Cooling water system equipment control device, cooling water system equipment, cooling tower control device and cooling tower

Abstract

To improve an energy saving effect of a cooling water system facility.SOLUTION: A cooling water system facility 30B comprises: a cooling water pump 45 for circulating cooling water with respect to a heat load; and a cooling tower 31 which includes a cooling tower fan 41 for emitting heat and in which return cooling water fed back through an incoming path is cooled by heat exchange with atmospheric air and supplied to the heat load via an outgoing path. A control device 200 for the cooling water system facility 30B comprises a first control unit 210 for controlling one accessory of the cooling tower fan 41 and the cooling water pump 45. The first control unit 210 includes: a first arithmetic section 230 for calculating a cooling index indicating a cooling ability of the cooling tower 31 based on a wet bulb temperature of the atmospheric air and a cooling tower inlet cooling water temperature; a second arithmetic section 240 for determining a rotation speed command value of the one accessory based on the cooling index; and a first correction section 250 for correcting the rotation speed command value of the one accessory in response to variations of the heat load.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] The present invention relates to a technology for saving energy in cooling water system facilities. [Background technology]

[0002] Cooling towers are widely used to cool down heat loads.

[0003] As shown in Figure 1, the cooling water system in a cooling water facility using a cooling tower (hereinafter referred to as "cooling water system facility") is composed of a cooling tower 31 equipped with a cooling tower fan 41, and a cooling water pump 45 that circulates cooling water, which is a cooling medium, between the heat load QL and the cooling tower 31.

[0004] The cooling tower 31 operates on the principle of lowering the water temperature by utilizing the heat of vaporization of the water, and dissipates heat by blowing air onto the sprayed water with a cooling tower fan 41 to promote the evaporation of the water.

[0005] Due to its cooling principle, the cooling capacity of the cooling tower 31 varies greatly depending on the state of the atmosphere (wet-bulb temperature of the atmosphere) into which heat is dissipated.

[0006] The cooling tower 31 is generally designed to be able to dissipate the maximum heat load of the target even in a high wet-bulb temperature zone where the cooling capacity is reduced.

[0007] As shown in the graph in Figure 2, the wet-bulb temperature of the atmosphere rises to about 25°C in the summer, but drops to about 5°C in the winter. As a result, cooling water system equipment operates at an over-specified level for most of the year, which can result in unnecessary energy consumption.

[0008] In order to make effective use of limited energy and realize a sustainable society, energy conservation by eliminating unnecessary energy consumption has become an issue, and it is necessary to control the energy consumption of the cooling tower fan 41 and cooling water pump 45, which are auxiliary equipment in the cooling water system, so that it matches the cooling capacity of the cooling tower 31, which varies depending on atmospheric conditions. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 6887537 Summary of the Invention [Problem to be solved by the invention]

[0010] The cooling capacity of the cooling tower 31 improves as the temperature difference between the "cooling tower inlet cooling water temperature" and the "atmospheric wet-bulb temperature" increases. Therefore, in the invention of the cooling water system equipment according to Patent Document 1, the temperature difference between the "cooling tower inlet cooling water temperature" and the "atmospheric wet-bulb temperature" is defined as the "cooling index ΔTq" and the cooling capacity of the cooling tower 31 is estimated.

[0011] 3 is a system configuration diagram of the cooling water system equipment according to Patent Document 1. In Patent Document 1, a control device 700 controls the rotation speed of a cooling tower fan 41 according to a program based on a cooling index ΔTq.

[0012] By controlling the rotation speed of the cooling tower fan 41 according to the cooling index ΔTq of the cooling tower 31, it becomes possible to control the rotation speed in accordance with the cooling capacity of the cooling tower 31, resulting in a significant energy-saving effect. However, because fluctuations in the heat load QL are not taken into consideration, there is room to further reduce the energy consumption of the cooling tower fan 41 and improve the energy-saving effect.

[0013] In addition, similar issues arise when controlling the rotation speed of the cooling water pump 45, not just the cooling tower fan 41. Furthermore, even when the cooling water system equipment is used to cool a heat load other than the condenser, it is desirable to reduce the energy consumption of the cooling tower fan 41 and the cooling water pump 45 and improve the energy saving effect.

[0014] One aspect of the present invention discloses a technique for improving the energy saving effect of cooling water system equipment. [Means for solving the problem]

[0015] The cooling water system equipment includes a cooling water pump that circulates cooling water to the heat load, and a cooling tower that has a cooling tower fan that dissipates heat, and cools the return cooling water that returns through the return pipe by exchanging heat with the atmosphere, and supplies it to the heat load through the outgoing pipe.

[0016] The control device for the cooling water system facility includes a first control unit that controls one of the auxiliary devices, the cooling tower fan or the cooling water pump.

[0017] The first control unit includes a first calculation unit that calculates a cooling index indicating the cooling capacity of the cooling tower based on the wet-bulb temperature of the atmosphere and the cooling water temperature at the inlet of the cooling tower, a second calculation unit that determines a rotation speed command value for the one auxiliary machine based on the cooling index, and a first correction unit that corrects the rotation speed command value for the one auxiliary machine in accordance with fluctuations in the thermal load. Note that the rotation speed of the other auxiliary machine may be controlled by any method. Feedback control may be used so that the controlled object coincides with a control target value, or other control methods may be used.

[0018] The present technology can be applied to a control method for cooling water system equipment, a control device for a cooling tower, a control method, and also to a control program for cooling water system equipment and a control program for a cooling tower. [Effects of the Invention]

[0019] This technology can improve the energy saving effect of cooling water system equipment. [Brief explanation of the drawings]

[0020] [Figure 1] Block diagram showing the cooling principle of a cooling tower [Figure 2] Graph showing annual wet bulb temperature changes [Figure 3] Cooling water system configuration diagram [Figure 4] A diagram showing the relationship between the product of the cooling index and the cooling fan rotation speed and the cooling index. [Figure 5]Cooling water system configuration diagram [Figure 6] Control device block diagram [Figure 7] Graph showing the relationship between the cooling index and the cooling tower fan rotation speed command value [Figure 8] Graph showing the relationship between relative humidity x and wet / dry temperature difference ΔTa [Figure 9] A chart summarizing the first-order term P and the constant term Q against the dry-bulb temperature Ta [Figure 10] Chart showing conditions for calculating power reduction [Figure 11] Graph showing the relationship between wet bulb temperature and fan rotation speed [Figure 12] Graph showing the relationship between wet bulb temperature and fan power [Figure 13] Graph showing the relationship between wet bulb temperature and fan power difference [Figure 14] Diagram showing the relationship between ΔT (heat load fluctuation) and ΔTq [Figure 15] Cooling water system configuration diagram [Figure 16] Control device block diagram [Figure 17] Cooling water system configuration diagram [Figure 18] Control device block diagram [Figure 19] Control device block diagram DETAILED DESCRIPTION OF THE INVENTION

[0021] An overview of the cooling water system equipment will be explained. The cooling water system equipment includes a cooling water pump that circulates cooling water to the heat load, and a cooling tower that has a cooling tower fan that dissipates heat, and cools the return cooling water that returns through the return pipe by exchanging heat with the atmosphere, and supplies it to the heat load through the outgoing pipe.

[0022] The control device for the cooling water system facility includes a first control unit that controls one of the auxiliary devices, the cooling tower fan or the cooling water pump.

[0023] The first control unit includes a first calculation unit that calculates a cooling index indicating the cooling capacity of the cooling tower based on the wet-bulb temperature of the atmosphere and the cooling tower inlet cooling water temperature, a second calculation unit that determines a rotation speed command value of the one auxiliary machine based on the cooling index, and a first correction unit that corrects the rotation speed command value of the one auxiliary machine in accordance with fluctuations in thermal load.

[0024] In this configuration, the energy consumption of the auxiliary equipment in the cooling water system can be controlled according to the cooling capacity of the cooling tower and fluctuations in the heat load, thereby making the cooling water system energy-efficient.

[0025] The optimum rotation speeds of the cooling tower fan and the cooling pump will be explained below.

[0026] 3, when the power generation facility is operating at rated output, the exhaust heat quantity (heat load QL) of the steam turbine 10 is constant. In order to control the internal temperature of the condenser 20 to a constant value under the condition that the exhaust heat quantity (heat load QL) of the steam turbine 10 is constant, it is necessary to control the heat exchange amount of the condenser 20 to a constant value.

[0027] The heat exchange amount of the condenser 20 is the condenser inlet / outlet cooling water temperature difference ΔT 32 Since it is proportional to the product of (the difference between the outlet cooling water temperature HWT and the inlet cooling water temperature LWT) and the cooling water flow rate F, ΔT 32 ×F = constant. In addition, the cooling water flow rate F is proportional to the rotation speed P rpm of the cooling water pump 45, and therefore the following formula (X1) is obtained.

[0028] ΔT 32 ×Prpm=constant...(X1)

[0029] FIG. 4 shows the difference in cooling water temperature between the inlet and outlet of the condenser 20, ΔT, when the internal temperature (vacuum) of the condenser 20 is controlled to be constant under the condition that the steam turbine exhaust heat quantity (heat load QL) is constant. 32 This is a graph showing the actual operating values ​​of ΔTq × F rpm against 32 The horizontal axis is ΔTq×Frpm.

[0030] As shown in Figure 4, ΔT32 Since ΔTq×Frpm is roughly proportional to

[0031] k1×(ΔTq×Frpm)=ΔT 32 ···(X2) k1 is a proportionality constant.

[0032] From equations (X1) and (X2), equation (X3) can be obtained. ΔT 32 ×Prpm=k1×(ΔTq×Frpm)×Prpm=constant ΔTq×Frpm×Prpm=constant=constant A...(X3)

[0033] From the operating data or cooling tower specifications, the cooling tower inlet cooling water temperature (= condenser outlet cooling water temperature) and wet-bulb temperature when the cooling tower fan 41 rotation speed F rpm = 100% and the cooling water pump 45 rotation speed P rpm = 100% are used as reference values ​​and substituted into equation (X3) to calculate the constant A.

[0034] The constant A is the cooling index ΔTq at the reference value, which is designated as ΔTq0. Substituting ΔTq0 into equation (X3), the following equation (X4) is obtained.

[0035] ΔTq×Frpm×Prpm=ΔTq0 (X4) ΔTq0 is a reference cooling index (hereinafter referred to as "reference cooling index"), and is the cooling index ΔTq when both the cooling tower fan 41 and the cooling water pump 45 are rotating at 100%.

[0036] When the heat load QL is constant, the relationship in equation (1) holds for the cooling index ΔTq, fan rotation speed Frpm%, and pump rotation speed Prpm%. As mentioned above, this has been verified using data on the actual operating values ​​of cooling water system equipment (Fig. 4), and can be applied not only to cooling water system equipment for condensers, but also to other uses.

[0037] ΔTq0=ΔTq×Frpm%×Prpm%=constant...(1)

[0038] Frpm% is the ratio of the fan rotation speed Frpm to the rated rotation speed (100%), and Prpm% is the ratio of the pump rotation speed Prpm to the rated rotation speed (100%). The "fan" is the cooling tower fan 41, and the "pump" is the cooling water pump 45.

[0039] Since fan power Pf and pump power Pp are generally proportional to the cube of their respective rotation speeds, the total auxiliary power P of the cooling water system is as follows: Here, the fan power when the fan is rotating at 100% is Pf0, and the pump power when the pump is rotating at 100% is Pp0. The symbol {^} indicates a power.

[0040] Pf=Pf0×Frpm%^3 Pp=Pp0×Prpm%^3 P = Pf + Pp (2)

[0041] From equation (1), Prpm% = △Tq0 / △Tq / Frpm%, and by substituting this into equation (2), P can be expressed as a function of Frpm%, as shown below. P=Pf0×Frpm%^3+Pp0×(△Tq0 / △Tq / Frpm%)^3···(2-1)

[0042] By differentiating equation (2-1) to find the minimum point F rpm% so that P is minimized, the optimal fan rotation speed F rpm% that minimizes P can be obtained as shown in equation (3).

[0043] In a similar manner, the optimum pump speed P rpm% that minimizes P can be obtained as shown in equation (4).

[0044] Frpm%=(Pp0 / Pf0)^(1 / 6)×(ΔTq0 / ΔTq)^(1 / 2)...(3) Prpm%=(Pf0 / Pp0)^(1 / 6)×(ΔTq0 / ΔTq)^(1 / 2)...(4)

[0045] When the thermal load QL fluctuates, it can be expressed by the following equation using the thermal load reference value QL0: Here, the "thermal load reference value QL0" is the thermal load QL when the fan and pump achieve their optimum rotation speeds in equation (3) or (4).

[0046] QL=kq×QL0 kq=QL / QL0 (5) (kq: heat load correction coefficient)

[0047] And, from equation (X3), the cooling index ΔTq is proportional to the heat load QL, so the reference cooling index at the heat load QL is kq × ΔTq0. Note that the constant A in equation (X3) is proportional to the heat load QL.

[0048] The optimum rotation speeds of the fan and pump when the reference cooling index is kq × ΔTq0 can be calculated from equations (1) and (2) as follows: Frpmkq% is the optimum rotation speed of the fan, and Prpmkq% is the optimum rotation speed of the pump.

[0049] Frpmkq%=(Pp0 / Pf0)^(1 / 6)×(kq×ΔTq0 / ΔTq)^(1 / 2) Frpmkq%=kq^(1 / 2)×Frpm% (3-1) Prpmkq%=(Pf0 / Pp0)^(1 / 6)×(kq×ΔTq0 / ΔTq)^(1 / 2) Prpmkq%=kq^(1 / 2)×Prpm% (4-1)

[0050] That is, for both the fan and the pump, the optimum rotation speed at the thermal load reference value QL0 can be determined by multiplying the optimum rotation speed by "kq^(1 / 2)".

[0051] The heat load QL is the product of the cooling water temperature difference ΔT at the cooling tower inlet and outlet and the cooling water flow rate F, and kq is calculated using equation (7). ΔT0 is the cooling water temperature difference ΔT at the cooling tower inlet and outlet when QL0 is reached, and F0 is the cooling water flow rate F when QL0 is reached.

[0052] QL = ΔT × F (6) kq=(ΔT×F) / (ΔT0×F0)···(7)

[0053] Therefore, by measuring the cooling tower inlet cooling water temperature HWT, the cooling tower outlet cooling water temperature LWT, and the cooling water flow rate F, the heat load correction coefficient kq can be calculated, and the optimal rotation speeds of the fan and pump can be calculated from equations (3-1) and (4-1).

[0054] Furthermore, the heat load correction coefficient kq is not limited to equation (7), and can be calculated using other indices depending on the application of the cooling water system equipment and the control details of the auxiliary equipment.

[0055] <Embodiment 1> 1. Cooling water system equipment configuration 5 is a block diagram showing the configuration of a cooling water system facility 30A that cools the condenser 20 of the steam power generation facility 1. The steam power generation facility 1 is, for example, a small-scale biomass power generation facility with a rated output of about 7000 [kw].

[0056] The steam power generation facility 1 includes a boiler (not shown) that generates steam, a steam turbine 10, a generator 15 that generates electricity using the steam turbine 10, a condenser 20 that is a heat exchanger, and a cooling water system facility 30A that supplies cooling water that is a cooling medium to the condenser 20.

[0057] The steam discharged from the steam turbine 10 into the condenser 20 exchanges heat with the cooling water flowing through the condenser 20 and returns to water, thereby maintaining a vacuum inside the condenser 20. Maintaining a vacuum in the condenser 20 stabilizes the rotation of the steam turbine 10, making it possible to maintain the power generation efficiency of the generator 15.

[0058] The condenser 20 has an internal thermometer 21. The internal thermometer 21 measures the internal temperature EXT of the condenser 20, that is, the temperature of exhaust steam inside the condenser.

[0059] The cooling water system equipment 30A includes a cooling tower 31, an outward pipe 32, an inward pipe 33, and two auxiliary machines, a cooling tower fan 41 and a cooling water pump 45.

[0060] Cooling water is supplied from a cooling tower 31 to the condenser 20 through an outward pipe 32. The return cooling water that has exchanged heat with steam in the condenser 20 passes through an inward pipe 33 from the condenser 20 and returns to the cooling tower 31.

[0061] The return cooling water returned to the cooling tower 31 is showered in the cooling tower to facilitate evaporation, and a portion of it evaporates through heat exchange with the atmosphere. The return cooling water is cooled by releasing the heat of vaporization generated as the water evaporates into the outside air. To promote water evaporation during this process, the cooling tower 31 has a cooling tower fan 41 that dissipates heat.

[0062] The rotation speed of the drive motor 42 that drives the cooling tower fan 41 can be controlled by a VVVF (variable voltage variable frequency) control device 43. By controlling the rotation speed of the drive motor 42, the air volume of the cooling tower fan 41 can be adjusted as desired.

[0063] The cooling water pump 45 is located in the outward pipe 32. The rotation speed of the drive motor 46 that drives the cooling water pump 45 can be controlled by a VVVF 47. By controlling the rotation speed of the drive motor 46, the cooling water flow rate F can be adjusted as desired.

[0064] The cooling tower 31 is provided with an atmospheric thermometer 51 and a relative hygrometer 52. The atmospheric thermometer 51 is a dry-bulb thermometer that measures the atmospheric dry-bulb temperature Ta, and the relative hygrometer 52 measures the relative humidity x.

[0065] Further, water thermometers 53 and 54 are provided on the outward pipe 32 and the return pipe 33. The water thermometer 53 is located at the inlet of the condenser 20 on the outward pipe 32 and measures the condenser inlet cooling water temperature (cooling tower outlet cooling water temperature) LWT. The water thermometer 54 is located at the inlet of the return pipe 33 to the cooling tower 31 and measures the cooling tower inlet cooling water temperature HWT. The measured values ​​of these respective meters 21, 51 to 54 are input to a control device 100, which will be described below.

[0066] The control device 100 of the cooling water system equipment 30A will be described below with reference to Fig. 6. The control device 100 has a first control unit 110 and a second control unit 180.

[0067] The first control unit 110 programmatically controls the rotation speed of the cooling tower fan 41 based on the cooling capacity of the cooling tower 31. As shown in FIG. 6 , the first control unit 110 includes a wet-bulb temperature calculation unit 120, a first calculation unit 130, a second calculation unit 140, and a first correction unit 150.

[0068] The wet-bulb temperature calculation unit 120 is a circuit that calculates the atmospheric wet-bulb temperature WBT from the atmospheric dry-bulb temperature Ta and relative humidity x. The measurement principle of the wet-bulb temperature WBT will be explained later.

[0069] As shown in equation (8), the first calculation unit 130 subtracts the atmospheric wet-bulb temperature WBT output from the wet-bulb temperature calculation unit 120 from the cooling tower inlet cooling water temperature HWT (the temperature of the return cooling water) to calculate a cooling index ΔTq that represents the cooling capacity of the cooling tower 31. The first calculation unit 130 can be configured, for example, by a differentiator.

[0070] ΔTq=HWT-WBT (8)

[0071] The cooling tower inlet cooling water temperature HWT (return cooling water temperature) is preferably an actual measurement value measured by a water thermometer 54, but may also be a predicted value (estimated value). For example, as disclosed in Patent Document 1, when the temperature inside the condenser is feedback-controlled to a constant value, the HWT becomes a constant value that is approximately 3°C lower than the temperature inside the condenser, and this value may also be used. In this case, the water thermometer 54 may be omitted.

[0072] The second calculation unit 140 has a program for calculating a rotation speed command value Frpm_0 corresponding to a cooling index ΔTq in a thermal load QL0 according to equation (3), and determines the rotation speed command value Frpm_0 from the cooling index ΔTq. The correlation characteristic Lv shown in Fig. 7 is a graph of equation (3), and for example, when the cooling index ΔTq is "A", the rotation speed command value Frpm_0 is determined to be "B".

[0073] The second calculation unit 140 may be configured using a function generator or a look-up table, as long as it calculates the rotation speed command value Frpm_0 corresponding to the cooling index ΔTq according to equation (3).

[0074] The first correction unit 150 corrects the rotation speed command value Frpm_0 determined by the second calculation unit 140 in accordance with fluctuations in the thermal load QL. In this embodiment, the thermal load QL is steam discharged from the steam turbine 10 into the condenser 20, and the thermal load QL fluctuates in conjunction with the generator output kW of the generator 15. Therefore, the rotation speed command value Frpm_0 is corrected in accordance with fluctuations in the generator output kW of the generator 15.

[0075] The first correction unit 150 includes a divider 151 , a signal generator 152 , a root calculator 153 , and a multiplier 155 .

[0076] The divider 151 receives the generator output kW from the generator 15 and receives the generator output reference value kW0 from the signal generator 152. The generator output reference value kW0 is, for example, the rated output of the generator 15. The generator output reference value kW0 is the generator output corresponding to the thermal load reference value QL0. The divider 151 calculates the ratio of the "generator output kW" to the "generator output reference value kW0" as the thermal load correction coefficient kq.

[0077] kq=kW / kW0 (9)

[0078] The root calculator 153 calculates the square root K of the heat load correction coefficient kq.

[0079] K = √kq (10)

[0080] A multiplier 155 multiplies the rotation speed command value Frpm_0 by the square root K of the heat load correction coefficient kq, and outputs the result to the VVVF 43.

[0081] Frpm_1=Frpm_0×K (11) Frpm_1 is the rotation speed command value after correction.

[0082] As a result, the rotation speed of the motor 42 of the cooling tower fan 41 is controlled to the rotation speed command value Frpm_1 by the VVVF 43. In other words, the rotation speed Frpm of the cooling tower fan 41 is controlled in accordance with the cooling capacity of the cooling tower 31, and further varies in conjunction with fluctuations in the heat load (generator output) QL.

[0083] The first correction unit 150 performs the correction in real time.

[0084] The second control unit 180 feedback controls the rotation speed P rpm of the cooling water pump 45 so that the internal temperature EXT of the condenser 20 coincides with the target internal temperature EXT0. The second control unit 180 has a differentiator 181 and a proportional integrator 185.

[0085] The difference calculator 181 receives the target internal temperature EXT0 of the condenser 20 from a setting device 190. The setting device 190 allows manual input of the target temperature EXT0.

[0086] The difference calculator 181 also receives an input of the internal temperature EXT of the condenser 20 measured by the internal thermometer 21. The difference calculator 181 subtracts the target internal temperature EXT0 from the internal temperature EXT measured by the internal thermometer 21 to calculate the deviation of the internal temperature EXT of the condenser 20 from the target temperature EXT0.

[0087] The proportional integrator 185 calculates a rotation speed command value P rpm based on the proportional component and cumulative component of the deviation output from the difference calculator 181 , and outputs it to the VVVF 47 of the cooling water pump 45 .

[0088] As a result, the rotation speed of the motor 46 of the cooling water pump 45 is controlled by the VVVF 47 to the rotation speed command value P rpm, so that the internal temperature EXT of the condenser 20 can be made to coincide with the target internal temperature EXT0.

[0089] The second control unit 180 is not limited to a case where the internal temperature EXT of the condenser 20 is feedback-controlled to the target internal temperature EXT0, but may be configured to feedback-control the internal pressure (absolute pressure) of the condenser 20 to the target internal pressure.

[0090] 2. Calculation principle of wet bulb temperature (WBT) Figure 8 is a graph showing the relationship between the relative humidity x and the wet-dry temperature difference ΔTa relative to the dry-bulb temperature Ta, with the horizontal axis representing the relative humidity x [%] and the vertical axis representing the wet-dry temperature difference ΔTab [°C]. The wet-dry temperature difference ΔTa is the value obtained by subtracting the wet-bulb temperature WBT from the dry-bulb temperature Ta.

[0091] ΔTa = Ta - WBT (12)

[0092] 8 are approximate lines that show the relationship between the relative humidity x and the wet / dry temperature difference ΔTa for dry-bulb temperatures of 5° C. to 35° C. Each of the approximate lines L1 to L7 can be expressed by the following linear approximation formula.

[0093] ΔTa=Px+Q (13) P is the linear term of the approximate line L (the slope of the line), Q is the constant term of the approximate line, and x is the relative humidity.

[0094] Figure 9 is a chart summarizing the linear term P and constant term Q of the linear approximation equation ΔTa for each dry-bulb temperature Ta. The linear term P is a negative value, and its magnitude (absolute value) increases as the dry-bulb temperature increases. The constant term Q is a positive value, and its magnitude (absolute value) decreases as the dry-bulb temperature increases.

[0095] From equations (12) and (13), the wet-bulb temperature WBT can be calculated using the following equation (14).

[0096] WBT=Ta-ΔTa=Ta-(Px+Q)...(14)

[0097] The wet-bulb temperature calculation unit 120 calculates the atmospheric wet-bulb temperature WBT from the atmospheric dry-bulb temperature Ta and relative humidity x based on equation (14). The data for "P" and "Q" may be stored in a memory or the like, and the value corresponding to the dry-bulb temperature Ta may be read and used, or the data may be calculated from the dry-bulb temperature Ta. The calculation method can be the method disclosed in JP 2020-134230 A. Note that the wet-bulb temperature WBT may be calculated using the value measured by a wet-bulb thermometer.

[0098] 3.Effectiveness In this configuration, the rotation speed of the cooling tower fan 41 is controlled using the cooling index ΔTq, which changes depending on the atmospheric conditions, making it possible to operate the cooling tower 31 according to its cooling capacity, thereby reducing the energy consumption of the cooling tower fan 41.

[0099] In this configuration, the rotation speed of the cooling tower fan 41 is corrected in accordance with fluctuations in the generator output kW, allowing operation in accordance with the generator output kW. This further reduces the energy consumption of the cooling tower fan 41, making the cooling water system equipment 30A more energy-efficient.

[0100] <Embodiment 2> In the first embodiment, an example is shown in which the cooling water system equipment 30A is used to cool steam discharged from the steam turbine 10 to the condenser 20. In the second embodiment, a case in which the cooling water system equipment 30B is used for an application other than the condenser 20 will be described.

[0101] When using cooling water system equipment for purposes other than the condenser 20 (cooling steam), it is necessary to select a feedback control target to replace the condenser internal temperature. Possible feedback control targets are the "cooling tower outlet cooling water temperature LWT" and the "cooling tower inlet cooling water temperature HWT," so a study was conducted to determine which is more suitable from the perspective of energy conservation.

[0102] The cooling tower design conditions are as shown in Figure 10. The power reduction effect was estimated using the cooling tower design conditions as the reference value. The control target was the cooling tower fan rotation speed. The calculations were performed using HWT and LWT as feedback control targets. Hereafter, the controlled HWT will be referred to as "HWT control" and the controlled LWT will be referred to as "LWT control." The control setting value (reference value) was HWT0 for HWT control and LWT0 for LWT control. Both controls were compared when the heat load QL fluctuated.

[0103] Figure 11 is a graph of the fan rotation speed, Figure 12 is a graph of the fan power, and Figure 13 is a graph showing the difference in fan power between HWT control and LWT control. The horizontal axis is the wet-bulb temperature.

[0104] In this calculation, in order to confirm the effect of fluctuations in the heat load QL, the temperature difference ΔT, which corresponds to the heat load QL, is changed in 1°C increments over a range of 5 to 10°C. ΔT = HWT - LWT.

[0105] When ΔT was lower than the reference value of 8°C, the fan speed and power were lower under HWT control than under LWT control. This can be attributed to the fact that the cooling index ΔTq is larger under HWT control than under LWT control, as shown in Figure 14.

[0106] When ΔT was the reference value of 8°C, the fan speed and power were the same for HWT control and LWT control.

[0107] When ΔT was higher than the reference value of 8°C, HWT control resulted in higher fan speed and power than LWT control. This is because as ΔT increased, HWT became higher than HWT0, and the cooling index ΔTq increased more than HWT control.

[0108] As shown in Figure 13, the difference in fan power between HWT control and LWT control becomes more negative as ΔT, which corresponds to the thermal load QL, becomes smaller, and furthermore, the higher the wet-bulb temperature becomes, the more negative it becomes.

[0109] Generally, the design conditions (reference values) of the cooling tower 31 are set to the case where the heat load QL is the largest, and in this embodiment, the same setting conditions (QL0 = maximum heat load) are used. Therefore, HWT control has a greater power reduction effect. Therefore, in this embodiment, the feedback control target is the HWT, that is, the cooling tower inlet cooling water temperature (return cooling water temperature).

[0110] Depending on the heat load QL, it may be necessary to keep the cooling water temperature at the heat exchanger inlet constant. When using this technology for such an application, it is also possible to set the feedback control target as LWT, i.e., the cooling tower outlet cooling water temperature (cooling water temperature).

[0111] FIG. 15 is a system configuration diagram of the cooling water system equipment 30B, and FIG.

[0112] The cooling water system equipment 30B includes a cooling tower 31, an outward pipe 32, an inward pipe 33, and two auxiliary machines, a cooling tower fan 41 and a cooling water pump 45.

[0113] The VVVF 43 is for controlling the cooling tower fan 41, and the VVVF 47 is for controlling the cooling water pump 45.

[0114] 15, an outgoing pipe 32 and a return pipe 33 are connected to the heat exchanger 500, and cooling water supplied from the cooling tower 31 exchanges heat with a counter fluid (object to be cooled) in the heat exchanger 500, thereby cooling the counter fluid. The cooling water returning from the heat exchanger 500 exchanges heat with the atmosphere in the cooling tower 31, and a part of the water is evaporated, thereby being cooled.

[0115] The cooling water system equipment 30B is provided with instruments such as an atmospheric thermometer 51, a relative hygrometer 52, a water thermometer 53, and a water thermometer 54. The atmospheric thermometer 51 is a dry-bulb thermometer that measures the dry-bulb temperature Ta of the atmosphere around the cooling tower, and the relative hygrometer 52 measures the relative humidity x around the cooling tower.

[0116] The water thermometer 53 is located at the outlet of the cooling tower 31 in the outflow pipe 32 and measures the cooling tower outlet cooling water temperature LWT.

[0117] The water thermometer 54 is located at the inlet portion of the return pipe 33 to the cooling tower 31, and measures the cooling tower inlet cooling water temperature HWT. The measured values ​​of these meters 51 to 54 are input to the control device 200, which will be described below.

[0118] As shown in FIG. 16, the control device 200 includes a first control unit 210 and a second control unit 280.

[0119] The first control unit 210 controls the rotation speed F rpm of the cooling tower fan 41 based on the cooling capacity of the cooling tower 31 by a program.

[0120] The first control unit 210 includes a wet-bulb temperature calculation unit 220 , a first calculation unit 230 , a second calculation unit 240 , and a first correction unit 250 .

[0121] The wet-bulb temperature calculation unit 220 calculates the atmospheric wet-bulb temperature WBT from the atmospheric dry-bulb temperature Ta and the relative humidity x.

[0122] As shown in equation (8), the first calculation unit 230 subtracts the atmospheric wet-bulb temperature WBT from the cooling tower inlet cooling water temperature HWT to calculate a cooling index ΔTq that represents the cooling capacity of the cooling tower 31. The first calculation unit 230 can be configured, for example, by a differentiator.

[0123] In this embodiment, since the HWT is feedback controlled, the actual measured value of the HWT is not used, but a target value HWT0 is used.

[0124] The second calculation unit 240 holds a program for calculating a rotation speed command value Frpm_0 of the cooling tower fan 41, and determines the rotation speed command value Frpm_0 of the cooling tower fan 41 from the cooling index ΔTq calculated by the first calculation unit 230. Frpm_0 is a rotation speed command value (optimum value) corresponding to the cooling index ΔTq at the heat load QL0.

[0125] The first corrector 250 corrects the rotation speed command value Frpm_0 determined by the second calculator 240 in accordance with fluctuations in the thermal load QL.

[0126] As already explained, the heat load QL can be expressed as the product of the "cooling tower inlet / outlet cooling water temperature difference ΔT" and the "cooling water flow rate F." QL=ΔT×F

[0127] When the rotation speed of the cooling water pump 45 is variable, the cooling water flow rate F changes in conjunction with the rotation speed Prpm of the cooling water pump 45. Therefore, in this embodiment, the rotation speed command value Frpm_0 of the cooling tower fan 41 is corrected in accordance with the fluctuation of "ΔT×Prpm". The cooling water flow rate F may be a value measured by a water meter instead of the rotation speed Prpm of the cooling water pump 45.

[0128] The first correction unit 250 includes a differentiator 251 , a multiplier 253 , a divider 255 , a signal generator 256 , a root calculator 257 , and a multiplier 259 .

[0129] The difference calculator 251 receives the cooling tower inlet cooling water temperature HWT measured by the water thermometer 54 and the cooling tower outlet cooling water temperature LWT measured by the water thermometer 53 as input.

[0130] The differentiator 251 subtracts the cooling tower outlet cooling water temperature LWT from the cooling tower inlet cooling water temperature HWT to calculate the cooling tower inlet / outlet cooling water temperature difference ΔT.

[0131] ΔT = HWT - LWT (15)

[0132] A multiplier 253 calculates the product of the cooling water temperature difference ΔT at the cooling tower inlet / outlet and the rotation speed command value Prpm of the cooling water pump 45, and outputs the product to a divider 255. Furthermore, a signal generator 256 outputs the product of a reference value ΔT0 and a reference value Prpm0 to the divider 255. ΔT0 is the temperature difference ΔT (reference value) at the thermal load QL0, and Prpm0 is the rotation speed command value Prpm (reference value) of the cooling water pump 45 at the thermal load QL0.

[0133] The divider 255 calculates the heat load correction coefficient kq from the following equation (16) based on the input value ΔT×Prpm of the multiplier 253 and the input value ΔT0×Prpm0 of the signal generator 356.

[0134] kq=ΔT×Prpm / (ΔT0×Prpm0) (16)

[0135] A root calculator 257 calculates the square root K of the heat load correction coefficient kq. K = √kq (17)

[0136] The multiplier 259 multiplies the rotation speed command value Frpm_0 determined by the second calculation unit 240 by the square root K of the heat load correction coefficient kq, and outputs the result to the VVVF 43.

[0137] Frpm_1=Frpm_0×K (18) Frpm_1 is the corrected rotation speed command value of the cooling tower fan.

[0138] As a result, the rotation speed of the motor of the cooling tower fan 41 is controlled by the VVVF 43 to the rotation speed command value Frpm_1.

[0139] The first correction unit 250 performs the correction in real time.

[0140] The second control unit 280 feedback controls the rotation speed P rpm of the cooling water pump 45 so that the cooling tower inlet cooling water temperature HWT coincides with the target temperature HWT0. The second control unit 280 has a differentiator 281 and a proportional integrator 285.

[0141] The difference calculator 281 receives a target temperature HWT0 of the cooling tower inlet cooling water temperature HWT from a setting device 290. The setting device 290 allows manual input of the target temperature HWT0.

[0142] The difference calculator 281 also receives as input the measured value of the cooling tower inlet cooling water temperature HWT measured by the water thermometer 54. The difference calculator 281 subtracts the target temperature HWT0 from the cooling tower inlet cooling water temperature HWT to calculate the deviation of the cooling tower inlet cooling water temperature HWT from the target temperature HWT0.

[0143] The proportional integrator 285 determines a rotation speed command value P rpm from the proportional component and cumulative component of the deviation output from the difference calculator 281 , and outputs it to the VVVF 47 .

[0144] As a result, the rotation speed of the motor of the cooling water pump 45 is controlled by the VVVF 47 to the rotation speed command value P rpm, so that the cooling tower inlet cooling water temperature HWT can be made to coincide with the target temperature HWT0.

[0145] In this embodiment, the rotation speed of the cooling tower fan 41 is corrected in accordance with fluctuations in the heat load QL, thereby enabling operation (fan rotation speed control) in accordance with the heat load QL. This allows for further reduction in the energy consumption of the cooling tower fan 41, thereby enabling energy conservation in the cooling water system equipment 30B.

[0146] In addition, in this embodiment, since the cooling tower inlet cooling water temperature HWT is the feedback target, the energy consumption of the cooling tower fan 41 can be reduced under the condition that the heat load QL is equal to or less than QL0 (maximum heat load), compared to when the cooling tower outlet cooling water temperature LWT is the feedback target. Therefore, the cooling water system equipment 30B can be made even more energy-efficient.

[0147] <Embodiment 3> In the second embodiment, a case has been described in which the rotation speeds of the cooling tower fan 41 and the cooling water pump 45 are controlled. In the third embodiment, a case in which only the rotation speed F rpm of the cooling tower fan 41 is controlled for the cooling tower alone will be described.

[0148] FIG. 17 is a system configuration diagram of the cooling water system equipment 30C, and FIG.

[0149] The cooling water system equipment 30C includes a cooling tower 31, an outflow pipe 32, a return pipe 33, and two auxiliary machines, a cooling tower fan 41 and a cooling water pump 45.

[0150] As shown in Figure 17, an outbound pipe 32 and a return pipe 33 are connected to the heat exchanger 500, and the cooling water supplied from the cooling tower 31 exchanges heat with the opposing fluid in the heat exchanger 500, thereby cooling the opposing fluid.

[0151] The cooling water system equipment 30C is also provided with an air temperature gauge 51, a relative humidity gauge 52, a water temperature gauge 53, a water temperature gauge 54, and a water level gauge 55 as instruments.

[0152] The water meter 55 is located in the outbound pipe 32 and measures the amount of cooling water supplied from the cooling tower 31 to the heat exchanger 500. The measured values ​​of these meters 51 to 55 are input to the control device 300, which will be described below.

[0153] The control device 300 programmatically controls the rotation speed F rpm of the cooling tower fan 41 based on the cooling capacity of the cooling tower 31.

[0154] As shown in FIG. 18, the control device 300 includes a wet-bulb temperature calculation unit 320, a first calculation unit 330, a second calculation unit 340, a first correction unit 350, and a second correction unit 360.

[0155] The wet-bulb temperature calculation unit 320 calculates the atmospheric wet-bulb temperature WBT from the atmospheric dry-bulb temperature Ta and the relative humidity x.

[0156] As shown in equation (8), the first calculation unit 330 subtracts the atmospheric wet-bulb temperature WBT from the cooling tower inlet cooling water temperature HWT to calculate a cooling index ΔTq that represents the cooling capacity of the cooling tower 31. The first calculation unit 330 can be configured, for example, by a differentiator.

[0157] The second calculation unit 340 holds a program for calculating a rotation speed command value Frpm_0 of the cooling tower fan 41, and determines the rotation speed command value Frpm_0 of the cooling tower fan 41 from the cooling index ΔTq. Frpm_0 is the rotation speed command value (optimum value) corresponding to the cooling index ΔTq at the heat load QL0.

[0158] The first correction unit 350 corrects the rotation speed command value Frpm_0 calculated by the second calculation unit 340 in accordance with fluctuations in the thermal load QL. The first correction unit 350 includes a difference calculator 351, a multiplier 353, a divider 355, a signal generator 356, and a multiplier 359.

[0159] The difference calculator 351 receives the cooling tower inlet cooling water temperature HWT measured by the water thermometer 54 and the cooling tower outlet cooling water temperature LWT measured by the water thermometer 53 as inputs.

[0160] The differentiator 351 subtracts the cooling tower outlet cooling water temperature LWT from the cooling tower inlet cooling water temperature HWT to calculate the cooling tower inlet / outlet cooling water temperature difference ΔT.

[0161] Multiplier 353 calculates the product of the temperature difference ΔT calculated by differentiator 351 and the cooling water flow rate F measured by water meter 55, and outputs the product to divider 355. Signal generator 356 outputs the product of reference value ΔT0 and reference value F0 to divider 355. ΔT0 is the temperature difference ΔT (reference value) at thermal load QL0, and F0 is the cooling water flow rate F (reference value) at thermal load QL0.

[0162] The divider 355 calculates the heat load correction coefficient kq from the input value ΔT×F of the multiplier 353 and the input value ΔT0×F0 of the signal generator 356 using the following equation (19).

[0163] kq=ΔT×F / (ΔT0×F0) (19)

[0164] A multiplier 359 multiplies the rotation speed command value Frpm_0 of the cooling tower fan 41 by a heat load correction coefficient kq and outputs the result.

[0165] Frpm_1=Frpm_0×kq (20) Frpm_1 is the rotation speed command value of the cooling tower fan 41 after heat load correction.

[0166] The second correction unit 360 further corrects the corrected rotation speed command value Frpm_1 based on the deviation of the cooling tower inlet cooling water temperature HWT from the target temperature HWT0. The second correction unit 360 has a differentiator 361, a proportional integrator 365, and an adder 367.

[0167] The difference calculator 361 calculates the deviation of the cooling tower inlet cooling water temperature HWT from the target temperature HWT0, based on the cooling tower inlet cooling water temperature HWT and its target temperature HWT0. The target temperature HWT0 uses the set value of the setter 290, and the cooling tower inlet cooling water temperature HWT uses the measured value of the water thermometer 54. The setter 290 allows manual input of the target temperature HWT0.

[0168] The proportional integrator 365 calculates a correction amount ΔF for the rotation speed command value Frpm_ 1 of the cooling tower fan 41 based on the proportional component and cumulative component of the deviation output by the multiplier 361 .

[0169] An adder 367 adds a correction amount ΔF to the rotation speed command value Frpm_1 to generate a rotation speed command value Frpm_2, and outputs the generated rotation speed command value Frpm_2 to the VVVF 43. Frpm_2=Frpm_1+ΔF (21)

[0170] As a result, the motor of the cooling tower fan 41 is controlled to a rotation speed command value Frpm_2, which is obtained by correcting the rotation speed command value Frpm_0 calculated from the cooling index ΔTq by the "fluctuation in the thermal load QL" and the "deviation in the HWT".

[0171] As a result, the rotation speed Frpm of the cooling tower fan 41 can be changed in accordance with fluctuations in the heat load QL, while performing feedback control so that the cooling tower inlet cooling water temperature HWT coincides with the target temperature HWT0.

[0172] <Embodiment 4> In the third embodiment, the thermal load QL was calculated based on the "cooling tower inlet / outlet cooling water temperature difference ΔT" and the "cooling water flow rate F." Then, the thermal load QL was compared with the reference value QL0 to calculate the thermal load correction coefficient kq.

[0173] QL=ΔT×F kq=QL / QL0 QL0 is the maximum heat load (reference value of heat load QL).

[0174] If the cooling water flow rate F can be considered to be almost constant, such as if the rotation speed P rpm of the cooling water pump 45 is constant, the heat load correction coefficient kq can be calculated from only the cooling tower inlet / outlet cooling water temperature difference ΔT.

[0175] kq=ΔT / ΔT0 (22) ΔT0 is the temperature difference (reference value of ΔT) at QL0.

[0176] 19 is a block diagram of a control device 400 that controls the cooling tower fan 41. The control device 400 includes a wet-bulb temperature calculation unit 320, a first calculation unit 330, a second calculation unit 340, a first correction unit 450, and a second correction unit 360, and differs from the control device 300 only in the first correction unit 450.

[0177] The first correction unit 450 includes a differentiator 451 , a divider 455 , a signal generator 456 , and a multiplier 459 .

[0178] The difference calculator 451 receives the cooling tower inlet cooling water temperature HWT measured by the water thermometer 54 and the cooling tower outlet cooling water temperature LWT measured by the water thermometer 53. The difference calculator 451 subtracts the cooling tower outlet cooling water temperature LWT from the cooling tower inlet cooling water temperature HWT to calculate the cooling tower inlet / outlet cooling water temperature difference ΔT.

[0179] The differentiator 451 outputs the calculated temperature difference ΔT to the divider 455. The signal generator 456 outputs the reference value ΔT0 to the divider 455.

[0180] The divider 455 calculates the heat load correction coefficient kq from the above equation (22) based on the "input value ΔT of the differentiator 451" and the "input value ΔT0 of the signal generator 456."

[0181] A multiplier 459 multiplies the rotation speed command value Frpm_0 of the cooling tower fan 41 determined by the second calculation unit 340 by the heat load correction coefficient kq to calculate a rotation speed command value Frpm_1.

[0182] In this configuration, the first corrector 450 can be simplified compared to the third embodiment. Also, the water meter 55 can be omitted.

[0183] <Other embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included within the technical scope of the present invention.

[0184] (1) In the first embodiment, the rotation speed of the cooling tower fan 41 is program-controlled in accordance with the cooling index ΔTq of the cooling tower 31, and the rotation speed of the cooling water pump 45 is feedback-controlled. The rotation speed of the cooling tower fan 41 may be feedback-controlled, and the rotation speed of the cooling water pump 45 may be program-controlled in accordance with the cooling index ΔTq of the cooling tower 31. The same applies to the second embodiment.

[0185] Furthermore, the feedback control may be a cascade type control, as long as it controls the auxiliary so as to reduce the deviation from the control target value.

[0186] (2) In the second embodiment, the cooling tower inlet cooling water temperature HWT is selected as the control object, and the rotation speed of the cooling water pump 45 is feedback-controlled. The cooling tower outlet cooling water temperature LWT may be selected as the control object, and the rotation speed of the cooling water pump 45 may be feedback-controlled. The same applies to the case where the rotation speed of the cooling tower fan 41 is feedback-controlled (third embodiment).

[0187] (3) In the first embodiment, the cooling index ΔTq of the cooling tower 31 is expressed using the temperature difference HWT-WBT between the cooling tower inlet cooling water temperature HWT and the atmospheric wet-bulb temperature WBT. The cooling index ΔTq of the cooling tower 31 may be determined by a method other than the temperature difference between the two temperatures HWT and WBT, as long as it is determined based on the cooling tower inlet cooling water temperature HWT and the atmospheric wet-bulb temperature WBT.

[0188] 30A, 30B, 30C cooling water system equipment 31 Cooling Tower 32 Outgoing pipe 33 Return Pipe 41 Cooling tower fan 45 Cooling water pump 100, 200, 300, 400 control device 110, 210 First control section 130, 230, 330 1st calculation section 140, 240, 340 2nd calculation section 150, 250, 350, 450 First correction section 360 Second Correction Section 180, 280 Second control section

Claims

1. A control device for cooling water system equipment, The cooling water system equipment includes: a cooling water pump that circulates cooling water against the heat load; a cooling tower having a cooling tower fan for dissipating heat, which cools return cooling water returning through a return pipe by heat exchange with the atmosphere and supplies the cooled return cooling water to the heat load through a forward pipe; The control device a first control unit that controls one of the cooling tower fan and the cooling water pump; The first control unit a first calculation unit that calculates a cooling index indicating the cooling capacity of the cooling tower based on a wet-bulb temperature of the atmosphere and a cooling water temperature at an inlet of the cooling tower; a second calculation unit that determines a rotation speed command value of the one auxiliary machine based on the cooling index; a first correction unit that corrects the rotation speed command value of the one auxiliary machine in accordance with a fluctuation in a thermal load, The first correction unit calculates a ratio of the magnitude of the thermal load to a reference value as a thermal load correction coefficient, and corrects the rotation speed command value based on the thermal load correction coefficient.

2. A control device for cooling water system equipment, The cooling water system equipment includes: a cooling water pump that circulates cooling water against the heat load; a cooling tower having a cooling tower fan for dissipating heat, which cools return cooling water returning through a return pipe by heat exchange with the atmosphere and supplies the cooled return cooling water to the heat load through a forward pipe; The control device a first control unit that controls one of the cooling tower fan and the cooling water pump; The first control unit a first calculation unit that calculates a cooling index indicating the cooling capacity of the cooling tower based on a wet-bulb temperature of the atmosphere and a cooling water temperature at an inlet of the cooling tower; a second calculation unit that determines a rotation speed command value of the one auxiliary machine based on the cooling index; The cooling tower fan is a cooling tower cooling system that is capable of controlling the cooling water temperature in accordance with a target temperature. The first correction unit calculates a ratio of the magnitude of the thermal load to a reference value as a thermal load correction coefficient, and corrects the rotation speed command value by multiplying the square root of the thermal load correction coefficient.

3. A control device for cooling water system equipment according to claim 2, The heat load is It is steam exhausted to the condenser from the steam turbine that drives the generator. The first correction unit estimates fluctuations in the thermal load using the amount of power generated by the generator.

4. A control device for a cooling water system facility according to claim 2, a control target of the first control unit is the cooling tower fan; When the rotation speed of the cooling water pump is variable, The first correction unit estimates the fluctuation of the heat load using the product of the cooling water temperature difference between the inlet and outlet of the cooling tower and the rotation speed of the cooling water pump.

5. A control device for a cooling water system facility according to claim 1, a control target of the first control unit is the cooling tower fan; When the rotation speed of the cooling water pump is constant, The first correction unit estimates the fluctuation of the heat load using a cooling water temperature difference between an inlet and an outlet of a cooling tower.

6. A cooling water system facility for cooling a heat load, a cooling water pump that circulates cooling water against the heat load; a cooling tower having a cooling tower fan for dissipating heat, which cools return cooling water returning through a return pipe by heat exchange with the atmosphere and supplies the cooled return cooling water to the heat load through a forward pipe; A cooling water system facility comprising the control device according to any one of claims 1 to 5.

7. A control device for a cooling tower that supplies cooling water to a heat load, comprising: the cooling tower has a cooling tower fan that dissipates heat, and cools the return cooling water returning through the return pipe by heat exchange with the atmosphere, and supplies the cooled water to the heat load through the outward pipe; The control device a first calculation unit that calculates a cooling index indicating the cooling capacity of the cooling tower based on a wet-bulb temperature of the atmosphere and a cooling water temperature at an inlet of the cooling tower; a second calculation unit that determines a rotation speed command value of the cooling tower fan based on the cooling index; a first correction unit that corrects a rotation speed command value of the cooling tower fan in accordance with a fluctuation in a heat load, The first correction unit calculates a ratio of the magnitude of the thermal load to a reference value as a thermal load correction coefficient, and corrects the rotation speed command value based on the thermal load correction coefficient.

8. A control device for a cooling tower according to claim 7, The cooling tower control device, wherein the first correction unit calculates the heat load correction coefficient using a cooling water temperature difference between an inlet and an outlet of the cooling tower.

9. A control device for a cooling tower according to claim 7 or claim 8, a second correction unit that corrects the rotation speed command value after correction by the first correction unit based on a deviation of a cooling tower inlet cooling water temperature from a target temperature.

10. a cooling tower fan to dissipate heat; A cooling tower comprising: the control device according to any one of claims 7 to 9.

Images