Hot water supply system

Abstract

This hot water supply system provides a system that can effectively utilize waste heat even when the hot water storage tank, which stores the hot water generated by the heating unit, has reached its maximum capacity, while also saving space in the installation of the hot water storage tank and simplifying its configuration. [Solution] The system includes a hot water storage tank 1, a water supply circuit 2 that supplies water to the hot water storage tank 1, and a hot water storage circuit 3 that stores hot water in the hot water storage tank 1. The hot water storage circuit 3 includes a hot water storage circuit 8 that stores hot water generated by a heating unit 7 in the hot water storage tank 1, and a waste heat storage circuit 10 that stores hot water generated by a waste heat heating unit 9 in the hot water storage tank 1. In addition to a hot water storage space 1A that stores hot water generated by the heating unit 7, the hot water storage tank 1 also has a waste heat storage space 1B that stores hot water from the waste heat storage circuit 10.

Description

Technical Field

[0001] The present invention relates to a hot water supply system including a hot water storage tank, a water supply circuit for supplying water to the hot water storage tank, a hot water storage circuit for storing hot water in the hot water storage tank, and a hot water supply circuit for supplying the hot water stored in the hot water storage tank to a hot water usage location.

Background Art

[0002] Patent Document 1 discloses a hot water supply system including a hot water storage tank, a water supply circuit for supplying water to the hot water storage tank, a hot water storage circuit for storing hot water in the hot water storage tank, and a hot water supply circuit for supplying the hot water stored in the hot water storage tank to a hot water usage location.

[0003] This hot water supply system includes a hot water tank 3 and a hot water storage tank 5 separate from this hot water tank. Even when the hot water storage amount in the hot water tank 3 reaches the maximum capacity, hot water can be stored in the hot water storage tank 5. Thus, when waste heat is generated from a fuel cell 6 or the like while the hot water storage amount in the hot water tank 3 has reached the maximum capacity, the hot water generated using that waste heat is stored in the hot water storage tank 5, effectively utilizing the waste heat generated from the fuel cell 6 or the like to achieve energy savings and efficiency improvement.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the hot water supply system described in Patent Document 1 required the installation of a separate hot water storage tank in addition to the hot water tank, necessitating a large space for installing these two tanks. Moreover, a hot water supply path and other components were also required to supply hot water between the hot water tank and the hot water storage tank, leading to a complex configuration.

[0006] In light of these circumstances, the main objective of the present invention is to provide a hot water supply system that can effectively utilize waste heat even when the amount of hot water stored in the hot water storage tank, which stores the hot water generated by the heating unit, has reached its maximum capacity, while also saving space in the installation of the hot water storage tank and simplifying its configuration. [Means for solving the problem]

[0007] The first characteristic configuration of the present invention is a hot water supply system comprising a hot water storage tank, a water supply circuit for supplying water to the hot water storage tank, a hot water storage circuit for storing hot water in the hot water storage tank, and a hot water supply circuit for supplying the hot water stored in the hot water storage tank to a hot water usage location, The hot water storage circuit comprises a hot water storage circuit that stores hot water generated by a heating unit in the hot water storage tank, and a waste heat storage circuit that stores hot water generated by a waste heat heating unit in the hot water storage tank. The hot water storage tank has a storage space for hot water generated by the heating unit, as well as a storage space for waste heat for hot water from the waste heat storage circuit. The aforementioned waste heat storage circuit is characterized by its waste heat utilization and storage operation, which involves supplying water to the storage tank while simultaneously storing the hot water generated by the waste heat heating unit in the storage tank.

[0008] With this configuration, even if waste heat is generated when the amount of hot water stored in the storage space of the hot water storage tank reaches its maximum capacity, the waste heat can be effectively utilized by performing waste heat utilization hot water storage operation and storing the hot water generated by the waste heat heating unit in the waste heat storage space of the hot water storage tank. Furthermore, although the hot water storage tank becomes larger by providing a waste heat storage space in addition to the hot water storage space, it is easier to reduce the space required to install the hot water storage tank compared to having two hot water storage tanks, each with its own separate space, and a hot water supply path connecting the two hot water storage tanks is not required, thus simplifying the configuration.

[0009] A second characteristic feature of the present invention is that, during the operation of the waste heat utilization hot water storage circuit, a water supply adjustment unit is provided to adjust the amount of water supplied to the hot water storage tank so as to maintain the temperature of the hot water in the storage tank at a predetermined temperature.

[0010] This configuration allows the temperature of the hot water in the storage tank to be maintained at a predetermined temperature while the hot water generated by the waste heat is stored in the storage tank. As a result, the temperature of the hot water supplied to the hot water usage points via the hot water supply circuit can be maintained at a predetermined temperature, making it an effective hot water supply system that can supply hot water at a stable temperature to the usage points.

[0011] A third characteristic feature of the present invention is that the waste heat storage circuit includes a first waste heat water supply circuit that supplies water to the storage tank, and a waste heat circulation circuit that extracts hot water from the storage tank and supplies it to the waste heat heating unit, and returns the hot water heated in the waste heat heating unit back to the storage tank.

[0012] According to this configuration, a first waste heat water supply circuit and a waste heat circulation circuit can be installed separately from the water supply circuit and the hot water storage circuit. Therefore, while using the water supply circuit and the hot water storage circuit as they are, and without affecting any of their components, it is possible to generate hot water using waste heat through the first waste heat water supply circuit and the waste heat circulation circuit. Furthermore, the first waste heat water supply circuit and the waste heat circulation circuit can be easily added to the existing water supply circuit and hot water storage circuit.

[0013] A fourth characteristic feature of the present invention is that the waste heat storage circuit has the waste heat heating unit located in the middle of the second waste heat water supply circuit that supplies water to the storage tank.

[0014] With this configuration, it is only necessary to install a heat dissipation heating unit at a point along the water supply to the hot water storage tank, and it is not necessary to have a circulation circuit to circulate the hot water in the storage tank, for example, thus simplifying the configuration. [Brief explanation of the drawing]

[0015] [Figure 1] Schematic diagram of the hot water supply system in the first embodiment [Figure 2] Schematic diagram of the hot water supply system showing the water supply operation and hot water storage operation in the first embodiment. [Figure 3] Schematic diagram of the hot water supply system showing the operation state of waste heat utilization hot water storage in the first embodiment. [Figure 4] This figure shows the state of hot water storage in the storage tank during and after the operation of waste heat utilization hot water storage in the first embodiment. [Figure 5] Schematic diagram of the hot water supply system in the second embodiment [Modes for carrying out the invention]

[0016] [First Embodiment] A first embodiment of the hot water supply system according to the present invention will be described with reference to the drawings. As shown in Figures 1 to 3, the hot water supply system includes a water supply circuit 2 that supplies water to the hot water storage tank 1, a hot water storage circuit 3 that stores hot water in the hot water storage tank 1, and a hot water supply circuit 5 that supplies the hot water stored in the hot water storage tank 1 to hot water usage points 4 such as hot water taps. The hot water supply system also includes a control unit H that controls each part of the hot water supply system. Incidentally, Figures 1 to 3 all show the same schematic configuration of the hot water supply system, but the state of hot water storage in the hot water storage tank 1 is different. Also, in Figures 2 and 3, the parts through which fluid flows are indicated by thick arrows.

[0017] The water supply circuit 2 is provided with a water supply line 21 for supplying water to the hot water storage tank 1 by means of tap water pressure or the like, and the water supply line 21 is provided with a water supply valve 6 for intermittently supplying water to the hot water storage tank 1. The water supply circuit 2 is configured to perform a water supply operation of supplying water to the hot water storage tank 1 through the water supply line 21 as indicated by the arrow (1) in FIG. 2 by opening the water supply valve 6.

[0018] As shown in FIGS. 1 to 3, the hot water storage circuit 3 includes a hot water storage circuit 8 for storing the hot water generated by the heating unit 7 in the hot water storage tank 1, and a waste heat storage circuit 10 for storing the hot water generated by the waste heat heating unit 9 in the hot water storage tank 1. The hot water supply system is provided in a facility such as a factory, for example, and stores the hot water generated by the heating unit 7 in the hot water storage tank 1, and is configured to store the hot water generated by the waste heat heating unit 9 that exchanges heat with the heat medium having waste heat generated in the facility in the hot water storage tank 1.

[0019] The hot water storage circuit 8 functions as a circulation circuit that takes out the hot water in the hot water storage tank 1 and supplies it to the heating unit 7, and returns the hot water heated by the heating unit 7 to the hot water storage tank 1, and is configured to perform a hot water storage operation of storing the hot water generated by the heating unit 7 in the hot water storage tank 1.

[0020] To add an explanation, in the hot water storage operation of the hot water storage circuit 8, by driving the circulation pump 13, as indicated by the arrow (2) in FIG. 2, the hot water taken out from the lower part of the hot water storage tank 1 is circulated through the hot water storage circuit 8 so as to return to the upper part of the hot water storage tank 1 via the heating unit 7, and the hot water circulating through the hot water storage circuit 8 is heated in the heating unit 7, and the hot water at the target hot water storage temperature (predetermined temperature) is returned to the upper part of the hot water storage tank 1. The heating unit 7 is configured by, for example, a heating device whose heating amount can be adjusted, and adjusts the heating amount so as to heat the hot water circulating through the hot water storage circuit 8 to the target hot water storage temperature.

[0021] By performing the water supply operation by the water supply circuit 2 and the hot water storage operation by the hot water storage circuit 8 in parallel, it is possible to maintain the temperature of the hot water stored in the hot water storage tank 1 at the target hot water storage temperature while supplying water to the hot water storage tank 1.

[0022] The waste heat storage circuit 10 includes a first waste heat water supply circuit 15 that supplies water to the storage tank 1, and a waste heat circulation circuit 16 that takes hot water from the storage tank 1 and supplies it to the waste heat heating unit 9, and returns the hot water heated in the waste heat heating unit 9 back to the storage tank 1. The waste heat storage circuit 10 is configured to perform a first waste heat utilization storage operation, which is a waste heat utilization storage operation in which hot water generated by the waste heat heating unit 9 is stored in the storage tank 1 while water is supplied to the storage tank 1 by the first waste heat water supply circuit 15.

[0023] To elaborate, the heat exhaust circulation circuit 16 is equipped with a heat exhaust circulation pump 18 that generates a flow of hot water and a heat exhaust temperature sensor 19 that detects the temperature of the hot water flowing downstream of the heat exhaust heating unit 9. The first heat exhaust water supply circuit 15 is equipped with a heat exhaust water supply valve 20 for adjusting the amount of water supplied. In the first waste heat utilization hot water storage operation of the waste heat storage circuit 10, the waste heat water supply valve 20 is opened, and water is supplied to the hot water storage tank 1 through the first waste heat water supply circuit 15, as shown by arrow (3) in Figure 3. Also, in the first waste heat utilization hot water storage operation of the waste heat storage circuit 10, the waste heat circulation pump 18 is driven, and as shown by arrow (4) in Figure 3, the hot water taken from the bottom of the hot water storage tank 1 is circulated through the waste heat circulation circuit 16 to return it to the top of the hot water storage tank 1 via the waste heat heating unit 9, and the hot water is heated in the waste heat heating unit 9 by heat exchange with a heat transfer medium that has waste heat. Furthermore, in the first waste heat utilization hot water storage operation, the waste heat storage circuit 10 is configured to adjust the opening degree of the waste heat water supply valve 20 according to the temperature detected by the waste heat temperature sensor 19, so that the temperature of the hot water, which is the sum of the water supplied to the hot water storage tank 1 by the first waste heat water supply circuit 15 and the hot water returned to the hot water storage tank 1 by the waste heat circulation circuit 16, becomes the target hot water storage temperature.

[0024] In this way, the first waste heat utilization hot water storage operation is performed by the waste heat storage circuit 10, which allows the temperature of the hot water stored in the hot water storage tank 1 to be maintained at a target storage temperature by utilizing waste heat while supplying water to the hot water storage tank 1. The waste heat water supply valve 20 corresponds to a water supply volume adjustment unit that adjusts the amount of water supplied to the hot water storage tank 1 in order to maintain the temperature of the hot water in the hot water storage tank 1 at a predetermined temperature while the waste heat utilization hot water storage operation is performed by the waste heat storage circuit 10.

[0025] The hot water storage tank 1 is open to the atmosphere. In addition to the hot water storage space 1A for storing hot water generated by the heating unit 7, the hot water storage tank 1 also has a heat exhaust storage space 1B for storing hot water from the heat exhaust storage circuit 10. Thus, since the hot water storage tank 1 has a heat exhaust storage space 1B in addition to the hot water storage space 1A, the capacity of the hot water storage tank 1 is set to be larger than the combined capacity of the hot water storage space 1A and the heat exhaust storage space 1B. Therefore, as shown in Figure 1, the hot water storage space 1A is allocated to the lower region of the storage space of the hot water storage tank 1, and the heat exhaust storage space 1B is allocated to the region located above the hot water storage space 1A in the storage space of the hot water storage tank 1. In this embodiment, for example, a larger space than the hot water storage space 1A is secured as the heat exhaust storage space 1B. In Figures 1 to 4, the intensity of the colors used to fill in the hot water is varied to make it easier to distinguish between the hot water stored in the hot water storage space 1A and the hot water stored in the heat waste storage space 1B.

[0026] Next, we will explain the control of each part of the hot water supply system by the control unit H. As shown in Figure 2, the control unit H is configured to control the water supply circuit 2 to start water supply operation by controlling the water supply valve 6 of the water supply circuit 2 when the amount of hot water stored in the hot water storage tank 1 falls below the set storage amount (the amount of hot water stored when the hot water storage space 1A is filled to capacity), and to stop water supply operation by controlling the water supply valve 6 of the water supply circuit 2 when the amount of hot water stored in the hot water storage tank 1 reaches the set storage amount (the state shown in Figure 4(A)).

[0027] Furthermore, the control unit H is configured to control the hot water storage circuit 8 to start hot water storage operation by controlling the heating unit 7 and circulation pump 13 of the hot water storage circuit 8 when the temperature of the hot water in the hot water storage tank 1 falls below the heat storage start temperature, which is a set temperature lower than the target hot water storage temperature, and to stop hot water storage operation by controlling the heating unit 7 and circulation pump 13 of the hot water storage circuit 8 when the temperature of the hot water in the hot water storage tank 1 rises above the target hot water storage temperature. In this manner, the water supply operation and the hot water storage operation are performed so that the hot water storage tank 1 maintains a state in which hot water at the target storage temperature is stored in the set storage volume.

[0028] Furthermore, when information indicating that heating is possible in the heat exhaust heating unit 9 (heat exhaust has been generated) is input to the control unit H, the control unit H controls the heat exhaust circulation pump 18 and the heat exhaust water supply valve 20 of the heat exhaust hot water storage circuit 10 to start the first heat exhaust utilization hot water storage operation. When information indicating that heating has changed from possible to impossible in the heat exhaust heating unit 9 (heat exhaust has stopped being generated) is input to the control unit H, or when the heat exhaust storage space 1B in the hot water storage tank 1 is filled with hot water, the control unit H controls the heat exhaust circulation pump 18 and the heat exhaust water supply valve 20 of the heat exhaust hot water storage circuit 10 to terminate the first heat exhaust utilization hot water storage operation.

[0029] As described above, the hot water storage circuit 3 includes a hot water storage circuit 8 that stores hot water generated by the heating unit 7 in the hot water storage tank 1, and a waste heat storage circuit 10 that stores hot water generated by the waste heat heating unit 9 in the hot water storage tank 1. The hot water storage tank 1 has a hot water storage space 1A for storing hot water generated by the heating unit 7, as well as a waste heat storage space 1B for storing hot water from the waste heat storage circuit 10. Therefore, even if waste heat is generated when the amount of hot water stored in the hot water storage space 1A of the hot water storage tank 1 has reached its maximum capacity, the waste heat can be effectively utilized by storing the hot water generated by the waste heat heating unit 9 in the waste heat storage space 1B of the hot water storage tank 1. Furthermore, compared to the case where there are two hot water storage tanks 1, each equipped with a separate hot water storage space 1A and a waste heat storage space 1B, it is easier to reduce the space required to install the hot water storage tanks 1, and a hot water supply path connecting the two hot water storage tanks 1 is unnecessary, thus simplifying the configuration.

[0030] The following explanation will describe the changes in the hot water storage state of the hot water storage tank 1, based on Figure 4. As shown in Figure 4(A), the control unit H operates the water supply circuit 2 and the hot water storage circuit 8 in parallel, so that hot water is stored in the hot water storage space 1A in the lower region of the hot water storage tank 1, and the hot water storage tank 1 has a set amount of hot water stored in it. The set amount of hot water can be set according to the amount of hot water used at the hot water usage points 4. For example, by setting the set amount of hot water to correspond to the total amount of hot water used at the hot water usage points 4 for several hours (for example, 5 to 6 hours), it is possible to secure enough hot water in the hot water storage tank 1 to adequately use hot water at the hot water usage points 4.

[0031] As shown in Figure 4(A), when a set amount of hot water is stored in the hot water storage space 1A, and waste heat is generated making heating possible in the waste heat heating unit 9, the control unit H performs the first waste heat utilization hot water storage operation, and as shown in Figures 4(B) and 4(C), hot water is also stored in the waste heat storage space 1B. The first waste heat utilization hot water storage operation continues from the state where waste heat generation has stopped and heating in the waste heat heating unit 9 is possible until it is no longer possible. Finally, as shown in Figure 4(D), hot water accumulates up to the top of the waste heat storage space 1B, and the waste heat storage space 1B is also filled with hot water and becomes full. Incidentally, the capacity of the waste heat storage space 1B can be set according to the amount of waste heat generated.

[0032] In this way, even if waste heat is generated when the amount of hot water stored in the storage space 1A of the hot water storage tank 1 has reached its maximum capacity, that waste heat can be stored in the hot water storage tank 1 as hot water, and the waste heat can be effectively utilized. By setting the capacity of the waste heat storage space 1B according to the amount of waste heat generated, the entire amount of waste heat can be stored in the hot water storage tank 1. For example, by applying the hot water supply system of this embodiment to a factory or the like where a large amount of waste heat is generated at once, it becomes an effective hot water supply system that can effectively utilize all of the generated waste heat.

[0033] As shown in Figures 4(E) and 4(F), as hot water is used at the hot water usage location 4, the hot water stored in the hot water storage tank 1 is consumed, and the storage space 1A returns to a state where the set amount of hot water is stored, as shown in Figure 4(A). Therefore, it is possible to maintain a state where the amount of hot water stored in the hot water storage space 1A is greater than the set amount as much as possible, thereby preventing the amount of hot water stored in the hot water storage tank 1 from falling below the set amount, reducing the number of operations between water supply and hot water storage, and thus reducing running costs.

[0034] [Second Embodiment] Next, a second embodiment of the hot water supply system according to the present invention will be described with reference to the drawings. In describing the second embodiment of the hot water supply system, the differences from the first embodiment will be mainly described, and the same configuration as the first embodiment will not be described.

[0035] As shown in Figure 5, the waste heat storage circuit 10 has a waste heat heating unit 9 installed at a point along the second waste heat supply water circuit 22 that supplies water to the storage tank 1. The waste heat storage circuit 10 is configured to generate hot water by heating the water supplied by the second waste heat water supply circuit 22 with the waste heat heating unit 9, and to perform a second waste heat utilization hot water storage operation in which the generated hot water is stored in the hot water storage tank 1.

[0036] To elaborate, the waste heat storage circuit 10 includes a second waste heat water supply circuit 22, a waste heat water supply valve 23, and a waste heat temperature sensor 19 that detects the temperature of the hot water flowing downstream of the waste heat heating unit 9. The waste heat water supply valve 23 corresponds to a water supply volume adjustment unit that adjusts the amount of water supplied to the storage tank 1 so as to maintain the temperature of the hot water in the storage tank 1 at a predetermined temperature while the waste heat storage circuit 10 is operating to store waste heat. In the second waste heat utilization hot water storage operation of the waste heat storage circuit 10, by opening the waste heat water supply valve 23, water is supplied to the hot water storage tank 1 through the second waste heat water supply circuit 22, as shown by the arrow (5) in Figure 5. At the same time, this water is heated in the waste heat heating unit 9 by heat exchange with a heat transfer medium that has waste heat, thereby generating hot water. In the second waste heat utilization hot water storage operation, the waste heat storage circuit 10 is configured to adjust the opening degree of the waste heat water supply valve 23 according to the temperature detected by the waste heat temperature sensor 19, so that the temperature of the hot water supplied to the hot water storage tank 1 by the second waste heat water supply circuit 22 becomes the target hot water storage temperature. In this way, by performing the second waste heat utilization hot water storage operation with the waste heat storage circuit 10, the temperature of the hot water stored in the hot water storage tank 1 can be maintained at the target hot water storage temperature by utilizing waste heat while supplying water to the hot water storage tank 1.

[0037] The control unit H is configured to control the heat exhaust water supply valve 23 of the heat exhaust hot water storage circuit 10 to start the second heat exhaust utilization hot water storage operation when it receives information indicating that heating is possible in the heat exhaust heating unit 9 (heat exhaust has been generated), and to control the heat exhaust water supply valve 23 to terminate the second heat exhaust utilization hot water storage operation when it receives information indicating that heating has changed from possible to impossible in the heat exhaust heating unit 9 (heat exhaust has stopped being generated), or when the heat exhaust storage space 1B in the hot water storage tank 1 is filled with hot water.

[0038] [Another embodiment] Other embodiments of the present invention will now be described. Note that the configurations of each embodiment described below are not limited to being applied individually, but can also be applied in combination with the configurations of other embodiments.

[0039] (1) In the first embodiment described above, a configuration in which a first waste heat water supply circuit 15 is provided separately from the water supply circuit 2 was described as an example, but the first waste heat water supply circuit 15 may be omitted by supplying water to the hot water storage tank 1 by the water supply circuit 2 while the waste heat utilization hot water storage operation is in operation.

[0040] (2) In the above embodiment, a configuration in which the heat exhaust storage space 1B is larger than the hot water storage space 1A was described as an example, but the relationship between the size of the heat exhaust storage space 1B and the hot water storage space 1A may be changed as appropriate, such as making the heat exhaust storage space 1B and the hot water storage space 1A the same size, or making the heat exhaust storage space 1B smaller than the hot water storage space 1A. [Explanation of Symbols]

[0041] 1. Hot water storage tank 1A Storage space for hot water 1B Heat Dissipation Storage Space 2 Water supply circuit 3. Hot water storage circuit 4. Locations where hot water is used 5 Hot water supply circuit 6. Water supply valve (water supply volume adjustment section) 7 Heating section 8. Hot water storage circuit 9 Heat dissipation heating section 10. Exhaust heat storage circuit 15. First heat dissipation water supply circuit 16 Exhaust heat circulation circuit 20. Heat exhaust water supply valve (water supply volume adjustment section) 22. Second heat dissipation water supply circuit 23. Heat exhaust water supply valve (water supply volume adjustment section)

Claims

1. In a hot water supply system comprising a hot water storage tank, a water supply circuit for supplying water to the hot water storage tank, a hot water storage circuit for storing hot water in the hot water storage tank, and a hot water supply circuit for supplying the hot water stored in the hot water storage tank to locations where hot water is used, The hot water storage circuit comprises a hot water storage circuit that stores hot water generated by a heating unit in the hot water storage tank, and a waste heat storage circuit that stores hot water generated by a waste heat heating unit in the hot water storage tank. The hot water storage tank has a storage space for hot water generated by the heating unit, as well as a storage space for waste heat for hot water from the waste heat storage circuit. The aforementioned waste heat storage circuit is a hot water supply system that performs waste heat utilization hot water storage operation, storing hot water generated by the waste heat heating unit in the hot water storage tank while supplying water to the hot water storage tank.

2. The hot water supply system according to claim 1, further comprising a water supply adjustment unit that adjusts the amount of water supplied to the hot water storage tank so as to maintain the temperature of the hot water in the storage tank at a predetermined temperature while the hot water storage operation using the waste heat storage circuit is in operation.

3. The hot water supply system according to claim 1 or 2, wherein the waste heat storage circuit comprises a first waste heat water supply circuit that supplies water to the hot water storage tank, and a waste heat circulation circuit that extracts hot water from the hot water storage tank and supplies it to the waste heat heating unit, and returns the hot water heated in the waste heat heating unit back to the hot water storage tank.

4. The hot water supply system according to claim 1 or 2, wherein the waste heat storage circuit has the waste heat heating unit located in the middle of the second waste heat water supply circuit that supplies water to the hot water storage tank.

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