JP2001108394A - Cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an efficient operation of a cooling tower and cool it under energy saving without heating within the cooling tower even if a heat exchanging efficiency of the cooling tower is changed under various kinds of factors. SOLUTION: There is provided a cooling device comprising a cooling tower having a heat transfer pipe and a fan, a chiller, a bypass pipe passage for feeding cooled fluid returning from equipment to be cooled to equipment in sequence from the cooling tower to be chiller; and a changing-over means for changing-over the pipe passage passing through the cooling tower. In the case that an inlet temperature of the cooling tower is lower than an outlet temperature of the cooling tower, the pipe passage passing through the cooling tower is closed, the bypass pipe passage is opened and operation is carried out only with the chiller. A value in which a surrounding air dry bulb or a wet bulb temperature is subtracted from the inlet temperature of the cooling tower at the time of changing-over operation is stored in a memory, only the chiller is operated. When either the surrounding air dry bulb or the wet bulb temperature subtracted from the inlet temperature of the cooling tower is larger than that of changing-over operation, controlling operation is carried out such that the pipe passage passing through the cooling tower is opened and the bypass pipe passage is closed, and the cooling tower and the chiller are operated to perform cooling operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for cooling a fluid to be cooled returning from a device to be cooled, and then sending the cooled fluid to the device to be cooled. The present invention relates to a cooling device that prevents the above.

[0002]

2. Description of the Related Art Conventionally, a cooling tower having a heat transfer pipe and a fan for blowing the heat transfer pipe, a compressor and a condenser as a cooling device capable of maintaining a constant temperature in a medium to low temperature range of about 18 to 29 ° C. And a chiller having an expansion valve, an evaporator, and a refrigerant circulating through the chiller, and a pipe for guiding the fluid to be cooled returning from the equipment to be cooled to the cooling tower and the evaporator, and then sending the fluid to the equipment. A cooling device has been proposed in Japanese Utility Model Laid-Open No. 61-84480.

The above-mentioned cooling device is a cooling device capable of maintaining a constant temperature in a medium to low temperature range of about 18 to 29 ° C. and preventing unnecessary supercooling. When the temperature of the fluid to be cooled entering the cooling tower is lower than the outside air dry bulb temperature, or when the cooling tower is an evaporative cooling tower, the temperature of the fluid to be cooled entering the cooling tower is lower than the outside air wet bulb temperature Sometimes the fluid to be cooled is heated in the cooling tower instead of being cooled when passing through the cooling tower, and the cooling in the chiller must be unnecessarily large, and the efficiency of the entire cooling device deteriorates I was letting it.

To solve this problem, Japanese Patent Application Laid-Open No. 2-197780 discloses a method of comparing the temperature of the fluid to be cooled entering the cooling tower with the temperature of the dry air bulb when the cooling tower is an air-cooled cooling tower. When using an evaporative cooling tower as a tower, compare the temperature of the fluid to be cooled entering the cooling tower with the outside air wet bulb temperature and cool through the cooling tower with the cooling tower and chiller, or bypass the cooling tower It has been proposed to control whether to cool only with a chiller.

[0005]

Normally, the cooling capacity of an air-cooled cooling tower and an evaporative cooling tower varies under various conditions even when the outside air dry bulb temperature or wet bulb temperature is the same. For example, when the amount of water to be sent to the load side to be cooled decreases, the outlet water temperature after exiting the cooling tower becomes higher than the dry water temperature compared to when the amount of water is large.
It is cooled to B or near the wet bulb temperature WB. In the case of the prior art, for example, when the amount of water is reduced in the case of an evaporative cooling tower, even though the outlet water temperature cooled by the cooling tower is low and the cooling tower still has the ability to cool, the control enters the cooling tower. Since the control is performed by comparing the inlet temperature of the fluid to be cooled and the outside air wet bulb temperature, when the difference between the inlet temperature and the outside air wet bulb temperature reaches a predetermined value, the operation is switched to the bypass operation and the cooling tower is not cooled, The operation is switched to the cooling operation control that cools only the chiller that consumes more power.

On the other hand, for example, in the case of an evaporative cooling tower, if the heat transfer coil in the cooling tower is contaminated, or if the amount of water sprayed on the heat transfer coil is too small to properly spray water on the heat transfer coil, the cooling tower may be damaged. The heat transfer coil in the inside becomes a combination of the cooling action by water spray and the cooling action by air cooling. In this case, in the prior art, the temperature is controlled by comparing the inlet temperature of water entering the cooling tower with the outside air wet bulb temperature.
At 8 ° C, the inlet water temperature is higher than this, and even if it is judged that cooling can still be performed by the cooling tower and the air is controlled to pass through the cooling tower, the outside air dry bulb temperature is usually higher than the wet bulb temperature, In many cases, the bulb temperature is higher than the inlet water temperature, so in this case, it is heated by passing through the cooling tower, and the cooling load in the chiller, which consumes a large amount of power after passing through the cooling tower, is increased. Result.

[0007] The present invention solves the above-mentioned problems, and even if the heat exchange efficiency of the cooling tower changes due to various influences, the cooling tower is efficiently operated without being heated in the cooling tower, and cooling is performed with energy saving. It is an object of the present invention to provide a cooling device that can be used.

[0008]

SUMMARY OF THE INVENTION The gist of the present invention is to circulate a cooling tower having a heat transfer pipe and a fan for blowing the heat transfer pipe, a compressor, a condenser, an expansion valve, and an evaporator. A chiller having a refrigerant, and a pipe to send a fluid to be cooled returning from a device to be cooled from the cooling tower to the evaporator in the order of the evaporator, and then to the device, and a bypass pipe that bypasses the cooling tower. In the cooling device provided with a switching means for switching between the bypass pipe and the pipe passing through the cooling tower, the cooling tower inlet temperature T1 of the cooling target fluid returning from the device to the cooling apparatus is lower than the cooling tower outlet temperature T2. At this time, the switching means is controlled so that the pipe passing through the cooling tower is closed and the bypass pipe is opened, and only the chiller is operated. Reduce DB When the value ΔTa is stored and only the chiller is operated, and the value ΔTb obtained by subtracting the outside air dry-bulb temperature DB from the cooling tower inlet temperature T1 becomes larger than the ΔTa, a pipe passing through the cooling tower is used. A cooling device characterized by operating the cooling tower and the chiller by controlling the switching means so as to open the path and close the bypass pipe, and thereafter repeats the above control.

Further, a cooling tower having a heat transfer pipe and a water spray mechanism for spraying water to the heat transfer pipe, a chiller having a compressor, a condenser, an expansion valve, an evaporator, and a refrigerant circulating therethrough, A conduit for guiding the fluid to be cooled returning from the device to be cooled to the cooling tower and the evaporator in this order, and then sending the fluid to the device; a bypass pipeline bypassing the cooling tower; and a bypass pipeline and the cooling tower. In the cooling device provided with a switching means for switching to a pipe passing through the cooling tower, when the cooling tower inlet temperature T1 of the fluid to be cooled returning from the device to the cooling device is lower than the cooling tower outlet temperature T2, the pipe passing through the cooling tower The switching means is controlled so that the path is closed and the bypass pipe is opened, and only the chiller is operated, and a value ΔTa obtained by subtracting the outside air wet bulb temperature WB from the cooling tower inlet temperature T1 at the time of the switching.
Is operated only with the chiller, and the value ΔT obtained by subtracting the outside air wet bulb temperature WB from the cooling tower inlet temperature T1 is ΔT.
When b becomes larger than ΔTa, the switching means is controlled to operate the cooling tower and the chiller so that the pipe passing through the cooling tower is opened and the bypass pipe is closed, and thereafter the aforementioned A cooling device characterized by repeating control. In the above, the condenser of the chiller can be a cooling device for cooling by a cooling tower.

[0010]

According to the present invention, there is provided a cooling tower according to the present invention, wherein the temperature of the cooling water entering the cooling tower is directly compared with the temperature of the cooling water exiting the cooling tower. Since the control is performed by judging whether to perform the bypass operation for bypassing the tower, the control is correctly performed irrespective of the cooling efficiency, the cooling capacity, and the like due to various requirements of the cooling tower. In addition, when the cooling tower outlet temperature becomes higher than the cooling tower inlet temperature and is switched to a bypass operation that bypasses the cooling tower, the cooling tower inlet temperature—the outside air dry-bulb temperature (in the case of an air-cooled cooling tower), or the inlet temperature—
The outside air wet bulb temperature (in the case of the evaporative cooling tower) = ΔTa is stored, and from this ΔTa, the cooling tower entrance temperature during operation—the outside air dry bulb temperature (air cooling type) or the entrance temperature—the outside air wet bulb temperature When (evaporation type) = ΔTb becomes large, the bypass operation is released again to guide the cooling tower to the cooling tower, and the cooling is performed by the cooling tower and the chiller. For this reason, in both the air-cooled cooling tower and the evaporative cooling tower, ΔTa at the time of switching to the bypass operation and ΔTb during the bypass operation are compared, and when ΔTa <ΔTb, it is led to the cooling tower again. From
It is controlled so that the cooling tower is guided to the cooling tower exactly when the cooling tower can be cooled, and the bypass operation is performed when the cooling tower cannot be cooled. Therefore, the cooling is not performed in the cooling tower, the cooling is performed with a minimum load for cooling by the chiller, and the cooling can be performed with energy saving. In the above condition, when the difference ΔTb during the bypass operation is larger than ΔTa at the time of switching to the bypass operation, a chattering phenomenon that repeats ON and OFF at the time of the switching operation occurs when the difference is 0 ° C. It is desirable to control under large conditions.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 are system diagrams of a cooling device showing an embodiment of the present invention. FIG. 1 shows a case where an air-cooled cooling tower is used as the cooling tower 1. The cooling tower 1 has a plurality of layers of heat transfer pipes 2 and a fan 3. The fan 3 driven by a motor 4 blows air taken in from an air suction port 5 to the heat transfer pipe 2 to blow the heat transfer pipe 2. Cool the water circulating inside. The chiller 10 has a compressor 11, a condenser 11, an expansion valve 13, and an evaporator 14. A refrigerant circulates through the chiller 10, the refrigerant is compressed in the compressor 11, and the condenser 1
The cycle of liquefying and radiating heat in 2 and evaporating and absorbing heat in the evaporator 14 through the expansion valve 13 is repeated.

On the other hand, the fluid to be cooled, for example, water returned from the equipment 20 to be cooled is supplied to the booster pump 21 and the first valve 2.
5, the heat transfer pipe 2 of the cooling tower 1, the evaporator 14, and the equipment 20 to be cooled finally through the circulation pump 22.
Sent out to A short circuit is provided between the upstream side of the first valve 25 and the upstream side of the evaporator 14, that is, the outlet side of the cooling tower 1 by a bypass pipe 28 having a bypass valve 27. Inlet water temperature detector 29 on the upstream side
However, an outlet water temperature detector 30 is mounted on the outlet side of the cooling tower. In the drawings, only one system is shown for the inflow / outflow piping to the cooling tower 1, the chiller 10, and the device 20, but all or a part of these may be configured by a plurality of systems. Further, the chiller 10 has one compressor 11, but may be a chiller 10 having a plurality of compressors 11.

Next, in FIG. 2, in addition to the heat transfer pipe 2 and the fan 3, the cooling tower 1 includes a watering header 6 provided above the heat transfer pipe 2 and a water receiving tank provided below the heat transfer pipe 2. 7 and
Watering pump 8 for supplying water in water receiving tank 7 to watering header 6
And the evaporative cooling tower 1 further provided with a watering mechanism having
An outside air wet bulb temperature detector 26 is used in place of the outside air dry bulb temperature detector. Further, the condenser 12 is provided in the cooling tower 1, and the entire apparatus is formed compact and the condenser 1 is formed.
2 efficiently dissipates heat. The condenser 12 shown in FIG.
May be provided separately from the cooling tower 1 as a water-cooled condenser in place of the air-cooled condenser in FIG. 1 so as to dissipate heat more efficiently.

In the above cooling device, the operation of the cooling tower 1 and the chiller 10 is performed when the temperature of the temperature detector 23 provided at the outlet of the evaporator 14 for the fluid to be cooled becomes higher than the set temperature range. When the amount of air blown by the fan 3 of the cooling tower 1 is increased and the temperature of the temperature detector 23 is still higher than the set temperature range, the compressor 11 of the chiller 10 is operated to operate the cooling tower 1 and the chiller 10 together. Cooling. In addition, the temperature detector 23
When the temperature of the chiller becomes lower than the set temperature range, the operation of the chiller 10 is first stopped, contrary to the above, and when the temperature of the chiller 10 is still lower than the set temperature range, control is performed so as to further reduce the air volume of the fan 3. I do.

According to the present embodiment, the control of leading to the cooling tower 1 or leading to the bypass bypassing the cooling tower 1 will be described with reference to FIG.
This will be described with reference to the flow of FIG. In the description, the outside air dry-bulb temperature DB is mainly used for the air-cooled cooling tower in FIG. 1, but the dry-bulb temperature in the air-cooled type is used for the evaporative cooling tower in FIG. 2. Since the same control can be performed by using the outside air wet bulb temperature WB instead of the DB, description will be made including the case of the air-cooled cooling tower and the case of the evaporative cooling tower. In this embodiment, in addition to detecting the inlet water temperature T1 to the cooling tower 1 by the cooling tower inlet water temperature detector 29, the outlet water temperature T2 exiting the cooling tower 1 by the cooling tower outlet water temperature detector 30, and the outside air dry bulb thermometer 3
0 indicates that the outside air temperature DB is constantly detected. As shown in steps S1 and S2 of the flow shown in FIG. 3, during the cooling tower operation in which the bypass operation is No, the inlet water temperature T1 and the outlet water temperature T2 are constantly compared. In step S2, the inlet water temperature T
When the outlet water temperature T2 becomes equal to or higher than 1 (when the cooling water is heated in the cooling tower in the summer, for example), the first valve 25 is closed so as to pass through the bypass pipe 28 shown in S3 and the bypass valve 2 is closed.
7 is opened. As a result, the fluid to be cooled is cooled only by the evaporator 14 by the chiller 10 without passing through the cooling tower 1. That is, the inlet water temperature T1 and the outlet water temperature T2 are directly compared to eliminate unnecessary heating caused by passing through the cooling tower 1 and unnecessary power loss caused by operating the cooling tower 1.

In S4, the inlet temperature T1—the dry bulb temperature D when the cooling tower operation is switched to the bypass operation.
B (outside air wet bulb temperature WB in the case of an evaporative cooling tower) = ΔTa
Is stored, and the bypass operation is continuously performed. During the bypass operation, the process moves from S4 to S1 and S5. During the bypass operation, whether the value of the inlet temperature T1 to the cooling tower 1-the open-air dry-bulb temperature DB (the open-air wet-bulb temperature WB in the case of the evaporative cooling tower) is always larger than the value of ΔTa + 2 ° C. stored in S4. If it is greater than ΔTa + 2 ° C., the bypass operation in S6 is released, the operation is switched to the operation leading to the cooling tower 1, and the process returns to S1. The above inlet temperature T1
The comparison of whether the dry-bulb temperature DB (WB) is greater than ΔTa + 2 ° C. indicates that the provision of ΔTa + 2 ° C. prevents a chattering phenomenon in which the switching to the cooling tower 1 and the bypass operation alternately occur. Therefore, in the present embodiment, Δ
T is increased by 2 ° C., and there is no practical problem, and the control is efficiently performed. By the control in step S5, the entrance temperature T1 during operation and the dry bulb temperature DB (wet bulb temperature WB) are compared with ΔTa when the operation is switched to the bypass operation.
When the condition that the cooling tower 1 can be cooled reliably is established, the operation is switched to the cooling tower, and the switching control between the accurate operation of the cooling tower and the cooling by only the chiller by the bypass operation is performed.

[0017]

As described above, the cooling device of the present invention has the following features.
Directly comparing the inlet temperature of the cooling water entering the cooling tower with the outlet temperature of the cooling water exiting the cooling tower, leading to the cooling tower,
Since the bypass operation for bypassing is controlled, the control is correctly performed irrespective of the cooling efficiency, the cooling capacity, etc. due to various requirements of the cooling tower. Further, when the cooling tower outlet temperature becomes higher than the cooling tower inlet temperature and the operation is switched to the bypass operation in which the cooling tower is bypassed, the cooling tower inlet temperature-the outside air dry-bulb temperature (in the case of the air-cooled cooling tower), or the inlet temperature-the outside air The wet-bulb temperature (in the case of the evaporative cooling tower) = ΔTa is stored, and from this ΔTa, the cooling tower inlet temperature during operation—the outside air dry-bulb temperature (air-cooled type) or the inlet temperature—the outside air wet-bulb temperature ( When the (evaporation type) = ΔTb becomes large, the bypass operation is released and guided to the cooling tower, and is cooled by the cooling tower and the chiller.
Since ΔTa at the time of switching to the bypass operation and ΔTb during the bypass operation are compared and controlled, the cooling operation is guided to the cooling tower when the cooling tower can reliably be cooled, and the bypass operation is performed when the cooling tower cannot be cooled. Is controlled.
Therefore, the cooling is not performed in the cooling tower, the cooling is performed with a minimum load for cooling by the chiller, and the cooling can be performed with energy saving.

[Brief description of the drawings]

FIG. 1 is a system diagram when an air-cooled cooling tower 1 according to an embodiment of the present invention is used.

FIG. 2 is a system diagram when an evaporative cooling tower 1 according to an embodiment of the present invention is used.

FIG. 3 is a control flow showing an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cooling tower 2 Heat transfer pipe 3 Fan 4 Motor 4 Air inlet 6 Watering header 7 Water receiving tank 8 Watering pump 10 Chiller 11 Compressor 12 Condenser 13 Expansion valve 14 Evaporator 21 Booster pump 22 Circulating pump 23 Cooling water temperature detector 24 Outside air dry bulb thermometer 25 First valve 26 Outside air wet bulb thermometer 27 Bypass valve 28 Bypass line 29 Cooling tower inlet water temperature detector 30 Cooling tower outlet water temperature detector

Claims (3)

[Claims] A cooling tower having a heat transfer pipe and a fan for blowing the heat transfer pipe, a chiller having a compressor, a condenser, an expansion valve, an evaporator, and a refrigerant circulating through the cooling tower; After guiding the fluid to be cooled returning from the device from the cooling tower in the order of the evaporator, a pipe for sending out to the device is provided,
In a cooling device provided with a bypass pipe bypassing the cooling tower, and switching means for switching between the bypass pipe and the pipe passing through the cooling tower, a cooling tower inlet temperature of a fluid to be cooled returning from the device to the cooling apparatus. When T1 is equal to or lower than the cooling tower outlet temperature T2,
The switching means is controlled so that the pipe passing through the cooling tower is closed and the bypass pipe is opened to cool only by the chiller, and the outside air dry bulb temperature DB is subtracted from the inlet temperature T1 of the cooling tower at the time of the switching. Is stored only in the chiller, and the cooling tower inlet temperature T1 is stored.
When the value ΔTb obtained by subtracting the outside air dry-bulb temperature DB from ΔTa becomes larger than the value ΔTa, the cooling means is controlled by controlling the switching means so as to open the pipe passing through the cooling tower and close the bypass pipe. And a chiller, and the above control is repeated thereafter. 2. A cooling tower having a heat transfer pipe and a water spray mechanism for spraying water on the heat transfer pipe; a chiller having a compressor, a condenser, an expansion valve, an evaporator, and a refrigerant circulating therethrough; A conduit for guiding the fluid to be cooled returning from the device to be cooled to the cooling tower and the evaporator in this order, and then sending the fluid to the device; a bypass pipeline bypassing the cooling tower; and a bypass pipeline and the cooling tower. A cooling device provided with a switching means for switching a pipe passing through the cooling tower when the cooling tower inlet temperature T1 of the fluid to be cooled returning from the device to the cooling device is lower than the cooling tower outlet temperature T2. Controlling the switching means so as to close the path and open the bypass line, and cool only with the chiller,
A value ΔTa obtained by subtracting the outside air wet bulb temperature WB from the cooling tower entrance temperature T1 at the time of the switching is stored, and cooling is performed only by the chiller, and the outside air wet bulb temperature WB is subtracted from the cooling tower entrance temperature T1. When the value ΔTb becomes larger than the ΔTa, the cooling tower and the chiller are operated by controlling the switching means so as to open the pipe passing through the cooling tower and close the bypass pipe, A cooling device characterized by repeating the above control. 3. The cooling device according to claim 1, wherein the condenser is cooled by the cooling tower.