HEAT SOURCE SYSTEM, CONTROL DEVICE, CONTROL METHOD, AND PROGRAM

Abstract

A heat source system includes a heat source machine, a cooling tower side outward path and a cooling tower side return path that are connected to the heat source machine, a load side outward path and a load side return path that are connected to the heat source machine, a heat exchange path provided in one of the load side return path and the cooling tower side outward path, a heat exchanger that performs heat exchange between the heat exchange path and the other one of the load side return path and the cooling tower side outward path, and a heat exchange adjustment valve capable of adjusting a flow rate of the heat exchange path.

Description

TECHNICAL FIELD

The present invention relates to a heat source system, a control device, a control method, and a program.

Priority is claimed on Japanese Patent Application No. 2016-237379, filed Dec. 7, 2016, the content of which is incorporated herein by reference.

BACKGROUND ART

Several techniques for adjusting a driving load of a heat source machine such as a freezer have been proposed. For example, Patent Literature 1 describes a heat source machine system that aims to drive the heat source machine always in a rated driving range and stabilize a driving state regardless of a heat demand on a heat load side. In this heat source machine system, a cooling tower or heating tower is connected to the heat source machine through an outward path and a return path. In addition, a heat load is connected to the heat source machine through the outward path and the return path. Furthermore, the return path from the cooling tower or the heating tower and the return path from the heat load are connected to a heat exchanger. The heat exchanger performs heat exchange between the return path from the cooling tower or the heating tower and the return path from the heat load.

CITATION LIST

Patent Literature

[Patent Literature 1]

Japanese Unexamined Patent Application, First Publication No. H07-280386

SUMMARY OF INVENTION

Technical Problem

In the heat source machine system described in Patent Literature 1, temperature control of the cooling water supplied to the heat source machine is complicated in that the temperature of the cooling water from the cooling tower or the heating tower changes due to the heat exchange. In a case in which accuracy of the temperature control of the cooling water is reduced, accuracy of temperature control of cold water supplied by the heat source machine system may be reduced. Furthermore, in a case in which a lower limit value is set to the temperature of the cooling water supplied to the heat source machine, the temperature of the cooling water may fall below the lower limit value, and the heat source machine may stop.

The present invention provides a heat source system, a control device, a control method, and a program capable of continuing driving of a heat source machine even in a case in which a cold heat amount required by a heat load is small, and relatively simply performing temperature control of cooling water.

Solution to Problem

According to a first aspect of the present invention, a heat source system includes a heat source machine, a cooling tower side outward path and a cooling tower side return path that are connected to the heat source machine, a load side outward path and a load side return path that are connected to the heat source machine, a heat exchange path provided in one of the load side return path and the cooling tower side outward path, a heat exchanger that performs heat exchange between the heat exchange path and the other one of the load side return path and the cooling tower side outward path, and a heat exchange adjustment valve capable of adjusting a flow rate of the heat exchange path.

The heat source system may include a cooling tower bypass path connecting the cooling tower side outward path and the cooling tower side return path with each other, and a cooling tower bypass valve capable of adjusting a flow rate of the cooling tower bypass path. The heat exchange path may be provided on the load side return path, and the heat exchanger may be disposed in the cooling tower side outward path at a position closer to the heat source machine than the cooling tower bypass path.

The heat source system may include a cooling tower bypass path connecting the cooling tower side outward path and the cooling tower side return path with each other, and a cooling tower bypass valve capable of adjusting a flow rate of the cooling tower bypass path. The heat exchange path may be provided in the cooling tower side outward path at a position closer to the heat source machine than the cooling tower bypass path.

The heat source system may include a load determination unit that determines whether or not a load of cold heat supply from the heat source machine is less than a load lower limit value, and a driving control unit that causes the heat exchanger to perform the heat exchange by controlling the heat exchange adjustment valve in a case in which the load determination unit determines that the load of the cold heat supply from the heat source machine is less than the load lower limit value.

According to a second aspect of the present invention, a control device is a control device that controls a heat source system including a heat source machine, a cooling tower side outward path and a cooling tower side return path that are connected to the heat source machine, a load side outward path and a load side return path that are connected to the heat source machine, a heat exchange path provided in one of the load side return path and the cooling tower side outward path, a heat exchanger that performs heat exchange between the heat exchange path and the other one of the load side return path and the cooling tower side outward path, and a heat exchange adjustment valve capable of adjusting a flow rate of the heat exchange path. The control device includes a load determination unit that determines whether or not a load of the heat source machine is less than a load lower limit value, and a driving control unit that causes the heat exchanger to perform the heat exchange by controlling the heat exchange adjustment valve in a case in which the load determination unit determines that the load of the heat source machine is less than the load lower limit value.

According to a third aspect of the present invention, a control method includes determining whether or not a load of a heat source machine of a heat source system is less than a load lower limit value, the heat source system comprising the heat source machine, a cooling tower side outward path and a cooling tower side return path that are connected to the heat source machine, a load side outward path and a load side return path that are connected to the heat source machine, a heat exchange path provided in one of the load side return path and the cooling tower side outward path, a heat exchanger that performs heat exchange between the heat exchange path and the other one of the load side return path and the cooling tower side outward path, and a heat exchange adjustment valve capable of adjusting a flow rate of the heat exchange path, and causing the heat exchanger to perform the heat exchange by controlling the heat exchange adjustment valve in a case in which it is determined that the load of the heat source machine is less than the load lower limit value.

According to a fourth aspect of the present invention, a program is for a computer that controls a load of a heat source machine of a heat source system comprising the heat source machine, a cooling tower side outward path and a cooling tower side return path that are connected to the heat source machine, a load side outward path and a load side return path that are connected to the heat source machine, a heat exchange path provided in one of the load side return path and the cooling tower side outward path, a heat exchanger that performs heat exchange between the heat exchange path and the other one of the load side return path and the cooling tower side outward path, and a heat exchange adjustment valve capable of adjusting a flow rate of the heat exchange path, the program causes the computer to execute determining whether or not the load of the heat source machine is less than a load lower limit value, and causing the heat exchanger to perform the heat exchange by controlling the heat exchange adjustment valve in a case in which it is determined that the load of the heat source machine is less than the load lower limit value.

Advantageous Effects of Invention

According to the heat source system, the control device, the control method, and the program described above, it is possible to continue driving of the heat source machine even in a case in which a cold heat amount required by a heat load is small, and it is possible to relatively simply perform temperature control of cooling water.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic block diagram showing a functional constitution of a heat source system according to an embodiment.

FIG. 2 is a schematic constitution diagram showing an example of a device constitution of a freezer plant main body 200 according to the embodiment.

FIG. 3 is a graph showing a driving range of a turbo freezer 300 according to the embodiment.

FIG. 4 is a flowchart showing an example of a process procedure in which a control device 100 controls the freezer plant main body 200 according to the embodiment.

FIG. 5 is a schematic constitution diagram showing another example of the device constitution of the freezer plant main body 200 according to the embodiment.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described, but the following embodiments do not limit the invention according to the claims. In addition, not all combinations of features described in the embodiments are essential to the solution of the invention.

FIG. 1 is a schematic block diagram showing a functional constitution of a heat source system according to the embodiment. As shown in FIG. 1, the heat source system 1 includes a control device 100 and a freezer plant main body 200. The control device 100 includes a communication unit 110, a storage unit 180, and a control unit 190. The control unit 190 includes a load determination unit 191 and a driving control unit 192.

The heat source system 1 supplies cold heat to a heat load. Specifically, the heat source system supplies cold water to the heat load. That is, the heat source system 1 supplies the cold heat to the heat load using water as a medium. The cold water supplied to the heat load by the heat source system 1 corresponds to an example of the cold heat.

While a freezer included in the freezer plant main body 200 stops at a light load, the heat source system 1 stably supplies the cold water even in a case in which a cold water amount required by the heat load rapidly increases from a small cold water amount. In a case in which the freezer stops at the light load, it takes time to activate the freezer again, and in a case in which the cold water amount required by the heat load rapidly increases, there is a possibility that the cold heat amount that is able to be supplied may be insufficient, or a possibility that cold water at a temperature required by the heat load may not be able to be supplied. Therefore, the heat source system 1 has a mechanism and a mode in which the freezer is not stopped even at the light load.

The control device 100 controls the freezer plant main body 200. A driving mode in which the control device 100 controls the freezer plant main body 200 includes a normal mode and a simulation load mode. The driving mode in which the control device 100 controls the freezer plant main body 200 is also referred to as a driving mode of the freezer plant main body 200.

While the freezer of the freezer plant main body 200 is stopped at the time of the light load in the normal mode, the driving of the freezer is caused to continue even at the time of the light load in the simulation load mode. The control device 100 is constituted using, for example, a computer such as a programmable logic controller (PLC) or a general work station.

The communication unit 110 communicates with the freezer plant main body 200. In particular, the communication unit 110 transmits a control signal to the freezer plant main body 200, and receives measured values by various sensors of the freezer plant main body 200.

The storage unit 180 stores various pieces of data. The storage unit 180 is constituted using a storage device included in the control device 100.

The control unit 190 controls each unit of the control device 100 to execute various processes. The control unit 190 is constituted, for example, by a central processing unit (CPU) included in the control device 100, which reads a program from the storage unit 180 and executes the program.

The load determination unit 191 determines whether or not the load of the heat source machine of the freezer plant main body 200 is less than a load lower limit value. The load lower limit value described here is a threshold value that is a determination reference of whether or not to stop the driving of the freezer at the light load in the normal mode.

The driving control unit 192 performs various arithmetic operations for controlling the freezer plant main body 200. In a case in which the driving mode of the freezer plant main body 200 is the simulation load mode and the load determination unit 191 determines that the load of the heat source machine of the freezer plant main body 200 is less than the load lower limit value, the driving control unit 192 controls the freezer plant main body 200 so as not to stop the freezer of the freezer plant main body 200. Specifically, the freezer plant main body 200 includes a heat exchanger that receives heat from the freezer as a simulated heat load, and the driving control unit 192 controls a heat exchange adjustment valve connected to the heat exchanger to cause the heat exchanger to perform the heat exchange. A load at which the freezer supplies the cold water is increased due to this heat exchange, and the freezer continues the driving without the light load stop.

FIG. 2 is a schematic constitution diagram showing an example of a device constitution of the freezer plant main body 200. In the example of FIG. 2, the freezer plant main body 200 includes a turbo freezer 300, a cooling tower 410, a cooling water pump 420, a cooling tower side three-way valve 430, a heat exchanger 500, a cold water pump 620, a heat load side three-way valve 630, an outward path side temperature sensor 711, a return path side temperature sensor 712, and a flow rate sensor 721. The turbo freezer 300 includes an evaporator 310, an evaporator pump 320, a turbo compressor 330, a condenser 340, a refrigerant pump 350, and an expansion valve 360. The freezer plant main body 200 is connected to a heat load 610.

The freezer plant main body 200 operates in accordance with control of the control unit 190, and supplies the cold water to the heat load 610.

The turbo freezer 300 corresponds to an example of the heat source machine, and supplies the cold water to the heat load 610 in response to a request from the heat load 610. The turbo freezer 300 is designed to stop at the time of the light load. In a case in which the load of the turbo freezer 300 is the load lower limit value, the turbo freezer 300 is stopped in accordance with the control of the control device 100.

However, the heat source machine included in the freezer plant main body 200 is not limited to the turbo freezer, and may be any heat source machine that stops at the time of the light load. For example, instead of the turbo freezer 300, the freezer plant main body 200 may include a heat source machine capable of supplying both of hot water and cold water to the heat load 610.

In the turbo freezer 300, the evaporator 310 performs heat exchange between the refrigerant of the turbo freezer 300 and the cold water supplied to the heat load 610. The evaporator 310 evaporates the refrigerant and reduces the temperature of the cold water by evaporation heat.

In order to promote the evaporation of the refrigerant, the evaporator 310 sprays the refrigerant toward a pipe from a spray port provided above the pipe through which the cold water flows. A refrigerant first path W31 is a path connecting a lower portion of the evaporator 310 and the spray port with each other. An evaporator pump 320 is provided in the refrigerant first path W31, and the evaporator pump 320 causes liquid refrigerant accumulated in the evaporator 310 to flow to the spray port.

The refrigerant gasified by the evaporator 310 flows to the turbo compressor 330 through a refrigerant second path W32 and is compressed. The gaseous refrigerant of which pressure and a temperature are increased by the compression flows to the condenser 340 through a refrigerant third path W33.

The condenser 340 cools and liquefies the refrigerant by performing the heat exchange between the gaseous refrigerant compressed by the turbo compressor 330 and the cooling water.

The refrigerant that has become liquid returns to the evaporator 310 through a refrigerant fourth path W34. A refrigerant pump 350 and an expansion valve 360 are provided in the fourth refrigerant path W34, and the refrigerant pump 350 transfers the liquid refrigerant from the condenser 340 to the evaporator 310. The refrigerant is easily evaporated by being decompressed by the expansion valve 360.

The turbo freezer 300 is stopped at the light load in accordance with the specification of the turbo compressor 330.

FIG. 3 is a graph showing a driving range of the turbo freezer 300. A horizontal axis of the graph of FIG. 3 indicates a load factor of the turbo freezer 300. A vertical axis indicates driving possibility or impossibility of the turbo freezer 300. As shown in FIG. 3, the turbo freezer 300 is able to be driven at a load factor of 30% or more. That is, the driving range of the turbo freezer 300 is a load factor of 30% or more. On the other hand, in a case in which the load factor is less than 30%, the turbo freezer 300 is stopped.

Therefore, in the simulation load mode, the heat exchanger 500 receives the cold water supplied to the turbo freezer 300 at the time of the light load of the turbo freezer 300, and thus the load of the turbo freezer 300 is increased. Therefore, the turbo freezer 300 is able to continue the driving even at the light load, and is able to supply the required amount of cold water to the heat load.

The turbo freezer 300 is connected to the cooling tower 410 through a cooling tower side outward path W11 and a cooling tower side return path W12. The cooling tower 410 exchanges heat with the refrigerant in the condenser 340 of the turbo freezer 300 to cool the heated cooling water. The cooling tower side outward path W11 is a path through which the cooling water heated by the condenser 340 flows to the cooling tower 410. The cooling tower side return path W12 is a path through which the cooling water cooled by the cooling tower 410 flows to the condenser 340.

The cooling water pump 420 circulates the cooling water between the turbo freezer 300 and the cooling tower 410. In the example of FIG. 2, the cooling water pump 420 is provided in the cooling tower side return path W12, and the cooling water flows from the cooling tower 410 to the turbo freezer 300.

In addition, the turbo freezer 300 is connected to the heat load 610 through a load side outward path W21 and a load side return path W22. The load side outward path W21 is a path through which the cold water cooled by the evaporator 310 of the turbo freezer 300 flows to the heat load 610. The load side return path W22 is a path through which the cold water used at the heat load 610 and of which temperature has increased flows to the evaporator 310.

The cold water pump 620 circulates the cold water between the turbo freezer 300 and the heat load 610. In the example of FIG. 2, the cold water pump 620 is provided in the load side return path W22 and causes the cold water to flow from the heat load 610 to the turbo freezer 300.

The heat load 610 may return all the cold water supplied from the evaporator 310 to the evaporator 310. Alternatively, the heat load 610 may take some or all of the cold water and not return the cold water to the evaporator 310. In a case in which the heat load 610 takes some or all of the cold water, for example, water may be supplied to the evaporator 310 from a water supply source, such as a water supply, instead of the cold water taken by the heat load 610. In this case, the supplied water may be normal temperature water.

In addition, the heat exchanger 500 is provided in the cooling tower side outward path W11. The heat exchanger 500 is connected to the load side return path W22 through a heat exchange path W23. The heat exchanger 500 performs heat exchange between the cooling tower side outward path W11 and the load side return path W22 by performing heat exchange between the cooling tower side outward path W11 and the heat exchange path W23. Specifically, the cold water branched from the load side return path W22 to the heat exchange path W23 absorbs heat from the cooling water flowing through the cooling tower side outward path W11. Due to this heat absorption, the temperature of the cold water returning to the turbo freezer 300 is increased, and the load by which the turbo freezer 300 supplies the cold water to the heat load 610 is increased. Therefore, even in a case in which the cold water amount required by the heat load 610 is small, the load of the turbo freezer 300 becomes equal to or greater than the load lower limit value, and the turbo freezer 300 continues the driving.

The load side return path W22 and the heat exchange path W23 are connected through a heat load side three-way valve 630. The heat load side three-way valve 630 is a flow rate adjustment valve corresponding to an example of the heat exchange adjustment valve, and adjusts the amount of the cold water branched from the load side return path W22 to the heat exchange path W23. The heat load side three-way valve 630 is also able to set the flow rate from the load side return path W22 to the heat exchange path W23 to zero. Therefore, the branch of the cold water from the load side return path W22 to the heat exchange path W23 is blocked.

Note that in place of the heat load side three-way valve 630, two two-way valves may be used to perform control similar to that of the three-way valve. The same applies to the other three-way valves.

A cooling tower bypass path W13 is provided between the cooling tower side outward path W11 and the cooling tower side return path W12. The temperature of the cooling water flowing to the condenser 340 is able to be adjusted by bypassing some of the cooling water flowing through the cooling tower side outward path W11 to the cooling tower side return path W12 by the cooling tower bypass path W13. The cooling tower side outward path W11 and the cooling tower bypass path W13 are connected with each other through a cooling tower side three-way valve 430. The cooling tower side three-way valve 430 is a flow rate adjustment valve corresponding to an example of a cooling tower bypass valve, and adjusts the amount of the cooling water bypassed from the cooling tower side outward path W11 to the cooling tower side return path W12.

The cooling tower side three-way valve 430 is also able to set the flow rate of the cooling water from the cooling tower side outward path W11 to the cooling tower bypass path W13 to zero. Therefore, the bypass of the cooling water from the cooling tower side outward path W11 to the cooling tower side return path W12 is blocked.

The cooling tower side three-way valve 430 is provided on a downstream side of the heat exchanger 500 in the cooling tower side outward path W11. The downstream side of the heat exchanger 500 in the cooling tower side outward path W11 is a side closer to the cooling tower 410 as viewed from the condenser 340.

Therefore, the cooling water flows through the cooling tower side three-way valve 430 after the heat exchange in the heat exchanger 500. Thus, the temperature of the cooling water passing through the cooling tower side three-way valve 430 does not change through the heat exchanger 500 before reaching the condenser 340. Accordingly, when the control unit 190 calculates a bypass amount of the cooling water on the basis of the temperature of the cooling water in the cooling tower side three-way valve 430, it is not necessary to consider the temperature change of the cooling water due to the heat exchanger 500. At this point, it is possible to avoid an increase of a load for which the control unit 190 calculates the bypass amount of the cooling water.

The outward path side temperature sensor 711 is provided in the load side outward path W21, and measures the temperature of the cold water flowing through the load side outward path W21. The return path side temperature sensor 712 is provided in the load side return path W22, and measures the temperature of the cold water flowing through the load side return path W22. The flow rate sensor 721 is provided in the load side outward path W21, and measures the flow rate of the cold water flowing through the load side outward path W21.

It is considered that a value obtained by multiplying a temperature difference obtained by subtracting the temperature measured by the outward path side temperature sensor 711 from the temperature measured by the return path side temperature sensor 712 by the flow rate measured by the flow rate sensor 721 indicates a cold water heat amount consumed by the heat load 610. That is, the cold water heat amount QI_CH consumed by the heat load 610 is expressed by Formula (1).

[Math. 1]

QI_CH=TL_CHo−TI_CHi×FL_CH   (1)

Here, TI_CHo indicates a cold water outlet temperature. As the cold water outlet temperature, it is possible to use the temperature of the cold water in the load side outward path W21 measured by the outward path side temperature sensor 711. TI_CHi indicates a cold water inlet temperature. As the cold water inlet temperature, it is possible to use the temperature of the cold water in the load side return path W22 measured by the return path side temperature sensor 712. FI_CH indicates a cold water flow rate. As the cold water flow rate, it is possible to use the flow rate of the cold water in the load side outward path W21 measured by the flow rate sensor 721.

Next, an operation of the heat source system 1 will be described with reference to FIG. 4.

FIG. 4 is a flowchart showing an example of a process procedure in which the control device 100 controls the freezer plant main body 200. The control device 100 performs the process of FIG. 4 in a case in which a driving start operation that is a user operation instructing to start the driving of the heat source system 1 is performed.

In the process of FIG. 4, the driving control unit 192 of the control device 100 activates the turbo freezer 300 (step S101). In addition, the driving control unit 192 waits for a lapse of a t2 time from the start of the activation of the turbo freezer 300 (step S102), and further waits for a lapse of a t1 time (step S103).

The t1 time is a control determination period in the control device 100. The control determination period referred to here is a period in which the driving control unit 192 repeats the process of determining the driving mode of the freezer plant main body 200 and controlling the freezer plant main body 200. The t2 time is an activation time of the turbo freezer 300. Specifically, the t2 time is an effect waiting time from the start of the activation of the turbo freezer 300 to appearance of the effect of cooling.

However, step S103 is not essential. Therefore, after waiting for the t2 time in step S102, the driving control unit 192 may shift to step S104 without waiting for the time in step S103.

Next, the driving control unit 192 determines the driving mode of the freezer plant main body 200 (step S104). For example, the driving control unit 192 calculates the cold water heat amount QI_CH consumed by the heat load 610 on the basis of Formula (1) described above. In addition, the driving control unit 192 determines the driving mode by comparing the calculated cold water heat amount QI_CH with a heat amount lower limit value Qmin. In a case in which Formula (2) is established, the driving control unit 192 determines that the driving mode of the freezer plant main body 200 is the normal mode.

[Math. 2]

QI_CH≥Qmin+h1   (2)

Here, h1 indicates a coefficient for hunting prevention.

On the other hand, in a case in which Formula (3) is established, the driving control unit 192 determines that the driving mode of the freezer plant main body 200 is the simulation load mode.

[Math. 3]

QI_CH<Qmin+h2   (3)

Here, h2 indicates a coefficient for hunting prevention.

The heat amount lower limit value Qmin may be determined in advance as a constant value. Alternatively, in a case in which a range of a load factor at which the driving is possible fluctuates due to a driving condition such as the cold water temperature and the cooling water temperature, the control device 100 may communicate with the turbo freezer 300 to receive the heat amount lower limit value Qmin.

In addition, the driving control unit 192 may determine the driving mode on the basis of the cold water inlet temperature Ti_CHi and the temperature lower limit Tmin, instead of the cold water heat amount QI_CH and the heat amount lower limit value Qmin. For example, in a case in which Formula (4) is established, the driving control unit 192 determines that the driving mode of the freezer plant main body 200 is the normal mode.

[Math. 4]

TI_CHi≥Tmin+h3   (4)

Here, h3 indicates a coefficient for hunting prevention.

On the other hand, in a case in which Formula (5) is established, the driving control unit 192 determines that the driving mode of the freezer plant main body 200 is the simulation load mode.

[Math. 5]

TI_CHi<Tmin+h4   (5)

Here, h4 indicates a coefficient for hunting prevention.

In a case in which it is determined in step S104 that the driving mode is the simulation load mode (step S104: simulation load mode), the driving control unit 192 performs simulation load driving control (step S111). In the simulation load driving control, the driving control unit 192 adjusts the flow rate of the cold water flowing through the heat exchanger 500 by controlling the heat load side three-way valve 630 so that the cold water heat amount QI_CH obtained by Formula (1) becomes equal to or greater than the heat amount lower limit value Qmin.

In addition, the driving control unit 192 waits for the lapse of the t2 time (step S112). In addition, the driving control unit 192 determines whether or not a driving end operation has been performed (step S131). The driving end operation referred to here is a user operation instructing an end of the driving of the heat source system 1.

In a case in which it is determined that the driving end operation has not been performed (step S131: NO), the process returns to step S104.

On the other hand, in a case in which it is determined that the driving end operation has been performed (step S131: YES), the driving control unit 192 stops the turbo freezer 300 (step S141). In addition, the driving control unit 192 ends the control of the freezer plant main body 200 (step S142).

After step S142, the process of FIG. 4 is ended.

On the other hand, in step S104, in a case in which it is determined that the driving mode is the normal mode (step S104: normal mode), the driving control unit 192 performs normal driving control (step S121). In the normal driving control, the driving control unit 192 stops the heat exchanger 500 by controlling the heat load side three-way valve 630 so that the flow rate of the cold water branched from the load side return path W22 to the heat exchange path W23 becomes zero.

In addition, the driving control unit 192 waits for the lapse of the t2 time (step S122). After step S122, the process shifts to step S131.

As described above, the heat exchange path W23 is provided in the load side return path W22, and the heat exchanger 500 exchanges heat between the heat exchange path W23 and the cooling tower side outward path W11. In addition, the heat load side three-way valve 630 is able to adjust the flow rate of the heat exchange path W23.

As described above, in the heat source system 1, since the heat exchanger 500 exchanges heat between the heat exchange path W23 and the cooling tower side outward path W11, the temperature change due to the heat exchange does not occur after the cooling water passes through the cooling tower 410. In this point, in the heat source system 1, it is possible to relatively simply perform the temperature control of the cooling water. Therefore, in the heat source system 1, it is possible to continue the driving of the turbo freezer 300 even in a case in which a cold water amount required by the heat load 610 is small, and it is possible to relatively simply perform the temperature control of the cooling water.

In addition, the cooling tower bypass path W13 is able to connect the cooling tower side outward path W11 and the cooling tower side return path W12 with each other, and the cooling tower side three-way valve 430 is able to adjust the flow rate of the cooling tower bypass path W13. The heat exchanger 500 is disposed on a side of the turbo freezer 300 (an upstream side of a path of the cooling water) with respect to the cooling tower bypass path W13 in the cooling tower side outward path W11.

Therefore, the cooling water flows through the cooling tower side three-way valve 430 after the heat exchange in the heat exchanger 500. Thus, the temperature of the cooling water passing through the cooling tower side three-way valve 430 does not change through the heat exchanger 500 before reaching the condenser 340. Accordingly, when the control unit 190 calculates the bypass amount of the cooling water on the basis of the temperature of the cooling water in the cooling tower side three-way valve 430, it is not necessary to consider the temperature change of the cooling water due to the heat exchanger 500. At this point, it is possible to avoid an increase of a load for which the control unit 190 calculates the bypass amount of the cooling water.

In addition, since the cooling water exchanges heat with the cold water in the heat exchanger 500 and is cooled, it is possible to effectively use the cold water.

In addition, the load determination unit 191 determines whether or not the load of the cold water supply to the heat load 610 is less than the load lower limit value. In a case in which the load determination unit 191 determines that the load of the cold water supply to the heat load 610 is less than the load lower limit value, the driving control unit 192 controls the heat load side three-way valve 630 to cause the heat exchanger 500 to perform the heat exchange.

Therefore, it is possible to continue the driving of the turbo freezer 300 even in a case in which the cold water amount required by the heat load 610 is small. In addition, since it is possible to stop the heat exchange in a case in which the load of the cold water supply to the heat load 610 is equal to or greater than the load lower limit value, it is possible to efficiently drive the turbo freezer 300.

Note that although the heat load side three-way valve 630 for adjusting the flow rate to the heat exchanger 500 is provided in the load side return path W22 in the constitution example of FIG. 2, the valve for adjusting the flow rate to the heat exchanger 500 may be provided on a side of the cooling tower side outward path W11. This point will be described with reference to FIG. 5.

FIG. 5 is a schematic constitution diagram showing another example of the device constitution of the freezer plant main body 200. In the example of FIG. 5, the freezer plant main body 200 includes a heat exchange three-way valve 240, the turbo freezer 300, the cooling tower 410, the cooling water pump 420, the cooling tower side three-way valve 430, the heat exchanger 500, the cold water pump 620, the outward path side temperature sensor 711, a return path side temperature sensor 712, and the flow rate sensor 721. The turbo freezer 300 includes the evaporator 310, the evaporator pump 320, the turbo compressor 330, the condenser 340, the refrigerant pump 350, and the expansion valve 360.

In addition, the freezer plant main body 200 is connected to the heat load 610.

While the heat exchanger 500 is provided in the cooling tower side outward path W11 in the example of FIG. 2, the heat exchanger 500 is provided in the load side return path W22 in the example of FIG. 5.

In addition, in the example of FIG. 2, the heat load side three-way valve 630 is provided in the load side return path W22, and the heat load side three-way valve 630 and the heat exchanger 500 are connected with each other by the heat exchange path W23. However, in the example of FIG. 5, the heat exchange three-way valve 240 is provided in the cooling tower side outward path W11, and the heat exchange three-way valve 240 and the heat exchanger 500 are connected with each other by a heat exchange path W14. The other points are the same as in the case of FIG. 2.

In the example of FIG. 5, the heat exchange three-way valve 240 corresponds to an example of the heat exchange three-way valve, and adjusts the amount of the cooling water branched from the cooling tower side outward path W11 to the heat exchange path W14.

In addition, the heat exchange three-way valve 240 is provided an upstream side of the cooling tower side three-way valve 430 in the cooling tower side outward path W11. The upstream side of the cooling tower side three-way valve 430 in the cooling tower side outward path W11 is a side closer to the turbo freezer 300 than the cooling tower side three-way valve 430 as viewed from the turbo freezer 300.

As described above, the heat exchange path W14 is provided in the cooling tower side outward path W11, and the heat exchanger 500 exchanges heat between the heat exchange path W23 and the load side return path W22. In addition, the heat exchange three-way valve 240 is able to adjust the flow rate of the heat exchange path W14.

As described above, in the heat source system 1, the heat exchanger 500 exchanges heat between the heat exchange path W14 and the load side return path W22, and the heat exchange path W14 is provided in the cooling tower side outward path W11. Therefore, the temperature change of the cooling water due to the heat exchange does not occur after passing through the cooling tower 410. In this point, in the heat source system 1, it is possible to relatively simply perform the temperature control of the cooling water. Therefore, in the heat source system 1, it is possible to continue the driving of the turbo freezer 300 even in a case in which the cold heat amount required by the heat load 610 is small, and it is possible to relatively simply perform the temperature control of the cooling water.

In addition, the heat exchange path W14 is provided on a side of the turbo freezer 300 (the upstream side of the path of the cooling water) with respect to the cooling tower bypass path W13 in the cooling tower side outward path W11.

Therefore, the cooling water branched to the heat exchange path W14 flows through the cooling tower side three-way valve 430 after the heat exchange in the heat exchanger 500. Thus, the temperature of the cooling water passing through the cooling tower side three-way valve 430 does not change through the heat exchanger 500 before reaching the condenser 340. Accordingly, when the control unit 190 calculates the bypass amount of the cooling water on the basis of the temperature of the cooling water in the cooling tower side three-way valve 430, it is not necessary to consider the temperature change of the cooling water due to the heat exchanger 500. At this point, it is possible to avoid an increase of a load for which the control unit 190 calculates the bypass amount of the cooling water.

In addition, since the cooling water exchanges heat with the cold water in the heat exchanger 500 and is cooled, it is possible to effectively use the cold water.

In addition, the processes of each unit may be performed by recording a program for realizing all or a part of the functions of the control unit 190 in a computer-readable recording medium, and causing a computer system to read and execute the program recorded in the recording medium. Note that the “computer system” referred to here is presumed to include an OS or hardware such as a peripheral device.

In addition, the “computer-readable recording medium” refers to a storage device such as a portable medium such as a flexible disk, a magneto-optical disc, a ROM, and a CD-ROM, or a hard disc that is installed inside the computer system. In addition, the program may be for realizing a part of the functions described above, or may be realized in combination with the program in which the functions described above is already recorded in the computer system.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific constitution is not limited to this embodiment, and design changes and the like without departing from the gist of the present invention are also included.

INDUSTRIAL APPLICABILITY

An embodiment of the present invention relates to a heat source system including a heat source machine, a cooling tower side outward path and a cooling tower side return path that are connected to the heat source machine, a load side outward path and a load side return path that are connected to the heat source machine, a heat exchange path provided in one of the load side return path and the cooling tower side outward path, a heat exchanger that performs heat exchange between the heat exchange path and the other one of the load side return path and the cooling tower side outward path, and a heat exchange adjustment valve capable of adjusting a flow rate of the heat exchange path.

According to the embodiment, it is possible to continue driving of the heat source machine even in a case in which a cold heat amount required by a heat load is small, and it is possible to relatively simply perform temperature control of cooling water.

REFERENCE SIGNS LIST

1 Heat source system

100 Control device

110 Communication unit

180 Storage unit

190 Control unit

191 Load determination unit

192 Driving control unit

200 Freezer plant main body

240 Heat exchange three-way valve

300 Turbo freezer

310 Evaporator

320 Evaporator pump

330 Turbo compressor

340 Condenser

350 Refrigerant pump

360 Expansion valve

410 Cooling tower

420 Cooling water pump

430 Cooling tower side three-way valve

500 Heat exchanger

610 Heat load

620 Cold water pump

630 Heat load side three-way valve

711 Outward path side temperature sensor

712 Return path side temperature sensor

721 Flow rate sensor

W11 Cooling tower side outward path

W12 Cooling tower side return path

W13 Cooling tower bypass path

W14, W23 Heat exchange path

W21 Load side outward path

W22 Load side return path

W31 Refrigerant first path

W32 Refrigerant second path

W33 Refrigerant third path

W34 Refrigerant fourth path

Claims

1. A heat source system comprising:

a heat source machine;

a cooling tower side outward path and a cooling tower side return path that are connected to the heat source machine;

a load side outward path and a load side return path that are connected to the heat source machine;

a heat exchange path provided in one of the load side return path and the cooling tower side outward path;

a heat exchanger that performs heat exchange between the heat exchange path and the other one of the load side return path and the cooling tower side outward path; and

a heat exchange adjustment valve capable of adjusting a flow rate of the heat exchange path.

2. The heat source system of claim 1, comprising:

a cooling tower bypass path connecting the cooling tower side outward path and the cooling tower side return path with each other; and

a cooling tower bypass valve capable of adjusting a flow rate of the cooling tower bypass path,

wherein the heat exchange path is provided on the load side return path, and

the heat exchanger is disposed in the cooling tower side outward path at a position closer to the heat source machine than the cooling tower bypass path.

3. The heat source system of claim 1, comprising:

a cooling tower bypass path connecting the cooling tower side outward path and the cooling tower side return path with each other; and

a cooling tower bypass valve capable of adjusting a flow rate of the cooling tower bypass path,

wherein the heat exchange path is provided in the cooling tower side outward path at a position closer to the heat source machine than the cooling tower bypass path.

4. The heat source system of claim 1, comprising:

a load determination unit that determines whether or not a load of cold heat supply from the heat source machine is less than a load lower limit value; and

a driving control unit that causes the heat exchanger to perform the heat exchange by controlling the heat exchange adjustment valve in a case in which the load determination unit determines that the load of the cold heat supply from the heat source machine is less than the load lower limit value.

5. A control device that controls a heat source system comprising:

a heat source machine;

a cooling tower side outward path and a cooling tower side return path that are connected to the heat source machine;

a load side outward path and a load side return path that are connected to the heat source machine;

a heat exchange path provided in one of the load side return path and the cooling tower side outward path;

a heat exchanger that performs heat exchange between the heat exchange path and the other one of the load side return path and the cooling tower side outward path; and

a heat exchange adjustment valve capable of adjusting a flow rate of the heat exchange path, the control device comprising:

a load determination unit that determines whether or not a load of the heat source machine is less than a load lower limit value; and

a driving control unit that causes the heat exchanger to perform the heat exchange by controlling the heat exchange adjustment valve in a case in which the load determination unit determines that the load of the heat source machine is less than the load lower limit value.

6. A control method comprising:

determining whether or not a load of a heat source machine of a heat source system is less than a load lower limit value, the heat source system comprising the heat source machine, a cooling tower side outward path and a cooling tower side return path that are connected to the heat source machine, a load side outward path and a load side return path that are connected to the heat source machine, a heat exchange path provided in one of the load side return path and the cooling tower side outward path, a heat exchanger that performs heat exchange between the heat exchange path and the other one of the load side return path and the cooling tower side outward path, and a heat exchange adjustment valve capable of adjusting a flow rate of the heat exchange path; and

causing the heat exchanger to perform the heat exchange by controlling the heat exchange adjustment valve in a case in which it is determined that the load of the heat source machine is less than the load lower limit value.

7. A non-transitory computer-readable recording medium storing a program for a computer that controls a load of a heat source machine of a heat source system comprising the heat source machine, a cooling tower side outward path and a cooling tower side return path that are connected to the heat source machine, a load side outward path and a load side return path that are connected to the heat source machine, a heat exchange path provided in one of the load side return path and the cooling tower side outward path, a heat exchanger that performs heat exchange between the heat exchange path and the other one of the load side return path and the cooling tower side outward path, and a heat exchange adjustment valve capable of adjusting a flow rate of the heat exchange path, the program causing the computer to execute:

determining whether or not the load of the heat source machine is less than a load lower limit value; and

causing the heat exchanger to perform the heat exchange by controlling the heat exchange adjustment valve in a case in which it is determined that the load of the heat source machine is less than the load lower limit value.