Hot water production system

Abstract

To provide a hot water production system which can stably perform heat supply to a load system using an air heat source heat pump by suppressing an increase in facility cost using a steam boiler.SOLUTION: A hot water production system for heating service water Wa used in load equipment X in a facility includes: a first heating device H1 having an air heat source heat pump 10 with a refrigerant evaporator 14, the first heating device H1 being capable of executing a heating operation for heating the service water Wa using the air heat source heat pump 10 and a defrost operation for performing a defrosting operation on the refrigerant evaporator 14; and a second heating device H2 which uses, as a heat source fluid, steam St generated in a steam boiler SB. The second heating device H2 heats the service water Wa at least during execution of the defrost operation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hot water production system for heating water. [Background technology]

[0002] Conventionally, systems that heat water for use in load facilities within a business facility have used air-source heat pumps to heat water. Air-source heat pumps have a refrigerant evaporator that enables heating using the heat of the air, and are known as an excellent heating method that is highly energy efficient and can reduce carbon dioxide emissions.

[0003] However, when the air in an air-source heat pump's evaporator absorbs heat and cools below the dew point, the water vapor in the air condenses, causing condensation on the evaporator's heat transfer surface. When the outside air temperature is low and the condensed water cools below 0°C, the water freezes on the evaporator's heat transfer surface, causing frosting. The frost layer that grows on the evaporator's heat transfer surface increases thermal resistance and ventilation resistance, causing a decrease in the evaporator's heat transfer performance. For this reason, defrosting is required to remove the frost layer that forms on the evaporator, especially in winter when the outside air temperature is low.

[0004] Patent Document 1 mentions that a defrosting operation is performed in a hot water production system equipped with an air-source heat pump. Known defrosting operation types include the reverse cycle defrosting operation disclosed in Patent Document 2 and the hot gas bypass operation disclosed in Patent Document 3, as well as electric heater and hot water spray types. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2024-014372 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-152174 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-107836 Summary of the Invention [Problem to be solved by the invention]

[0006] The greater the difference in heat between the outlet hot water temperature and the outside air temperature, and the longer the heating operation time, the more frequently the defrosting operation is required. In addition, water heating is not possible during defrosting. Therefore, in order to meet the heat demand during defrosting operation, measures such as installing a large hot water storage tank in advance to store hot water overnight have been required, which has led to increased equipment costs.

[0007] Furthermore, factories and other business establishments have traditionally used steam boilers as heat sources for production and air conditioning. Steam has a large amount of latent heat and can easily reach temperatures above 100°C through pressure control, making it an excellent heat source fluid. For this reason, while there is a trend toward switching to heat pumps in order to reduce carbon dioxide emissions, there is also a desire to utilize existing steam boiler facilities by converting them to carbon-neutral fuels.

[0008] In view of the above-mentioned problems, the present invention aims to provide a hot water production system that uses a steam boiler to reduce increases in equipment costs and that can stably supply heat to load equipment using an air-source heat pump. [Means for solving the problem]

[0009] The hot water production system of the present invention is a hot water production system that heats water used in load equipment within a business premises, and is equipped with a first heating device that has an air-source heat pump with a refrigerant evaporator and is capable of performing a heating operation that heats water using the air-source heat pump and a defrost operation that defrosts the refrigerant evaporator, and a second heating device that uses steam generated in a steam boiler as a heat source fluid, and the second heating device is configured to heat the water at least when the defrost operation is being performed.

[0010] More specifically, the above configuration may be such that the air-source heat pump circulates the refrigerant through the compressor, the heat dissipation heat exchanger, the expansion valve, and the refrigerant evaporator in that order when the heating operation and the defrost operation are performed, and the second heating device may include a heat exchanger between the expansion valve and the refrigerant evaporator that transfers heat from the vapor to the refrigerant when the defrost operation is performed.

[0011] More specifically, the above configuration may further include a third heating device that uses the steam as a heat source fluid, and the third heating device may include a heat exchange section that transfers heat from the steam to the service water, or a mixing section that mixes the steam with the service water.

[0012] More specifically, the above configuration may be such that the air-source heat pump is configured to perform the defrosting operation using a reverse cycle or hot gas bypass method, and the second heating device includes a heat exchange section that transfers heat from the steam to the service water, or a mixing section that mixes the steam with the service water.

[0013] More specifically, the above configuration may include an air temperature detection means for detecting the temperature of the heat source air before heat exchange in the refrigerant evaporator, and a refrigerant temperature detection means for detecting the temperature of the refrigerant after heat exchange in the refrigerant evaporator, and the need for the defrosting operation may be determined based on the temperatures detected by the air temperature detection means and the refrigerant temperature detection means, and the defrosting operation may be performed if it is determined that the defrosting operation is necessary. [Effects of the Invention]

[0014] According to the hot water production system of the present invention, it is possible to suppress increases in equipment costs by using a steam boiler, and to stably supply heat to load equipment using an air-source heat pump. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic configuration diagram of a hot water producing system according to a first embodiment. [Figure 2] FIG. 10 is a schematic configuration diagram of a hot water producing system according to a second embodiment. [Figure 3] FIG. 10 is a schematic configuration diagram of an air-source heat pump according to a second embodiment. [Figure 4] FIG. 10 is a configuration diagram of an air-source heat pump of another type according to the second embodiment. [Figure 5] FIG. 10 is a schematic configuration diagram of a hot water producing system according to a third embodiment. [Figure 6] FIG. 10 is a schematic configuration diagram of a hot water producing system according to a fourth embodiment. [Figure 7] FIG. 10 is a schematic configuration diagram of a hot water producing system according to a fifth embodiment. [Figure 8] FIG. 10 is a schematic configuration diagram of a hot water producing system according to a sixth embodiment. [Figure 9] FIG. 10 is a schematic configuration diagram of a hot water producing system according to a seventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Each embodiment of the present invention will be described below with reference to the drawings.

[0017] 1. First embodiment FIG. 1 is a schematic diagram of a hot water production system 100 according to a first embodiment. As shown in the figure, the hot water production system 100 includes an air-source heat pump 10, a heat exchanger 21 having a first heat exchanger 21a and a second heat exchanger 21b, a three-way valve 22, a steam mixer 23, a steam boiler SB, a steam header SH, a water tank K, a first pump P1, a second pump P2, a first valve V1, a second valve V2, first to seventh lines L1 to L7, a water output line Lx, a steam output line Ly, a temperature sensor S1, and a control unit C. The air-source heat pump 10 constitutes a first heating device H1, the heat exchanger 21 constitutes a second heating device H2, and the steam mixer 23 constitutes a third heating device H3. The hot water production system 100 heats water Wa to be used by load equipment X within a business facility.

[0018] In this context, establishments refer to individual locations where the production of goods or the provision of services is carried out as a business, such as factories, commercial facilities, medical institutions, welfare facilities, accommodation facilities, or research facilities. Service water refers to water used in connection with the production of goods or the provision of services. Heated service water can be used directly as cleaning water or indirectly as heat transfer water.

[0019] If the business establishment is a factory, the load equipment would be production equipment (equipment directly involved in the production of goods) such as food and beverage manufacturing plants, automobile, metal product, and machinery and equipment manufacturing plants. An example of load equipment other than factory production equipment is a steam boiler unit (heat source equipment involved in the operation of production equipment), in which case part of the heated water is used as boiler feed water.

[0020] The first line L1 is a line that distributes the water Wa from the water tank K via the second pump P2 to the three-way valve 22. The second line L2 is a line that distributes the water Wa from the three-way valve 22 to a predetermined position α via a condenser 12 described below. The third line L3 is a line that distributes the water Wa from the predetermined position α to the water tank K via a steam mixer 23. The fourth line L4 is a line that distributes the water Wa from the three-way valve 22 to the predetermined position α.

[0021] The fifth line L5 forms a circulation path for the intermediate medium Rm that passes through the first heat exchanger 21a, the first pump P1, and the second heat exchanger 21b. The sixth line L6 is a line that circulates steam St from the steam header SH through the first valve V1 to the steam mixer 23. The seventh line L7 is a path for steam St that is formed to pass from the steam header SH through the second valve V2 and the first heat exchanger 21a in that order, and its end is open to the outside. The arrangement of pumps, valves, etc. in the hot water production system 100 can be changed as appropriate as long as the hot water production system 100 functions normally.

[0022] The steam boiler SB is configured as, for example, a steam boiler with a gas-fired or oil-fired burner, or a steam boiler with an electric heater, and generates steam St. The steam boiler SB may be configured with multiple steam boilers. The steam St generated by the steam boiler SB is sent to a steam header SH via a steam output line Ly. The steam header SH can send the steam St to each output destination (the sixth line L6 and the seventh line L7 in the example shown in FIG. 1). The steam header SH may also be configured to send the steam St to other output destinations not shown.

[0023] The water tank K serves to store the water Wa to be supplied to the load equipment X. When the load equipment X is a hot water supply load (described later), the water tank K is connected to a makeup water line extending from a water supply source and having a makeup water valve, and is also provided with a water level sensor (not shown). The makeup water valve opens when the water level sensor detects a decrease in the water level in the water tank K, and closes when the water tank K detects a full tank. The temperature sensor S1 is located downstream of the steam mixer 23 on the second line L2, and continuously detects the temperature T1 of the water Wa. Information on the temperature T1 detected by the temperature sensor S1 is sent to the control unit C.

[0024] The water output line Lx is a path for sending the water Wa from the hot water producing system 100 to the load equipment X. When the load equipment X is a heat supply load (a load equipment that returns the water Wa after heat utilization to the hot water producing system 100), the water output line Lx includes not only a path for sending the water Wa from the hot water producing system 100 to the load equipment X, but also a path for returning the water Wa after heat utilization from the load equipment X to the hot water producing system 100. When the load equipment X is a hot water supply load (a load equipment that consumes the water Wa and does not return the water Wa to the hot water producing system 100), a path for returning the water Wa after heat utilization from the load equipment X to the hot water producing system 100 is not necessary, but the hot water producing system 100 is configured to replenish the water Wa sent to the load equipment X. The load equipment X in the first embodiment is basically assumed to be a heat supply load, and the load equipment X in the second to seventh embodiments described below is basically assumed to be a hot water supply load.

[0025] As shown in Figure 1, the air-source heat pump 10 includes a compressor 11, a condenser 12, an expansion valve 13, and an evaporator 14 (refrigerant evaporator), which are connected by a refrigerant circulation line Lc. A second heat exchanger 21b is disposed in the refrigerant circulation line Lc between the expansion valve 13 and the evaporator 14. A refrigerant R can be circulated through the refrigerant circulation line Lc in the direction indicated by the arrow in Figure 1.

[0026] The compressor 11 has a motor as a drive source, and compresses the refrigerant R received from the upstream evaporator 14 to produce high-temperature, high-pressure refrigerant R, which is then sent downstream. The rotation speed of the compressor 11 can be controlled by the control unit C.

[0027] The condenser 12 functions as a heat dissipation heat exchanger, and exchanges heat between the water Wa sent through the water input line (the second line L2 in the example shown in FIG. 1) and the refrigerant R sent from the compressor 11, thereby condensing the refrigerant R. The water Wa (heated water Wa) that has undergone heat exchange in the condenser 12 is sent out through the second line L2.

[0028] The expansion valve 13 passes the refrigerant R sent from the condenser 12, thereby reducing the pressure and temperature of the refrigerant R. The evaporator 14 functions as an endothermic heat exchanger, exchanging heat between the heat source air Ar (outside air) and the refrigerant R sent from the expansion valve 13, and evaporating the refrigerant R by absorbing heat from the heat source air Ar.

[0029] The evaporator 14 in this embodiment is, for example, a fin-tube heat exchanger, and is configured to use a blower fan 14a to continuously send heat-source air Ar to a number of fins provided on the surface of a heat transfer tube (part of the refrigerant circulation line Lc) through which the refrigerant R passes. In addition, a refrigerant temperature sensor 14x (a form of refrigerant temperature detection means) that detects the temperature of the refrigerant R after heat exchange in the evaporator 14 is provided near the outlet of the heat transfer tube in the evaporator 14 through which the refrigerant R passes, and an air temperature sensor 14y (a form of air temperature detection means) that detects the temperature of the heat-source air Ar before heat exchange in the evaporator 14 is provided near the upstream side of the fin.

[0030] The control unit C controls each part of the hot water production system 100 so that the system 100 operates appropriately. For example, the control unit C can drive the air-source heat pump 10 and the pumps P1 and P2. Furthermore, the control unit C can switch the valves V1 and V2 between a conductive state (a state in which steam St or water Wa is conducted) and a non-conductive state (a state in which steam St or water Wa is not conducted), and can control the flow state of the water Wa through the three-way valve 22. In this embodiment, as shown in FIG. 1 , the water Wa can be circulated in the direction indicated by the colored arrows, the steam St can be circulated in the direction indicated by the hollow arrows, and the intermediate medium Rm can be circulated in the direction indicated by the dashed arrows.

[0031] In the hot water producing system 100, a heating operation for heating the water Wa and a defrosting operation for defrosting the evaporator 14 can be performed.

[0032] For example, the control unit C starts the heating operation when the temperature T1 (detection information from the temperature sensor S1) drops to the lower limit of a predetermined appropriate range Z (a range in which an appropriate heat supply to the load equipment X is possible) so that the temperature T1 is maintained within that range, and stops the heating operation when the temperature T1 rises to the upper limit of the appropriate range Z. When performing normal heating operation, the control unit C circulates the refrigerant R in the air-source heat pump 10, sets the valves V1 and V2 to a non-conductive state, controls the three-way valve 22 to a state in which the water Wa flows from the first line L1 to the second line L2, and drives the second pump P2.

[0033] As a result, the water Wa in the water tank K circulates through the first line L1, the second line L2, and the third line L3 in that order. The circulating water Wa is heated in the condenser 12 of the air-source heat pump 10. As a result, the temperature of the water in the water tank K can be increased using the air-source heat pump 10.

[0034] Furthermore, when normal heating operation is insufficient to heat the water Wa (for example, when the appropriate range Z is set to a temperature range that exceeds the heating capacity of the air-source heat pump 10), the water Wa can be heated by a heating operation (assisted heating operation) that uses steam St in addition to the air-source heat pump 10. When performing this assisted heating operation, the control unit C circulates the refrigerant R in the air-source heat pump 10, controls the first valve V1 to be in a conductive state and the second valve V2 to be in a non-conductive state, controls the three-way valve 22 to allow the water Wa to flow from the first line L1 to the second line L2, and drives the second pump P2. Note that the amount of heating by the steam St may be controlled, for example, by adjusting the aperture of the first valve V1 so that the temperature is raised by a predetermined temperature difference from the outlet temperature of the condenser 12.

[0035] As a result, the water Wa in the water tank K circulates through the first line L1, the second line L2, and the third line L3 in that order, and is heated in the condenser 12 of the air-source heat pump 10. The circulating water Wa is further heated by being mixed with steam St in the steam mixer 23. Therefore, it is possible to raise the temperature of the water Wa in the water tank K more than when normal heating operation is performed.

[0036] Furthermore, in this embodiment, even in a situation where heating operation using the air-source heat pump 10 is not possible due to maintenance or the like, it is possible to heat the water Wa through heating operation using steam St (steam heating operation). When performing this steam heating operation, the control unit C controls the first valve V1 to a conductive state and the second valve V2 to a non-conductive state, controls the three-way valve 22 to a state in which the water Wa flows from the first line L1 to the third line L3 (i.e., a state in which the water Wa bypasses the condenser 12), and drives the second pump P2.

[0037] As a result, the water Wa in the water tank K circulates through the first line L1, the fourth line L4, and the third line L3 in that order, and is heated by being mixed with the steam St in the steam mixer 23. Therefore, it is possible to increase the temperature of the water Wa in the water tank K without using the air-source heat pump 10.

[0038] Furthermore, during the heating operation, the control unit C determines whether a defrosting operation is required for the evaporator 14. In this embodiment, the control unit C determines whether a defrosting operation is required based on the temperatures detected by the air temperature sensor 14y and the refrigerant temperature sensor 14x. More specifically, the control unit C determines that a defrosting operation is required when the difference ΔT between the temperatures detected by the air temperature sensor 14y and the refrigerant temperature sensor 14x exceeds a specified value Ts.

[0039] As the frost layer grows on the heat transfer surface of the evaporator 14, thermal resistance and ventilation resistance increase, and the difference ΔT between the temperature detected by the air temperature sensor 14y and the temperature detected by the refrigerant temperature sensor 14x becomes larger. Therefore, when the difference ΔT exceeds the specified value Ts, it is possible to determine that a defrosting operation for the evaporator 14 is necessary. The specific value of the specified value Ts may be set appropriately in advance so that the need for a defrosting operation can be appropriately determined. For example, when it is desired to determine whether a defrosting operation is necessary when frost on the heat transfer surface is in the early stages of growth, the specified value Ts is set to a relatively small value, and when it is desired to determine whether a defrosting operation is necessary when frost is in the advanced growth stage, the specified value Ts is set to a relatively large value.

[0040] In this embodiment, as described above, the necessity of a defrosting operation is determined based on the temperatures detected by the air temperature sensor 14y and the refrigerant temperature sensor 14x, and therefore, it is possible to very accurately determine whether a defrosting operation is required. However, the method for determining whether a defrosting operation is required is not limited to the method described above, and various methods, including well-known methods, may be used, for example, a method for determining whether a defrosting operation is required based on the temperature detected by only one of the air temperature sensor 14y and the refrigerant temperature sensor 14x.

[0041] When it is determined that a defrosting operation is necessary, the control unit C executes the defrosting operation described above. When executing the defrosting operation, the control unit C circulates the refrigerant R in the air-source heat pump 10, sets the first valve V1 to a non-conductive state, sets the second valve V2 to a conductive state, and drives the first pump P1. The defrosting operation in the first embodiment is performed in a forward cycle in which the refrigerant R circulates in the same direction as during heating operation.

[0042] As a result, the vapor St flows through the first heat exchanger 21a, and the heat of this vapor St is transferred to the intermediate medium Rm. Furthermore, as this intermediate medium Rm flows through the second heat exchanger 21b, the heat of the vapor St is transferred to the refrigerant R of the air-source heat pump 10. In other words, the refrigerant R is heated by the heat of the vapor St.

[0043] The heated refrigerant R flows through the evaporator 14, thereby realizing a defrosting operation for the evaporator 14. Furthermore, when the refrigerant R that has passed through the evaporator 14 flows through the condenser 12, the heat of the steam St remaining in the refrigerant R is transferred to the water Wa, and the water Wa is heated by the heat of the steam St.

[0044] Note that when the defrosting operation is performed, the steam heating operation described above (with the second valve V2 in a conductive state) may be performed in parallel. In addition, in this embodiment, in the series of paths formed by the first to third lines L1 to L3, the steam mixer 23 and the air-source heat pump 10 (condenser 12) are installed in series, so that only one pump is installed, thereby enabling consideration to be given to reducing power consumption.

[0045] 2. Second embodiment Next, a second embodiment will be described. In the following description, emphasis will be placed on the differences from the first embodiment, and descriptions of the commonalities with the first embodiment may be omitted.

[0046] 2 is a schematic configuration diagram of a hot water producing system 100 according to a second embodiment. As shown in the figure, the hot water producing system 100 according to the second embodiment includes a steam boiler SB, a steam header SH, a water output line Lx, a steam output line Ly, a control unit C, an air-source heat pump 10a, an eleventh pump P11, an eleventh valve V11, a steam mixer 23, a temperature sensor S1, and eleventh to thirteenth lines L11-L13. The air-source heat pump 10a constitutes a first heating device, and the steam mixer 23 constitutes a second heating device H2.

[0047] The eleventh line L11 is a line that distributes the service water Wa supplied from the outside to the air-source heat pump 10a via the eleventh pump P11. The twelfth line L12 is a line that distributes the service water Wa from the air-source heat pump 10a to the steam mixer 23. The thirteenth line L13 is a line that distributes the service water Wa from the steam header SH to the steam mixer 23 via the eleventh valve V11. The service water output line Lx is a line that distributes the service water Wa from the steam mixer 23 to the load equipment X, and has a temperature sensor S1 disposed therein.

[0048] Figure 3 is a schematic diagram of an air-source heat pump 10a. As shown in this figure, the air-source heat pump 10a includes a compressor 11, a condenser 12, an expansion valve 13, an evaporator 14, and a four-way valve 15, which are connected by a refrigerant circulation line Lc. The refrigerant R can be circulated through the refrigerant circulation line Lc. The compressor 11, condenser 12, expansion valve 13, and evaporator 14 are basically the same as those in the first embodiment.

[0049] 3, four-way valve 15 has connection points a to d to which ends of refrigerant circulation line Lc are connected. Refrigerant circulation line Lc extending from connection point b is connected to connection point d via condenser 12, expansion valve 13, and evaporator 14 in this order. On the other hand, refrigerant circulation line Lc extending from connection point c is connected to connection point a via compressor 11.

[0050] Four-way valve 15 is configured to be switchable between a first state in which connection point a is connected to connection point b and connection point c is connected to connection point d, and a second state in which connection point a is connected to connection point d and connection point b is connected to connection point c. Switching of four-way valve 15 between the first state and the second state is controlled by control unit C.

[0051] The hot water producing system 100 of the second embodiment can also perform a heating operation to heat the water Wa and a defrosting operation to defrost the evaporator 14. In the hot water producing system 100 having the air-source heat pump 10a shown in Fig. 3, a defrosting operation using a reverse cycle method (reverse cycle defrosting operation) is performed as the defrosting operation.

[0052] With respect to the air-source heat pump 10a shown in Figure 3, the heating operation can be performed with the four-way valve 15 in a first state, and the defrost operation can be performed with the four-way valve 15 in a second state. That is, when the four-way valve 15 is in the first state, the refrigerant R circulates in the direction indicated by the solid arrow in Figure 3. At this time, the refrigerant R absorbs heat from the heat-source air Ar in the evaporator 14 and is vaporized, while the refrigerant R releases heat to the water Wa in the condenser 12 and is condensed. This achieves a heating operation in which the water Wa is heated using the air-source heat pump 10a.

[0053] On the other hand, when the four-way valve 15 is in the second state, the refrigerant R circulates in the direction indicated by the dotted arrow in Fig. 3. As a result, the refrigerant R flows in the reverse direction, and the frost adhering to the evaporator 14 is melted by the heat generated by the refrigerant R, thereby realizing a reverse cycle defrosting operation.

[0054] Furthermore, the configuration of the air-source heat pump 10a may be the configuration shown in Fig. 4 instead of the configuration shown in Fig. 3. In the hot water production system 100 having the air-source heat pump 10a shown in Fig. 4, a defrosting operation using a hot gas bypass method (hot gas bypass defrosting operation) is performed as the defrosting operation.

[0055] The air-source heat pump 10a shown in Figure 4 includes a compressor 11, a three-way valve 16, a condenser 12, an expansion valve 13, and an evaporator 14, which are connected by a refrigerant circulation line Lc. Furthermore, the air-source heat pump 10a is provided with a bypass line Lb that connects the three-way valve 16 to a predetermined position β (a position between the expansion valve 13 and the evaporator 14) of the refrigerant circulation line Lc.

[0056] 4, the three-way valve 16 has connection points a to c to which the ends of the refrigerant circulation line Lc or the bypass line Lb are connected. The refrigerant circulation line Lc extending from the connection point b is connected to the connection point a via the condenser 12, the expansion valve 13, the evaporator 14, and the compressor 11 in this order. On the other hand, the bypass line Lb extending from the connection point c is connected to a predetermined position β.

[0057] The three-way valve 16 is configured to be switchable between a first state in which the refrigerant R is conducted from connection point a to connection point b, and a second state in which the refrigerant R is conducted from connection point a to connection point c. The switching between the first state and the second state of the three-way valve 16 is controlled by the control unit C. With respect to the air-source heat pump 10a shown in FIG. 4, the heating operation can be performed with the three-way valve 16 in the first state, and the defrosting operation can be performed with the three-way valve 16 in the second state.

[0058] That is, when the three-way valve 16 is in the first state, the refrigerant R circulates as shown by the solid arrows in Fig. 4. At this time, the refrigerant R absorbs heat from the heat-source air Ar in the evaporator 14 and vaporizes, while the refrigerant R releases heat to the water Wa and condenses in the condenser 12. This achieves a heating operation in which the water Wa is heated using the air-source heat pump 10a.

[0059] On the other hand, when the three-way valve 16 is in the second state, the refrigerant R circulates as shown by the dotted arrows in Fig. 4. That is, the direction of circulation of the refrigerant R is the same as during heating operation, but the refrigerant R circulates while bypassing the condenser 12 and the expansion valve 13. This performs hot gas bypass defrost operation using the heat of the compressor 11, and achieves a defrosting operation that melts the frost that has adhered to the evaporator 14.

[0060] When performing normal heating operation, the control unit C circulates the refrigerant R in the air-source heat pump 10a and drives the eleventh pump P11 with the eleventh valve V11 in a non-conductive state. This allows the water Wa supplied to the eleventh line L11 to be heated by the air-source heat pump 10a, making it possible to increase the temperature of the water Wa sent to the load equipment X via the water output line Lx.

[0061] When normal heating operation does not heat the water Wa sufficiently, the water Wa can be heated by heating operation (assisted heating operation) that uses steam St in addition to the air-source heat pump 10. When performing this assisted heating operation, the control unit C circulates the refrigerant R in the air-source heat pump 10a and drives the eleventh pump P11 by placing the eleventh valve V11 in a conducting state. As a result, the water Wa heated by the air-source heat pump 10 is further heated by mixing with the steam St in the steam mixer 23, and the temperature of the water Wa sent to the load equipment X via the water output line Lx can be further increased.

[0062] Furthermore, when the defrosting operation is performed, the control unit C also controls the eleventh valve V11 to be in a conducting state and drives the eleventh pump P11, so that the water Wa can be heated by a heating operation using steam St (steam heating operation). Note that even in a situation where the heating operation using the air-source heat pump 10a cannot be performed due to maintenance or the like, the water Wa can still be heated by the steam heating operation.

[0063] 3. Third embodiment Next, a third embodiment will be described. In the following description, the emphasis will be placed on the differences from the second embodiment, and the description of the commonalities with the second embodiment may be omitted.

[0064] 5 is a schematic configuration diagram of a hot water producing system 100 according to a third embodiment. As shown in the figure, the hot water producing system 100 of the third embodiment includes a steam boiler SB, a steam header SH, a water output line Lx, a steam output line Ly, a control unit C, an air-source heat pump 10a, a water tank K, a pump P21, a valve V21, a temperature sensor S1, a line L21, and a line L22. The air-source heat pump 10a constitutes a first heating device H1, and the water tank K constitutes a second heating device H2 that mixes water Wa with steam St.

[0065] The 21st line L21 is a line that circulates the service water Wa supplied from the outside to the service water tank K via the 21st pump P21 and the air-source heat pump 10a in that order. The 22nd line L22 is a line that circulates steam St from the steam header SH to the service water tank K via the 21st valve V21. The service water output line Lx is a line that circulates the service water Wa from the service water tank K to the load equipment X. The service water tank K serves to store the service water Wa to be supplied to the load equipment X, and has a temperature sensor S1 disposed therein.

[0066] When performing normal heating operation, the control unit C circulates the refrigerant R in the air-source heat pump 10a and drives the 21st pump P21 with the 21st valve V21 in a non-conductive state. As a result, the water Wa supplied to the 21st line L21 is heated by the air-source heat pump 10a, making it possible to increase the temperature of the water Wa in the water tank K (the temperature of the water Wa supplied to the load equipment X).

[0067] When normal heating operation does not heat the water Wa sufficiently, the water Wa can be heated by a heating operation (assisted heating operation) that uses steam St in addition to the air-source heat pump 10a. When performing this assisted heating operation, the control unit C circulates the refrigerant R in the air-source heat pump 10a and drives the 21st pump P21 by placing the 21st valve V21 in a conductive state. As a result, the water Wa in the water tank K is further heated by mixing with the steam St, and the temperature of the water Wa can be further increased.

[0068] Furthermore, when the defrosting operation is performed, the control unit C also controls the 21st valve V21 to be in a conducting state and drives the 21st pump P21, making it possible to heat the water Wa through heating operation using steam St (steam heating operation). Note that even in a situation where heating operation using the air-source heat pump 10a is not possible due to maintenance or the like, the water Wa can still be heated through steam heating operation.

[0069] 4. Fourth embodiment Next, a fourth embodiment will be described. In the following description, the emphasis will be placed on the differences from the third embodiment, and the description of the commonalities with the third embodiment may be omitted.

[0070] 6 is a schematic configuration diagram of a hot water producing system 100 according to a fourth embodiment. As shown in the figure, the hot water producing system 100 according to the fourth embodiment includes a steam boiler SB, a steam header SH, a water output line Lx, a steam output line Ly, a control unit C, an air-source heat pump 10a, a water tank K, a second pump P21, a second valve V21, a temperature sensor S1, a first line L21, a second line L22, and a heat exchanger 24. The air-source heat pump 10a constitutes a first heating device H1, and the heat exchanger 24 constitutes a second heating device H2.

[0071] The 21st line L21 is a line that circulates water Wa supplied from outside, sequentially via the 21st pump P21, the air-source heat pump 10a, and the heat exchanger 24, to the water tank K. The 22nd line L22 is a path that circulates steam St from the steam header SH through the 21st valve V21 and the heat exchanger 24, and its end is open to the outside.

[0072] When assisted heating operation or steam heating operation is performed, in the third embodiment, the water Wa in the water tank K is heated by mixing steam St with the water Wa. However, in the fourth embodiment, heat is transferred from the steam St to the water Wa in the heat exchanger 24, thereby heating the water Wa using steam St.

[0073] 5. Fifth embodiment Next, a fifth embodiment will be described. In the following description, the emphasis will be placed on the differences from the third embodiment, and the description of the commonalities with the third embodiment may be omitted.

[0074] 7 is a schematic configuration diagram of a hot water producing system 100 according to a fifth embodiment. As shown in the figure, the hot water producing system 100 of the fifth embodiment includes a steam boiler SB, a steam header SH, a water output line Lx, a steam output line Ly, a control unit C, an air-source heat pump 10a, a first water tank K1, a second water tank K2, a first pump P31, a second pump P32, a first valve V31, a temperature sensor S1, and first to fifth lines L31-L35. The air-source heat pump 10a constitutes a first heating device H1, and the second water tank K2 constitutes a second heating device H2 that mixes water Wa with steam St.

[0075] The 31st line L31 is a line that circulates the water Wa from the air-source heat pump 10a to the first water tank K1. The 32nd line L32 is a line that circulates the water Wa from the first water tank K1 to the air-source heat pump 10a. These lines L31 and L32 form a circulation line Lz for the water Wa that includes the air-source heat pump 10a and the first water tank K1.

[0076] The 33rd line L33 is a line that distributes water Wa from the first water tank K1 to the second water tank K2 via the 31st pump P31. The 34th line L34 is a line that distributes steam St from the steam header SH to the second water tank K2 via the 31st valve V31. The 35th line L35 is a line that distributes water Wa that is supplied from the outside to the first water tank K1 via the 32nd pump P32.

[0077] The water output line Lx is a line that circulates the water Wa from the second water tank K2 to the load equipment X. A temperature sensor S1 is disposed in the second water tank K2. The first water tank K1 serves to temporarily store the water Wa that is heated by the air-source heat pump 10a, and the second water tank K2 serves to store the water Wa that is to be supplied to the load equipment X.

[0078] When performing normal heating operation, the control unit C circulates the refrigerant R in the air-source heat pump 10a and circulates the water Wa in the circulation line Lz, and drives the 31st pump P31 with the 31st valve V31 in a non-conductive state. As a result, the water Wa in the first water tank K1 is heated by the air-source heat pump 10a, and this heated water Wa is sent to the second water tank K2, making it possible to increase the temperature of the water Wa in the second water tank K2 (the temperature of the water Wa supplied to the load equipment X). Note that the water Wa that has decreased in the first water tank K1 is replenished through the 35th line L35 by driving the 32nd pump P32.

[0079] When normal heating operation does not heat the water Wa sufficiently, the water Wa can be heated by a heating operation (assisted heating operation) that uses steam St in addition to the air-source heat pump 10a. When performing this assisted heating operation, the control unit C circulates the refrigerant R in the air-source heat pump 10a and drives the 31st pump P31 by placing the 31st valve V31 in a conductive state. As a result, the water Wa in the second water tank K2 is further heated by mixing with the steam St, and the temperature of the water Wa can be further increased.

[0080] Furthermore, when performing the defrosting operation, the control unit C can place the 31st valve V31 in a conductive state and heat the water Wa by a heating operation using steam St (steam heating operation). Note that even in a situation where heating operation using the air-source heat pump 10a is not possible due to maintenance or the like, the water Wa can still be heated by the steam heating operation.

[0081] 6. Sixth embodiment Next, a sixth embodiment will be described. In the following description, the emphasis will be placed on the differences from the fifth embodiment, and the description of the commonalities with the third embodiment may be omitted.

[0082] 8 is a schematic configuration diagram of a hot water producing system 100 according to a sixth embodiment. As shown in the figure, the hot water producing system 100 according to the sixth embodiment includes a steam boiler SB, a steam header SH, a water output line Lx, a steam output line Ly, a control unit C, an air-source heat pump 10a, a first water tank K1, a second water tank K2, a thirty-first pump P31, a thirty-second pump P32, a thirty-first valve V31, a temperature sensor S1, thirty-first to thirty-fifth lines L31 to L35, and a heat exchanger 24. The air-source heat pump 10a constitutes a first heating device H1, and the heat exchanger 24 constitutes a second heating device H2.

[0083] The 33rd line L33 is a line that circulates the water Wa in the first water tank K1 to the second water tank K2, successively passing through the 31st pump P31 and the heat exchanger 24. The 34th line L34 is a path that circulates the steam St from the steam header SH, successively passing through the 31st valve V31 and the heat exchanger 24, and has an end that is open to the outside.

[0084] When assisted heating operation or steam heating operation is performed, in the fifth embodiment, the water Wa in the second water tank K2 is heated by mixing steam St with the water Wa. However, in the sixth embodiment, heat is transferred from the steam St to the water Wa in the heat exchanger 24, thereby heating the water Wa using steam St.

[0085] 7. Seventh embodiment Next, a seventh embodiment will be described. In the following description, emphasis will be placed on the differences from the second embodiment, and a description of the commonalities with the second embodiment may be omitted.

[0086] 9 is a schematic configuration diagram of a hot water producing system 100 according to a seventh embodiment. As shown in the figure, the hot water producing system 100 according to the seventh embodiment includes a steam boiler SB, a steam header SH, a water output line Lx, a steam output line Ly, a control unit C, an air-source heat pump 10a, a 41st pump P41, 41st to 43rd valves V41 to V43, a heat exchanger 24, a water tank K, a temperature sensor S1, and 41st to 44th lines L41 to L44. The air-source heat pump 10a constitutes a first heating device H1, and the heat exchanger 24 constitutes a second heating device H2.

[0087] The air-source heat pump 10a of the seventh embodiment is configured such that, compared to the air-source heat pump 10a configured as shown in Fig. 3, it has a first heat radiation heat exchanger 12a and a second heat radiation heat exchanger 12b instead of the condenser 12. That is, the air-source heat pump 10a of the seventh embodiment is configured by connecting the compressor 11, four-way valve 15, first heat radiation heat exchanger 12a, second heat radiation heat exchanger 12b, expansion valve 13, and evaporator 14 in a ring shape, and is capable of performing reverse cycle defrost operation, similar to the air-source heat pump 10a configured as shown in Fig. 3.

[0088] The 41st line L41 is a line that circulates the service water Wa that is supplied from the outside via the 41st valve V41 to the service water tank K. The 42nd line L42 is a line that circulates the service water Wa from a predetermined position on the 41st line L41 (a position upstream of the 41st valve V41) via the 42nd valve V42 and the second heat dissipation heat exchanger 12b in this order to a predetermined position on the 41st line L41 (a position downstream of the 41st valve V41).

[0089] The 43rd line L43 is a line that circulates the water Wa from the water tank K to the water tank K via the 41st pump P41, the first heat-dissipating heat exchanger 12a, and the heat exchanger 24 in this order. The 44th line L44 is a path through which steam St flows from the steam header SH to the 43rd valve V43 and the heat exchanger 24 in that order, and its end is open to the outside. The water tank K serves to store the water Wa to be supplied to the load equipment X, and has a temperature sensor S1 disposed therein.

[0090] When performing normal heating operation, the control unit C circulates the refrigerant R in the air-source heat pump 10a, while also placing the 41st and 43rd valves V41 and V43 in a non-conductive state and the 42nd valve V42 in a conductive state, and driving the 41st pump P41. As a result, the water Wa supplied to the 41st line L41 is heated by the second heat-dissipation heat exchanger 12b and then supplied to the water tank K. Furthermore, the water Wa in the water tank K is heated by the first heat-dissipation heat exchanger 12a and then returned to the water tank K. In this way, the air-source heat pump 10a can be used to increase the temperature of the water Wa delivered to the load equipment X via the water output line Lx. Note that the states of the 41st and 42nd valves V41 and V42 may be changed depending on the situation.

[0091] When normal heating operation does not heat the water Wa sufficiently, the water Wa can be heated by a heating operation (assisted heating operation) that uses steam St in addition to the air-source heat pump 10. When performing this assisted heating operation, the control unit C basically performs control equivalent to the normal heating operation described above, but the 43rd valve V43 is set to a conductive state. This allows the water Wa in the water tank K to be further heated by heat transfer from the steam St in the heat exchanger 24, making it possible to further increase the temperature of the water Wa.

[0092] Furthermore, when the defrosting operation is performed, the control unit C also controls the 43rd valve V43 to be in a conductive state and drives the 41st pump P41, thereby enabling the water Wa to be heated by a heating operation using the steam St (steam heating operation). In this embodiment, when the reverse cycle defrosting operation is performed, heat is removed from the water Wa as it passes through the first heat dissipation heat exchanger 12a. However, because heat can be transferred from the steam St to the water Wa in the heat exchanger 24, a decrease in the temperature of the water Wa in the water tank K can be prevented and the temperature of the water Wa can also be increased. Furthermore, even in a situation where the heating operation using the air-source heat pump 10a is not possible due to maintenance or the like, the water Wa can be heated by the steam heating operation.

[0093] 8. Summary As described above, the hot water production system 100 of each embodiment is a system equipped with a first heating device H1 that has an air-source heat pump 10 with an evaporator 14 and is capable of performing a heating operation to heat the water Wa using the air-source heat pump 10 and a defrost operation to defrost the evaporator 14, and a second heating device H2 that uses steam St generated in a steam boiler SB as a heat source fluid and heats the water Wa at least when the defrost operation is being performed.

[0094] The first heating device H1 may have a plurality of air-source heat pumps 10, or may further have heating means other than the air-source heat pumps 10. Furthermore, the first heating device H1 may be configured to heat the water Wa with a separately provided intermediate heat exchanger, instead of a configuration in which the water Wa is heated with a heat dissipation heat exchanger (condenser 12). In this case, for example, the heat dissipation heat exchanger and the intermediate heat exchanger may be connected by a circulation line for an intermediate medium (water), and heat may be exchanged between the water Wa and the intermediate medium while circulating the intermediate medium.

[0095] In the first embodiment, the air-source heat pump 10 is configured to circulate the refrigerant R through the compressor 11, condenser 12 (heat dissipation heat exchanger), expansion valve 13, and evaporator 14 in this order during both heating operation and defrost operation. The second heating device H2 is configured to include a heat exchanger 21 between the expansion valve 13 and the evaporator 14 in the air-source heat pump 10, which transfers heat from the vapor St to the refrigerant R during defrost operation. The heat exchanger 21 is not limited to the form in which heat is transferred from the vapor St to the refrigerant R via an intermediate medium Rm as in the example of the first embodiment, and a heat exchanger that transfers heat directly from the vapor St to the refrigerant R via a heat transfer surface may also be used.

[0096] In the first embodiment, the second heating device H2 heats the water Wa via the air-source heat pump 10. More specifically, a heat exchanger 21 is disposed between the expansion valve 13 and the evaporator 14, and defrosting operation is performed in a forward cycle, whereby the latent heat of the steam St is used to evaporate and superheat the refrigerant liquid (refrigerant R) sent from the expansion valve 13 to the evaporator 14, thereby generating superheated refrigerant gas that has both a heat quantity usable for defrosting (heat dissipation from the evaporator 14) and a heat quantity usable for water heating (heat dissipation from the condenser 12). This makes it possible to continue supplying heat to the load equipment X while performing defrosting during the defrosting operation.

[0097] Furthermore, the hot water producing system 100 of the first embodiment is a system equipped with a third heating device H3 that uses steam St as a heat source fluid and includes a steam mixer 23 (one embodiment of a mixing section according to the present invention) that mixes the steam St with the water Wa. Therefore, by operating the third heating device H3 during heating operation of the air-source heat pump 10, two-stage heating by the heat pump 10 and the steam St (assisted heating by the steam St) is possible. Note that the third heating device H3 may be provided with a heat exchanger or the like (heat exchange section) that transfers heat from the steam St to the water Wa instead of the steam mixer 23 (mixing section).

[0098] Furthermore, by providing the third heating device H3, it is possible to minimize carbon dioxide emissions and running costs by adjusting the ratio of the heating amounts of the air-source heat pump 10 and the steam St according to the required temperature of the load equipment X. Furthermore, in winter when the outside air temperature is low, if the hot water outlet temperature that satisfies the required temperature of the load equipment X cannot be obtained even when the compressor 11 is adjusted to maximum output, the latent heat of the steam St can be used to raise the temperature of the water Wa to the required temperature.

[0099] Furthermore, by providing the third heating device H3, backup heating using steam St becomes possible by operating the third heating device H3 during maintenance of the air-source heat pump 10. Also, if a power aggregator requests a downward demand response (DR) or if the power consumption of the entire factory needs to be limited to an upper limit or less, there may be a situation where it is necessary to reduce the thermal output of the air-source heat pump 10 or stop the air-source heat pump 10. In such cases, backup heating using steam St becomes possible by operating the third heating device H3.

[0100] In the second to seventh embodiments, the air-source heat pump 10a is configured to perform defrosting operation using a reverse cycle or hot gas bypass system, and the second heating device H2 is configured to include a heat exchange unit that transfers heat from the steam St to the service water Wa, or a mixing unit that mixes the steam St with the service water Wa. More specifically, in the second embodiment (see FIG. 2), a steam mixer 23 is provided as the mixing unit, in the third embodiment (see FIG. 5), a service water tank K is provided as the mixing unit, in the fifth embodiment (see FIG. 7), a second service water tank K2 is provided as the mixing unit, and in the fourth, sixth, and seventh embodiments (see FIGS. 6, 8, and 9), a heat exchanger 24 is provided as the heat exchange unit. In this way, the second heating device H2 heats the service water Wa without passing through the air-source heat pump 10a.

[0101] During defrosting operation using the reverse cycle or hot gas bypass method, the condenser 12 of the air-source heat pump 10a is unable to heat the water Wa, but by providing the second heating device H2, the latent heat of the steam St is used to heat the water Wa, making it possible to continue supplying heat. Also, during reverse cycle defrosting operation, the high-temperature water Wa in the water tank K is circulated to the condenser 12, and the amount of heat required for defrosting can be obtained from the steam St, thereby shortening the defrosting time.

[0102] Furthermore, in the hot water production systems 100 of the second to seventh embodiments, two-stage heating (assisted heating with steam St) is possible using the heat pump 10a and steam St by operating the second heating device H2 during heating operation of the air-source heat pump 10a.

[0103] Furthermore, by providing the second heating device H2, it is possible to minimize carbon dioxide emissions and running costs by adjusting the ratio of the heating amounts of the air-source heat pump 10a and the steam St according to the required temperature of the load equipment X. Furthermore, in winter when the outside air temperature is low, if the hot water outlet temperature that satisfies the required temperature of the load equipment X cannot be obtained even when the compressor 11 is adjusted to maximum output, the latent heat of the steam St can be used to raise the temperature of the water Wa to the required temperature.

[0104] Furthermore, by providing the second heating device H2, backup heating using steam St can be provided by operating the second heating device H2 during maintenance of the air-source heat pump 10a. Furthermore, if a power aggregator requests a downward DR or if the power consumption of the entire factory needs to be limited to an upper limit, it may be necessary to reduce the thermal output of the air-source heat pump 10a or stop the air-source heat pump 10a. In such cases, backup heating using steam St can be provided by operating the second heating device H2.

[0105] Although the embodiments of the present invention have been described above, the above embodiments are illustrative in all respects and should not be considered limiting. The technical scope of the present invention is defined by the claims, not by the description of the above embodiments, and should be understood to include all modifications that fall within the meaning and scope of the claims.

[0106] <Contribution to the United Nations-led Sustainable Development Goals (SDGs)> The hot water production system disclosed herein uses an air-source heat pump that heats water using electricity and does not use fossil fuels. Therefore, by promoting the reduction of carbon dioxide emissions, it can contribute to the achievement of Goal 13 of the Sustainable Development Goals (SDGs), "Take urgent action to combat climate change." [Industrial Applicability]

[0107] The present invention can be used in a hot water production system for heating water. [Explanation of symbols]

[0108] 10, 10a Air Source Heat Pump 11 Compressor 12 Condenser 12a 1st radiation heat exchanger 12b 2nd heat radiation heat exchanger 13 Expansion valve 14 Evaporator (refrigerant evaporator) 14x refrigerant temperature sensors 14y Air Temperature Sensor 15 Four-way valve 16 Three-way valve 21 Heat exchanger 21a 1st heat exchanger 21b Second heat exchanger 22 Three-way valve 23 Steam Mixer 24 Heat exchanger 100 Hot water production system C control section H1 1st heating device H2 2nd heating device H3 3rd heating device K water tank K1 First water tank K2 Second water tank L1~L44 1st~44th lines Lb bypass line Lc refrigerant circulation line Lx Water output line Ly steam output line P1~P41 1st~41st pumps R refrigerant Rm intermediate medium S1 Temperature Sensor SB Steam Boiler SH Steam Header St Steam V1~V43 1st to 43rd valves Wa water X load equipment

Claims

1. A hot water production system that heats water used in load equipment within a business establishment, a first heating device having an air-source heat pump with a refrigerant evaporator, and capable of performing a heating operation for heating water using the air-source heat pump and a defrosting operation for defrosting the refrigerant evaporator; a second heating device that uses steam generated by the steam boiler as a heat source fluid, The second heating device heats the water at least when the defrosting operation is being performed.

2. the air-source heat pump is configured to circulate a refrigerant through a compressor, a heat dissipation heat exchanger, an expansion valve, and the refrigerant evaporator in this order during the heating operation and the defrost operation; The hot water producing system according to claim 1 , wherein the second heating device includes a heat exchanger between the expansion valve and the refrigerant evaporator, which transfers heat from the vapor to the refrigerant when the defrosting operation is performed.

3. Further provided is a third heating device using the steam as a heat source fluid, 3. The hot water producing system according to claim 2, wherein the third heating device includes a heat exchange section that transfers heat from the steam to the water, or a mixing section that mixes the steam with the water.

4. The air-source heat pump is configured to perform the defrosting operation in a reverse cycle or hot gas bypass manner, 2. The hot water producing system according to claim 1, wherein the second heating device includes a heat exchange section that transfers heat from the steam to the water, or a mixing section that mixes the steam with the water.

5. an air temperature detection means for detecting the temperature of the heat source air before heat exchange in the refrigerant evaporator; a refrigerant temperature detection means for detecting the temperature of the refrigerant after heat exchange in the refrigerant evaporator; 5. A hot water production system as described in any one of claims 1 to 4, wherein the necessity of the defrosting operation is determined based on the detected temperatures of the air temperature detection means and the refrigerant temperature detection means, and the defrosting operation is performed when it is determined that the defrosting operation is necessary.

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