JP3934024B2 - Operation method of open cooling tower during freezing and freezing cooling tower used for freezing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for operating an open cooling tower during freezing and freezing, and an open cooling tower used therefor.
[0002]
[Prior art]
Conventionally, when the cooling tower is operated when the temperature of the outdoor wet bulb at the place where the cooling tower is installed is below the freezing point, the inside and outer periphery of the cooling tower may freeze even during operation.
In the open cooling tower, the packed plates and louvers freeze, and in the closed cooling tower, the heat exchanger freezes. As a countermeasure, the cooling water having a predetermined outlet temperature is obtained by flowing a circulating cooling water containing an antifreeze liquid with a sealed type. (For example, see Patent Document 1 and Patent Document 2 published after the original application of the present application).
[0003]
[Patent Document 1]
Japanese Unexamined Patent Publication No. 2002-213898 (paragraphs [0004] to [0017])
[0004]
[Patent Document 2]
JP-A-4-270897 (paragraph [0011])
[0005]
In addition, when the type is an open type, a heater is attached to the air intake, but it is heated for cooling, which is contrary to energy saving and cost saving. The problem is particularly remarkable in a cooling tower that needs to be operated continuously for 24 hours.
On the other hand, as an aspect of the operation method of the cooling tower, for example, a free cooling method is adopted in which only the cooling tower is operated by stopping the operation of the refrigerator in the air conditioning equipment, and the cooling water cooled by the cooling tower is used for cooling. Has been. In this method, the temperature of the cooling water can be lowered as the outside wet bulb temperature is lowered.
In winter, the cooling tower is often operated when the temperature of the outside air wet bulb at the place where the cooling tower is installed is near freezing point. In extreme cold regions, it is also known that the cooling tower freezes even when the cooling water is flowing.
[0006]
[Problems to be solved by the invention]
With regard to the use of the above-mentioned hermetic cooling tower, the circulating cooling water into which the antifreezing liquid is injected does not come into direct contact with the external airflow, so there is no fear that the circulating cooling water is contaminated, but the cooling capacity is not sufficiently exhibited by the use of the antifreezing liquid. In addition, there is a fear that the hermetic cooling tower is an indirect cooling method, so that the heat exchange efficiency is lower than that of the open type and the initial cost is high. Further, it takes time and effort to inject the antifreeze liquid, and the maintenance cost and running cost increase. Therefore, a method for producing low-temperature cooling water using an open cooling tower with better heat exchange efficiency is desired.
[0007]
However, when the open-type cooling tower is operated when the temperature of the outside air wet bulb is below the freezing point, the cooling water begins to freeze on the corrugated packed plate that is an open-type heat exchanger. The air flow rate decreases and the outlet temperature of the cooling water tends to increase, which hinders the continuous operation of the open cooling tower and the desired cooling performance.
This invention can melt frozen ice without installing a new heating facility, and can operate continuously without stopping the cooling tower. As a result, an inexpensive open-type cooling tower can be adopted, which is effective in saving space and cost. Cooling system and operating method of open-type cooling tower during freezing in free cooling, which can obtain cooling water with almost a predetermined outlet temperature even when some freezing occurs on the outside air intake and packed plate of the cooling tower. It aims at providing the open type cooling tower used for this.
Another object of the present invention is that, in the free cooling, the watering amount is divided and set stepwise in advance according to the outside air wet bulb temperature pattern, and the forward / reverse rotation of the blower is controlled effectively. Operation of an open-type cooling tower during freezing and free cooling that can provide circulating cooling water with a predetermined outlet temperature even when freezing occurs to some extent between the outside air intake and packed plate of the cooling tower. It is to provide an open-type cooling tower used in the above.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, in the operation method of the open-type cooling tower at the time of freezing in free cooling in which cooling load is cooled using cooling water obtained by operating only the open-type cooling tower,
The number of rotations and the direction of rotation of the cooling tower fan can be controlled,
When the outside air wet bulb temperature of the ambient air around the installation location of the cooling tower is below the freezing point, the sprinkling amount of the cooling water flowing from the upper water tank provided on the cooling tower onto the packing plate is the outside air humidity of the ambient air around the installation location. Set the watering amount from the upper water tank so that the watering amount is higher as the bulb temperature is lower, and the watering amount is lower as the outdoor wet bulb temperature is higher.
A) A step of controlling the rotational speed of the blower so as to keep the cooling water outlet temperature of the cooling tower at a set value.
B) After that, when the cooling water outlet temperature rises due to icing on the filling plate and reaches the first target value set slightly higher than the set value, the blower is changed from normal rotation to reverse rotation. Switching step.
C) Next, during the reverse rotation of the blower, the cooling water outlet temperature once rose and then rose again, and reached the second target value set higher than the set value and slightly lower than the first target value. Sometimes switching the blower from reverse to forward rotation.
As the cooling water outlet temperature changes due to the icing state on the packed plate, the steps A) to C) are repeated, and the operation method of the open cooling tower during freezing in free cooling is provided.
The cooling of the cooling load includes cooling of the liquid, storage of articles, and cooling of the heat generating equipment in addition to cooling.
Operating only the cooling tower means that only the cooling tower system is employed as a heat source for supplying cold heat, and the cooling operation is performed without cooling by another heat source such as a cooling water system from a refrigerator. The cooling tower system (piping system) includes auxiliary equipment such as a pump, a water treatment device, and an automatic valve attached to the cooling pipe, and these equipments are naturally operated together with the cooling tower.
The vicinity of the freezing point means a temperature in the vicinity of the wet bulb temperature of 0 ° C., which is the temperature at which water freezes, and the vicinity of the freezing point indicates an outside air wet bulb temperature below the range temperature.
The range of the outside air wet bulb temperature below the freezing point is, for example, -10 ° C to + 1 ° C.
For example, the operating method of the present invention is started at a slightly high outside air wet bulb temperature (such as 1.5 ° C.) by predicting that the outside air wet bulb temperature becomes 0 ° C., or there is a phenomenon such as water supercooling. The operation may be started at a sphere temperature of −0.5 ° C. or lower.
[0009]
In order to solve the above-described problem, the amount of circulating cooling water sprayed from the upper water tank onto the packed plate in the operation method of the open cooling tower of the present invention is divided into several stages according to the outside air wet bulb temperature. The water volume is increased as the outdoor wet bulb temperature is lower, and the water volume is set stepwise as the outdoor wet bulb temperature is higher. In this way, it is preferable to set the amount of sprinkled cooling water stepwise in order to prevent hunting of the motors of the pump and the blower.
[0010]
In order to solve the above problems, the forward rotation time of the blower in the operation method of the open cooling tower of the present invention is set longer than the reverse rotation time, and the total time of one cycle is about 20 from the relationship with the outside air wet bulb temperature. It is characterized by being 60 minutes from minutes. In this way, when the forward rotation time of the blower is set longer than the reverse rotation time, and the total time of one cycle is about 20 to 60 minutes from the relationship with the outside air wet bulb temperature, the outside air wet bulb temperature is low Takes longer time for one cycle, promotes melting of ice, and takes longer time for one cycle when the outside air wet bulb temperature is high, so it is difficult to obtain sufficient air volume in the cooling tower body. If the length of the cooling tower is prolonged, the original function of the cooling tower will be killed, sufficient time will be taken for normal rotation, and the cooling performance of the cooling tower will not be significantly reduced compared to the conventional one. Demonstrate.
[0011]
In order to solve the above-mentioned problem, the open cooling tower is operated with an average blocking rate of 40% to 80% due to freezing of the air passage in the packed plate in the operation method of the open cooling tower of the present invention. Features. Even in such a closed state with ice, circulating cooling water having a desired outlet temperature is obtained by forward and reverse operation of the blower.
Here, the blockage rate indicates the ratio of the front area of the air passage that is closed by ice to the total front area of the air passage of the filling plate in the vicinity of the outside air intake portion. It can be exemplified by the ratio of the load current value to the rated current of the motor, which is measured by an ammeter.
[0012]
In order to solve the above-mentioned problem, when the blowing current of the drive motor of the blower due to icing in the operation method of the open cooling tower of the present invention is measured as a load current, and the load current is equal to or more than a value corresponding to an occlusion ratio of 80% And the OR signal of the measurement signal when the upper limit value of the outlet temperature is exceeded is used as the blower stop and reverse command signal, and the measurement signal when the load current is equal to or less than the value corresponding to a blockage rate of 40% due to freezing It is desirable that the rotation direction of the blower be returned to normal rotation by an OR signal of a measurement signal when the outlet temperature is equal to or lower than a set value.
[0013]
In order to solve the above-mentioned problem, when the outside air wet bulb temperature in the operating method of the open cooling tower of the present invention fluctuates beyond the outside air wet bulb temperature in each stage, the outside wet bulb temperature at that time is changed. It is supposed to change to a corresponding predetermined watering amount.
[0014]
In order to solve the above-mentioned problem, a water film is placed on a packed plate in the range of each set watering amount in the operating method of the open cooling tower of the present invention in accordance with the set watering amount in that section. To form. At that time, based on the change in the outlet temperature, the rotational speed of the motor of the blower and its forward / reverse rotation are controlled in conjunction with the amount of water spray.
[0015]
In order to solve the above-mentioned problems, the temperature of the outside wet bulb in the operation method of the open type cooling tower of the present invention is divided into at least 3 stages, preferably 5 stages in the range of -10 ° C to + 1 ° C. Within the range of the outside air wet bulb temperature, the water spray amount is set to a predetermined value in advance to prevent complete freezing on the cooling water filling plate.
[0016]
In order to solve the above-mentioned problem, by changing the water spray amount in the operation method of the open type cooling tower of the present invention, the water spray state, for example, the water spray area is adjusted to prevent complete freezing on the cooling water filling plate.
[0017]
In order to solve the above-mentioned problem, the related invention is used for free cooling using cooled circulating cooling water obtained by operating only the open type cooling tower when the temperature of the outside air wet bulb at the open type cooling tower installation site is below the freezing point temperature. An open cooling tower
A temperature sensor for detecting the inlet temperature of the cooling tower of the circulating cooling water system and a temperature sensor for detecting the outlet temperature of the cooling tower of the circulating cooling water system are provided, and the outside wet bulb temperature at the place where the cooling tower is installed is determined. In order to obtain, a relative hygrometer that measures the relative humidity in the vicinity of the outside air intake of the cooling tower and a thermometer that measures the dry bulb temperature are installed,
A blower is installed at the exhaust port of the cooling tower, and the motor of this blower is a variable speed control type whose rotation direction can be rotated forward and backward.
The motor of the circulating pump arranged in the circulating cooling water system is a variable speed control type,
At least the temperature sensor, a relative hygrometer, and a thermometer are electrically connected to the data calculation unit, and the water spray amount is further reduced as the outside air wet bulb temperature of the air around the installation site is lower. There is a sprinkling amount setting unit that continuously sets the sprinkling amount so that the sprinkling amount decreases as the outdoor wet bulb temperature increases.
When the wet bulb temperature at the cooling tower installation location is near freezing point, the set value of the outlet temperature of the cooling tower, and the upper limit value, the lower limit value, and the target value slightly higher than the set value with respect to this set value as a boundary Along with the temperature setting part where the value is set,
Each of the data calculation units is further provided with a setting unit in which a time table in the rotation direction of the blower according to the outlet temperature is preset.
A control unit that controls the rotation speed of the motor of the blower based on the outlet temperature by the data calculation unit and controls the rotation direction according to the time table set in the setting unit is the data calculation unit. The open cooling tower is electrically connected to a motor drive control circuit.
[0018]
In order to solve the above-mentioned problem, the related invention is an open circuit used for free cooling using cooled circulating cooling water obtained by operating only the cooling tower when the outside air wet bulb temperature at the open-type cooling tower installation site is below the freezing point temperature. A cooling tower,
A temperature sensor for detecting the inlet temperature of the circulating cooling water system and a temperature sensor for detecting the outlet temperature of the circulating cooling water system are provided, and this cooling is performed in order to obtain the outdoor wet bulb temperature at the place where the cooling tower is installed. A relative hygrometer that measures the relative humidity near the outside air intake of the tower and a thermometer that measures the dry bulb temperature are installed, respectively.
A blower is installed at the exhaust port of the cooling tower, and the motor of this blower is a variable speed control type whose rotation direction can rotate forward and backward,
The motor of the circulating pump arranged in the circulating cooling water system is a variable speed control type,
At least the temperature sensor, a relative hygrometer, and a thermometer are electrically connected to the data calculation unit, and the amount of circulating cooling water sprayed from the upper water tank onto the filling plate is determined as the temperature of the outside wet bulb temperature. In accordance with the above, it is divided into several stages, the lower the wet bulb temperature, the greater the amount of water, the higher the outdoor wet bulb temperature, the lower the amount of water, and the lower the amount of water set stepwise, and the blower according to the outlet temperature. A setting unit in which a time table in the rotation direction is set in advance,
The data calculation unit controls the number of rotations of the motor of the circulation pump based on the outside air wet bulb temperature range, and selects the watering amount of the corresponding category among the watering amounts of the several categories set in stages. Further, a control unit that controls the rotation speed of the motor of the blower based on the outlet temperature and controls the rotation direction according to a time table set in the setting unit is provided for the data calculation unit and each motor. The open cooling tower is electrically connected to a drive control circuit.
[0019]
In order to solve the above-mentioned problem, the related invention is directed to the cooling circulating cooling water obtained by stopping the operation of the refrigerator when the temperature of the outside air wet bulb at the open-type cooling tower installation site is near the freezing point and operating only the cooling tower. As an open cooling tower used for free cooling indirectly,
A temperature sensor for detecting the inlet temperature of the cooling tower of the circulating cooling water system and a temperature sensor for detecting the outlet temperature of the cooling tower of the circulating cooling water system are provided, and the outside wet bulb temperature at the place where the cooling tower is installed is determined. In order to obtain, a relative hygrometer that measures the relative humidity in the vicinity of the outside air intake of the cooling tower and a thermometer that measures the dry bulb temperature are installed,
The blower motor provided at the exhaust port of the cooling tower is a variable speed control type whose rotation direction can be rotated forward and reverse,
The motor of the circulating pump arranged in the circulating cooling water system is a variable speed control type,
At least the temperature sensor, a relative hygrometer, and a thermometer are electrically connected to the data calculation unit, and the amount of circulating cooling water sprayed from the upper water tank onto the filling plate is determined as the temperature of the outside wet bulb temperature. In accordance with the above, it is divided into several stages, the lower the wet bulb temperature, the greater the amount of water, the higher the outdoor wet bulb temperature, the lower the amount of water, and the lower the amount of water set stepwise, and the blower according to the outlet temperature. A setting unit in which a time table in the rotation direction is set in advance,
The data calculation unit controls the number of rotations of the motor of the circulation pump based on the outside air wet bulb temperature range, and selects the watering amount of the corresponding category among the watering amounts of the several categories set in stages. Further, a control unit that controls the rotation speed of the motor of the blower based on the outlet temperature and controls the rotation direction according to a time table set in the setting unit is provided for the data calculation unit and each motor. The open cooling tower is electrically connected to a drive control circuit.
The vicinity below freezing includes the outside wet bulb temperature in the vicinity of freezing, in addition to the range of outside freezing bulb temperature below freezing, that is, below the wet bulb temperature of 0 ° C. Specifically, it refers to an outdoor wet bulb temperature of 1 ° C. or less.
[0020]
In the switching from the normal rotation to the reverse rotation of the blower, the time taken from the normal rotation to the stop, the duration of the stop state, and the time taken from the stop to the steady reverse rotation are set by timers, respectively. In switching from reverse rotation to normal rotation, it is preferable that the time taken from the steady reverse rotation to the stop, the duration of the stopped state, and the time taken from the stop to the normal forward rotation are respectively set by timers.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
This form is a typical embodiment of the invention of the open type cooling tower according to claims 8 and 9.
In FIG. 1, A indicates a cross-flow type open cooling tower, and a packing plate 11 made of a synthetic resin corrugated plate is loaded in the cooling tower A below the upper water tank 10.
The dropped water tank 14 of the lower water tank 13 that receives the circulating cooling water sprayed on the filling plate 11 is piped to the air conditioner as a cooling load, and is connected to the air conditioner without passing through the refrigerator during free cooling. It is possible to selectively communicate with an exchanger (not shown).
During the free cooling, the circulating cooling water is indirect or direct contact with the cooling water (secondary circulating cooling water) on the air conditioner supplied to the heat exchanger, and after cooling it, it is supplied to the upper water tank 10. A circulating cooling water system is constructed which is cooled again by direct contact with the external airflow and used by circulation.
[0022]
A temperature sensor 16 for detecting the cooling tower outlet temperature of the circulating cooling water system is provided, and in order to obtain the outside air wet bulb temperature at the place where the cooling tower A is installed, A relative hygrometer 18 for measuring the humidity and a dry bulb thermometer 19 for measuring the dry bulb temperature are installed.
A flow meter 21 for measuring the circulating cooling water flow rate is installed in the return pipe 20 of the circulating cooling water system.
A difference between the flow rate of the circulating cooling water detected by the flow meter 21 and a set value is obtained, and based on the difference, the motor of the circulation pump P uses a device that increases or decreases the number of revolutions, for example, an inverter. A flow rate regulator (not shown) for increasing or decreasing the frequency is provided.
At least the sensor 16, the relative hygrometer 18, the dry bulb thermometer 19, and the flow meter 21 are electrically connected to the data calculation unit 27, and the measured value of the relative hygrometer 18 and the dry bulb hygrometer 19 has a calculation mechanism for obtaining the wet bulb temperature based on the measured value of 19 and when the outside wet bulb temperature at the place where the cooling tower A is installed is 0 ° C. or less, the circulating cooling water outlet of the cooling tower A A temperature set value t2 ° C, a first target value t4 ° C higher than the set value, and a second target value t3 ° C higher than the set value and slightly lower than the first target value are preset.
[0023]
In addition, the external airflow that has cooled the circulating cooling water through direct contact with the circulating cooling water flowing through the filling plate 11 from the outside air intake portion 17 and flowing down on the surface of the filling plate 11 is passed through the mixing chamber 23 from the exhaust port 24. A blower 25 for exhausting outside the cooling tower A is installed at the exhaust port 24.
The blower 25 uses a device that increases or decreases the number of rotations, for example, an inverter. The inverter 25 is driven and controlled by a motor, and the direction of rotation is controlled forward and reverse. Note that this motor is preferably a geared motor or a motor in which a gear box is laid.
[0024]
Furthermore, the amount of circulating cooling water sprayed from the upper water tank 10 onto the filling plate 11 is divided into several stages as program parameters stored in the data calculation unit 27 according to the outside air wet bulb temperature. The lower the outside wet bulb temperature, the more water is set, and the higher the outside wet bulb temperature is, the smaller the amount of water is set in advance so as to be controlled stepwise (FIG. 2).
Preferably, the water wet bulb temperature is in a range of −10 ° C. to + 1 ° C., the water spray amount is divided into five stages, and the water spray amount is set to a predetermined value in advance within the range of the outdoor air wet bulb temperature in each section. .
When the outdoor air wet bulb temperature fluctuates beyond the outdoor air wet bulb temperature at each stage, the water spray is changed to a predetermined watering amount corresponding to the outdoor air wet bulb temperature at that time.
The data calculating unit 27 increases or decreases the frequency of the inverter circuit 22 of the motor based on the result calculated by the data calculating unit 27 to control the rotation speed of each motor, and the rotation direction of the blower 25 is controlled. A control unit 28 that controls forward and reverse rotation is connected. The data calculation unit 27 also increases / decreases the frequency of the inverter circuit 26 for controlling the rotation speed of the circulation pump P, and shares the control unit 28 with the inverter circuit 22.
[0025]
The operation of the open-type cooling tower configured as described above will be described together with a typical embodiment of the invention of the operation method of the open-type cooling tower during freezing in free cooling according to claims 1 to 3 and 6. .
When icing occurs in the cooling tower A, the blower 25 of the cooling tower A is reversely rotated, and the temperature of the circulating cooling water itself or the heat of the motor of the blower 25 is sent to the freezing place to melt the ice.
[0026]
More specifically, the outside air relative humidity and the dry bulb temperature in the vicinity of the outside air intake 17 of the cooling tower A are measured by the hygrometer 18 and the thermometer 19, and these measured values are input to the data calculator 27. The outdoor wet bulb temperature is calculated based on these measured values.
When the obtained outdoor wet bulb temperature is equal to or lower than the free cooling possible temperature, the operation of the refrigerator is stopped, the cooling tower A is operated, and the free cooling is performed. The operation pattern is as shown in FIG.
In the data calculation unit 27, a set value t2 of the circulating cooling water outlet temperature of the cooling tower A, a first target value t4 slightly higher than the set value, and a second value slightly higher than the set value and slightly lower than the first target value. A target value t3 is set in advance.
Further, the amount of circulating cooling water sprayed from the upper water tank 10 onto the filling plate 11 is set in several stages according to the wet bulb temperature, and the wet bulb temperature is low. The higher the wet water temperature and the higher the wet bulb temperature, the lower the water amount and preset in 5 stages (see FIG. 2).
The outside air wet bulb temperature at the installation location of the cooling tower A at the start of operation of the cooling tower A is set to be below the freezing point, for example, 1 ° C.
[0027]
At this time, an inverter circuit for the circulation pump P is selected so that the water spray amount corresponding to the obtained outside air wet bulb temperature is selected from the set number of the water sprays and the water spray amount of the selected partition is obtained. A command signal is issued from the control unit 28 to the control circuit 28, the frequency of the inverter circuit 22 is changed, the rotational speed of the motor of the circulation pump P is adjusted, and the sprinkling amount of the circulating cooling water is set to the numerical value of the selected section. In the example illustrated in FIG. 2, the amount of water spray is set in increments of 2 ° C.
The flow rate of the sprinkling amount after this selection is constantly measured by the flow meter 21, the fluctuation of the sprinkling amount in the same section is monitored, and the frequency of the inverter circuit 22 is feedback controlled.
[0028]
After selecting the section and setting the watering amount to a set value, a command signal is issued from the control unit 28 to the inverter circuit 26 of the blower 25 according to the outlet temperature, and the frequency control of the inverter circuit 26 and the fan 25 are controlled. Forward / reverse control is performed as follows (see FIG. 3).
In the wet bulb temperature range for each single section, the blower 25 is controlled by frequency control of the inverter circuit 26 so as to keep the cooling water outlet temperature at a set value in a state where the previously set watering amount is maintained. Controls the normal rotation speed. As the ice on the filling plate 11 freezes, the air passage closes, the rotational speed of the blower 25 increases, and the outlet temperature rises even when it reaches the steady rotational speed. This rise in temperature is due to the fact that icing occurs near the outer periphery of the cooling tower, that is, in the vicinity of the outside air intake 17, and the intake of outdoor air serving as a cooling heat source for the water to be cooled is hindered. And until the said outlet temperature reaches the 1st target value a little higher than the said setting value, the fan 25 provided in the cooling tower A continues normal rotation driving | operation.
Thereafter, when the outlet temperature reaches the first target value, the rotation of the blower 25 is stopped over a predetermined time from the normal rotation (see symbol A in FIG. 3). The stop state is continued for a predetermined time (see symbol B in FIG. 3).
[0029]
After completion of the predetermined stop time, the blower 25 is started to operate at low speed reverse rotation, and the speed is increased to steady reverse rotation over a predetermined time (see reference sign D in FIG. 3). The operation in which outside air is taken in from the side of the cooling tower (louver 12) and exhausted from the exhaust port 24 is the operation in which the air flow is reversed. That is, the part closest to the outside air intake until then becomes the part closest to the warm air outlet after the heat exchange. Since sprinkling is not stopped, the temperature of the cooling water heated by the cooling load and the heat generated by the motor of the fan 25 of the cooling tower are combined to send warm air to the filling plate on the louver 12 side that is an icing portion. The frozen parts will be thawed.
[0030]
During the reverse rotation operation of the blower 25, the outlet temperature rapidly rises and then rises again. Here, icing occurs in the inner periphery of the cooling tower, that is, in the vicinity of the mixing chamber 23. At that time, as described above, the introduction of outdoor air is insufficient, and in order to compensate for this, the rotational speed of the blower 25 is increased according to a preset set value, but when the temperature rises and reaches the second target value, The rotation of the blower 25 is stopped over a predetermined time set from reverse rotation (see symbol E in FIG. 3).
The stop state is continued for a set predetermined time (see symbol F in FIG. 3).
After completion of the predetermined stop time, the rotation of the blower 25 is started at a low speed and a positive rotation, and the speed is increased until a regular positive rotation is performed over a set predetermined time (see symbol H in FIG. 3).
[0031]
Thereafter, the outlet temperature rapidly decreases and reaches a set value.
The outlet temperature rises again with freezing on the filling plate 11, and every time the first target value is reached, the blower 25 is repeatedly stopped, reversely rotated, stopped, and forward rotated as one cycle to set the outlet temperature. Keep near value.
During such operation, when the outdoor wet bulb temperature falls from 0 ° C. to, for example, −4 ° C., the division in use is changed, and the amount of water spray is set in advance to be larger than that at 0 ° C. Using the section corresponding to −4 ° C., the amount of water spray of the newly designated section is sprayed on the filling plate 11 and the same operation as described above is performed.
If the outside wet bulb temperature is a temperature below the freezing point, for example, −4 ° C. from the beginning, a section corresponding to −4 ° C. may be selected and the same operation as described above may be performed.
[0032]
Embodiment 2
This form is a typical embodiment of the open type cooling tower according to claim 7, and the configuration different from that of the first embodiment is that at least the temperature sensor, the relative hygrometer, and the temperature are included in the data calculation unit. A meter is electrically connected, and the amount of water sprayed is such that the amount of water sprayed increases as the ambient air wet bulb temperature of the ambient air is lower, and the amount of water spray decreases as the ambient air wet bulb temperature increases. The water spray amount setting unit for continuously setting the water spray amount is different from that of the first embodiment in that the amount of water sprayed in the circulating cooling water is set according to the temperature of the external air wet bulb. The higher the outside air wet bulb temperature is, the smaller the amount of water is set continuously in advance (corresponding to a typical embodiment of the invention of claim 1). The rest is the same as in the first embodiment.
[0033]
Embodiment 3
This embodiment is a typical embodiment of the invention described in claims 4 to 5, and the configuration different from the embodiment 1 is that the blockage rate of the air passage due to freezing on the filling plate 11 is 40% to 80%. The cooling tower A is operated. Specifically, the operating state of the blower 25 of the cooling tower A is changed when the lower limit and the upper limit of the blockage rate of the air passage are predetermined rates, for example, 40% and 80%. More preferably, the blowing resistance of the blower 25 is measured as the load current of the motor, and the measurement signal when the load current is equal to or higher than the 80% occlusion rate due to freezing and the circulating cooling water outlet temperature are the first target value. The OR signal of the measurement signal in the case of exceeding is used as a command signal from normal rotation to reverse rotation, and the blower 25 is changed from normal rotation to reverse rotation. The rotation direction of the blower 25 is returned to the normal rotation by the measurement signal when the load current is equal to or less than the value corresponding to the blockage rate of 40% due to freezing and the OR signal of the measurement signal when the load current is equal to or less than the preset value of the outlet temperature. By doing so, the predetermined outlet temperature is stabilized and the reliability of the operation of the cooling tower is increased.
Others are the same as in the first embodiment.
In this way, the outlet temperature of the circulating cooling water is substantially maintained at the set value while avoiding the sealing of the air passage due to icing on the filling plate 11 and the outside air intake port 17 when the outside air wet bulb temperature is 0 ° C. or less, Supply cooling water of desired temperature.
The cooling tower is an open type cooling tower and can be implemented regardless of the type as long as it has a blower.
The supply source of the circulating cooling water is an air conditioner, a cooling device, a storage / preservation device, or other equipment that requires cooling of about 5 ° C. to 10 ° C. The air conditioner (not shown) is a heat exchanger. The air conditioner and the fan coil unit may be communicated with each other through a pipe without going through.
[0034]
【The invention's effect】
In the invention of the operation method according to any one of claims 1 to 6, the amount of water spray is set so as to change according to the outside air wet bulb temperature, and the number of rotations and the direction of rotation of the blower are controlled, so Even in a state where icing has occurred to some extent, effective cooling is possible, and a desired cooling water outlet temperature can be obtained. Moreover, the range of the outside wet-bulb temperature which can operate the said cooling tower can be expanded, and this open type cooling tower can be used also in severe winter places, such as Hokkaido, Tohoku, and Hokuriku.
[0035]
In particular, in the invention according to claim 2, hunting of the motor of the pump and the blower is performed by setting the watering amount in stages according to the temperature pattern and controlling the rotation direction of the blower during the free cooling. In addition, effective cooling and a target cooling water outlet temperature can be obtained even when some degree of freezing occurs between the outside air inlet and the packed plate of the cooling tower. Moreover, the range of the outdoor wet bulb temperature in which the cooling tower can be operated can be expanded, and this open type cooling tower can be used even in severe winter areas such as Hokkaido, Tohoku and Hokuriku.
In addition, by controlling the drive motor of the blower and the drive motor of the cooling water circulation pump based on the outside air wet bulb temperature, these motors can be reliably controlled in response to the change in the outside air wet bulb temperature, The said effect can be exhibited more notably.
[0036]
In particular, in the invention according to claim 3, by setting the forward rotation time of the blower longer than the reverse rotation time, when the outside wet bulb temperature is low, a longer cycle time is taken to melt the ice. If the outdoor wet bulb temperature is high, the cycle time should be shortened, and the reversing time that makes it difficult to obtain a sufficient amount of air in the cooling tower body will be lengthened. Thus, the cooling performance can be exhibited without taking a sufficient amount of forward rotation time and without significantly lowering the original cooling performance of the cooling tower as compared with a general-purpose product.
[0037]
According to a fourth aspect of the present invention, the air-cooling rate of the air passages in the packed plate is set to an average of 40% to 80%, and the open-type cooling tower is operated to allow a blower while allowing a blocked state due to ice. Thus, circulating cooling water having a desired outlet temperature can be obtained by forward and reverse operations, and the operation of the cooling tower can be appropriately automated.
In the invention described in claim 5, the blowing resistance of the drive motor of the blower due to icing is measured when the load current exceeds a value corresponding to 80% of the blockage rate due to icing, and when the upper limit of the outlet temperature is exceeded. The OR signal of the blower is the stop and reverse command signal of the blower, and the OR signal of the measurement signal when the load current is equal to or less than a value corresponding to a blockage rate of 40% due to freezing and the OR signal of the measurement signal when the outlet temperature is equal to or less than the set value By returning the rotation direction of the blower to normal rotation, the circulating cooling water can be efficiently cooled as icing is thawed, and the above-described effects can be exhibited in a state where icing is allowed to some extent.
[0038]
In a sixth aspect of the present invention, the rotational speed of the motor of the blower is controlled based on the change in the outlet temperature and the rotational direction thereof is controlled to be forward / reversely rotated within the range of the set watering amount. In this way, a predetermined outlet temperature can always be obtained in the free cooling regardless of the change in the outside wet bulb temperature.
[0039]
In the invention of the open type cooling tower according to the seventh aspect, the operation method according to the first to sixth aspects can be carried out, and the effect can be exhibited.
In the invention of the open type cooling tower according to the eighth aspect, the operation method according to the second to sixth aspects can be carried out, and the effect can be exhibited.
In the invention of the open type cooling tower according to the ninth aspect, the operation method according to the second to sixth aspects can be carried out, and the effect can be exhibited.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the entirety of an embodiment.
FIG. 2 is a schematic diagram showing a control pattern of the watering amount in FIG. 1;
FIG. 3 is a schematic diagram of an operation pattern of the blower in FIG. 1;
[Explanation of symbols]
A Open cooling tower
P Circulation pump
10 Upper water tank
11 Filling plate
12 louvers
15, 16 Temperature sensor
18 Relative hygrometer
19 Dry bulb thermometer
21 Flow meter
22, 26 Inverter circuit
23 Mixing chamber
25 Blower
27 Data operation part
28 Control unit

Claims (9)

In the operation method of the open cooling tower during freezing in free cooling in which cooling water is cooled using cooling water obtained by operating only the open cooling tower,
The number of rotations and the direction of rotation of the cooling tower fan can be controlled,
When the outside air wet bulb temperature of the ambient air around the installation location of the cooling tower is below the freezing point, the sprinkling amount of the cooling water flowing from the upper water tank provided on the cooling tower onto the packing plate is the outside air humidity of the ambient air around the installation location. Set the watering amount from the upper water tank so that the watering amount is higher as the bulb temperature is lower, and the watering amount is lower as the outdoor wet bulb temperature is higher.
A) A step of controlling the rotational speed of the blower so as to keep the cooling water outlet temperature of the cooling tower at a set value.
B) After that, when the cooling water outlet temperature rises due to icing on the filling plate and reaches the first target value set slightly higher than the set value, the blower is changed from normal rotation to reverse rotation. Switching step.
C) Next, during the reverse rotation of the blower, the cooling water outlet temperature once rose and then rose again, and reached the second target value set higher than the set value and slightly lower than the first target value. Sometimes switching the blower from reverse to forward rotation.
A method of operating an open cooling tower during freezing in free cooling, wherein the steps A) to C) are repeated as the cooling water outlet temperature changes due to the frozen state on the packed plate. Sprinkling amount of circulating cooling water from the upper water tank on the filling plate is set in several stages according to the outside air wet bulb temperature, the lower the outside air wet bulb temperature, the more water amount, The method for operating an open cooling tower during freezing in free cooling according to claim 1, wherein the amount of water is set stepwise as the outdoor wet bulb temperature increases. 3. The free cooling according to claim 1 or 2, wherein the forward rotation time of the blower is set longer than the reverse rotation time, and the total time of one cycle is about 20 to 60 minutes in relation to the outside wet bulb temperature. To operate an open cooling tower during icing. 4. The open type at the time of freezing in free cooling, wherein the open type cooling tower is operated with an average blockage rate due to freezing of the air passage in the packed plate being 40% to 80%. Cooling tower operation method. The blower resistance of the drive motor of the blower due to icing is measured as a load current, and the measurement signal when the load current is equal to or higher than the 80% occlusion rate due to icing and the OR of the measurement signal when the outlet temperature exceeds the upper limit value are measured. The signal is the blower stop and reverse command signal,
The rotation direction of the blower is returned to normal rotation by an OR signal of a measurement signal when the load current is equal to or less than a value corresponding to a blockage rate of 40% due to icing and a set value of the outlet temperature or less. The operation method of the open type cooling tower at the time of freezing in free cooling in claim 1, 2, 3 or 4. The rotation speed of the motor of the blower is controlled based on the change in the outlet temperature, and the rotation direction is controlled to be forward / reversely rotated in the range of the set watering amount. Item 5. A method for operating an open cooling tower during freezing in free cooling according to item 2, 3 or 4. It is an open type cooling tower used for free cooling that cools the cooling load using the cooling water obtained by operating only the open type cooling tower,
A temperature sensor for detecting the inlet temperature of the cooling tower of the circulating cooling water system and a temperature sensor for detecting the outlet temperature of the cooling tower of the circulating cooling water system are provided, and the outside wet bulb temperature at the place where the cooling tower is installed is determined. In order to obtain, a relative hygrometer that measures the relative humidity in the vicinity of the outside air intake of the cooling tower and a thermometer that measures the dry bulb temperature are installed,
A blower is installed at the exhaust port of the cooling tower, and the motor of this blower is a variable speed control type whose rotation direction can be rotated forward and backward.
The motor of the circulating pump arranged in the circulating cooling water system is a variable speed control type,
At least the temperature sensor, a relative hygrometer, and a thermometer are electrically connected to the data calculation unit, and the water spray amount is further reduced as the outside air wet bulb temperature of the air around the installation site is lower. There is a sprinkling amount setting unit that continuously sets the sprinkling amount so that the sprinkling amount decreases as the outdoor wet bulb temperature increases.
When the wet bulb temperature at the cooling tower installation location is near freezing point, the set value of the outlet temperature of the cooling tower, and the upper limit value, the lower limit value, and the target value slightly higher than the set value with respect to this set value as a boundary Along with the temperature setting part where the value is set,
Each of the data calculation units is further provided with a setting unit in which a time table in the rotation direction of the blower according to the outlet temperature is preset.
A control unit that controls the rotation speed of the motor of the blower based on the outlet temperature by the data calculation unit and controls the rotation direction according to the time table set in the setting unit is the data calculation unit. An open-type cooling tower which is electrically connected to a motor drive control circuit. It is an open type cooling tower used for free cooling that cools the cooling load using the cooling water obtained by operating only the open type cooling tower,
A temperature sensor for detecting the inlet temperature of the cooling tower of the circulating cooling water system and a temperature sensor for detecting the outlet temperature of the cooling tower of the circulating cooling water system are provided, and the outside wet bulb temperature at the place where the cooling tower is installed is determined. In order to obtain, a relative hygrometer that measures the relative humidity in the vicinity of the outside air intake of the cooling tower and a thermometer that measures the dry bulb temperature are installed,
A blower is installed at the exhaust port of the cooling tower, and the motor of this blower is a variable speed control type whose rotation direction can be rotated forward and backward,
The motor of the circulating pump arranged in the circulating cooling water system is a variable speed control type,
At least the temperature sensor, a relative hygrometer, and a thermometer are electrically connected to the data calculation unit, and the amount of the circulating cooling water sprayed from the upper water tank onto the filling plate is determined based on the outside air wet bulb temperature. In accordance with the above, it is divided into several stages, the amount of water is increased as the wet bulb temperature is lower, and the amount of water is set stepwise as the outdoor wet bulb temperature is higher, and the blower according to the outlet temperature And a setting unit in which a time table in the rotation direction is set in advance.
The data calculation unit controls the number of rotations of the motor of the circulation pump based on the outside wet bulb temperature range, and selects the watering amount of the corresponding section among the watering amounts of the several sections set stepwise. Further, a control unit for controlling the rotation speed of the motor of the blower based on the outlet temperature and controlling the rotation direction according to a time table set in the setting unit is provided for the data calculation unit and each motor. An open-type cooling tower which is electrically connected to a drive control circuit. Open-type cooling that is used for free cooling that indirectly uses the cooled circulating cooling water that is obtained by stopping the operation of the refrigerator when the temperature of the outside wet-bulb at the place where the open-type cooling tower is installed is near freezing point and operating only the cooling tower A tower,
A temperature sensor for detecting the inlet temperature of the cooling tower of the circulating cooling water system and a temperature sensor for detecting the outlet temperature of the cooling tower of the circulating cooling water system are provided, and the outside wet bulb temperature at the place where the cooling tower is installed is determined. In order to obtain, a relative hygrometer that measures the relative humidity in the vicinity of the outside air intake of the cooling tower and a thermometer that measures the dry bulb temperature are installed,
The blower motor provided at the exhaust port of the cooling tower is a variable speed control type whose rotation direction can be rotated forward and reverse,
The motor of the circulating pump arranged in the circulating cooling water system is a variable speed control type,
At least the temperature sensor, a relative hygrometer, and a thermometer are electrically connected to the data calculation unit, and the amount of the circulating cooling water sprayed from the upper water tank onto the filling plate is determined based on the outside air wet bulb temperature. In accordance with the above, it is divided into several stages, the amount of water is increased as the wet bulb temperature is lower, and the amount of water is set stepwise as the outdoor wet bulb temperature is higher, and the blower according to the outlet temperature And a setting unit in which a time table in the rotation direction is set in advance.
The data calculation unit controls the number of rotations of the motor of the circulation pump based on the outside wet bulb temperature range, and selects the watering amount of the corresponding section among the watering amounts of the several sections set stepwise. Further, a control unit for controlling the rotation speed of the motor of the blower based on the outlet temperature and controlling the rotation direction according to a time table set in the setting unit is provided for the data calculation unit and each motor. An open-type cooling tower which is electrically connected to a drive control circuit.

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