JP4735369B2 - Cooling tower operation method - Google Patents

Description

  The present invention relates to a method for operating a cooling tower, and more particularly, to a method for operating an open cooling tower and a closed cooling tower.

  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 from the vent to the opening. A fan for generating an air flow in the main body so that outside air passes, a supply path for supplying the circulating water from the reservoir to the cooling load device, and the circulating water supplied to the cooling load device are recovered to the main body. A recovery path, a water supply path for supplying circulating water to the storage section, and a drainage path for discharging part of the circulating water from the storage section. 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, the circulating water replenished from the water supply path is stored in the storage part of the main body. The circulating water stored in the storage unit is supplied to the cooling load device through the supply path to cool 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 an opening at the top and a sprinkled water reservoir at the bottom, a cylindrical main body having a vent on the side, and so that outside air passes from the vent to the opening. 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 inside of the main body and the cooling load device, and a terminal portion extending from the storage portion and having the end portion of the main body In the inside, provided with a moving path of sprayed water, a water supply path for replenishing the reservoir with the sprayed water, and a drainage path for discharging a part of the sprayed water from the reservoir Yes. 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 replenished from the water supply path is stored in the storage section of the main body, and this spray water flows through the movement path and is sprayed from the spray port toward the storage section 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 contacts 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.

  In the open type cooling tower and the closed type cooling tower as described above, the circulating water and the spray water usually contain corrosive ions such as chloride ions and scale generating factors such as calcium carbonate and silica. Such corrosive ions and scale generation factors evaporate part of the circulating water and spray water, so the concentration in the circulating water and spray water gradually increases. Promotes corrosion and promotes the generation of scale. Therefore, in the cooling tower, circulating water and spray water are partially released through the discharge path when the electrical conductivity increases in order to prevent excessive concentrations of corrosive ions and scale generating factors. At the same time, concentration management is performed to dilute with new water supply from the water supply path (see Patent Document 1).

  On the other hand, circulating water and sprayed water use the algae metabolites adhering to the piping and the like as nutrients in the circulation, and parasitize protozoa such as amoeba, and Legionella spp. This Legionella spp. May circulate in the atmosphere along with the airflow, and part of the circulating water and spray water. May infect people.

Therefore, Non-Patent Document 1 describes that when Legionella spp. Are detected in 10 ² CFU / 100 ml or more in the above circulating water in the open cooling tower and in the above spray water in the closed cooling tower, cleaning of the circulating system, Disinfection is recommended, and after the implementation of measures such as cleaning and disinfection, it is recommended that the detected number of Legionella in circulating water and sprayed water be maintained below 10 CFU / 100 ml.

  Non-Patent Document 1 recommends the addition of a chlorine agent such as hypochlorous acid to these waters in order to suppress the growth of Legionella in circulating water and spray water. However, the chlorinating agent exerts a significant bactericidal effect against bacteria such as coliforms, but is less effective against Legionella spp. This is thought to be because Legionella spp. Are present in biofilms and amoeba that are less permeable to chlorinating agents, and Legionella spp. Are less susceptible to chlorinating agents. In particular, Legionella spp. Present in a cysted amoeba are said to be resistant even in an environment with a chlorine concentration of 50 mg / liter and not easily killed.

JP 2003-269888 A Supervised by the Ministry of Health and Welfare Planning Division, published by the Building Management Education Center “New Legionellosis Prevention Guidelines (issued in May 2003, 5th edition)”

  An object of the present invention is to effectively suppress the growth of Legionella in the cooling tower.

The present invention according to the first aspect includes a cylindrical main body having an opening at the top and a circulating water reservoir for cooling the cooling load device at the bottom, and a ventilation hole on the side, and opening from the ventilation hole. A fan with adjustable rotation speed for generating an air flow in the main body so that outside air passes to the part, a supply path for supplying circulating water from the storage part to the cooling load device, and supply to the cooling load device A recovery path for recovering the circulated water to the main body, a water supply path to the storage section, and a drainage path for releasing a part of the circulating water from the storage section. It is related with the operating method of the cooling tower which is arrange | positioned under a fan in the inside and which has a water spout for sprinkling circulating water toward a storage part. In this operation method, circulating water whose pH is set to 9.0 or more is flowed in the order of the supply path, the cooling load device, and the recovery path from the storage section, and is continuously sprinkled from the water spout to the storage section. When the pH of the circulating water exceeds 9.0 and the electrical conductivity exceeds a predetermined value in the reservoir , the drainage path is maintained so that the circulating water pH is maintained at 9.0 or higher. And a step of discharging a part of the circulating water from the reservoir through the water supply path to the reservoir. Circulating water is soft water, and by adjusting the rotation speed of the fan, the amount of outside air passing from the vent to the opening is adjusted to increase the concentration rate based on the M alkali component concentration, thereby increasing the pH. Is set to 9.0 or higher.

  In this operation method, the circulating water supplied to the storage unit is supplied to the cooling load device through the supply path to cool 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.

  Here, since the circulating water in circulation is set to pH 9.0 or higher, the reproduction of Legionella is effectively suppressed without adding a chlorine agent such as hypochlorous acid. . In addition, this operation method releases a part of the circulating water through the drainage route in a timely manner in order to prevent excessive concentrations of corrosive ions, scale generating factors, etc. in the circulating water, and the water supply route. Even when the circulating water is diluted by supplying water to the reservoir, the pH of the circulating water is maintained at 9.0 or higher, so that the growth of Legionella can be stably suppressed.

The present invention according to the second aspect is a tubular type having an opening at the top and a reservoir for sprayed water for cooling the circulating water for cooling the cooling load device at the bottom, and a vent on the side. In order to circulate circulating water between the main body, a fan capable of adjusting the rotation speed for generating an air flow in the main body so that outside air passes from the vent hole to the opening, and the cooling load device. Circulation path of the water, a movement path of the sprayed water that extends from the storage section and whose end is disposed below the fan in the main body, a water supply path to the storage section, and a part of the sprayed water is discharged from the storage section And a drainage path for the cooling tower, and the terminal part of the movement path has a sprinkling port for sprinkling spray water toward the storage part. In this operation method, in parallel with circulating the circulating water between the main body and the cooling load device, the sprayed water whose pH is set to 9.0 or more is supplied from the reservoir to the moving path, Water is sprayed from the water and continuously circulated to the reservoir, and when the pH of the sprayed water exceeds 9.0 and the electrical conductivity exceeds a predetermined value in the reservoir, the circulating sprayed water is circulated. a step of discharging a part of the sprayed water from the reservoir through the drainage path and supplying the reservoir to the reservoir through the drainage path so that the pH is maintained at 9.0 or higher. The sprinkling water is soft water, and the pH is increased by adjusting the rotation speed of the fan to increase the concentration rate based on the M alkali component concentration while adjusting the amount of outside air passing from the vent to the opening. Is set to 9.0 or higher.

  In this operation method, the cooling load device is cooled by circulating circulating water between the main body and the cooling load device. In parallel with this, the sprayed water stored in the storage part 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 contacts 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, in this cooling tower, the spray water stored in the storage part is circulated through the movement path.

  Here, since the circulating spray water is set to pH 9.0 or higher, the reproduction of Legionella is effectively suppressed without adding a chlorine agent such as hypochlorous acid. . In addition, this operation method releases part of the sprayed water through the drainage route in a timely manner in order to prevent excessive concentrations of corrosive ions and scale-generating factors in the sprayed water, and the water supply route. Since the pH of the spray water is maintained at 9.0 or more even when the spray water is diluted by supplying water to the reservoir, the propagation of Legionella can be stably suppressed.

  The present invention according to the first aspect circulates circulating water whose pH is set to 9.0 or higher, releases part of the circulating water through the drainage path, and supplies water to the storage section from the water supply path. Since this pH is maintained even when the circulating water is diluted, it is possible to effectively suppress the growth of Legionella in the cooling tower.

  The present invention according to the second aspect circulates the spray water whose pH is set to 9.0 or more, releases part of the spray water through the drainage path, and supplies water to the storage section from the water supply path. Since this pH is maintained even when the spray water is diluted, it is possible to effectively suppress the growth of Legionella in the cooling tower.

1st form With reference to FIG. 1, an example of the cooling water circulation system which can implement one form of the operating method of the cooling tower 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 cooling load device 130.

  The cooling tower 110 is an open cooling tower for supplying 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 (an example of a vent hole) for introducing outside air on the side surface, 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. The inverter 146 is connected to a control device 147 for controlling the operation of the cooling tower 110. The control device 147 includes a temperature sensor 148 and a pH sensor 162. The temperature sensor 148 is disposed in the storage unit 143 and is for measuring the temperature of the circulating water stored in the storage unit 143. The pH sensor 162 is disposed in the storage unit 143 and is for measuring the pH of the circulating water stored in the storage unit 143.

  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. Moreover, the storage part 143 is provided with the drainage path 160 extended from a bottom part. The drainage path 160 is for discharging a part of the circulating water stored in the storage unit 143, and has a control valve 161. The control valve 161 is an electromagnetic valve, and can control the discharge amount of circulating water based on a command signal from the control device 147.

  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 valve 124 for controlling the amount of raw water supplied to the water softener 122. The valve 124 is controlled by the control device 147. The water softener 122 is for softening the raw water from the raw water supply path 121. Specifically, the hardness, that is, calcium ions and magnesium ions contained in the raw water from the raw water supply channel 121 is removed to make the raw water soft water. The water supply path 123 is for supplying the soft water from the water softener 122 to the storage part 143 of the cooling tower 110.

  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. The other end of the recovery path 151 is connected to the cooling water discharge part 131. 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.

Next, an operation method of the cooling tower 110 will be described.
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 the raw water is supplied from the raw water supply path 121 to the water softener 122 by operating the 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 circulating water) in the storage unit 143 is continuously supplied to the cooling water introduction unit 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. That is, 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. On the contrary, when the fan 144 is rotated at a low speed, the amount of outside air flowing into the main body 140 from the louver 142 is reduced, so that the cooling capacity of the circulating water in the cooling tower 110 is lowered. 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 cooling tower 110, the yield of circulating water sprinkled from the recovery path 151 is also determined by the rotational speed of the fan 144. That is, 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 circulating water sprayed from the recovery path 151 is easily evaporated and the outside air and the main body from the opening 141 together with the outside air. It becomes easy to scatter to 140 outside, and the yield of circulating water becomes low. On the contrary, when the fan 144 is rotated at a low speed, the amount of outside air flowing into the main body 140 from the louver 142 is reduced, so that the circulating water sprayed from the recovery path 151 is less likely to evaporate and the opening 140 through the main body 140. It becomes difficult to scatter outside, and the yield of circulating water increases.

  Therefore, the control device 147 controls the inverter 146 based on the operation load state of the cooling tower 110, specifically, the temperature of the circulating water measured by the temperature sensor 148, and changes the rotational speed of the motor 145 to change the fan 144. Adjust the rotation speed. Specifically, when the circulating water temperature measured by the temperature sensor 148 is high, the motor 145 is rotated at a high speed by the inverter 146 and the rotation speed of the fan 144 is increased. When the circulating water temperature measured by the temperature sensor 148 is low, the motor 145 is rotated at a low speed by the inverter 146 and the rotation speed of the fan 144 is decreased. Thus, the cooling tower 110 can sufficiently cool the circulating water according to the operation load state, and energy saving required for the rotational drive of the fan 144 can be achieved. Further, if the cooling tower 110 is operated in this way, the amount of outside air flowing into the main body 140 from the louver 142 can be controlled according to the operation load state of the cooling tower 110, so that the circulating water is excessively evaporated. It is possible to suppress scattering. As a result, circulating water can be saved, and the amount of soft water supplied from the water supply device 120 to the main body 140 can be suppressed.

  By the way, the circulating water is soft water and partly evaporates together with the outside air flowing into the cooling tower 110 as described above, so that it is gradually concentrated on the basis of the M alkali component concentration. That is, in the circulating water, the M alkali component concentration increases. Further, in the cooling tower 110, the rotation speed of the fan 144 can be adjusted by the inverter 146, thereby suppressing the circulating water from being excessively scattered. If the rotational speed of the fan 144 is reduced within a range in which the circulating water can be sufficiently cooled, loss of the M alkali component in the circulating water can be suppressed. For this reason, the circulating water circulating in the cooling tower 110 effectively increases the concentration ratio based on the M alkali component concentration, and the M alkali component concentration tends to increase. And with such a raise of M alkali component density | concentration, the pH of circulating water changes to the alkali side. In this embodiment, the pH change associated with the concentration of the circulating water is utilized to maintain the pH of the circulating water at 9.0 or higher, preferably 9.2 or higher.

  Incidentally, the amount of circulating water increases as the rotational speed of the fan 144 increases. Since the circulating water that has been scattered contains an M alkali component, the M alkali component is lost if the amount of circulating water scattered is large. As a result, in the circulating water, the M alkali component concentration is less likely to rise above a certain level, and the pH is less likely to be maintained at 9.0 or higher or 9.2 or higher. Therefore, in this embodiment, it is preferable that the pH of the circulating water is constantly measured by the pH sensor 162 and the rotational speed of the fan 144 is controlled based on the measurement result. More specifically, the control device 147 controls the inverter 146 based on the measurement result of the pH sensor 162, and adjusts the rotation speed of the fan 144 to be low enough to cool the circulating water. Is preferred. If it does in this way, since scattering of circulating water will be suppressed and it will become easy to raise the concentration rate of circulating water on the basis of M alkali ingredient concentration, it will be easy to maintain the pH of circulating water at 9.0 or more or 9.2 or more. Become.

  When the pH of the circulating water is maintained at 9.0 or higher or 9.2 or higher as described above, the circulating water circulating from the storage unit 143 in the order of the supply path 149, the cooling load device 130, the recovery path 151, and the storage unit 143 is , Legionella spp. Growth is suppressed, Legionella count is supervised by Ministry of Health and Welfare, Health Sanitation Bureau Planning Division, Building Management Education Center "New edition Legionellosis prevention guideline (issued in May 2003, 5th edition)" It can be maintained at less than 10 CFU / 100 ml as recommended in Non-Patent Document 1).

  By the way, the circulating water is concentrated as described above, and the concentrations of various dissolved substances, for example, corrosive ions such as chloride ions and scale generating factors such as silica increase with the M alkali component concentration. As a result, the cooling tower 110 is in a state where corrosion and scale are likely to occur at the site where the circulating water contacts. For this reason, in this operation method, part of the circulating water stored in the storage unit 143 is discharged at a predetermined timing, and new soft water is supplied from the supply device 120 into the storage unit 143 at the same time. Thereby, since circulating water is diluted and the density | concentration of a corrosive ion and a scale generation factor falls, it becomes difficult to generate | occur | produce corrosion and a scale with respect to the cooling tower 110. FIG. However, since the concentration of the M alkali component decreases simultaneously with the dilution of the circulating water, the pH decreases, and it may be difficult to suppress the growth of Legionella spp.

  Therefore, in this operation method, the pH of the circulating water stored in the storage unit 143 is monitored by the pH sensor 162, and the circulating water is diluted so that the pH is maintained at 9.0 or higher. Specifically, when the pH of the circulating water sufficiently exceeds 9.0 (for example, when the pH reaches about 9.5 due to the concentration of the M alkali component), the control valve 161 is opened. A part of the circulating water is discharged from the drainage path 160, and at the same time, the valve 124 is opened to supply new soft water from the water supply path 123 to the reservoir 143. Then, when the pH of the circulating water diluted with newly supplied soft water is lowered to around 9.0 (for example, when the pH is lowered to about 9.2), the control valve 161 is closed and the circulating water is closed. At the same time, the valve 124 is closed and the supply of soft water to the reservoir is stopped.

  Here, by constantly monitoring the pH of the circulating water and repeating the dilution operation of the circulating water as described above in accordance with the fluctuation of the pH, the circulating water remains in a state where the pH is maintained at 9.0 or more. The concentration of corrosive ions and scale generating factors will be reduced. For this reason, according to this operation method, reproduction of Legionella genus bacteria in circulating water can be suppressed effectively, and corrosion and scale generation of cooling tower 110 can be controlled simultaneously.

2nd form With reference to FIG. 2, an example of the cooling water circulation system which can implement the other form of the operating method of the cooling tower which concerns on this invention is demonstrated. In FIG. 2, the cooling water circulation system 200 mainly includes a cooling tower 210, a water supply device 220, and a cooling load device 230.

  The cooling tower 210 is a hermetic cooling tower for supplying the cooling load device 230 with circulating water for cooling it, a cylindrical main body 240 having an opening 241 in the upper part, and a circulating path for circulating water. 250 and the movement path 260 of the spray water for cooling circulating water are mainly provided.

  The main body 240 is provided with a louver 242 (an example of a vent hole) 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. . The storage unit 243 includes a drainage path 270 extending from the bottom. The drainage path 270 is for discharging a part of the sprayed water stored in the storage unit 243 and has a control valve 271. The control valve 271 is an electromagnetic valve, and can control the discharge amount of sprayed water based on a command signal from a control device 247 described later.

  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 inverter 246 is connected to a control device 247 for controlling the operation of the cooling tower 210. The control device 247 includes a temperature sensor 248 and a pH sensor 272. The temperature sensor 248 is disposed in the storage unit 243 and measures the temperature of the spray water stored in the storage unit 243. The pH sensor 272 is disposed in the storage unit 243, and is for measuring the pH of the spray water stored in the storage unit 243.

  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. 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 mainly includes a raw water supply path 221, a water softener 222, and a water supply path 223. One end of the raw water supply path 221 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 222. The raw water supply path 221 has a valve 224 for controlling the amount of raw water supplied to the water softener 222. The valve 224 is controlled by the control device 247. The water softener 222 is for softening raw water from the raw water supply path 221. Specifically, the hardness contained in the raw water from the raw water supply path 221, that is, calcium ions and magnesium ions are removed to make the raw water soft water. The water supply path 223 is for supplying the soft water from the water softener 222 to the storage unit 243 of the cooling tower 210.

  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 portion 231.

Next, a method for operating the cooling tower 210 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.

  When raw water is supplied from the raw water supply path 221 to the water softener 222 by operating the valve 224, the raw water is softened by removing the hardness in the water softener 222. The soft water is supplied from the water softener 222 to the storage unit 243 of the cooling tower 210 through the water supply path 223 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 increased. Conversely, 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, so that the spray water is gently cooled and the cooling capacity of the circulating water by the spray water is lowered. 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.

  Further, in the cooling tower 210, the yield of spray water sprayed from the nozzle 261 of the moving path 260 is also 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 sprayed water sprayed from the nozzle 261 is likely to evaporate, and together with the outside air, from the opening 241 to the main body. It becomes easy to scatter outside 240, and the yield of spray water becomes low. On the contrary, 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, so that the sprayed water sprayed from the nozzle 261 is difficult to evaporate and the opening 241 is outside the main body 240. The yield of spray water becomes high.

  Therefore, the control device 247 controls the inverter 246 based on the operating load state of the cooling tower 210, specifically, the temperature of the sprayed water measured by the temperature sensor 248, and changes the rotational speed of the motor 245 to change the fan 244. Adjust the rotation speed. Specifically, when the spray water temperature measured by the temperature sensor 248 is high, the motor 245 is rotated at a high speed by the inverter 246 to increase the rotation speed of the fan 244. In addition, when the spray water temperature measured by the temperature sensor 248 is low, the motor 245 is rotated at a low speed by the inverter 246 and the rotation speed of the fan 244 is decreased. Thereby, the cooling tower 210 can sufficiently cool the spray water according to the operation load state, and energy saving required for the rotational drive of the fan 244 can be achieved. Further, if the cooling tower 210 is operated in this way, the amount of outside air flowing into the main body 240 from the louver 242 can be controlled in accordance with the operation load state of the cooling tower 210, so that the sprinkled water may evaporate excessively. It is possible to suppress scattering. As a result, the spray water can be saved, and the amount of soft water supplied from the water supply device 220 to the main body 240 can be suppressed.

  By the way, the spray water is soft water and partially evaporates with the outside air flowing into the cooling tower 210 as described above, so that it is gradually concentrated on the basis of the M alkali component concentration. That is, the M alkali component concentration increases in the spray water. Further, in the cooling tower 210, the rotation speed of the fan 244 can be adjusted by the inverter 246, thereby suppressing the sprayed water from being excessively scattered. If the rotational speed of the fan 244 is reduced within a range in which the sprayed water can be sufficiently cooled, loss of the M alkali component in the sprayed water can be suppressed. For this reason, the concentration of the sprayed water circulating in the cooling tower 210 is increased based on the M alkali component concentration. That is, the cooling tower 210 can increase the concentration ratio of spray water compared to the conventional hermetic cooling tower, and the M alkali component concentration tends to increase. And with such a raise of M alkali component density | concentration, pH of spray water changes to the alkali side. In this embodiment, the pH change accompanying the concentration of the spray water is utilized, and the pH of the spray water is maintained at 9.0 or higher, preferably 9.2 or higher.

  Incidentally, the amount of scattered water increases as the rotational speed of the fan 244 increases. The scattered sprayed water contains the M alkali component, so that the M alkali component is lost if the amount of sprayed water is large. As a result, in the sprayed water, the M alkali component concentration is less likely to rise above a certain level, and the pH is less likely to be maintained at 9.0 or higher or 9.2 or higher. Therefore, in this embodiment, it is preferable that the pH of the spray water is constantly measured by the pH sensor 272 and the rotational speed of the fan 244 is controlled based on the measurement result. More specifically, the control device 247 controls the inverter 246 based on the measurement result of the pH sensor 272 and adjusts the rotation speed of the fan 244 to be low enough to cool the spray water. Is preferred. If it does in this way, since scattering of spray water will be suppressed and it will become easy to raise the concentration rate of spray water on the basis of M alkali ingredient concentration, it will be easy to maintain pH of spray water above 9.0 or above 9.2. Become.

  When the pH of the spray water is maintained at 9.0 or higher or 9.2 or higher as described above, the circulating water that circulates from the storage unit 243 through the movement path 260 is inhibited from breeding Legionella, and the number of Legionella is counted. 10 CFU / 100 milliliters recommended by the Ministry of Health and Welfare Planning Department of the Ministry of Health and Welfare and issued by the Building Management Education Center “New Legionellosis Prevention Guidelines (issued 5th May 2003)” (Non-Patent Document 1 above) Can be kept below.

  By the way, the spray water is concentrated as described above, and the concentrations of various dissolved substances, for example, corrosive ions such as chloride ions and scale generating factors such as silica increase with the M alkali component concentration. As a result, the cooling tower 210 is likely to be corroded and scaled at the site where the spray water contacts. For this reason, in this operation method, a part of the sprayed water stored in the storage unit 243 is discharged at a predetermined timing, and new soft water is supplied from the supply device 220 into the storage unit 243 at the same time. As a result, the spray water is diluted, and the concentrations of the corrosive ions and the scale generation factor are reduced, so that it is difficult for the cooling tower 110 to generate corrosion and scale. However, since the M alkali component concentration is simultaneously reduced by dilution of the spray water, the pH is lowered and it may be difficult to suppress the growth of Legionella spp.

  Therefore, in this operation method, the pH of the spray water stored in the storage unit 243 is monitored by the pH sensor 272, and the spray water is diluted so that the pH is maintained at 9.0 or higher. Specifically, when the pH of the spray water sufficiently exceeds 9.0 (for example, when the pH reaches about 9.5 due to concentration of M alkali component), the control valve 271 is opened. Part of the spray water is discharged from the drainage path 270, and at the same time, the valve 224 is opened to supply new soft water from the water supply path 223 to the storage unit 243. Then, when the pH of the circulating water diluted with the newly supplied soft water is lowered to about 9.0 (for example, when the pH is lowered to about 9.2), the control valve 271 is closed and the spray water is closed. At the same time, the valve 224 is closed and the supply of soft water to the reservoir is stopped.

  Here, by constantly monitoring the pH of the spray water and repeating the dilution operation of the spray water as described above in accordance with the change in pH, the spray water remains in a state where the pH is maintained at 9.0 or higher. The concentration of corrosive ions and scale generating factors will be reduced. For this reason, according to this operation method, propagation of Legionella in the spray water can be effectively suppressed, and at the same time, corrosion of the cooling tower 110 and generation of scale can be suppressed.

Modification (1) In each of the above-described embodiments, the pH of these circulating water and sprayed water is set to 9.0 or more by concentrating the circulating water or sprayed water. It can also be set to 9.0 or more by electrolysis.

  When adjusting the pH by adding a drug, an injection device for injecting the drug is disposed in the storage units 143 and 243 of the cooling towers 110 and 210. The chemicals used here can adjust the pH of circulating water and spray water to 9.0 or higher, and usually include alkali metal hydrogen carbonate, alkali metal carbonate and alkali metal hydroxide. At least one alkali metal compound selected from the group consisting of: Examples of the alkali metal hydrogen carbonate include sodium hydrogen carbonate and potassium hydrogen carbonate. Examples of the alkali metal carbonate include sodium carbonate and potassium carbonate. Further, examples of the alkali metal hydroxide include sodium hydroxide and potassium hydroxide.

  In this case, for example, the pH sensors 162 and 272 constantly monitor the pH of the circulating water and spray water, and the above-mentioned chemicals are appropriately injected into the reservoirs 143 and 243 so that the pH of the circulating water and spray water is 9.0. Set to maintain above.

  On the other hand, in the case of electrolysis, an electrolysis apparatus 300 as shown in FIG. 3 is attached to the cooling towers 110 and 210. The electrolyzer 300 mainly includes an electrolytic cell 310 and a power source 320. In the electrolytic bath 310, a pair of electrodes 311 and 312 for electrolyzing circulating water or sprayed water are disposed, and a diaphragm 313 is provided between the pair of electrodes 311 and 312 so that the cathode chamber 314 and An anode chamber 315 is formed. A water sampling channel 316 for taking out a part of circulating water or spray water from the storage parts 143 and 243 of the cooling towers 110 and 210 is connected to the electrolytic bath 310. The water sampling channel 316 is for supplying circulating water or spray water to the cathode chamber 314 and the anode chamber 315, respectively. Connected to the cathode chamber 314 is an electrolyzed water supply path 317 for supplying alkaline electrolyzed water generated by electrolysis of circulating water or sprayed water into the reservoirs 143 and 243. Similarly, a discharge path 318 for discharging acidic electrolyzed water generated by electrolysis of circulating water or sprayed water to the outside of the system is connected to the anode chamber 315. The power source 320 is for applying a voltage necessary for electrolysis of circulating water or sprayed water between the pair of electrodes 311 and 312, and is controlled by the control devices 147 and 247.

  In the cooling towers 110 and 210 including the electrolyzer 300, a part of circulating water or spray water is supplied from the storage units 143 and 243 through the water sampling channel 316 into the electrolytic cell 310. The circulating water or sprayed water supplied to the electrolytic cell 310 is electrolyzed by a voltage applied between the pair of electrodes 311 and 312, and alkaline electrolyzed water is generated on the cathode chamber 314 side, and acidic electrolysis is performed on the anode chamber 315 side. Water is produced. The alkaline electrolyzed water generated here is supplied to the reservoirs 143 and 243 through the electrolyzed water supply path 317. The acidic electrolyzed water is discharged out of the system through the discharge path 318. In this way, if a part of the circulating water or sprayed water stored in the storage units 143 and 243 is continuously supplied to the electrolyzer 300 and the generated alkaline electrolyzed water is supplied to the storage units 143 and 243, the circulation is performed. The water or spray water has a high pH and is set to 9.0 or higher.

  As described above, when the pH of the circulating water and the spray water is set by injection or electrolysis of the medicine, the pH of the circulating water and the spray water is easily maintained at 9.0 or higher even during the dilution. The amount of circulating water and spray water discharged from 243 can be increased, and the degree of dilution of the circulating water and spray water can be increased to more effectively reduce the concentration of corrosive ions and scale generating factors.

(2) In each of the above-described embodiments, the timing for releasing the circulating water and the sprayed water is determined based on the pH value. In the determination of the discharge timing, the electrical conductivity of the circulating water and the sprayed water is determined. Can also be referred to. That is, when the electrical conductivity exceeds a predetermined value, a part of the circulating water and the spray water can be discharged. Since the electrical conductivity increases with increasing concentrations of corrosive ions and scale generation factors, the concentration of corrosive ions and scale generation factors accelerates corrosion and scale generation when the release timing is determined with reference to this. When the concentration is low, the circulating water and spray water are not diluted unnecessarily, and the pH can be maintained and the reproduction of Legionella can be more stably suppressed.

Test Example 3,200 kinds of Legionella spp. Were inoculated in each of three types of soft water adjusted to pH 7, 9 and 10, and left at 36 ° C. for 3 days. At the time of inoculation, 2 days and 3 days, 0.1 ml of this soft water was applied to a cysteine-containing BCYEα agar medium and cultured at 36 ° C. for 7 days, and the number of Legionella was examined. . The number of Legionella was examined based on the number of colonies formed in the medium. The results are shown in Table 1.

  According to Table 1, when the pH is 7, the number of Legionella is increased compared to the time of inoculation, but when the pH is 9 and 10, the number of Legionella is decreased compared to the time of inoculation. . From this result, it can be seen that if the pH of the soft water is maintained at 9.0 or higher, the reproduction of Legionella can be effectively suppressed.

The schematic of an example of the cooling water circulation system which can implement the operation method of the present invention. Schematic of the other example of the cooling water circulation system which can implement the operating method of this invention. The schematic of the electrolyzer which can be utilized in each said cooling water circulation system.

Explanation of symbols

110, 210 Cooling tower 123, 223 Water supply path 130, 230 Cooling load device 140, 240 Main body 141, 241 Opening part 142, 242 Louver 143, 243 Storage part 144, 244 Fan 149 Supply path 151 Recovery path 152, 261 Nozzle 160, 270 Drainage route 250 Circulation route 260 Movement route

Claims (2)

A cylindrical main body having an opening at the top and a circulating water reservoir for cooling the cooling load device at the bottom, and a vent on the side, and so that outside air passes from the vent to the opening. A fan capable of adjusting a rotation speed for generating an air flow in the main body, a supply path for supplying the circulating water from the storage unit to the cooling load device, and the cooling load device supplied to the cooling load device A recovery path for recovering the circulating water to the main body, a water supply path to the storage section, and a drainage path for discharging a part of the circulating water from the storage section, and an end portion of the recovery path However, the cooling tower is disposed below the fan in the main body and has a sprinkling port for sprinkling the circulating water toward the reservoir,
The circulating water whose pH is set to 9.0 or more is allowed to flow from the storage part in the order of the supply path, the cooling load device, and the recovery path, and water is sprayed from the watering port to continuously circulate to the storage part. Process,
When the pH of the circulating water exceeds 9.0 and the electrical conductivity exceeds a predetermined value in the reservoir, the pH of the circulating water during circulation is maintained at 9.0 or higher . It said releasing portion of the circulating water from the reservoir through the drain path, and, and a step for supplying water from the water supply path to said reservoir,
The circulating water is soft water, and the concentration rate based on the M alkali component concentration while adjusting the amount of the outside air passing from the vent hole to the opening by adjusting the rotational speed of the fan. PH is set to 9.0 or more by increasing
How to operate the cooling tower. A cylindrical main body having a vent hole on a side surface having an opening at the top and a sprinkling water reservoir for cooling circulating water for cooling the cooling load device at the bottom, and the opening from the vent A fan capable of adjusting the rotation speed for generating an air flow in the main body so that outside air passes, and a circulation path for circulating the circulating water between the main body and the cooling load device The sprinkling water movement path, the water supply path to the storage section, and a part of the sprinkling water from the storage section, the terminal section extending from the storage section and having the end portion disposed below the fan in the main body And a drainage path for discharging the cooling path, wherein the end part of the movement path has a sprinkling port for sprinkling the spray water toward the storage part,
In parallel with circulating the circulating water between the main body and the cooling load device, the sprayed water whose pH is set to 9.0 or more is supplied from the storage unit to the moving path, and the scattering water is supplied. Water is sprayed from the water port and continuously circulated to the reservoir;
When the pH of the sprayed water exceeds 9.0 and the electrical conductivity exceeds a predetermined value in the reservoir, the pH of the circulating sprayed water is maintained at 9.0 or higher . the releasing part of the sprayed water from the reservoir through the drain path, and, and a step for supplying water from the water supply path to said reservoir,
The spray water is soft water, and the concentration rate based on the M alkali component concentration while adjusting the amount of the outside air passing from the vent hole to the opening by adjusting the rotational speed of the fan. PH is set to 9.0 or more by increasing
How to operate the cooling tower.

Images