlorite aqueous solution which concerns on this invention.

Explanation of symbols

160, 270 Sodium hypochlorite aqueous solution production apparatus 170 Container 180 Electrode group 181 Anode 182a, 182b Cathode 171 Saturated saline replenishment path 172 Soft water replenishment path 176 Supply path

Claims (4)

An apparatus for producing an aqueous sodium hypochlorite solution by electrolysis of an aqueous sodium chloride solution,
A cylindrical vertical container capable of storing the sodium chloride aqueous solution;
An electrode group including an anode and a cathode for electrolyzing the sodium chloride aqueous solution,
The electrode group is disposed at a lower part of the vertical container,
Equipment for producing sodium hypochlorite aqueous solution.   The vertical container has a supply path for the sodium chloride aqueous solution and a supply path for dilution water for diluting the sodium chloride aqueous solution at the lower end, and discharges the manufactured sodium hypochlorite aqueous solution. The apparatus for producing an aqueous sodium hypochlorite solution according to claim 1, further comprising a discharge passage for the upper end portion. A method for producing a sodium hypochlorite aqueous solution by electrolysis of a sodium chloride aqueous solution, comprising:
Storing the sodium chloride aqueous solution in a cylindrical vertical container;
Disposing an electrode group including an anode and a cathode at a lower part of the vertical container, and supplying power to the electrode group;
The manufacturing method of the sodium hypochlorite aqueous solution containing this. 1-3% concentration of the aqueous sodium chloride solution, the power supplied to the electrode group at ^{0.2~0.5mV / mm 2 0.5~1.0mA / mm 2} , the power to the electrode assembly The manufacturing method of the sodium hypochlorite aqueous solution of Claim 3 which sets the supply time to 3 to 6 hours, respectively.

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