JP5955495B2 - Cold water circulation system - Google Patents

Description

  The present invention relates to a cold water circulation system. In particular, the present invention relates to a cold water circulation system that saves energy without using a power inverter.

  Conventionally, as a cold water circulation system, a cold water heat storage tank for storing feed cold water and return cold water, a cold water primary pump for sending return cold water from a high temperature part of the cold water heat storage tank to a low temperature part of the cold water heat storage tank through a refrigerator, and a power inverter And a chilled water secondary pump for sending the feed chilled water from the low temperature part of the chilled water storage tank to the load facility, and a pump operation controller for controlling the operation of the chilled water secondary pump. A chilled water circulation system is known that controls the operating frequency of a power inverter so that the detected temperature difference between the temperature and the temperature of the return chilled water approaches the rated design temperature difference of the load equipment (see, for example, Patent Document 1).

  Since the chilled water circulation system described in Patent Document 1 has the above-described configuration, the amount of chilled water fed from the chilled water secondary pump equipped with the power inverter to the load facility can be controlled to an optimum amount, so from the viewpoint of energy saving. An excellent effect can be exhibited.

JP 2007-155232 A

  However, since the chilled water circulation system described in Patent Document 1 uses a power inverter, there is a limit in reducing the equipment cost. In particular, when the power inverter panel equipment is retrofitted with existing equipment, the equipment cost, including construction costs, may increase, or the power inverter board may not be installed due to space problems. There is room.

  Accordingly, an object of the present invention is to provide a chilled water circulation system that has energy saving performance substantially equivalent to that when a power inverter is used for a chilled water secondary pump, but can reduce equipment costs.

In order to achieve the above object, the present invention provides a load facility in which the required amount of water is continuously adjusted by a control valve, a refrigerator that cools return chilled water from the load facility and feeds it to the load facility, and a load A chilled water primary pump that supplies the chilled water that flows through the piping connected to the refrigerator from the facility, and a feed chilled water that operates at the power frequency in the area where it is installed and flows from the refrigerator to the piping connected to the load facility a has a plurality of cold secondary pump for supplying the load equipment, a return valve for controlling the feed feed pressure of cold water that is water to load equipment between the chilled water secondary pump and load facility, chilled water secondary pump as the feed of cold water pressure between the went back to feed cold water can Kayes towards the suction part of the cold water secondary pump tube that is water to the load equipment, and chilled water secondary pump and load facility from reaches the set value to adjust the return valve to And a pump driving controller for controlling such a pump driving controller, the detected temperature difference between the chilled water temperature and return feeding cold water temperature, the direction in which the absolute value of the difference between the nominal design temperature difference of the load equipment is reduced If the set value exceeds the preset maximum pressure for each total number of operating chilled water secondary pumps, the number of operating chilled water secondary pumps is increased and the set value is set. Is controlled to a preset value lower than the set value, and when the set value becomes less than the preset minimum pressure for each total number of operating chilled water secondary pumps, the chilled water secondary pump is operated. A chilled water circulation system is provided that performs control to reduce the number of units and raise the set value to a preset value higher than the set value . (In addition, adjusting the amount of water supply means changing the water supply pressure.)

Further, the pump driving controller may control the opening degree of the return valve.

Further, in the chilled water circulation system, the pump operation controller continues the predetermined time when the absolute value of the difference between the detected temperature difference and the rated design temperature difference deviates from the preset allowable value. Alternatively, the set value can be corrected when it has accumulated too much within a preset time, and the pressure of the feed cold water to the load facility can be adjusted to the corrected set value .

  In the chilled water circulation system, a pressure variable unit that changes the pressure of the feed chilled water supplied to the load facility may be further provided in the front stage of the load facility.

  In the cold water circulation system, the pressure variable unit may be a pressurizing pump that is smaller than the cold water secondary pump.

  The chilled water circulation system further includes a plurality of load facilities, and the feed chilled water is fed to each of the plurality of load facilities through a plurality of feed pipes, and each of the plurality of load facilities is returned to the chilled water through a plurality of return pipes. The chilled water temperature is a temperature set in advance in the first aggregate portion of the plurality of feed pipes, and the return chilled water temperature is measured in the second aggregate portion of the plurality of return pipes. Also good.

  According to the chilled water circulation system according to the present invention, it is possible to provide a chilled water circulation system that has energy saving performance almost the same as that when a power inverter is used for a chilled water secondary pump, but can reduce equipment costs.

It is a schematic diagram of the structure of the cold water circulation system which concerns on 1st Embodiment. It is a flow of operation of the cold water circulation system concerning a 1st embodiment. It is a schematic diagram of the structure of the cold-water circulation system which concerns on the modification of 1st Embodiment. It is a schematic diagram of the structure of the cold water circulation system which concerns on 2nd Embodiment.

[First Embodiment]
(Outline of the configuration of the cold water circulation system)
FIG. 1 shows an outline of the configuration of the cold water circulation system according to the first embodiment of the present invention.

  The chilled water circulation system according to the first embodiment is, for example, a chilled water circulation system including a chilled water circulation facility that continuously supplies cold heat for air conditioning and production cooling water to a predetermined load facility. The load facility is, for example, a dehumidification coil or a cooling coil of an air conditioner, a heat exchanger for production cooling water, a dry coil, or the like.

  The chilled water circulation system according to the first embodiment supplies load equipment 81A in which the required amount of water is continuously adjusted by a control two-way valve 16 as a control valve, and returns cold water from the load equipment 81A to the refrigerator 3. The chilled water primary pump 1 that cools the chilled water returned from the load facility 81A and feeds the chilled water to the load facility 81A, and the chilled water supplied to the load facility 81A as the chilled water. The secondary pump 5 is provided via a return valve 7a as a pressure control unit for controlling the pressure of the feed cold water fed to the load facility 81A, and a part of the feed cold water fed to the load facility 81A is used as a cold water secondary pump. And a pump operation controller 131 for adjusting the amount of chilled water fed from the chilled water secondary pump 5 to the load equipment 81A by controlling the opening degree of the return valve 7a.Note that the cold water circulation system according to the first embodiment can include one or more cold water secondary pumps 5.

  Further, the cold water circulation system according to the present embodiment includes a feed header 6a and a feed header 6b that connect a pipe through which cold water from the refrigerator 3 flows and a pipe that feeds the cold water to the load equipment 81A, and the load equipment 81A. The return header 9 connects the pipe through which the return cold water flows and the pipe that supplies the return cold water to the refrigerator 3. A pipe through which cold water from the refrigerator 3 flows is connected to the feed header 6b, and a pipe for supplying the feed cold water to the load facility 81A is connected to the feed header 6a. Further, the feed header 6b and the return header 9 are connected to each other by piping. And as an example, the cold water secondary pump 5 is arrange | positioned so that the feed header 6a and the feed header 6b may be connected between the feed header 6a and the feed header 6b.

  A return pipe 7 is provided between the feed header 6a and the feed header 6b via a return valve 7a. The return pipe 7 has a function of returning a part or all of the feed cold water fed from the refrigerator 3 to the load facility 81A from the feed header 6a to the feed header 6b. The return pipe 7 is a pressure release valve that releases the pressure in the feed pipe when the cold water secondary pump 5 is operated when the control two-way valve 16 as the control valve of the load equipment 81A is fully closed. Can also be included.

(Cold water primary pump 1)
The cold water primary pump 1 sends the return cold water returning to the return header 9 from the load facility 81 </ b> A to the refrigerator 3. The chilled water circulation system according to the first embodiment includes the number of chilled water primary pumps 1 corresponding to the number of refrigerators 3 included in the chilled water circulation system. Note that the cold water circulation system according to the first embodiment can include one or more cold water primary pumps 1. That is, the cold water circulation system according to the present embodiment can include a plurality of refrigerators 3.

(Refrigerator 3)
The refrigerator 3 cools the return cold water from the load facility 81A supplied from the cold water primary pump 1 to a target temperature. The cooled cold water (that is, feed cold water) is supplied from the refrigerator 3 to the cold water secondary pump 5 through the feed header 6b. Here, the refrigerator 3 is accompanied by a cooling tower 31 for cooling the return cold water, and a cooling water pump 32 for circulating the return cold water between the refrigerator 3 and the cooling tower 31 as auxiliary equipment. The auxiliary machine and the cold water primary pump 1 operate in conjunction with the operation of the refrigerator 3. Hereinafter, when there are auxiliary equipment for the cold water primary pump 1 and auxiliary equipment and the refrigerator 3 that is always operated in conjunction with these, it may be referred to as the refrigerator 3 including all of them.

(Cold water secondary pump 5)
Of the cold water supplied from the refrigerator 3 to the feed header 6b, the cold water secondary pump 5 supplies a necessary amount of cold water (that is, feed cold water) to the load facility 81A. The cold water secondary pump 5 operates at a power frequency (for example, 50 Hz or 60 Hz) in an area where the cold water circulation system is installed, for example. Then, the cold water secondary pump 5 supplies the feed cold water supplied from the refrigerator 3 to the load facility 81A via the feed header 6a as the first aggregate portion.

  Each of the plurality of cold water secondary pumps 5 has a water supply pipe for supplying the cold water to the load facility 81A. Specifically, the plurality of water pipes are connected to the feed header 6a, and the feed cold water flowing through each of the plurality of water pipes merges at the feed header 6a. The feed header 6a has a feed pipe connected to the load facility 81A. The feed cold water is supplied to the load facility 81A through the feed pipe. Moreover, the pressure gauge 60 which measures the pressure in the feed header 6a of the feed water supplied to the load equipment 81A is installed in the feed header 6a. The pressure gauge 60 supplies a pressure signal indicating the measured pressure to the pump operation controller 131.

  Further, a return pipe 7 is connected to the feed header 6a at a position adjacent to the plurality of feed pipes. A return valve 7a is provided between the feed header 6a and the feed header 6b. The return valve 7a controls the opening of the valve (for example, PID control) by the pump operation controller 131 on the basis of the pressure signal measured by the pressure gauge 60, thereby supplying the cold water supplied to the load facility 81A. Adjust the pressure to match the target value. In addition, the pressure which the pressure gauge 60 shows becomes the pressure of the cold water which returns to the feed header 6b via the feed pressure of the feed cold water and the return valve 7a.

(Load equipment)
The load facility 81A cools the object 17A to be cooled (for example, indoor air when the load facility 81A is an air conditioner, or production device cooling water when the load facility 81A is a plate heat exchanger). The load facility 81A includes a control two-way valve 16 as a control valve that automatically controls the amount of feed cold water flowing into the load facility 81A according to the temperature of the cooling object 17A that is a load, and a control two-way valve 16 It has a control signal transmitter 24A for controlling the opening degree and a temperature detector 23A for detecting the temperature of the cooling object 17A. The control valve included in the load facility 81A can be a control three-way valve. This control valve may be provided at least on either the upstream side or the downstream side of the load facility.

  The control signal transmitter 24A acquires a temperature signal indicating the temperature of the cooling object 17A detected by the temperature detector 23A, and controls opening and closing of the control two-way valve 16 based on the acquired temperature signal. Specifically, the control signal transmitter 24A adjusts the opening degree of the control two-way valve 16 continuously, that is, without steps, so that the temperature of the cooling object 17A approaches a preset temperature. Thereby, the required amount of feed cold water is continuously supplied to the load facility 81A.

  The feed cold water supplied to the load facility 81A is used for cooling the load of the load facility 81A (that is, the cooling object 17A). The temperature of the feed chilled water supplied to the load equipment 81A rises in proportion to the magnitude of the load heat quantity and returns to the chilled water. The return chilled water passes through the return pipe connected to the load facility 81 </ b> A and is supplied to the return header 9 as the second aggregate portion to which the return pipe is connected. The return cold water from the return header 9 is supplied to the refrigerator 3 via the cold water primary pump 1.

(Pump operation controller 131)
The pump operation controller 131 controls the opening degree of the return valve 7a so that the detected temperature difference between the feed cold water temperature and the return cold water temperature approaches the rated design temperature difference of the load facility 81A. The amount of water fed to the load facility 81A (that is, the feed cold water supplied from the refrigerator 3 to the feed header 6b and from the feed header 6b to the feed header 6a) is controlled. That is, the pump operation controller 131 adjusts the control two-way valve 16 to cool the cooling object 17A toward a preset temperature, while the rated temperature difference in the heat exchange design of the load equipment 81A. The amount of feed cold water is controlled by controlling the opening degree of the return valve 7a.

  Here, the rated design temperature difference of the load facility 81A means that the load facility 81A exhibits the rated capacity when the load facility 81A is operating to exhibit the rated capacity described in the design specification of the load facility 81A. In this case, the flow rate of cold water is supplied to the load facility 81A, the temperature of the cold water when the cold water enters the load facility 81A, and the temperature of the cold water that is heat-exchanged in the load facility 81A and exits from the load facility 81A Temperature difference. The rated design temperature difference is a predetermined temperature difference, and is set uniformly in one chilled water circulation system. In addition, the rated design temperature difference in the present embodiment is based on the temperature difference based on the design specifications of the load facility 81A (that is, the temperature of the cold water entering the load facility 81A and the load facility 81A after heat exchange in the load facility 81A). A value obtained by adding a certain correction to the temperature difference between the temperature of the discharged water and the temperature can be set as the rated design temperature difference (for example, a value obtained by subtracting 0.5 ° C. from the temperature difference in the load facility 81A). It can be set as the rated design temperature difference).

  In the first embodiment, the pump operation controller 131 gives priority to controlling the amount of feed cold water by controlling the opening degree of the return valve 7a. For example, when the amount of feed cold water requested by the load facility 81A cannot be controlled by controlling the opening degree of the return valve 7a, the pump operation controller 131 controls the number of operating cold water secondary pumps 5. (In other words, increase or decrease in the number of operating units).

  Here, the temperature of the feed chilled water is measured, for example, at a portion where the chilled water cooled by the refrigerator 3 is once collected, such as the feed header 6a, the collective piping, and the collecting tank (part of the heat storage water tank). Temperature. The feed temperature detector 18 supplies a temperature signal indicating the measured temperature (hereinafter sometimes referred to as “feed cold water temperature”) to the pump operation controller 131. In addition, the temperature of the return cold water is measured by, for example, a return temperature detector 19 installed in a return header 9 or a pipe or a collection tank connected to a subsequent stage of the return header 9. The return temperature detector 19 supplies a temperature signal indicating the measured temperature (hereinafter sometimes referred to as “return cold water temperature”) to the pump operation controller 131.

  The pump operation controller 131 then detects a detected temperature difference (that is, feed cold water) calculated from the feed cold water temperature measured by the feed temperature detector 18 and the return cold water temperature measured by the return temperature detector 19. The opening degree of the return valve 7a is controlled based on the detected temperature difference so that the absolute value of the difference between the difference between the temperature and the return cold water temperature) and the rated design temperature difference of the load facility 81A decreases. That is, the pump operation controller 131 sets ΔT = T2 when the feed cold water temperature measured by the feed temperature detector 18 is T1 and the return cold water temperature measured by the return temperature detector 19 is T2. The opening degree of the return valve 7a is controlled so that the value of -T1 approaches the rated design temperature difference. As a result, the pump operation controller 131 adjusts the amount of feed cold water supplied from the cold water secondary pump 5 to the load facility 81A.

(Opening control mechanism of return valve 7a)
The pump operation controller 131 includes an opening degree control unit that controls the opening degree of the return valve 7a. The opening degree control unit presets the difference between the detected temperature difference (ΔT) between the measured feed chilled water temperature (T1) and the measured return chilled water temperature (T2) and the rated design temperature difference of the load equipment 81A. The absolute value of the difference between the detected temperature difference and the rated design temperature difference when the time deviating from the specified allowable value has accumulated for a predetermined time continuously or accumulated within the time set in advance. The opening degree of the return valve 7a is changed in the direction in which the value becomes smaller. Thereby, the chilled water circulation system can maintain the temperature of the chilled water so as to be the optimum temperature difference in the heat exchange design in the refrigerator 3 (that is, the rated design temperature difference). The amount of fed cold water can be controlled so as to improve the overall operation efficiency with the refrigerator 3.

  Note that the preset allowable value is set to about ± 0.5 to 1.0 ° C., for example. In the present embodiment, the “preset allowable value”, “predetermined predetermined time”, and “predetermined time” indicate that the efficiency of the chilled water circulation system is optimum after the operation of the chilled water circulation system is started. Can be adjusted.

(Cooling water secondary pump 5 operation number control mechanism)
The pump operation controller 131 has an operation number control unit that increases or decreases the operation number of the cold water secondary pumps 5. The operating number control unit starts the operation when the pressure of the feed water reaches the preset maximum return valve pressure, and when the return valve pressure is maintained for a preset time, the number of operating cold water secondary pumps 5 Increase. In addition, the operating number control unit starts the time when the pressure of the feed water reaches the preset minimum return valve pressure, and when the return valve pressure is maintained for a preset time, the cold water secondary pump 5 Reduce the number of units in operation. Thereby, the chilled water circulation system can increase or decrease the amount of chilled water supplied to the load facility 81A to a range that is difficult only by adjusting the opening of the return valve 7a. The chilled water circulation system adjusts the opening degree of the return valve 7a and controls the number of chilled water secondary pumps 5 to operate the chilled water 3 at a high operating efficiency (coefficient of performance). The temperature range can be maintained.

  Here, the maximum return valve pressure in the present embodiment is set according to the maximum pressure of the feed water required by the load facility 81A included in the chilled water circulation system according to the present embodiment. In addition, the minimum return valve pressure in the present embodiment is based on the shape of the piping system of the cold water circulation system including the load facility 81A for the purpose of sending the predicted minimum amount of cold water to the load facility 81A. It is preferable to set the minimum required pressure in the facility 81A. The maximum return valve pressure and the minimum return valve pressure can be adjusted as appropriate so that the operation of the chilled water circulation system is optimized. Note that the pressure measured by the pressure gauge 60 can be used as the pressure of feed water (that is, the return valve pressure).

(Outline of operation of the cold water circulation system)
The outline | summary of operation | movement of the cold water circulation system which concerns on 1st Embodiment is demonstrated. First, when the chilled water circulation system is activated, the initial pressure (hereinafter referred to as “return valve set pressure”) of the feed water returned from the return pipe 7 to the feed header 6b measured by the pump operation controller 131, the chilled water secondary The cold water circulation system starts with the initial number of pumps 5. Thereafter, the detected temperature difference between the measured feed cold water temperature and the measured return cold water temperature is brought close to the rated design temperature difference of the load equipment 81A (ie, the detected temperature difference and the rated design temperature difference). Based on the detected temperature difference, corrections are made to the control of the opening degree of the return valve 7a and the control of the number of operating chilled water secondary pumps 5 based on the detected temperature difference. The operation of the cold water circulation system is continued.

  Then, after the chilled water circulation system has been operated for a certain period of time, the pump operation controller 131 compares the detected temperature difference with the rated design temperature difference. Further, the pump operation controller 131 determines whether or not the difference between the detected temperature difference and the rated design temperature difference exceeds a predetermined allowable value. The pump operation controller 131 determines the current opening degree of the return valve 7a as the absolute value of the difference between the detected temperature difference and the rated design temperature difference when the time exceeding the allowable value continues for a predetermined time. Correct in the direction that becomes smaller. That is, the pump operation controller 131 determines the pressure of the feed cold water returned from the return pipe 7 to the feed header 6b (hereinafter sometimes referred to as “return valve pressure”) between the detected temperature difference and the rated design temperature difference. Correct so that the absolute value of becomes smaller. Thereby, the cold water circulation system continues the operation of bringing the detected temperature difference close to the rated design temperature difference. A part of the feed cold water returned to the feed header 6b may be supplied again to the refrigerator 3 via a pipe connecting the feed header 6b and the return header 9.

  Here, the cold water secondary pump 5 can have a control valve for adjusting the discharge pressure of the feed cold water. The pump operation controller 131 continues the control of the operation of the chilled water circulation system, and when there are a plurality of chilled water secondary pumps 5 in operation, the chilled water fed from each of the plurality of chilled water secondary pumps 5 is provided. The discharge pressure in the water supply pipe on the discharge side of the cold water secondary pump 5 can be individually adjusted by controlling the control valve of each cold water secondary pump 5 so that the discharge pressures are substantially the same.

  By controlling the opening degree of the return valve 7a of the pump operation controller 131 (that is, control of the return valve pressure), the pressure of the feed cold water in the return valve 7a is predicted in advance from the design capacity value of the pump, or the actual operation results. When the maximum return valve pressure determined in advance is reached, the pump operation controller 131 adds one unit of the cold water secondary pump 5 to be operated. Moreover, when the pressure of the feed cold water in the return valve 7a reaches the minimum return valve pressure determined in advance based on the operation results, the pump operation controller 131 reduces the number of the cold water secondary pumps 5 to be operated by one. . The pump operation controller 131 is designed to suppress the sudden change in the total discharge pressure of the operating cold water secondary pump 5 when the number of the cold water secondary pumps 5 is increased or decreased. Adjust as appropriate.

(Details of operation of the cold water circulation system)
Hereinafter, the operation of the cold water circulation system according to the first embodiment will be described in more detail with reference to a flowchart.

  FIG. 2 shows an example of the operation flow of the cold water circulation system according to the first embodiment of the present invention.

  First, the cold water circulation system according to the first embodiment is activated. In this case, the cold water circulation system starts the operation by setting the initial number P of the cold water secondary pumps 5 set in advance and setting the return valve setting pressure to the initial value PaIn (step 10; hereinafter, Step is represented as “S”). Specifically, the operation of the initial number P of chilled water secondary pumps 5 is started at the opening degree of the return valve 7a at which the return valve set pressure (initial value PaIn) measured by the pump operation controller 131 is reached. Here, the initial number P is set to 80% of the total number of the chilled water secondary pumps 5 as an example.

  Next, the feed temperature detector 18 measures the temperature (T1) of the feed cold water (S12). The feed temperature detector 18 supplies a temperature signal indicating the measured feed cold water temperature to the pump operation controller 131. On the other hand, the return temperature detector 19 measures the temperature (T2) of the return cold water (S14). The return temperature detector 19 supplies a temperature signal indicating the measured return cold water temperature to the pump operation controller 131.

  Subsequently, the pump operation controller 131 calculates a detected temperature difference (ΔT = T2−T1) from the temperature of the feed cold water (actual value: T1) and the temperature of the return cold water (actual value: T2). Then, the pump operation controller 131 compares the detected temperature difference with the rated design temperature difference (ΔTS) of the load facility 81A (S16). When ΔT is equal to or less than ΔTS (ΔT ≦ ΔTS), the process proceeds to S18 (Case 1), and when large (ΔT> ΔTS), the process proceeds to S34 (Case 2). Here, as an example, the rated design temperature difference ΔTS is set in a range of about 5 ° C. to 8 ° C.

[Case 1]
First, Case 1 will be described. The pump operation controller 131 compares ΔT with a value obtained by subtracting the lower allowable value K1 from ΔTS. Then, the pump operation controller 131 determines that ΔT is equal to or less than the value obtained by subtracting the lower allowable value K1 from ΔTS (ΔT ≦ ΔTS−K1) (S18: Y), ΔT ≦ ΔTS. The time for which the relationship of -K1 continues is measured (S20). On the other hand, if ΔT> ΔTS−K1) (S18: N), the pump operation controller 131 continues to acquire a temperature signal indicating the actually measured temperature (T2) of the return chilled water. The lower allowable value K1 is variable, but is set to 0.5 ° C., for example.

  When the time during which the relationship ΔT ≦ ΔTS−K1 continues is continued for a predetermined time Y1 (S20: Y), the pump operation controller 131 sets in advance from the current return valve pressure set value PaX. The return valve pressure correction value Pa1 is reduced (S22). On the other hand, when the time during which the relationship of ΔT ≦ ΔTS−K1 continues does not continue for a predetermined time Y1 (S20: N), the pump operation controller 131 returns the measured temperature (T1) of the feed cold water and the return A temperature signal indicating the measured temperature (T2) of the cold water is continuously acquired. Here, the predetermined time Y1 is about 90 seconds as an example.

  Next, the pump operation controller 131 compares the current return valve pressure set value PaX with a predetermined minimum return valve pressure Pamin (S24). Here, the minimum return valve pressure Pamin is set to a pressure that is predicted to be necessary for each number of the chilled water secondary pumps 5 that are operated for the purpose of sending chilled water having the minimum necessary pressure in the load facility. The Further, the pump operation controller 131 can automatically adjust the minimum return valve pressure Pamin in order to improve the energy saving property of the cold water circulation system while continuing the operation of the cold water circulation system. The minimum return valve pressure Pamin may be set manually.

  When the current return valve pressure PaX is equal to or higher than the minimum return valve pressure Pamin (PaX ≧ Pamin) (S24: Y), the pump operation controller 131 stands by until the effect waiting time Y3 elapses (S26: N). Then, after the effect waiting time Y3 has elapsed, the pump operation controller 131 continues to acquire temperature signals indicating the measured temperature (T1) of the feed cold water and the measured temperature (T2) of the return cold water (S26: Y). . The effect waiting time Y3 is set in a range of 120 seconds to 180 seconds, for example.

  On the other hand, when the current return valve pressure PaX is less than the minimum return valve pressure Pamin (PaX <Pamin) (S24: N), the pump operation controller 131 reduces the number of operating cold water secondary pumps 5 by 1 (S28). . Furthermore, the pump operation controller 131 adjusts the water supply pressure of the cold water secondary pump 5 that is in operation, and the water supply pressure of the cold water secondary pump 5 that is currently in operation is equal to the water supply pressure before the operation number is reduced. The opening degree of the return valve 7a is controlled so as to be the pressure, and the current return valve pressure PaX is adjusted to a preset pressure Pa3 (S30). Note that Pa3 is a pressure higher than PaX.

  Next, the pump operation controller 131 is set in advance for the purpose of stabilizing the operation of the chilled water circulation system after adjusting the opening of the return valve 7a and setting the return valve pressure to a predetermined pressure Pa3. Wait until the effect waiting time Y5 elapses (S32: N). After the effect waiting time Y5 has elapsed, the pump operation controller 131 continues to acquire a temperature signal indicating the actually measured temperature (T2) of the return cold water (S32: Y). Here, as an example, the effect waiting time Y5 is set within a range of about 120 seconds to 180 seconds. For example, the effect waiting time Y5 is set to 120 seconds.

[Case2]
Next, Case2 will be described. The pump operation controller 131 compares ΔT with a value obtained by adding the upper allowable value K2 to ΔTS. Then, the pump operation controller 131 has a relationship of ΔT ≧ ΔTS + K2 when ΔT is a value equal to or larger than the value obtained by adding the upper allowable value K2 to ΔTS (ΔT ≧ ΔTS + K2) (S34: Y). The continuing time is measured (S36). On the other hand, when ΔT <ΔTS + K2 (S34: N), the pump operation controller 131 continues to acquire temperature signals indicating the temperature of the feed cold water (T1) and the temperature of the return cold water (T2). Here, the upper allowable value K2 is 0.3 ° C., for example.

  When the time during which the relationship of ΔT ≧ ΔTS + K2 continues for a predetermined time Y2 (S36: Y), the pump operation controller 131 returns the current return valve pressure set value PzX to a preset value. The valve pressure correction value Pa2 is added (S38). On the other hand, when the time during which the relationship ΔT ≧ ΔTS + K2 continues does not continue for a predetermined time Y2 (S36: N), the pump operation controller 131 displays a temperature signal indicating the actually measured temperature (T2) of the return cold water. Continue to get. Here, the predetermined time Y2 is about 90 seconds as an example.

  Next, the pump operation controller 131 compares the current return valve pressure set value PaX with a preset maximum return valve pressure Pamax (S40). Here, the maximum return valve pressure Pamax is set for each total number of the chilled water secondary pumps 5 being operated, and is determined in view of the amount and required pressure of the feed chilled water required by the load facility 81A included in the chilled water circulation system. Is done. When the current return valve pressure setting value PaX is equal to or lower than the maximum return valve pressure Pamax (PaX ≦ Pamax) (S40: Y), the pump operation controller 131 waits until the effect waiting time Y4 elapses (S42: N). ). Then, after the effect waiting time Y4 has elapsed, the pump operation controller 131 continues to acquire temperature signals indicating the actually measured temperature (T1) of the feed cold water and the actually measured temperature (T2) of the return cold water (S42: Y). . The effect waiting time Y4 is set, for example, in the range of 120 seconds to 180 seconds.

  On the other hand, when the return valve pressure set value PaX exceeds the maximum return valve pressure Pamax (PaX> Pamax) (S40: N), the pump operation controller 131 increases the number of operating cold water secondary pumps 5 by 1 (S44). ). Further, the pump operation controller 131 makes the water supply pressure of the cold water secondary pump 5 in operation equal, and the water supply pressure of the cold water secondary pump 5 currently in operation is equal to the water supply pressure before increasing the number of operating units. The opening degree of the return valve 7a is controlled so as to be the water supply pressure, and the current return valve pressure set value PaX is adjusted to a preset pressure Pa4 (S46). Note that Pa4 is a pressure lower than PaX.

  Next, the pump operation controller 131 is predetermined for the purpose of stabilizing the operation of the chilled water circulation system after adjusting the opening of the return valve 7a and setting the return valve pressure to a predetermined pressure Pa4. Wait until the effect waiting time Y5 elapses (S32: N). After the effect waiting time Y5 has elapsed, the pump operation controller 131 continues to acquire temperature signals indicating the temperature of the feed cold water (T1) and the temperature of the return cold water (T2) (S32: Y).

  By each of the above steps, the detected temperature difference ΔT (= T2−T1) between the feed chilled water temperature T1 measured by the feed temperature detector 18 and the return chilled water temperature T2 measured by the return temperature detector 19 is calculated as a load facility. Control to bring the rated design temperature difference ΔTS of 81A closer to TS is performed by controlling the opening degree of the return valve 7a by the pump operation controller 131 and controlling the number of operating chilled water secondary pumps 5, and the chilled water circulation system. Operation is continued.

(Effects of the first embodiment)
The chilled water circulation system according to the first embodiment sets the temperature of the feed chilled water in advance and controls the amount of feed chilled water in a direction to reduce the absolute value of the difference between the detected temperature difference and the rated design temperature difference. Is controlled by controlling the opening degree of the return valve 7a, so that the amount of water supplied by the cold water secondary pump 5 is controlled to an optimum amount that does not become excessive or insufficient without installing a power inverter in the cold water secondary pump 5. it can. Thereby, the driving power (namely, energy consumption) of the whole chilled water circulation system can be reduced, energy efficiency can be improved, and the equipment cost of the chilled water circulation system can be reduced.

  More specifically, the chilled water circulation system according to the first embodiment is configured to measure the temperature and measurement of the feed chilled water corresponding to the amount of cold heat required by the load facility that is constantly changing during operation of the chilled water circulation system. Since the control of making the amount of chilled water delivered variable while bringing the detected temperature difference from the temperature of the returned chilled water close to the rated design temperature difference of the load equipment, the load equipment 81A is the temperature difference of the heat exchange part as designed. It is possible to supply the load facility 81 </ b> A with an appropriate flow rate of feed cold water that can sufficiently function and is neither excessive nor insufficient. As a result, the total power of the chilled water primary pump 1 and the chilled water secondary pump 5 for circulating the chilled water can be greatly reduced and returned compared to the water supply method in which the feed pressure is made constant (that is, the amount of water tends to be excessive). The temperature of the cold water can be brought close to the rated suction temperature of the refrigerator 3. As a result, the coefficient of performance of the refrigerator 3 can be improved. Furthermore, according to the chilled water circulation system according to the present embodiment, even if the amount of cooling heat in the load facility 81A is changed, the temperature of the return chilled water is increased because the pressure of the fed chilled water is changed and set. It can suppress that it becomes too low or becomes too low, and the fall of the operating efficiency of the refrigerator 3 can be suppressed. Therefore, according to the chilled water circulation system according to the present embodiment, the power of the chilled water secondary pump 5 can be reduced and the power of the refrigerator 3 can be reduced to cool the same amount of cooling heat as in the prior art. .

  Further, the chilled water circulation system according to the present embodiment does not immediately start the operation when the excess or deficiency of the chilled water required by the load facility 81A is slight, but only when the limit amount is exceeded for a certain period of time. Therefore, the appropriate opening degree of the return valve 7a and the number of operating secondary chilled water pumps 5 can be determined gradually and reliably. As a result, the chilled water circulation system can be controlled in a manner close to the judgment criteria of a skilled coordinator, and the operation of the facility can be automatically managed.

  Furthermore, the chilled water circulation system according to the present embodiment automatically reduces the number of operating refrigerators 3 to the minimum number and automatically operates the refrigerator 3 with the highest efficiency operation. The overall energy reduction can be realized automatically.

(Modification of the first embodiment)
FIG. 3: shows the outline | summary of a structure of the cold water circulation system which concerns on the modification of the 1st Embodiment of this invention.

  The cold water circulation system according to the modification of the first embodiment is different from the cold water circulation system according to the first embodiment except that the number of load facilities is different. It has the same configuration as the system. Therefore, except for the differences, detailed description is omitted.

  The chilled water circulation system according to the modification of the first embodiment includes a plurality of load facilities (for example, load facility 81A and load facility 81B). Then, the return chilled water from the load facility 81A and the load facility 81B passes through the return pipe connected to the load facility 81A and the return pipe connected to the load facility 81B to the return header 9 as the second aggregate portion. Supplied. The return cold water from the load equipment 81A and the load equipment 81B merges in the return header 9. Then, the return cold water supplied to the return header 9 is supplied to the refrigerator 3 via the cold water primary pump 1.

  Moreover, the cold water from the refrigerator 3 is supplied to the feed header 6b. The cold water secondary pump 5 supplies necessary amount of feed cold water to the load equipment 81A and the load equipment 81B among the cold water supplied from the refrigerator 3 to the feed header 6b. The feed cold water is supplied to each of a plurality of load facilities through a plurality of feed pipes connected to a feed header 6a as a first aggregate portion. Note that the load facility 81A and the load facility 81B have substantially the same configuration.

(Outline of operation of the cold water circulation system according to the modification of the first embodiment)
The operation of the cold water circulation system when the cold water circulation system is activated is the same as that of the cold water circulation system according to the first embodiment. However, based on the detected temperature difference, the value of the detected temperature difference between the measured feed chilled water temperature and the measured return chilled water temperature approaches the rated design temperature difference between the load facility 81A and the load facility 81B. Corrections are made to the control of the opening degree of the return valve 7a and the control of the number of operating cold water secondary pumps 5 in the pump operation controller 131, and the operation of the cold water circulation system is continued.

  Then, after the chilled water circulation system has been operated for a certain period of time, the pump operation controller 131 compares the detected temperature difference with the rated design temperature difference. Further, the pump operation controller 131 determines whether or not the difference between the detected temperature difference and the rated design temperature difference exceeds a predetermined allowable value. The pump operation controller 131 determines the current opening degree of the return valve 7a as the absolute value of the difference between the detected temperature difference and the rated design temperature difference when the time exceeding the allowable value continues for a predetermined time. Correct in the direction that becomes smaller. Thereby, the cold water circulation system continues the operation of bringing the detected temperature difference close to the rated design temperature difference.

  Then, by controlling the opening degree of the return valve 7a of the pump operation controller 131, the pressure of the feed cold water in the return valve 7a is changed in advance (in consideration of the number of the cold water secondary pumps 5 operating at that time). When the maximum return valve pressure predicted from the design capacity value or determined in advance based on the operation performance is reached, the pump operation controller 131 adds one unit of the cold water secondary pump 5 to be operated. Moreover, when the pressure of the feed cold water in the return valve 7a reaches the minimum return valve pressure determined in advance based on the operation results, the pump operation controller 131 reduces the number of the cold water secondary pumps 5 to be operated by one. .

  In controlling the operation of the chilled water circulation system, for example, when it is known in advance that the load facility 81A requires a higher water supply source pressure than the load facility 81B, the temperature detector included in the load facility 81A. It is possible to provide a mechanism for supplying in advance an alarm signal indicating a temperature abnormality (insufficient cooling) due to an insufficient amount of cold water from 23A and the control signal transmitter 24A to the pump operation controller 131. In this case, based on the alarm signal, the pump operation controller 131 increases the amount of cold water from the cold water secondary pump 5 to the load facility 81A until the alarm signal disappears (for example, reduces the opening degree of the return valve 7a). Control) with the highest priority.

[Second Embodiment]
FIG. 4 shows an outline of the configuration of the cold water circulation system according to the second embodiment of the present invention.

  The chilled water circulation system according to the second embodiment is different from the chilled water circulation system according to the modification of the first embodiment, except that a pressurizing pump is further provided in the front stage of the load facility. The same structure as the cold water circulation system which concerns on the modification of a form is provided. Therefore, except for the differences, detailed description is omitted.

  In the chilled water circulation system according to the second embodiment, the pressure of the chilled water fed from the chilled water secondary pump 5 among the plurality of load facilities (that is, the load facility 81A and the load facility 81B) is the inlet side of the load facility. In other words, a pressurizing pump 40 as a pressure variable unit is provided in the front stage of the load facility that is significantly reduced in the front side of the control two-way valve 16 into which the feed cold water supplied toward the load facility flows. The pressurizing pump 40 changes the pressure of the feed cold water supplied to the load facility. Specifically, the pressurizing pump 40 pressurizes the pressure of the feed cold water supplied to the load facility to a pressure required by the load facility. The pressurizing pump 40 can be a pump smaller than the cold water secondary pump 5.

  The load facility in which the pressure of the feed chilled water is significantly reduced at the inlet of the load facility is, for example, a load installed at a position far away from the chilled water secondary pump 5 among a plurality of load facilities provided in the chilled water circulation system. From the position where the facility or the chilled water secondary pump 5 is installed as a reference, the load facility installed at a particularly high place from that position, or until the chilled water sent by the chilled water secondary pump 5 reaches the load facility It is a load facility or the like having a particularly large pressure loss in the piping.

  In addition, the valve as a pressure variable part can also be provided in piping at the entrance side of the load facility. By adjusting this valve, the pressure of the feed cold water supplied to the load facility can be reduced or increased. With this valve, the balance of the water pressure of the entire chilled water circulation system can be adjusted, and in the stage before the chilled water directed to each load facility passes through each control two-way valve 16, the fed chilled water can be distributed appropriately. As a result, the present system can be operated more effectively.

  In the cold water circulation system according to the second embodiment, since the pressurization pump 40 can be installed in the front stage of the load equipment, even if the load equipment is installed at a position away from the cold water secondary pump 5 or the like. In addition, it is possible to appropriately supply the load equipment with feed water at a pressure required for the load equipment.

  While the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. In addition, it should be noted that not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

DESCRIPTION OF SYMBOLS 1 Cold water primary pump 3 Refrigerator 5 Cold water secondary pump 6 Feed header 7 Return pipe 7a Return valve 9 Return header 11 Flow meter 16 Control two-way valve 17A, 17B Cooling object 18 Feed temperature detector 19 Return temperature detector 23A, 23B Temperature detector 24A, 24B Control signal transmitter 31 Cooling tower 32 Cooling water pump 40 Pressurizing pump 60 Pressure gauge 81A, 81B Load equipment 131 Pump operation controller

Claims (6)

Load equipment whose required water volume is continuously adjusted by the control valve;
A refrigerator that cools the return chilled water from the load facility and feeds it to the load facility; and
A cold water primary pump for supplying the return cold water flowing through a pipe connected to the refrigerator from the load facility to the refrigerator;
A plurality of chilled water secondary pumps operating at a power frequency in an installed area and supplying the feed chilled water flowing through a pipe connected from the refrigerator to the load facility to the load facility;
Has a return valve for controlling the pressure of the feed cold water to be water to load equipment between the load facility and the chilled water secondary pump, the feed from the previous SL chilled water secondary pump is water in the load facility and went back tube can Kayes towards the suction part before Symbol chilled water secondary pump cold water,
A pump operation controller that controls to adjust the return valve so that the pressure of the feed cold water between the cold water secondary pump and the load facility becomes a set value ;
The pump operation controller corrects the set value in a direction in which the absolute value of the difference between the detected temperature difference between the feed cold water temperature and the return cold water temperature and the rated design temperature difference of the load equipment decreases. Control
When the set value exceeds a preset maximum pressure for each total number of the chilled water secondary pumps being operated, the number of chilled water secondary pumps to be operated is increased, and the set value is set to be higher than the set value. Control to lower to a lower preset value,
When the set value is less than the preset minimum pressure for each total number of the chilled water secondary pumps being operated, the number of chilled water secondary pumps to be operated is reduced, and the set value is set from the set value. Chilled water circulation system that performs control to raise to a higher preset value . Before SL pump operation controller, chilled water circulation system according to claim 1 for controlling the opening of the return valve. The pump operation controller is configured such that the time when the absolute value of the difference between the detected temperature difference and the rated design temperature difference deviates from a preset allowable value continuously for a predetermined time or in advance The chilled water circulation system according to claim 2, wherein the set value is corrected when the accumulated value has passed within a set time, and the pressure of the feed cold water to the load facility is adjusted to the corrected set value .   The cold water circulation system according to claim 3, further comprising a pressure variable unit that changes a pressure of the feed cold water supplied to the load facility in front of the load facility.   The chilled water circulation system according to claim 4, wherein the pressure variable unit is a pressurizing pump smaller than the chilled water secondary pump. A plurality of the load facilities;
The feed cold water is fed through a plurality of feed pipes to each of the plurality of load facilities,
Each of the plurality of load facilities sends the return cold water to the refrigerator through a plurality of return pipes,
The feed cold water temperature is a temperature set in advance in a first assembly portion of the plurality of feed pipes,
The chilled water circulation system according to any one of claims 1 to 5, wherein the return chilled water temperature is measured at a second assembly portion of the plurality of return pipes.

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