JP4437262B2 - cooling tower - Google Patents

Description

The present invention relates to a cooling tower, the concrete, on water quality management technology of an open cooling tower counter-flow and cross-flow type.

  In general, supply low-temperature cooling water to a cooling load device that requires cooling, such as a cooling device or a chiller / heater, and spray high-temperature cooling water returning from the cooling load device into the atmosphere. Open-type cooling towers are widely used in which low-temperature cooling water is regenerated by the latent heat of vaporization and recirculated to the cooling load device.

  In such circulating cooling water of the open type cooling tower, a part of the cooling water evaporates for heat dissipation, so that impurities such as silica contained in the cooling water are concentrated. If the concentrated impurities adhere to the heat transfer tube or the like of the cold load device as scale, the heat transfer performance may be deteriorated and the heat transfer tube or the like may be corroded.

  In order to prevent such scale adhesion, in general, a part of the circulating cooling water is drained (blow down) periodically to supply new cooling water, thereby maintaining the concentration ratio of impurities below the control value. Things have been done. However, if the blowdown amount is set to a constant amount according to the rated circulating cooling water amount of the cooling tower, the cooling water will be blown down more than necessary even though the cooling load is small and the evaporation amount is small depending on the season and time. It is uneconomical.

  Therefore, Patent Document 1 proposes that the conductivity of the cooling water is measured and the cooling water is blown down when the concentration ratio of impurities in the cooling water exceeds the control value. According to this, since the blowdown amount can be controlled in accordance with the evaporation amount correlated with the cooling load, the cooling water is not discarded unnecessarily, and the operation cost can be reduced.

JP 47-24392 A

  However, in the case of the water quality management method using the conductivity meter described in Patent Document 1, if the water quality management value is set strictly in order to reduce the amount of blowdown, an impurity scale may adhere to the conductivity meter itself. If the scale adheres to the conductivity meter, the conductivity is measured in a lower direction, so that the blowdown amount is reduced, and the scale is more likely to adhere, which is not preferable for the heat transfer tube. Therefore, it is necessary to set the water quality control value to the safe side or to periodically maintain the conductivity meter to keep the impurity concentration stably below the allowable value.

  On the other hand, it is known that a chemical that suppresses the adhesion of impurity scales is injected into cooling water to increase the allowable concentration ratio of impurities (for example, 2 times). In addition, there is a problem that it is necessary to periodically perform water quality analysis and chemical injection management in a relatively short period in order to stably maintain the impurity concentration in the cooling water below the allowable value.

  An object of the present invention is to reduce maintenance and operation costs, and to stably maintain an impurity concentration in cooling water of a cooling tower below an allowable value.

In order to solve the above problems, the present invention provides a casing having an opening at the top, a water spray nozzle for cooling water provided at the top of the casing, a water tank for cooling water provided at the bottom of the casing, A blower that is provided in the opening of the casing and circulates air in the casing; a cooling water pump that sucks cooling water in the water tank, supplies the cooling water to a cooling load, and circulates it to the watering nozzle; and a water level of the water tank Water level control means for supplying make-up water so as to keep the temperature within a set range, an overflow pipe whose opening position is set at a water level higher than the upper limit of the set range, and a water quality management means for managing the quality of the cooling water The water quality management means includes: an evaporation amount calculating means for obtaining an evaporation amount of cooling water in the cooling tower; and an evaporation amount obtained by the evaporation amount calculating means. A replenishing water amount calculating means for obtaining a replenishing water amount required for maintaining the impurity concentration in the cooling water below an allowable value, and a replenishing water supply for replenishing the cooling tower with the replenishing water amount obtained by the replenishing water amount calculating means Means, a flow rate detector for detecting the amount of the makeup water to be replenished by the water level control means, and a supplementary water amount integrated value (ΣV) by integrating the amount of makeup water detected by the flow rate detector every set time. ), And the evaporation amount calculation means calculates the evaporation amount integrated value (ΣQ / Qs) by integrating the evaporation amount at each set time, and the makeup water amount calculation means The required replenishment water amount (Vq) for maintaining the impurity concentration below an allowable value is obtained based on the evaporation amount integrated value every time, and the required replenishment water amount and the replenished water amount integrated value (ΣV )When Characterized in that the difference between the supply water of the replenishing water supplier.

  That is, the present invention has been made in view of the fact that the concentration of impurities in the cooling water can be determined by obtaining the amount of evaporation because the concentration of the cooling water evaporates and the concentration of impurities in the cooling water increases to increase the concentration. It is. If the impurity concentration is obtained in this way, a new replenishment amount of cooling water required to maintain the concentration below the allowable value can be obtained by calculation. Then, by replenishing the determined amount of new cooling water, the impurity concentration in the cooling water can be reduced to an allowable value or less, and problems associated with the scale adhering to the heat transfer tubes and the like can be avoided. In particular, since a measuring instrument such as a conductivity meter and chemicals are not used, maintenance and operation costs can be reduced, and the impurity concentration in the cooling water can be stably maintained below an allowable value.

  Here, the evaporation amount of the cooling water is obtained as a heat release amount based on the difference between the return temperature of the cooling water returned from the cooling load and the supply temperature of the cooling water supplied to the cooling load and the amount of cooling water distributed to the cooling tower. The calculated heat release amount can be calculated as being covered by the latent heat of vaporization of the cooling water. That is, the difference between the return temperature of the cooling water and the supply temperature is basically caused by the latent heat of vaporization of the evaporated cooling water, and correlates with the amount of the circulating cooling water. Therefore, the return temperature and the supply temperature are detected by a temperature sensor that is normally provided, and the amount of cooling water can be easily calculated by obtaining the amount of cooling water based on, for example, the operating state amount of the cooling load.

By the way, if only new cooling water having the same amount as the evaporation amount is replenished, the impurity concentration gradually increases due to impurities contained in the new cooling water, so that it is necessary to replenish the cooling water more than the evaporation amount. Therefore, the allowable value of the impurity concentration of F times the impurity concentration of the replenishing water, when the evaporation amount was Va, by controlling the supply amount of water Vq F · Va / (F- 1) to be the target, impurities The concentration can be kept near the tolerance.

  In this case, it is preferable that the evaporation amount calculation means stops the accumulation of the evaporation amount within a set time (for example, 20 seconds or more) after the operation of the cooling water pump. This is because the cooling water temperature fluctuates immediately after the cooling water pump is started, and the reliability is lacking.

  The water level control means can use a ball tap type automatic valve. Alternatively, a water level sensor that detects the water level of the water tank and an electromagnetic valve that is provided in the makeup water pipe and that is opened and closed according to the water level detected by the water level sensor can be provided.

  Furthermore, it is preferable that the overflow pipe is set at a water level that is at least the height of the system return water when the cooling water pump is stopped, rather than the upper limit of the setting range of the water tank water level.

  According to the present invention, maintenance and operation costs can be reduced, and the impurity concentration in the cooling water of the cooling tower can be stably maintained within an allowable range.

Hereinafter, the present invention will be described based on embodiments.
(Embodiment 1)
FIG. 1 shows a cooling water system configuration diagram including a cooling tower and a cooling load of an embodiment to which the water quality management method of the present invention is applied, and FIG. 2 shows a flowchart of a water quality management procedure of this embodiment.

  As shown in FIG. 1, the cooling tower 1 includes a cylindrical casing 2, an air inlet 3 is formed on the lower side surface of the casing 2, and a cooling water tank 4 is provided at the bottom. In addition, the filler 5 is accommodated in the casing 2 above the position of the air inlet 3, and the cooling water sprinkling nozzle 6 is disposed above the filler 5. An opening 7 is provided at the top of the casing 2, and a blower 8 is provided in the opening 7. The suction port of the cooling pump 9 is communicated with the vicinity of the bottom of the water tank 4, and the discharge port of the cooling pump 9 is transferred to a heat exchanger that is a cooling load provided in the chiller / heater 11 through the cooling water supply pipe 10. It is connected to one end of the thermal coil 12. The other end of the heat transfer coil 12 is connected to the watering nozzle 6 of the cooling tower 1 through a cooling water return pipe 13.

  A water supply pipe 14 is inserted into the water tank 4, and a ball tap type automatic valve 15 serving as a water level control means is provided at the tip of the water tank 4. As will be described later, the water level of the water tank 4 is maintained within a set range. Further, a makeup water pipe 17 branched from the water supply pipe 14 and provided with an electromagnetic valve 16 is provided in the upper part of the water tank 4. A flow rate detector 18 for measuring the amount of water supply is provided in the water supply piping 14 upstream of the branch portion of the makeup water piping 17. Usually, tap water is used as makeup water, and therefore a water meter can be applied to the flow rate detector 18. Further, the water tank 4 is provided with an overflow pipe 19 communicated with a drain groove (not shown) so that the cooling water does not overflow from the upper end of the water tank 4 to the surroundings. The upper end opening of the overflow pipe 19 is set at a position higher than the upper limit of the water level setting range of the water tank 4.

  On the other hand, a temperature sensor 20 for detecting the cooling water inlet temperature is provided at the connection between the cooling water supply pipe 10 and the heat transfer coil 12, and at the connection between the cooling water return pipe 13 and the heat transfer coil 12, A temperature sensor 21 for detecting the coolant outlet temperature is provided. The chiller / heater 11 is provided with a control panel 22 for controlling the cooling water pump 9 and the electromagnetic valve 16 so that detection signals from the flow rate detector 18 and the temperature sensors 20 and 21 are inputted. The control panel 22 incorporates water quality management means according to the feature of the present invention that manages the quality of the cooling water based on detection signals from the flow rate detector 18 and the temperature sensors 20 and 21. That is, the water quality management means maintains the impurity concentration in the cooling water below the allowable value based on the evaporation amount calculating means for obtaining the evaporation amount of the cooling water in the cooling tower 1 and the evaporation amount obtained by the evaporation amount calculating means. The replenishing water amount calculating means for obtaining the replenishing water amount required for the replenishing water, and the solenoid valve 16 is controlled to open and close based on the required replenishing water amount obtained by the replenishing water amount calculating means to replenish the cooling water to the water tank 4 of the cooling tower 1 And a makeup water supply means.

  Here, the structure of the ball tap type automatic valve 15 which is a water level control means for holding the water level of the water tank 4 within a set range will be described with reference to the schematic diagram shown in FIG. The position OFL of the upper end opening of the overflow pipe 19 is set to a lower position with a slight margin than the position ML of the upper end edge of the water tank 4. On the other hand, when the cooling water pump 9 is stopped, the cooling water remaining in the watering nozzle 6, the cooling water return pipe 13, the heat transfer coil 12, etc. flows down to the water tank 4 as system return water, and the water level of the water tank 4 Rises to the water level SDL when stopped. Accordingly, the position OFL of the upper end opening of the overflow pipe 19 is set to a higher position with a margin than the stop water level SDL. Further, the upper limit water level HL during normal operation is set in anticipation of the rise in the water level at the time of stop, and the lower limit water level LL during normal operation is set to a water level at which the cooling pump 9 does not inhale air. The ball tap type automatic valve 15 swings in the vertical direction according to the water level in the water tank 4 and opens a valve body (not shown) when the water level reaches the lower limit water level LL and reaches the upper limit water level HL. It is configured to close the valve body when it does. With this configuration, the operation level of the water tank 4 is kept within the set range of the lower limit water level LL and the upper limit water level HL according to the operation state of the cooling tower 1 by the action of the ball tap type automatic valve 15. It has come to be.

Next, the structure of the water quality management means in the control panel 22 of the cooling tower 1 of the present embodiment configured as described above will be described together with the operation. First, the principle of the cooling water quality management method of this embodiment will be described. The present invention obtains the evaporation amount from the heat radiation amount in the cooling tower 1, obtains the concentration degree (concentration ratio) of the impurities in the cooling water based on the evaporation amount, and a new necessary for making the impurity concentration below the allowable value. The replenishment amount of cooling water is obtained by calculation. Therefore, factors such as the amount of evaporation related to the calculation are defined as follows. In addition, water quality management control of a present Example shall be performed based on the integrated value for every set time (for example, 30 minutes).

Integrated value of heat dissipation: ΣQ
Necessary makeup water volume: Vq
Evaporation: Va
Drainage (blowdown amount): Vb
Impurity concentration in make-up water: c
Permissible concentration ratio of impurities: F
Water latent heat of vaporization: Qs (for example, 600 kcal / L)
Integrated value of makeup water: ΣV
The amount of impurities entering the cooling water by the replenishing water replenished via the ball tap automatic valve 15 or the electromagnetic valve 16 is c · Vq, and the amount of impurities coming out of the cooling water by the drainage is c · F · Vb. is there. Since the condition that the amount of impurities enters and exits is c · Vq = c · F · Vb, the following equation (1) is established.

Vb = Vq / F (1)
In addition, the following equation (2) is established from the balance of water supply / exit.

Vq = Va + Vb (2)
If the heat radiation in the cooling tower is all due to the latent heat of vapor evaporation Qs, the following equation (3) is established.

Va = ΣQ / Qs (3)
From the above formulas (1) to (3), the required replenishment water amount Vq is represented by the following formula (4).

Vq = ΣQ + Vq / F
(1-F) Vq = F · ΣQ / Qs
Vq = F · ΣQ / ((1-F) Qs) (4)
Further, the drainage amount Vb which is the blowdown amount is expressed by the following equation (5).

Vb = ΣQ / ((F-1) Qs) (5)
Therefore, the required replenishment water amount Vq is calculated at each set time, compared with the integrated value ΣV of the actual replenishment water amount within the set time, and the solenoid valve 16 is opened and cooled so that the following equation (6) is satisfied. By replenishing water, the concentration ratio of the impurities in the cooling water can be kept below the allowable value F.

ΣV ≧ Vq (6)
Here, the integrated value ΣV of the actual replenishing water amount is obtained by counting the number of pulses transmitted from the water meter and multiplying the flow rate per pulse every set time when a water meter is used as the flow rate detector 18. Ask. The allowable concentration ratio F is set by the ratio between the impurity concentration c obtained from the water quality analysis result of the makeup water and the reference allowable concentration of the circulating cooling water.

Further, the integrated value ΣQ of the heat dissipation amount of the cooling water can be obtained by the following equation (7). In this equation, CTi is the cooling water inlet temperature (cooling water supply temperature) of the heat transfer coil 12 detected by the temperature sensor 20, and CTo is the cooling water outlet temperature (cooling) of the heat transfer coil 12 detected by the temperature sensor 21. Water return temperature). Further, the temperature correction value K is for correcting the temperature measurement error due to variation in the temperature sensor 20 and 21 each other, the shipping inspection or commissioning of the plant, the temperature of the site is their temperature sensors 20, 21 that are provided The temperature is actually measured based on the same conditions, and for example, CTi-CTo = K is obtained and stored in the control panel 22.

(When CTo-CTi + K ≦ 0)
ΣQ = ΣQ
(When CTo-CTi + K> 0)
ΣQ = ΣQ + (CTo−CTi + K) × w × t (7)
Here, w is the amount of circulating cooling water (L / min), for example, a different value for each model of the cooling / heating load, and t is the measurement time interval (calculation cycle: min) of the cooling / heating load capacity.

  Based on the integrated value ΣQ of the heat dissipation amount thus obtained, the replenishment water amount Vq required to keep the allowable concentration magnification F or less is obtained by the above equation (4). Note that when the temperature is high such as midsummer, the natural evaporation amount may not be negligible. Therefore, if there is a difference from the reference value of the permissible concentration factor F by performing a water quality analysis, the correction value R of the makeup water amount is set. It is desirable to use the following equation (8) obtained by correcting the makeup water amount Vq of equation (4).

Vq = F · ΣQ / ((1-F) Qs) × R (8)
The necessary makeup water amount Vq obtained in this way is compared with the integrated value ΣV of the actual makeup water amount obtained based on the detection output of the flow rate detector 18, and if Vq> ΣV, it is determined that the water supply is necessary. Then, the difference (Vq−ΣV) is obtained, and the electromagnetic valve 16 is opened to supply coolant until the difference (Vq−ΣV) becomes zero. By replenishing the cooling water, the water level of the water tank 4 rises, and a part of the cooling water containing the concentrated impurities is drained through the overflow pipe 19 to keep the impurity concentration in the cooling water below the allowable value. Can do. On the other hand, if Vq ≦ ΣV, it is determined that replenishment of the cooling water is unnecessary.

  Based on such a principle, processing executed by the water quality management means of the control panel 22 will be described along the flowchart shown in FIG. The flowchart of FIG. 2 is executed periodically. First, in step S1, the integrated value ΣV of the makeup water amount and the integrated value ΣQ of the heat release amount stored in the memory are rewritten to the current values and reset. Next, in step S2, it is determined whether or not the cooling water pump is in operation. If it is not in operation, the process proceeds to step S6 to close or confirm that the electromagnetic valve 16 is closed, and then returns to step S2.

  If the cooling pump is in operation, the process proceeds to step S3, where it is determined whether or not a set time of 30 minutes or more has elapsed since the previous replenishment. If not, the process proceeds to step S6 and has passed. If so, the process proceeds to step S4. In step S4, the required makeup water amount Vq is compared with the integrated value ΣV of the actual makeup water amount. If Vq> ΣV, it is determined that water supply is necessary, the process proceeds to step S5, the solenoid valve 16 is opened, and the step Return to S4. On the other hand, if Vq ≦ ΣV, it is determined that cooling water is not required, and the process returns to step S1.

  FIG. 4 shows a flowchart of the detailed processing procedure of the process of rewriting the integrated value ΣV of the makeup water amount and the integrated value ΣQ of the heat release amount to the current values in step S1 of FIG. The process of FIG. 4 is performed for every predetermined calculation cycle. First, in step S11, it is determined whether or not the chiller / heater 11 is in operation. If it is in operation, the process proceeds to step S12, where the integrated value ΣV of the makeup water amount is integrated and stored in the memory. Next, the process proceeds to step S13, and it is determined whether or not the cooling water pump is in operation and a set time (for example, 20 seconds) or more has elapsed after startup. If this determination is affirmative (Y), the process proceeds to step S14, the count of T1 (timer) that counts the set integration time (for example, 30 minutes) is advanced, and the integration of the integrated value ΣQ of the heat release amount is executed. Store in memory. On the other hand, if the determination in step S11 is negative (N), the process proceeds to step S15, the accumulation of the integrated value ΣV of the makeup water amount is stopped, and the process further proceeds to step S16 to temporarily stop the count of T1 (timer). At the same time, the integration of the integrated value ΣQ of the heat dissipation amount is temporarily stopped. If the determination in step S13 is negative (N), the process proceeds to step S16, where the count of T1 (timer) is temporarily stopped and the integration of the integrated value ΣQ of the heat release amount is temporarily stopped.

  As described above, according to the present embodiment, the heat dissipation amount is obtained based on the difference between the return temperature of the cooling water and the supply temperature of the cooling water and the amount of the cooling water flowing through the cooling tower 1, and the obtained heat dissipation amount is The amount of cooling water evaporated in the cooling tower 1 is calculated as being covered by the latent heat of vaporization of the cooling water, and a new amount of cooling water replenishment necessary for maintaining the concentration ratio of impurities in the cooling water below the allowable value is obtained. Since it is obtained by calculation and replenished with the obtained amount of new cooling water, it is possible to avoid problems associated with scales adhering to the heat transfer tubes and the like. In particular, since a measuring instrument such as a conductivity meter and chemicals are not used, maintenance and operation costs can be reduced, and the impurity concentration in the cooling water can be stably maintained below an allowable value.

Specifically, the allowable value of the impurity concentration of F times the impurity concentration of the replenishing water, the evaporation amount when the Va, the replenishment water Vq by controlling in the F · Va / (F-1 ) target the Therefore, the impurity concentration can be maintained near the allowable value.

In addition, since the accumulation of evaporation is stopped within a set time (for example, 20 seconds or more) after the cooling water pump starts operation, fluctuations in the cooling water temperature immediately after starting the cooling water pump are eliminated. It is possible to improve the reliability of the integrated value of evaporation.
(Embodiment 2)
FIG. 5 shows a configuration diagram of a cooling water system including a cooling tower and a cooling load according to another embodiment to which the water quality management method of the present invention is applied. The present embodiment differs from the embodiment of FIG. 1 in that a water level sensor 31 that detects the water level of the water tank 4 and a water level provided in the makeup water pipe 17 instead of the ball tap type automatic valve 15 that is a water level control means. The electromagnetic valve 16 is opened and closed according to the water level detected by the sensor 31. Since other configurations are the same as those of the embodiment of FIG. 1, the same reference numerals are given and description thereof is omitted.

  As shown in FIG. 5, the water level sensor 31 is a three-core type level switch. As described with reference to FIG. 3, when the water level of the water tank 4 reaches the lower limit water level LL or lower, the off signal is set to the upper limit water level HL or higher. The ON signal is output to the control panel 22 when the value reaches the control panel 22. The control panel is configured to open the electromagnetic valve 16 when the water level of the water tank 4 reaches the lower limit water level LL or lower and close the electromagnetic valve 16 when the water level reaches the upper limit water level HL. As a result, the water level of the water tank 4 is maintained within the set range of the lower limit water level LL and the upper limit water level HL.

  That is, as shown in FIG. 6, the on / off state of the water level sensor 31 is determined (step S21). When the water level falls below the lower limit water level LL and the water level sensor 31 is turned off, the electromagnetic valve 16 is opened. When water is supplied (step S22), the water level rises to reach the upper limit water level HL, and when the water level sensor 31 is turned on, the electromagnetic valve 16 is closed to stop water supply.

  When the water level sensor 31 is turned on, the process proceeds to step S23, where it is determined whether or not a set time (for example, 20 seconds) has elapsed since the cooling water pump started operation. If this determination is affirmative (Y), the process proceeds to step S24, and it is determined whether or not the T1 (timer) counter exceeds a set integration time (for example, 30 minutes). If this determination is affirmative (Y), the process proceeds to step S25, where the required make-up water amount Vq is compared with the integrated value ΣV of the actual make-up water amount, and if Vq> ΣV and it is determined that water supply is necessary, Proceeding to step S26, the solenoid valve 16 is opened, and the process returns to step S25. On the other hand, if it is determined in step S25 that Vq ≦ ΣV and replenishment of the cooling water is not necessary, the process proceeds to step S27, where the T1 (timer) counter, the replenishment water amount integrated value ΣV and the heat dissipation amount integrated value ΣQ Set to zero. And it progresses to step S28 and the solenoid valve 16 is closed. Moreover, when the judgment in step S23 and step S24 is negative (N), it progresses to step S28, the solenoid valve 16 is closed, and it complete | finishes.

  According to this embodiment, the same effect as the water quality management of Embodiment 1 of FIG. 1 can be produced.

  In either case of the first and second embodiments, when the cooling / heating load is unnecessary (for example, when the chiller / heater 11 is in the heating mode operation), the solenoid valve 16 is closed to prevent water supply. Needless to say. When the chiller / heater 11 is switched from the heating mode operation to the cooling mode operation, the electromagnetic valve 16 is opened and water filling is performed up to a predetermined water level HL as in the conventional case. In this case, when water is filled with the ball tap automatic valve 15 of the first embodiment, the valve opening is automatically throttled as the water level approaches the upper limit water level HL, so it takes time to fill the water. On the other hand, in the case of the second embodiment, since the electromagnetic valve 16 can be fully opened until the water level sensor 31 is turned on, the water filling time can be shortened.

1 is a configuration diagram of a cooling water system including a cooling tower and a cooling load of an embodiment to which a water quality management method of the present invention is applied. It is a flowchart which shows the process sequence of one Embodiment of the water quality management method of this invention. It is a schematic diagram explaining the water level control of a water tank. It is a flowchart which shows the renewal processing procedure by rewriting the integrated value ΣV of the makeup water amount and the integrated value ΣQ of the heat release amount to the current values. It is a cooling water system | strain block diagram containing the cooling tower and cooling-heat load of other embodiment to which the water quality management method of this invention is applied. It is a flowchart which shows the process sequence of embodiment of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cooling tower 4 Water tank 6 Sprinkling nozzle 8 Blower 9 Cooling water pump 10 Supply piping 11 Cold / hot water 12 Heat transfer coil 13 Return piping 14 Water supply piping 15 Ball tap type automatic valve 16 Solenoid valve 17 Supply water pipe 18 Flow rate detector 19 Overflow piping 20 , 21 Temperature sensor 22 Control panel

Claims (5)

A casing having an opening at the top, a sprinkling nozzle for cooling water provided at the top of the casing, a water tank for cooling water provided at the bottom of the casing, and a water tank provided at the opening of the casing. A blower that circulates air, a cooling water pump that sucks cooling water in the water tank and supplies it to a cooling load and circulates it to the watering nozzle, and supplies makeup water so as to keep the water level of the water tank in a set range In a cooling tower comprising water level control means, an overflow pipe whose opening position is set at a water level higher than the upper limit of the setting range, and water quality management means for managing the quality of the cooling water,
The water quality management means maintains the impurity concentration in the cooling water below an allowable value based on the evaporation amount calculating means for determining the evaporation amount of the cooling water in the cooling tower, and the evaporation amount obtained by the evaporation amount calculating means. and replenishing water amount calculating means for calculating the supply quantity of cooling water required, an auxiliary water supply amount and the makeup water supply means for supplying the cooling tower as determined by該補water supply amount calculating means, the supplementary water which is replenished by the level control means A flow rate detector for detecting the amount of water, and a replenishment water amount integrating means for integrating the amount of make-up water detected by the flow rate detector every set time to obtain a replenishment water amount integrated value (ΣV),
The evaporation amount calculation means integrates the evaporation amount for each set time to obtain an evaporation amount integrated value (ΣQ / Qs),
The makeup water amount calculation means obtains the necessary makeup water amount (Vq) for maintaining the impurity concentration below an allowable value based on the evaporation amount integrated value at each set time, and calculates the necessary makeup water amount and the makeup water amount integration means. A cooling tower characterized in that the difference between the supplementary water amount integrated value (ΣV) obtained by the above equation is the supplementary water amount of the supplementary water supply means . 2. The cooling tower according to claim 1 , wherein the evaporation amount calculation unit stops the accumulation of the evaporation amount within a set time after the operation of the cooling water pump is started. The cooling tower according to claim 1 , wherein the water level control means is a ball tap type automatic valve. The water level control means includes a water level sensor (31) for detecting the water level of the water tank, and an electromagnetic valve provided in a makeup water pipe and opened and closed according to the water level detected by the water level sensor. The cooling tower according to claim 1 . The overflow pipe has cooling that remains in the water spray nozzle, the cooling water return pipe, the heat transfer coil of the cooling load, and the like when the cooling water pump is stopped at least when the opening position is higher than the upper limit of the setting range . The cooling tower according to claim 1 , wherein the cooling tower is set to a water level obtained by adding a height of system return water in which water returns to the water tank .

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