JP2011179755A - Cold-water circulating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cold-water circulating system that prevents operation performance of a refrigerator from being reduced. <P>SOLUTION: The cold-water circulating system includes a load facility 81A, a refrigerator 3, a cold-water primary pump 1, a cold-water secondary pump 5 having a power inverter 51 and supplying cold-water of an amount corresponding to the operating frequency of the power inverter 51 to the load facility 81A, and a pump operation controller 131 controlling the water amount of the cold-water to be fed from the refrigerator 3 to the load facility 81A by controlling the operating frequency. The pump operation controller 131 controls the water amount to be fed to the load facility 81A by controlling the operating frequency to a direction in which an absolute value of a difference between a temperature difference calculated from a preset control target temperature of the cold-water to be fed from the refrigerator 3 to the load facility 81A and a return cold-water temperature obtained by measuring a temperature of cold-water returned from the load facility 81A to the refrigerator 3 and a rated design temperature difference of the load facility 81A, based on the calculated temperature difference. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cold water circulation system. In particular, the present invention relates to a cold water circulation system that can save energy.

  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 water supplied from the chilled water secondary pump to the load facility can be controlled to an optimum amount, so that it exhibits extremely excellent effects from the viewpoint of energy saving. Can do.

JP 2007-155232 A

  However, in the chilled water circulation system described in Patent Document 1, when the actual feed chilled water temperature changes, the control target temperature of the return chilled water calculated by adding the rated design temperature difference based on this changes to the ideal value. There is a case where it is far from the rated design temperature (cold water return rated temperature) on the side of taking in cold water of a certain refrigerator. For example, when the capacity of the cooling tower of the refrigerator is insufficient in the summer, a situation may occur in which the actual feed cold water temperature becomes too higher than the target feed cold water temperature. If a value obtained by adding a rated design temperature difference to this is controlled as the control target temperature of the return chilled water, the temperature of the return chilled water is also far from the ideal value (rated design temperature). For this reason, due to an overload on the refrigerator, the actual capacity of the feed cold water may further increase without being able to sufficiently cool the original capacity of the refrigerator. Therefore, there is room for improvement in the control for circulating the cold water for sufficiently stably cooling the returned cold water returning from the load facility.

  Accordingly, an object of the present invention is to provide a chilled water circulation system capable of minimizing the circulation amount of chilled water while enhancing the reliability of the refrigerator to continue a highly efficient cooling operation in order to achieve further stable energy saving. There is.

  In order to achieve the above-mentioned 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 cold water from the load facility and feeds it to the load facility, and a return A chilled water primary pump that supplies chilled water to the refrigerator and a power inverter, and a water supply amount and a water supply pressure corresponding to the operating frequency of the power inverter (hereinafter referred to as the “water supply amount” means the “water supply amount and water supply pressure”). A chilled water secondary pump that supplies chilled water to the load facility, and a pump operation controller that adjusts the amount of chilled water fed from the refrigerator to the load facility by controlling the operating frequency, From the preset control target temperature of the feed cold water sent from the refrigerator to the load facility and the return cold water temperature obtained by measuring the temperature of the return cold water returned from the load facility to the refrigerator by the pump operation controller Calculation Cold water circulation system that adjusts the amount of water delivered to the load equipment by controlling the operating frequency based on the calculated temperature difference in a direction that the absolute value of the difference between the calculated temperature difference and the rated design temperature difference of the load equipment decreases Is provided.

  In the chilled water circulation system, the time when the pump operation controller deviates from the preset allowable value for the absolute value of the difference between the calculated temperature difference and the rated design temperature difference continues for a predetermined time. Or when it has accumulated too much within a preset time, the amount of cold water fed to the load facility can be adjusted.

  In the chilled water circulation system, the pump operation controller increases the number of chilled water secondary pumps when the operating frequency of the power inverter reaches a preset maximum frequency, and reaches a preset minimum frequency. In some cases, the number of operating cold water secondary pumps can be reduced.

  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 pressure pump 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. Is supplied to the refrigerator, the control target temperature is a temperature set in advance in the first aggregate portion of the plurality of feed pipes, and the return cold water temperature is measured in the second aggregate portion of the plurality of return pipes May be.

  According to the chilled water circulation system according to the present invention, the chilled water circulation system capable of minimizing the circulation amount of the chilled water while increasing the reliability of the refrigerator to continue the efficient cooling operation in order to achieve further stable energy saving. Can provide.

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, the refrigerator 3 that cools the returned chilled water from the load facility 81 </ b> A and feeds the chilled water to the load facility 81 </ b> A, and the power inverter 51 are attached, and the amount of water fed according to the operating frequency of the power inverter 51 By controlling the operation of the cold water secondary pump 5 for supplying the cold water (that is, the cold water sent from the refrigerator 3) to the load facility 81A and the power inverter 51 attached to the cold water secondary pump 5. A pump operation controller 131 that adjusts the amount of cold water fed from the secondary pump 5 to the load facility Note that the cold water circulation system according to the first embodiment can include one or more cold water secondary pumps 5.

  In addition, 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 supplies feed 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 the cold water secondary pump 5 to which the power inverter 51 is attached is arrange | positioned as an example so that the feed header 6a and the feed header 6b may be connected between the feed header 6a and the feed header 6b.

  Further, between the feed header 6a and the feed header 6b, excess water (hereinafter referred to as “excess water”) in the feed cold water sent from the refrigerator 3 to the load facility 81A is transferred from the feed header 6a to the feed header 6b. A return pipe 7 to be returned may be connected. However, although details will be described later, in the chilled water circulation system according to the present embodiment, the amount of the chilled water fed to the load facility 81A is controlled by the power inverter 51, and thus the return pipe 7 may not be provided. That is, the return pipe 7 does not need to be removed when it is provided in an existing cold water circulation system. Moreover, when the existing cold water circulation system is not provided with the return pipe 7, it is not necessary to newly install the return pipe 7. Note that 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 a control valve of the load facility 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. Here, the chilled water secondary pump 5 is provided with a power inverter 51 that adjusts the amount of water sent by the chilled water secondary pump 5 by automatically changing the frequency of the operating power (that is, the operating frequency). The frequency of the power inverter 51 is controlled by the pump operation controller 131. That is, the cold water secondary pump 5 supplies a necessary amount of feed cold water to the load facility 81A via the feed header 6a in accordance with the frequency of the power inverter 51 controlled by the pump operation controller 131.

  Each of the plurality of cold water secondary pumps 5 has a water supply pipe for supplying the supplied cold water to the load facility. 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 feed 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.

(Load equipment)
The load facility 81A cools the cooling object 17A (for example, indoor air when the load facility 81A is an air conditioner). 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 converter 24A for controlling the opening 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 converter 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 converter 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 cold water supplied to the load facility 81A rises in proportion to the size of the load and returns to the cold water. The return cold water is supplied to the return header 9 through a return pipe connected to the load facility 81A. 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 operates the number of chilled water secondary pumps 5 and the operating frequency of the power inverter 51 so that the calculated temperature difference between the feed chilled water temperature and the return chilled water temperature approaches the rated design temperature difference of the load equipment 81A. And control. Thereby, the pump operation controller 131 controls the amount of cold water fed from the refrigerator 3 to the load facility 81A. That is, the pump operation controller 131 controls the number of operating chilled water secondary pumps 5 and the operating frequency of the power inverter 51 so as to ensure the maximum temperature difference in the heat exchange design of the load facility 81A. Control the amount of water delivered.

  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 chilled water circulation system according to the present embodiment is a temperature difference based on the design specification of the load facility 81A (that is, the temperature of the cold water entering the load facility 81A is heat-exchanged in the load facility 81A). A value obtained by adding a certain correction to the temperature of the water discharged from the load equipment 81A later) can also be set as the rated design temperature difference (for example, a value obtained by subtracting 0.5 ° C. from the temperature difference). Can be set as the rated design temperature difference in the load equipment 81A).

  In the first embodiment, the pump operation controller 131 gives priority to controlling the operation frequency of the power inverter 51 and controlling the water supply amount of the cold water secondary pump 5. For example, when the amount of feed cold water requested by the load facility 81A cannot be controlled by the control of the operation frequency, the pump operation controller 131 controls the number of operating cold water secondary pumps 5 (that is, Control the increase / decrease in the number of operating units).

  Here, the temperature of the feed cold water is set, for example, as a target temperature to be controlled (hereinafter sometimes referred to as “control target temperature”) in the feed temperature setting unit 18 installed in the feed pipe or feed header 6a. Is done. That is, in the present embodiment, the temperature of the feed cold water fed from the refrigerator 3 to the load facility 81A is a predetermined temperature (that is, a control target temperature). The feed temperature setter 18 can also measure the feed cold water temperature. The feed temperature setter 18 can also supply a temperature signal indicating the measured temperature to the pump operation controller 131. In this embodiment, the pump operation controller 131 and the feed temperature setting unit 18 are separate from each other. However, when the feed temperature setting unit 18 has a function as a temperature setting unit, The temperature setting device 18 can be integrated with the pump operation controller 131 as a part of the pump operation controller 131. For example, the pump operation controller 131 can include a dial switch or a dip switch that sets a control target temperature. In addition, a control target temperature may be programmed and set in advance in a ROM included in a control board (not shown) in the pump operation controller 131.

  Further, the temperature of the return cold water is measured by, for example, a return temperature detector 19 installed in the return header 9 or a pipe connected to the preceding 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.

Then, the pump operation controller 131 calculates the temperature difference calculated from the control target temperature set in the feed temperature setter 18 and the return chilled water temperature indicated by the temperature signal received from the return temperature detector 19 (that is, The difference between the control target temperature and the return chilled water temperature) and the rated design temperature difference of the load facility 81A are controlled to control the operating frequency based on the calculated temperature difference. That is, when the pump driving controller 131, the control target temperature set in the temperature setting device 18 for feeding the T _1SP, the by the return chilled water temperature measured at the temperature detector 19 for return to the T _2PV, [Delta] T = The operating frequency of the power inverter 51 is controlled so that the value of T _2PV -T _1SP 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.

(Frequency control mechanism of power inverter 51)
The pump operation controller 131 has a frequency control unit that controls the operation frequency of the power inverter 51. The frequency control unit has a difference between a calculated temperature difference (ΔT) between a predetermined control target temperature (T _1SP ) and the measured return chilled water temperature (T _2PV ) and a rated design temperature difference of the load facility 81A in advance. Calculates the operating frequency of the power inverter 51 and the rated design when the time deviating from the set allowable value has accumulated a predetermined time continuously or accumulated within the time set in advance. The absolute value of the difference from the temperature difference is changed to be 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 feed 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 fixed time”, and “predetermined time” indicate that the efficiency of the chilled water circulation system is optimal after the start of the chilled water circulation system operation. 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 increases the operating number of the chilled water secondary pumps 5 when the operating frequency continues for a preset time starting from when the operating frequency of the power inverter 51 reaches the preset maximum frequency. Let In addition, the operation number control unit starts the operation when the operation frequency of the power inverter 51 reaches the preset minimum frequency, and the operation number of the chilled water secondary pumps 5 when the operation frequency continues for a preset time. Reduce. Thereby, the chilled water circulation system can increase or decrease the amount of chilled water supplied to the load facility 81 </ b> A to a difficult range only by adjusting the operating frequency of the power inverter 51. The chilled water circulation system adjusts the operating frequency of the power inverter 51 and controls the number of operating chilled water secondary pumps 5 so that the temperature of the returned chilled water is operated with high operating efficiency (coefficient of performance). The temperature range can be maintained.

  Here, the maximum frequency in the present embodiment is preferably set to a commercial operation frequency (for example, 50 Hz or 60 Hz) in a region where the chilled water circulation system according to the present embodiment is used. In addition, the lowest frequency in the present embodiment is set in the load facility after considering 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 to a frequency (for example, 25 to 35 Hz) that can be generated. The maximum frequency and the minimum frequency can be adjusted as appropriate so that the operation of the chilled water circulation system is optimized.

(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 chilled water circulation system is operated at the initial operating frequency of the power inverter 51 and the initial number of the chilled water secondary pumps 5 set in advance in the pump operation controller 131. Thereafter, the value of the calculated temperature difference between the preset feed cold water temperature and the actually measured return cold water temperature is brought close to the rated design temperature difference of the load equipment 81A (that is, the calculated temperature difference and the rated temperature difference). Based on the calculated temperature difference, the frequency of the power inverter 51 in the pump operation controller 131 and the number of operating chilled water secondary pumps 5 are modified to operate the chilled water circulation system. Will continue.

  Then, after the chilled water circulation system has been operated for a certain period of time, the pump operation controller 131 compares the calculated temperature difference with the rated design temperature difference. Then, the pump operation controller 131 determines whether or not the difference between the calculated temperature difference and the rated design temperature difference exceeds a predetermined allowable value. The pump operation controller 131 determines the operating frequency of the power inverter 51 that is currently operating when the time exceeding the allowable value continues for a predetermined time, and the difference between the calculated 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 calculated temperature difference close to the rated design temperature difference.

  Here, 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 power is adjusted so that their discharge pressures are substantially the same. Correction can be made to the set frequency of the inverter 51.

  When the operation frequency of the power inverter 51 reaches the maximum frequency by controlling the operation of the chilled water circulation system, the pump operation controller 131 adds one chilled water secondary pump 5 to be operated. When the operating frequency of the power inverter 51 reaches the lowest frequency, 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 for operating frequency of the power inverter 51 for the purpose of suppressing a 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.

(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 chilled water circulation system starts operation at the initial set frequency HzIn with the number P of the initial chilled water secondary pumps 5 set in advance (step 10; hereinafter, step is expressed as “S”). Specifically, the operation of the initial number P of the cold water secondary pumps 5 is started at the initial frequency HzIn of the power inverter 51 preset in the pump operation controller 131. Here, the initial number P is set to 80% of the total number of the chilled water secondary pumps 5 as an example. Moreover, the initial frequency HzIn is set to 48.5 Hz as an example.

Next, the feed temperature setter 18 supplies a temperature signal indicating the set feed cold water temperature to the pump operation controller 131. And the temperature based on the said temperature signal is set to the pump operation controller 131 as control target temperature ( _T1SP ) (S12). Here, the control target temperature (T _1SP ) of the feed cold water is set, for example, at a temperature in the range of 7.0 ° C. or more and 8.0 ° C. or less. In addition, the temperature of feed cold water does not necessarily need to be a rated value (that is, the rated temperature on the inlet side of the load facility 81A). Next, the return temperature detector 19 measures the temperature (T _2PV ) 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 temperature difference (ΔT = T _2PV −T) from the temperature of the feed cold water (set value [control target temperature]: T _1SP ) and the temperature of the return cold water (actual value: T _2PV ). _1SP ) is calculated. Then, the pump operation controller 131 compares the calculated temperature difference with the rated design temperature difference (ΔTS) between the load facility 81A and the load facility 81B (S16). When ΔT is equal to or smaller 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. or more and 8 ° C. or less.

[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, when ΔT is a value equal to or less than the value obtained by subtracting the lower allowable value K1 from ΔTS (ΔT ≦ ΔTS−K1) (S18: Y), the relationship of ΔT ≦ ΔTS−K1 is continued. The time to perform 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 (T _2PV ) of the return chilled water. The lower allowable value K1 is variable, but is set to 0.5 ° C., for example.

And when the time which the relationship of (DELTA) T <= (DELTA) TS-K1 continues only for the predetermined time Y1 (S20: Y), the pump operation controller 131 preset from the present operating frequency HzX of the power inverter 51. The operating frequency Hz1 is reduced (S22). The operating frequency Hz1 is set to 1.5 Hz, for example. On the other hand, when the time for which the relationship of ΔT ≦ ΔTS−K1 continues does not continue for a predetermined time Y1 (S20: N), the pump operation controller 131 indicates the temperature indicating the actually measured temperature (T _2PV ) of the return cold water. Continue to acquire the signal. Here, the predetermined time Y1 is about 90 seconds as an example.

  Next, the pump operation controller 131 compares the current operation frequency HzX with the lowest frequency Hzmin (S24). Here, the minimum frequency Hzmin is set to a frequency that can generate a pressure predicted to be necessary for the purpose of sending a minimum amount of cold water in the load facility, and is 30 Hz as an example. Further, the pump operation controller 131 can automatically adjust the minimum frequency Hzmin 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 frequency Hzmin may be set manually.

When the operation frequency HzX is equal to or higher than the minimum frequency Hzmin (HzX ≧ Hzmin) (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 a temperature signal indicating the actually measured temperature (T _2PV ) 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 operating frequency HzX is less than the lowest frequency Hzmin (HzX <Hzmin) (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 current operating frequency HzX of the plurality of power inverters 51 is adjusted to a preset operating frequency Hz3 (for example, a frequency close to the maximum frequency, for example, 48.5 Hz) so as to be the pressure (S30). ). When the characteristics of the plurality of chilled water secondary pumps 5 are different from each other, the pump operation controller 131 stores the operation frequency Hz3 as data in association with the secondary pump identifier that uniquely identifies each chilled water secondary pump 5. The operating frequency Hz3 is adjusted based on such data.

Next, after setting the operation frequency Hz3 of the power inverter 51, the pump operation controller 131 waits until a predetermined effect waiting time Y5 elapses for the purpose of stabilizing the operation of the chilled water circulation system ( 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 (T _2PV ) of the returned 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 measures the time during which the relationship of ΔT ≧ ΔTS + K2 continues 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). (S36). On the other hand, when ΔT <ΔTS + K2 (S34: N), the pump operation controller 131 continues to acquire a temperature signal indicating the temperature of the return cold water (T _2PV ). Here, the upper allowable value K2 is 0.3 ° C., for example.

And when the time which the relationship of (DELTA) T> = (DELTA) TS + K2 continues continues only for the predetermined time Y2 (S36: Y), the pump operation controller 131 is the operation frequency preset to the present operation frequency HzX of the power inverter 51. Hz2 is added (S38). The operating frequency Hz2 is set to 1.5 Hz, for example. 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 _generates a temperature signal indicating the actually measured temperature (T _2PV ) of the return chilled water. Continue to acquire. Here, the predetermined time Y2 is about 90 seconds as an example.

Next, the pump operation controller 131 compares the current operation frequency HzX with a preset maximum frequency Hzmax (S40). Here, the preset maximum frequency Hzmin is, for example, a commercial frequency in a region where the chilled water circulation system is installed (that is, 50 Hz or 60 Hz). When the operation frequency HzX is equal to or lower than the maximum frequency Hzmax (HzX ≦ Hzmax) (S40: Y), the pump operation controller 131 stands by 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 a temperature signal indicating the actually measured temperature (T _2PV ) 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 operating frequency HzX exceeds the maximum frequency Hzmax (HzX> Hzmax) (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 current operating frequency HzX of the plurality of power inverters 51 is adjusted to a preset operating frequency Hz4 (for example, 30 Hz) so as to be the water supply pressure (S46). When the characteristics of the plurality of chilled water secondary pumps 5 are different from each other, the pump operation controller 131 stores the operation frequency Hz4 as data in association with the secondary pump identifier, and based on such data, the operation frequency Adjust Hz4.

Next, after setting the operation frequency Hz4 of the power inverter 51, the pump operation controller 131 waits until a predetermined effect waiting time Y5 elapses for the purpose of stabilizing the operation of the chilled water circulation system ( S32: N). After the effect waiting time Y5 has elapsed, the pump operation controller 131 continues to acquire a temperature signal indicating the temperature of the return cold water (T _2PV ) (S32: Y).

By each of the above steps, the calculated temperature difference ΔT (= T _2PV −T _1SP ) between the control target temperature T _1SP set by the feed temperature setter 18 and the temperature T _2PV actually measured by the return temperature detector 19 is loaded. Control to bring the rated design temperature difference ΔTS of the equipment 81A and the load equipment 81B closer to each other is performed by controlling the operating frequency of the power inverter 51 and the number of operating chilled water secondary pumps 5 by the pump operation controller 131. Driving continues.

(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 that reduces the absolute value of the difference between the calculated temperature difference and the rated design temperature difference. The amount of water fed by the cold water secondary pump 5 can be controlled to an optimum amount that does not become excessive or insufficient. Thereby, the driving power (consumption energy) of the whole cold water circulation system can be reduced, and energy efficiency can be improved.

  More specifically, the chilled water circulation system according to the first embodiment has a preset feed chilled water temperature corresponding to the amount of heat required by the load facility that is constantly changing during operation of the chilled water circulation system. Control is made to make the water supply variable while making the calculated temperature difference from the measured return cold water temperature close to the rated design temperature difference of the load equipment, so the load equipment functions sufficiently with the temperature difference of the heat exchange part as designed. In addition, it is possible to supply the load equipment with feed water that has an appropriate flow rate that is neither excessive nor insufficient. This makes it possible to significantly reduce the power of the chilled water circulation system and to bring the temperature of the return chilled water closer to the rated suction temperature of the refrigerator, compared to a method in which the feed pressure is constant (ie, the amount of water tends to be excessive). it can. As a result, the coefficient of performance of the refrigerator can be improved. Furthermore, according to the chilled water circulation system according to the present embodiment, even when the load of the load facility is changed, the temperature of the feed chilled water is set in advance, so that the temperature of the returned chilled water becomes too high or too low. (That is, the temperature of the return chilled water is a rated value and can be set to an optimum value), and a decrease in operating performance of the refrigerator can be suppressed. Therefore, according to the cold water circulation system according to the present embodiment, the power of the cold water secondary pump 5 can be reduced and the power of the refrigerator can be reduced, so that the energy saving effect can be increased.

  In addition, the chilled water circulation system according to the present embodiment does not start the operation immediately when the excess or deficiency of the chilled water required by the load facility is slight, and operates the chilled water secondary pump 5 only when the limit amount is exceeded for a certain time. Since the frequency and the number of operating units are changed, the appropriate operating frequency and the operating number of the secondary chilled water pumps 5 can be determined gently 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.

(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 calculated temperature difference, the value of the calculated temperature difference between the preset cold water temperature and the actually measured return cold water temperature approaches the rated design temperature difference between the load equipment 81A and the load equipment 81B. Then, the frequency of the power inverter 51 and the number of operating cold water secondary pumps 5 in the pump operation controller 131 are corrected, and the operation of the cold water circulation system is continued.

  After the chilled water circulation system has been operated for a certain period of time, the pump operation controller 131 compares the calculated temperature difference with the rated design temperature difference, and the difference between the calculated temperature difference and the rated design temperature difference is determined in advance. Determine whether the value is exceeded. The pump operation controller 131 determines the operating frequency of the power inverter 51 that is currently operating when the time exceeding the allowable value continues for a predetermined time, and the difference between the calculated 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 calculated temperature difference close to the rated design temperature difference.

  When the operation frequency of the power inverter 51 reaches the maximum frequency by controlling the operation of the chilled water circulation system, the pump operation controller 131 adds one chilled water secondary pump 5 to be operated. When the operating frequency of the power inverter 51 reaches the lowest frequency, the pump operation controller 131 reduces the number of the cold water secondary pumps 5 to be operated by one.

  Further, 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 pressure than the load facility 81B, the temperature detector 23A and the control signal included in the load facility 81A A mechanism for supplying an alarm signal indicating a temperature abnormality in advance from the converter 24A to the pump operation controller 131 can be provided. In this case, based on the alarm signal, the pump operation controller 131 performs control to increase the amount of feed cold water supplied from the cold water secondary pump 5 to the load facility 81A until the alarm signal disappears.

[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 preceding stage of the load facility that is most lowered 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 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.

  In addition, the load equipment in which the pressure of feed cold water falls most at the entrance of the load equipment is, for example, a load equipment installed at a position farthest from the cold water secondary pump 5 among a plurality of load equipments included in the cold water circulation system. Or, based on the position where the chilled water secondary pump 5 is installed as a reference, until the chilled water sent from the chilled water secondary pump 5 reaches the load facility. This is a load facility or the like having a large pressure loss portion in the pipe.

  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 increased or decreased. With this valve, the balance of the water pressure in the entire chilled water circulation system can be adjusted, and the feed chilled water can be appropriately distributed to each load facility.

  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 6a, 6b Feed header 7 Return pipe 8 Load equipment 9 Return header 11 Flow meter 16 Control two-way valve 17A, 17B Cooling object 18 Feed temperature setting device 19 Return temperature Detector 24A, 24B Control signal converter 31 Cooling tower 32 Cooling water pump 40 Pressure pump 51 Power inverter 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 to the refrigerator;
A cold water secondary pump having a power inverter, and supplying the load cold water with the water supply amount and the water supply pressure according to the operation frequency of the power inverter to the load facility;
A pump operation controller that adjusts the amount of water supplied from the refrigerator to the load facility by controlling the operation frequency;
The pump operation controller is obtained by measuring a preset control target temperature of the feed cold water fed from the refrigerator to the load facility and a temperature of the return cold water returned from the load facility to the refrigerator. By controlling the operating frequency based on the calculated temperature difference in a direction in which the absolute value of the difference between the calculated temperature difference calculated from the returned chilled water temperature and the rated design temperature difference of the load equipment decreases. A cold water circulation system for adjusting the amount of water supplied to the load facility.   The time when the absolute value of the difference between the calculated temperature difference and the rated design temperature difference deviates from a preset allowable value, the pump operation controller continuously for a predetermined time, or in advance The chilled water circulation system according to claim 1, wherein the amount of the chilled water supplied to the load facility is adjusted when the accumulated amount has passed within the set time.   When the operating frequency of the power inverter reaches a preset maximum frequency, the pump operation controller increases the number of operating cold water secondary pumps, and when the operating frequency of the power inverter reaches a preset minimum frequency, The cold water circulation system according to claim 2, wherein the number of operating next pumps is reduced.   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 cold water circulation system according to claim 4, wherein the pressure variable unit is a pressurizing pump smaller than the cold water secondary pump. A plurality of the load facilities;
The feed cold water is fed to each of the plurality of load facilities through a plurality of feed pipes,
Each of the plurality of load facilities sends the return cold water to the refrigerator through a plurality of return pipes,
The control target 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 2 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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