Hot water production system

Abstract

To provide a hot water producing system which has increased reduction effect of a CO2 emission amount and reduces running cost, even when an output hot water temperature is high.SOLUTION: A hot water producing system 1 includes first heating means 2 which heats service water W1 to a first temperature while the service water is made to flow through a condenser 92 of a heat pump type water heater of a heat pump type hot water system 10, and second heating means 3 which exchanges the heat of the service water heated by the first heating means 2 indirectly with steam S generated from a steam boiler device 30, so as to heat the service water to a second temperature higher than the first temperature.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hot water producing system. [Background technology]

[0002] 2. Description of the Related Art Conventionally, hot water producing systems have been known. For example, Patent Document 1 discloses a system that produces hot water using a heat pump in order to wash or sterilize workpieces such as food with hot water. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-133522 A Summary of the Invention [Problem to be solved by the invention]

[0004] Currently, many factories and business establishments are working on "decarbonization" to move away from fossil fuels in order to reduce emissions of CO2, a typical greenhouse gas. As a result, as shown in Patent Document 1, systems using heat pumps are increasingly being adopted as systems for producing hot water. However, heat pumps have the characteristic that, although the COP (coefficient of performance) is high and the effect of reducing CO2 emissions is high when the hot water outlet temperature is low, the COP is low and the effect of reducing CO2 emissions is also reduced when the hot water outlet temperature is increased. In addition, when the hot water outlet temperature is increased, the running costs are also high because the COP is low.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a hot water production system that is highly effective in reducing CO2 emissions and can reduce running costs even when the outlet hot water temperature is increased. [Means for solving the problem]

[0006] The present invention includes a first heating means (e.g., first heating means 2) that heats water to a target hot water supply temperature while flowing it through a heat pump hot water heater (e.g., a hot water heater of a heat pump hot water supply system 10), a second heating means (e.g., second heating means 3) that indirectly heat exchanges the water heated to the target hot water supply temperature by the first heating means with steam generated in a steam boiler (e.g., steam boiler device 30) and adjusted to a target steam pressure, thereby raising the temperature of the water to a target hot water outlet temperature that is set higher than the target hot water supply temperature, and a control means that controls the first heating means and the second heating means, The second heating means includes a heating heat exchanger (e.g., heating heat exchanger 210, second heating heat exchanger 220) that indirectly exchanges heat between the hot water heated by the water heater and the steam generated by the steam boiler, a hot water tank (e.g., hot water tank 40) that stores the hot water heated by the heating heat exchanger, and a hot water storage temperature sensor (e.g., hot water storage temperature sensor 41) that detects the temperature of the hot water in the hot water tank, The control means The temperature detected by the hot water storage temperature sensor is The set target outlet temperature So that The present invention relates to a hot water production system that adjusts the output sharing between the water heater and the steam boiler.

[0007] The second heating means includes a steam header (e.g., steam header 51) that collects steam generated in the steam boiler, and a heating steam supply valve (e.g., heating steam supply valve 54) that adjusts the amount of steam supplied from the steam header. The control means includes a boiler control unit (e.g., boiler control unit 120) that controls the steam boiler so that the header pressure of the steam header becomes the target steam pressure. Temperature detected by the hot water temperature sensor and a steam supply control unit (for example, steam supply control unit 130) that controls the heating steam supply valve so that the target hot water outlet temperature becomes the set target hot water outlet temperature.

[0008] In addition, the second heating means is before A first water level sensor (e.g., first water level sensor 42) that detects the water level in the hot water tank, a heating steam supply line (e.g., heating steam supply line L2) that supplies steam generated by the steam boiler to the heating heat exchanger, and a heating steam supply valve (e.g., heating steam supply valve 54) provided in the heating steam supply line. And,and the first heating means comprises a water supply line that supplies water to the water heater, a hot water supply line that supplies hot water heated by the water heater to the heating heat exchanger, and a hot water temperature sensor that detects the hot water supply temperature flowing through the hot water supply line, and when the water level detected by the first water level sensor falls below a first set water level when the water level in the hot water tank drops, the control means starts the supply of water through the water supply line and the supply of hot water through the hot water supply line when the water level detected by the first water level sensor rises above a second set water level that is higher than the first set water level, and stops the supply of water through the water supply line and the supply of hot water through the hot water supply line when the water level detected by the first water level sensor rises above a second set water level that is higher than the first set water level, and when the supply of water is being performed, controls the water heater so that the detected temperature of the hot water supply temperature sensor becomes the target hot water supply temperature, and controls the opening of the heating steam supply valve so that the detected temperature of the hot water storage temperature sensor becomes the target hot water outlet temperature.

[0009] The system further includes a bypass water supply line (e.g., bypass water supply line L5) that supplies water to the hot water tank without passing through the water heater, a bypass water supply valve (e.g., bypass water supply valve 62) provided on the bypass water supply line, a backup steam supply line (e.g., backup steam supply line L12) that supplies steam generated by the steam boiler to the hot water tank, and a backup steam supply valve (e.g., backup steam supply valve 212) provided on the backup steam supply line, and it is preferable that the control means opens the bypass water supply valve when the water level detected by the first water level sensor falls below a third set water level that is lower than the first set water level when the water level in the hot water tank drops, and controls the opening of the heating steam supply valve and the backup steam supply valve so that the detected temperature of the hot water storage temperature sensor becomes the target hot water outlet temperature, and closes the bypass water supply valve when the water level detected by the first water level sensor exceeds a fourth set water level that is higher than the third set water level when the water level in the hot water tank rises.

[0010] In addition, it is preferable that the temperature zone for controlling the opening degree of the backup steam supply valve is a lower temperature zone than the temperature zone for controlling the opening degree of the heating steam supply valve.

[0011] The hot water supply line includes a bypass water supply line that supplies water to the hot water tank without passing through the hot water heater, a bypass water supply valve provided on the bypass water supply line, a circulation line (e.g., a stored water circulation line L13) through which the hot water stored in the hot water tank is circulated, an auxiliary heat exchanger that performs indirect heat exchange between the hot water flowing through the circulation line and steam, and a return temperature sensor (e.g., a return temperature sensor 222) that detects the temperature of the hot water returned from the auxiliary heat exchanger to the hot water tank. It is preferable that steam generated in the steam boiler is supplied to an auxiliary heat exchanger, and that the control means opens the bypass water supply valve when the water level detected by the first water level sensor falls below a third set water level lower than the first set water level when the water level in the hot water tank drops, and controls the opening of the heating steam supply valve so that the temperature detected by the return temperature sensor becomes the target hot water outlet temperature, and closes the bypass water supply valve when the water level detected by the first water level sensor exceeds a fourth set water level higher than the third set water level when the water level in the hot water tank rises.

[0012] In addition, it is preferable that the heating-use steam supply line circulates steam generated in the steam boiler through the auxiliary heat exchanger, and then through the heating-use heat exchanger.

[0013] In addition, the present invention includes a bypass water supply line that supplies water to the hot water tank without passing through the water heater, a bypass water supply valve provided on the bypass water supply line, a preheating heat exchanger (e.g., preheating heat exchanger 75) that indirectly exchanges heat between the water flowing through the bypass water supply line and steam, a preheating steam supply line (e.g., preheating steam supply line L10) that supplies steam generated by the steam boiler to the preheating heat exchanger, and a preheating steam supply valve provided on the preheating steam supply line. It is preferable that the control means is provided with a steam supply valve (e.g., a preheating steam supply valve 76), and when the water level detected by the first water level sensor falls below a third set water level that is lower than the first set water level when the water level in the hot water tank drops, the control means opens the bypass water supply valve and opens the preheating steam supply valve, and when the water level detected by the first water level sensor exceeds a fourth set water level that is higher than the third set water level when the water level in the hot water tank rises, the control means closes the bypass water supply valve.

[0014] Furthermore, it is preferable that the first heating means includes multiple water heaters (e.g., water heaters 11, 12, 13), and the hot water tank has multiple water level thresholds set for changing the number of water heaters in operation, and that the control means executes number control to increase the number of water heaters in operation by one each time the water level detected by the first water level sensor falls below the water level threshold by one step when the water level in the hot water tank drops, and to execute number control to decrease the number of water heaters in operation by one each time the water level detected by the first water level sensor exceeds the water level threshold by one step when the water level in the hot water tank rises.

[0015] Further, the first heating means includes a plurality of the water heaters (e.g., water heaters 11, 12, 13), and the hot water tank is set with a plurality of water level thresholds for changing the number of the water heaters in operation and / or the target hot water temperature, and the water heaters are capable of switching between a plurality of target hot water temperatures in a temperature range higher than a first temperature and lower than the target hot water outlet temperature, and the control means executes control to raise the target hot water temperature of the water heater by one step while maintaining the number of the water heaters in operation when the water level detected by the first water level sensor exceeds the water level threshold by one step during operation with the target hot water temperature of the water heater set to the first temperature, and executes control to raise the target hot water temperature of the water heater by one step while maintaining the number of the water heaters in operation, and executes control to raise the target hot water temperature of the water heater by one step when the water level detected by the first water level sensor exceeds the water level threshold by one step during operation with the target hot water temperature of the water heater increased by one step or more. When the target hot water temperature of the water heater is set to the first temperature, control is executed to reduce the number of operating water heaters by one and at the same time return the target hot water temperature to the first temperature, or control is executed to further increase the target hot water temperature of the water heater by one step while maintaining the number of operating water heaters, and when the water level detected by the first water level sensor falls one step below the water level threshold while operating with the target hot water temperature of the water heater set to the first temperature, control is executed to increase the number of operating water heaters by one and at the same time increase the target hot water temperature of the water heater by one or more steps, and when the water level detected by the first water level sensor falls one step below the water level threshold while operating with the target hot water temperature of the water heater increased by one or more steps, control is executed to decrease the target hot water temperature of the water heater by one step while maintaining the number of operating water heaters.

[0016] It is also preferable to provide a water supply tank (e.g., water supply tank 60) for storing water to be supplied to the water heater and / or water supply to the steam boiler, and a switching means (e.g., switching means 80) for switching the destination of hot water supplied from the water heater to the hot water tank or the water supply tank.

[0017] It is also preferable that the first heating means includes a plurality of the water heaters (e.g., water heaters 11, 12, 13), and the hot water tank has a plurality of water level thresholds set for changing the number of hot water supply units of the water heaters, and the control means controls the switching means to increase the number of hot water supply units of the water heaters for the hot water tank by one each time the water level detected by the first water level sensor falls below the water level threshold by one step when the water level in the hot water tank drops, and to simultaneously decrease the number of hot water supply units of the water heaters for the water supply tank by one each time the water level detected by the first water level sensor falls below the water level threshold by one step when the water level in the hot water tank rises, and to simultaneously decrease the number of hot water supply units of the water heaters for the hot water tank by one each time the water level detected by the first water level sensor exceeds the water level threshold by one step, and to simultaneously increase the number of hot water supply units of the water heaters for the water supply tank by one each time.

[0018] It is also preferable that a second water level sensor is provided for detecting the water level in the water supply tank, and the control means stops the water heater that is supplying hot water to the water supply tank when the water level detected by the second water level sensor reaches the water supply stop water level, and operates the water heater that is stopped when the detected water level reaches the water supply start water level.

[0019] It is also preferable to provide a water supply tank for storing water to be supplied to the water heater and / or feed water to be supplied to the steam boiler, and a drain recovery line for recovering steam drain generated in the heating heat exchanger in the water supply tank.

[0020] The present invention also includes a first heating step of heating water to a target hot water supply temperature while passing the water through a heat pump water heater, and a second heating step of indirectly exchanging the water heated to the target hot water supply temperature in the first heating step with steam generated in a steam boiler, the steam being adjusted to a target steam pressure, to heat the water to a target hot water outlet temperature set higher than the target hot water supply temperature, The second heating step includes storing the heated hot water in a hot water tank by indirect heat exchange between the hot water heated by the water heater and the steam generated by the steam boiler in a heating heat exchanger, and detecting the temperature of the hot water in the hot water tank with a hot water storage temperature sensor; During the first heating step and the second heating step, The temperature detected by the hot water storage temperature sensor is The set target outlet temperature So that The present invention relates to a hot water production method for adjusting the output sharing between the water heater and the steam boiler. Effect of the Invention

[0021] According to the present invention, it is possible to provide a hot water producing system that is highly effective in reducing CO2 emissions and is also capable of reducing running costs, even when the outlet hot water temperature is increased. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic diagram showing a hot water producing system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a heat pump circuit of the water heater of the embodiment. [Diagram 3] FIG. 2 is a functional block diagram showing a configuration of a control unit in the embodiment. [Figure 4] FIG. 4 is a schematic diagram for explaining the hot water storage control of the embodiment. [Diagram 5] A diagram showing the number of operating water heaters and the total amount of make-up water in the hot water storage control of the above embodiment. [Figure 6] FIG. 6 is a diagram showing a modified example of the hot water storage control shown in FIG. [Figure 7] FIG. 1 is a schematic diagram showing a first comparative example in which a hot water producing system is constructed using only steam from a steam boiler device as heating means. [Figure 8] FIG. 11 is a schematic diagram showing a second comparative example in which a hot water production system is constructed using only a heat pump hot water supply system as a heating means. [Figure 9] FIG. 2 is a schematic diagram showing the hot water producing system of the embodiment. [Figure 10] 6 is a graph showing the effects of the above embodiment. [Figure 11] FIG. 4 is a schematic diagram showing a hot water producing system according to a second embodiment of the present invention. [Figure 12] FIG. 11 is a schematic diagram showing a hot water producing system according to a third embodiment of the present invention. [Figure 13] FIG. 11 is a schematic diagram showing a hot water producing system according to a fourth embodiment of the present invention. [Figure 14] FIG. 11 is a schematic diagram showing a hot water producing system according to a fifth embodiment of the present invention. [Figure 15] FIG. 4 is a schematic diagram for explaining the contents of the hot water temperature control in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] First Embodiment Hereinafter, a hot water producing system 1 according to a first embodiment of the present invention will be described with reference to the drawings. Note that in this specification, the term "line" is a general term for a line, such as a flow path, a pathway, or a pipe, through which a fluid can flow.

[0024] FIG. 1 is a schematic diagram showing a hot water producing system 1 of the present embodiment. The hot water production system 1 of this embodiment comprises a first heating means 2 that heats service water W1 to a first temperature by flowing it through (passing it once) through a condenser of a heat pump water heater, and a second heating means 3 that indirectly exchanges heat between the service water W1 heated by the first heating means 2 and steam S generated in a steam boiler, thereby raising the temperature of the service water W1 to a second temperature higher than the first temperature.

[0025] The first heating means 2 is composed of a heat pump type hot water supply system 10 and includes a plurality of heat pump type hot water heaters, in this embodiment, a first heat pump type hot water heater 11, a second heat pump type hot water heater 12, and a third heat pump type hot water heater 13 (hereinafter also referred to as the first hot water heater 11, the second hot water heater 12, and the third hot water heater 13). Each of the heat pump type hot water heaters 11, 12, and 13 (hereinafter also referred to as the hot water heaters 11, 12, and 13) preferably has an electrically driven refrigerant compressor, and heats the water W1 supplied from a water supply tank 60 described later to a first temperature, for example, 50 to 70°C, by circulating it through a condenser of the heat pump type hot water supply system 10.

[0026] Here, all of the multiple water heaters 11, 12, 13 have the same configuration, and all of the water heaters have a heat pump circuit 90. Therefore, the heat pump circuit 90 of the first water heater 11 will be described as a representative of these. 2, the heat pump circuit 90 of the first hot water heater 11 includes a refrigerant compressor 91, a condenser 92, an expansion valve 93, and an evaporator 94. The refrigerant compressor 91, the condenser 92, the expansion valve 93, and the evaporator 94 are connected in sequence in a ring shape by a refrigerant circulation line L7, thereby forming the heat pump circuit 90.

[0027] The electrically driven refrigerant compressor 91 has a motor 95 as a drive source, and compresses gaseous refrigerant R such as fluorocarbon gas into a high-temperature, high-pressure refrigerant. The condenser 92 condenses and liquefies the refrigerant R from the refrigerant compressor 91. The expansion valve 93 reduces the pressure and temperature of the refrigerant R by passing the refrigerant R sent from the condenser 92. The evaporator 94 evaporates the refrigerant R sent from the expansion valve 93 using heat source water W8 sent through a heat source water supply line L8 as a heat source. Note that the heat source water supply line L8 is not shown in FIG. 1.

[0028] The heat source for the heat pump circuit 90 is not limited to heat source water such as waste hot water, but various heat source gases can be used, such as exhaust gas (combustion gas, exhaust steam, etc.) from factory equipment, cooling air containing waste heat, and outside air not containing waste heat. In the case where the evaporator is structured such that the heat transfer surface is exposed to the outside, the heat source gas is supplied to the heat transfer surface by a fan (for example, air ventilation). In the case where the evaporator is structured such that the heat transfer surface is present within a closed space (for example, a shell), the heat source gas is supplied to the heat transfer surface by a blower.

[0029] In this way, in the heat pump circuit 90 of the first hot water heater 11, the refrigerant R absorbs heat from the outside and vaporizes in the evaporator 94, while the refrigerant R radiates heat to the outside and condenses in the condenser 92. Using this principle, the heat pump circuit 90 of the first hot water heater 11 pumps up heat from the heat source water W8 in the evaporator 94, and heats the water W1 from the heat pump water supply line L3 in the condenser 92. Then, the water W1, which has been heated by passing through the condenser 92 and turned into hot water, is supplied to the second heating means 3 through the hot water supply line L1.

[0030] In addition, in the heat pump circuit 90 of the first hot water heater 11, the opening degree of the expansion valve 93 is adjusted so that the degree of superheating of the refrigerant R (the inlet refrigerant temperature of the refrigerant compressor 91) is constant, or so that the degree of subcooling of the refrigerant R (the inlet refrigerant temperature of the expansion valve 93) is constant.

[0031] The heat pump circuit 90 of the first hot water heater 11 may be configured to be able to change its output. For example, the rotation speed of the motor 95 of the refrigerant compressor 91 may be configured to be able to be changed by inverter control.

[0032] 1, each of water heaters 11, 12, 13 is provided with a hot water temperature sensor 14, 15, 16 that detects the hot water temperature from each of water heaters 11, 12, 13. Note that hot water temperature sensors 14, 15, 16 only need to be provided in water heaters 11, 12, 13, and may be provided within water heaters 11, 12, 13 or may be provided downstream of water heaters 11, 12, 13 in hot water supply line L1 before the junction.

[0033] The water W1 (hereinafter also referred to as hot water W1) heated by multiple water heaters 11, 12, and 13 is joined together by the hot water supply line L1, further heated by the second heating means 3, and supplied to the hot water tank 40 described below.

[0034] Next, a description will be given of the second heating means 3. The second heating means 3 includes a steam boiler device 30, a heating heat exchanger 210, and a heating steam supply line L2 that supplies steam S generated in the steam boiler device 30 to the heating heat exchanger 210. The steam boiler device 30 is preferably a steam boiler having a gas-fired or oil-fired burner, and is composed of, for example, a plurality of once-through boilers 31 that generate steam S. The second heating means 3 uses steam S generated by the steam boiler device 30 to raise the temperature of the water W1 heated by the first heating means 2 to a second temperature higher than the first temperature.

[0035] The heating steam supply line L2 includes a steam header 51 in which steam S generated in the multiple once-through boilers 31 is collected, a connection line 52 that connects the multiple once-through boilers 31 and the steam header 51, and a steam supply line 53 that supplies the steam S collected in the steam header 51 to the heating heat exchanger 210. The steam supply line 53 is provided with a heating steam supply valve 54. The steam header 51 is also provided with a pressure gauge 55 for detecting the header pressure.

[0036] The hot water supply line L1 is provided with the above-mentioned heating heat exchanger 210. The heating heat exchanger 210 is an indirect heat exchanger, and performs indirect heat exchange between the hot water W1 sent from the first heating means 2 and flowing through the hot water supply line L1, and the steam S from the steam boiler device 30 flowing through the steam supply line 53. As a result, the hot water W1 heated to a first temperature by the first heating means 2 is heated by the heating heat exchanger 210 to a second temperature higher than the first temperature, for example, 75 to 95°C. In this indirect heat exchange, mainly sensible heat of the steam S is utilized. The hot water W1 heated by the heating heat exchanger 210 is supplied to the hot water tank 40 through a hot water supply line L1.

[0037] The hot water tank 40 stores the hot water W1 supplied from the second heating means 3. The hot water tank 40 includes a hot water temperature sensor 41 that detects the temperature of the stored hot water TW (hereinafter, also referred to as stored water TW), and a first water level sensor 42 that detects the water level WL of the stored hot water TW.

[0038] The hot water producing system 1 of this embodiment includes a water supply tank 60 that stores water. The water stored in the water supply tank 60 is supplied to the water heaters 11, 12, and 13 via a heat pump water supply line L3.

[0039] Each of the water heaters 11, 12, 13 is provided with a water supply pump 17, 18, 19 for supplying the water W1 to each of the water heaters 11, 12, 13. Note that the water supply pumps 17, 18, 19 only need to be provided in the water heaters 11, 12, 13, and may be provided in the water supply lines in the water heaters 11, 12, 13, or may be provided in the heat pump water supply line L3 after branching corresponding to each of the water heaters 11, 12, 13.

[0040] Water supply pumps 17, 18, 19 are each driven with their rotation speed adjusted by, for example, inverter control, thereby adjusting the amount of water supplied to water heaters 11, 12, 13. Note that a configuration may be adopted in which a flow rate adjustment valve is provided corresponding to each water heater 11, 12, 13, and the amount of water supplied to water heaters 11, 12, 13 is adjusted by controlling the opening degree of the flow rate adjustment valve. When a flow rate adjustment valve is provided, water supply pumps 17, 18, 19 are driven at a predetermined rotation rate (constant drive frequency).

[0041] The water stored in the water supply tank 60 is supplied to the steam boiler apparatus 30 as boiler feed water via a boiler feed water line L4. A boiler feed water pump 32 is provided on the boiler feed water line L4. The boiler feed water pump 32 is driven, for example, by inverter control, so as to adjust the amount of water supplied to the steam boiler apparatus 30. The boiler feed water pump 32 may be provided for each of the multiple once-through boilers 31, or may be provided within the steam boiler apparatus 30. The amount of water supplied may be adjusted by a flow control valve.

[0042] Furthermore, the hot water producing system 1 of this embodiment includes a bypass water supply line L5 for directly supplying the service water stored in the water supply tank 60 to the hot water tank 40. The bypass water supply line L5 is provided with a bypass water supply pump 61 and a bypass water supply valve 62. When the bypass water supply valve 62 is opened, the service water stored in the water supply tank 60 is replenished as make-up water to the hot water tank 40. At this time, the service water W5 (hereinafter also referred to as cold water W5) is supplied into the hot water tank 40 through the bypass water supply line L5.

[0043] The hot water producing system 1 of this embodiment includes a control unit 100 for performing various controls. Fig. 3 is a functional block diagram showing the configuration of the control unit 100. As shown in Fig. 3, the control unit 100 includes a hot water supply control unit 110, a boiler control unit 120, a steam supply control unit 130, and a hot water storage control unit 140.

[0044] As described above, the control unit 100 is composed of a plurality of functional blocks, but each block does not necessarily need to be physically separated, and the functions of the plurality of blocks may be realized by one CPU. The control unit 100 may be divided into two or more parts, taking into consideration the arrangement and wiring of the devices to be controlled. For example, from the viewpoint of independent control of water heaters and boilers, it is preferable to incorporate the function of the water heater control unit 110 into the local control unit of each water heater, and the function of the boiler control unit 120 into a unit control panel that controls a group of boilers.

[0045] The hot water supply control unit 110 controls the heat pump hot water supply system 10. More specifically, it controls the operation of the water heaters 11, 12, and 13, such as starting and stopping the operation of each of them. The hot water supply control unit 110 also controls water supply pumps 17, 18, and 19 based on the temperatures detected by the hot water temperature sensors 14, 15, and 16 to adjust the amount of hot water W1 supplied from the water heaters 11, 12, and 13. A feedback control using a PID algorithm is preferably used to adjust the amount of hot water supplied. For example, in the case of first water heater 11, hot water supply control unit 110 controls the rotation speed of water supply pump 17 to adjust the amount of hot water supply so that the temperature detected by hot water supply temperature sensor 14 becomes a predetermined target hot water supply temperature. The same applies to the control of second water heater 12 and third water heater 13. In addition, a flow rate adjustment valve may be provided corresponding to each of the water heaters 11, 12, and 13, and the amount of hot water supplied may be adjusted by controlling the opening degree of the flow rate adjustment valve. As a result, hot water W1 supplied from water heaters 11, 12, 13 is heated to a first temperature corresponding to the target hot water supply temperature so that the hot water W1 is always at the target hot water supply temperature. When the amount of heat source input to the heat pump circuit is small, the amount of hot water supplied is reduced so that the hot water temperature is maintained at the target hot water temperature.

[0046] Here, the target hot water supply temperature is set, for example, to 50 to 85° C. More preferably, it is 50 to 70° C. This preferable target hot water supply temperature will be described later with reference to FIGS.

[0047] The boiler control unit 120 controls the number of steam boiler units 30 to be increased or decreased based on the header pressure value detected by the pressure gauge 55 provided in the steam header 51. More specifically, the amount of deviation between the header pressure value and the target steam pressure value is calculated so that the header pressure value becomes the target steam pressure value, and the number of boilers to be increased or decreased is calculated. This number increase or decrease control is publicly known, as disclosed in, for example, JP 2015-140975 A, and therefore will not be described here.

[0048] The steam supply control unit 130 controls the opening of the heating steam supply valve 54 based on the temperature detected by the hot water storage temperature sensor 41. More specifically, the steam supply control unit 130 controls the opening of the heating steam supply valve 54 to adjust the supply amount of steam S so that the temperature detected by the hot water storage temperature sensor 41 becomes a predetermined target hot water storage temperature. It is preferable to use feedback control for adjusting this supply amount. For example, the operation amount for the heating steam supply valve 54 is calculated by a PID algorithm so that the temperature detected by the hot water storage temperature sensor 41 converges to the target hot water storage temperature, and the steam supply control unit 130 outputs an opening designation signal to the actuator circuit of the heating steam supply valve 54. By performing such steam supply control, indirect heat exchange is performed between the hot water W1 and the steam S in the heating heat exchanger 210 so that the temperature of the stored water TW in the hot water tank 40 (hereinafter also referred to as the stored hot water temperature) is always at the target stored hot water temperature. As a result, the hot water W1 is heated to a second temperature corresponding to the target stored hot water temperature.

[0049] Here, the target hot water storage temperature is a temperature higher than the target hot water supply temperature (first temperature), and is preferably set to 75 to 95° C. This preferable target hot water storage temperature will be described later with reference to FIGS.

[0050] The hot water storage control unit 140 controls the bypass water supply valve 62 and the water heaters 11, 12, and 13 based on the detection result of the first water level sensor . 4, the first water level sensor 42 is configured as an electrode type water level detector equipped with a plurality of electrodes, including a first electrode 421, a second electrode 422, a third electrode 423, a fourth electrode 424, and a fifth electrode 425. Although not shown, the first water level sensor 42 may further include an electrode that constitutes a common electrode and an electrode for detecting an abnormal water level. Each of the electrodes 421 to 425 detects whether the water level WL of the stored water TW in the hot water tank 40 has reached the lower end of each electrode rod, depending on whether the lower end of the electrode rod is immersed in water.

[0051] Here, the water level detected by the first electrode 421 is water level LL, the water level detected by the second electrode 422 is water level L, the water level detected by the third electrode 423 is water level M, the water level detected by the fourth electrode 424 is water level H, and the water level detected by the fifth electrode 425 is water level HH. As shown in Fig. 4, the electrodes are inserted into the hot water tank 40 so that the height positions of the lower ends are, in order from the lowest, the first electrode 421, the second electrode 422, the third electrode 423, the fourth electrode 424, and the fifth electrode 425. The water levels detected by these electrodes become multiple-stage water level thresholds for controlling changes in the number of operating water heaters 11, 12, and 13, etc.

[0052] In this embodiment, the hot water storage control unit 140 controls the bypass water supply valve 62 and the water heaters 11, 12, and 13 based on the detection result of the first water level sensor 42. More specifically, when the hot water storage control unit 140 detects that the first water level sensor 42 has fallen below the water level LL, it opens the bypass water supply valve 62. Furthermore, when the water level in the hot water tank 40 is falling, the hot water storage control unit 140 executes a number control to increase the number of operating water heaters by one each time the water level detected by the first water level sensor 42 falls below the water level threshold by one step, and when the water level in the hot water tank 40 is rising, it executes a number control to decrease the number of operating water heaters by one each time the water level detected by the first water level sensor 42 exceeds the water level threshold by one step. This number control is performed, for example, at water level H, water level M, and water level L when the water level is falling, and at water level M, water level HH when the water level is rising. The hot water storage control unit 140 may control the water heaters 11 , 12 , and 13 via the hot water supply control unit 110 .

[0053] Here, a specific description will be given of a case where the water level WL in the hot water tank 40 changes from a state in which it is located within the range of water level LL to water level L shown in FIG. The water TW stored in the hot water tank 40 is supplied to a hot water demand point (not shown) through the hot water outlet line L6. When the amount of hot water W6 supplied from the hot water tank 40 to the hot water demand point exceeds the amount of hot water W1 supplied to the hot water tank 40 from the water heaters 11, 12, and 13 as the first heating means 2, the water level WL in the hot water tank 40 drops (see arrow A in FIG. 4). When the lower end of the first electrode rod 421 is exposed above the water surface at a certain point in time, the first water level sensor 42 detects that the water level WL has fallen below the water level LL.

[0054] When the hot water storage control unit 140 detects that the water level WL has fallen below the water level LL, it determines that the hot water tank 40 is on the verge of a dry spell, and puts all three water heaters 11, 12, and 13 into operation to supply as much hot water W1 as possible to the hot water tank 40, while opening the bypass water supply valve 62 to directly replenish the cold water W5 stored in the water supply tank 60 to the hot water tank 40.

[0055] In this way, when the water level WL falls below the water level LL, i.e., when the hot water tank 40 is on the verge of running out of water, the water level WL is quickly restored by supplying hot water W1 heated by the first heating means 2, as well as cold water W5 that has not passed through the first heating means 2.

[0056] By carrying out such control, the water level WL recovers (see arrow B in FIG. 4). Then, when the water surface comes into contact with the second electrode rod 422 and the tip of the second electrode rod 422 is immersed in the water surface, the first water level sensor 42 detects that the water level WL has exceeded the water level L. When the hot water storage control unit 140 detects that the water level WL has exceeded the water level L (entered the range between the water level L and the water level M), it determines that the hot water tank 40 has recovered from the state immediately before the drought, and closes the bypass water supply valve 62. Note that, since the water level WL is still not high at this point, the operation of all three water heaters 11, 12, and 13 continues.

[0057] Next, when the water level WL rises further and the tip of the third electrode rod 423 is immersed in the water surface, the first water level sensor 42 detects that the water level WL has exceeded the water level M (entered the range from water level M to water level H). At this time, it is determined that there is a little extra water in the storage tank, so one of the three water heaters is stopped, and only two water heaters continue to operate. For example, of the water heaters 11, 12, and 13, the third water heater 13 is stopped, and only the first and second water heaters 11 and 12 continue to operate. The bypass water supply valve 62 is kept closed.

[0058] Next, when the water level WL rises further and the tip of the fourth electrode rod 424 is immersed in the water surface, the first water level sensor 42 detects that the water level WL has exceeded the water level H (entered the range from water level H to water level HH). At this time, it is determined that there is more water storage capacity, so two of the three water heaters are stopped and only one water heater continues to operate. For example, of the water heaters 11, 12, and 13, the second and third water heaters 12 and 13 are stopped and only the first water heater 11 continues to operate. Note that the bypass water supply valve 62 remains closed.

[0059] Next, when the water level WL rises further and the tip of the fifth electrode 425 is immersed in the water surface, the first water level sensor 42 detects that the water level WL has exceeded the water level HH. At this time, it is determined that the amount of stored water is sufficient, and the operation of one more water heater is stopped. In other words, the operation of all water heaters 11, 12, and 13 is stopped. Note that bypass water supply valve 62 remains closed.

[0060] Next, a case where the water level WL starts to drop from this state will be described. When the water level WL drops (see arrow C in Figure 4) and the lower end of the fourth electrode rod 424 becomes exposed above the water surface, the first water level sensor 42 detects that the water level WL has fallen below the water level H (entered the range between water level M and water level H). When the hot water storage control unit 140 detects that the water level WL has fallen below the water level H, it resumes the operation of only one of the three water heaters. For example, of the water heaters 11, 12, and 13, it resumes the operation of the first water heater 11.

[0061] Here, if the water level WL rises after it falls below the water level H and the tip of the fifth electrode rod 425 is submerged in the water surface, that is, if it is detected that the water level WL has risen above the water level HH, it is determined that the amount of stored water has again become sufficient, and as described above, operation of all water heaters 11, 12, and 13 is stopped.

[0062] On the other hand, after the water level WL falls below water level H, when the water level WL falls further (see arrow D in Figure 4) and the lower end of the third electrode rod 423 is exposed above the water surface, the first water level sensor 42 detects that the water level WL has fallen below water level M (entered the range from water level L to water level M). When the hot water storage control unit 140 detects that the water level WL has fallen below the water level M, it operates only two of the three water heaters. For example, among the water heaters 11, 12, and 13, it operates the first and second water heaters 11 and 12.

[0063] From this state, when the water level WL further drops and the lower end of the second electrode rod 422 becomes exposed above the water surface, the first water level sensor 42 detects that the water level WL has fallen below the water level L (entered the range between water level LL and water level L). When the hot water storage control unit 140 detects that the water level WL has fallen below the water level L, it executes the operation of all three water heaters 11, 12, and 13.

[0064] If the water level WL drops further from this state and the lower end of the first electrode rod 421 becomes exposed above the water surface, that is, if it is detected that the water level WL has fallen below the water level LL, the hot water storage control unit 140 determines that the hot water tank 40 is on the verge of a dry spell, and, as described above, places all three water heaters 11, 12, and 13 in operation and opens the bypass water supply valve 62.

[0065] In this way, the number of operating water heaters is increased or decreased according to the water level WL in the hot water tank 40, so it is possible to appropriately manage the water level WL in the hot water tank 40. Also, power consumption can be reduced.

[0066] As shown in Fig. 4, the hot water storage control unit 140 shifts the number of operating water heaters in a given water level range between when the water level is rising and when the water level is falling. For example, in the water level range between water level L and water level M, the number of operating units is three when the water level is rising, while the number of operating units is two when the water level is falling. This is to prevent a situation in which the water heater is frequently started and stopped when the water level WL fluctuates around the water level threshold. This reduces the risk of failure of the water heater and hot water supply control equipment (such as the water supply pump and water supply valve) for supplying hot water.

[0067] Instead of shifting the number of operating water heaters in a predetermined water level range between when the water level rises and when the water level falls, a status confirmation time may be provided. In other words, when it is determined that the water level WL has remained below a predetermined water level threshold for a first predetermined time, control such as switching the number of operating water heaters may be performed. For example, if it is determined that the water level WL has remained below the water level HH for a predetermined period of time during the process of the water level WL decreasing as shown by arrow C in Figure 4, the number of operating water heaters is switched from 0 to 1. By setting a status check time in this manner, it is possible to prevent a situation in which the water heaters are frequently started and stopped, even if the number of operating water heaters in the water level range of H to HH, which is a predetermined water level range, is the same when the water level is rising and falling. Note that similar status check times are set for other water level thresholds as well.

[0068] It is also possible to adopt a configuration in which, when it is determined that the state in which the water level WL exceeds a predetermined water level threshold has continued for a second predetermined time, control such as switching the number of water heaters in operation is executed. For example, in the process of the water level WL rising as shown by arrow B in Fig. 4, when it is determined that the state in which the water level WL exceeds the water level LL has continued for a predetermined time, the bypass water supply valve 62 may be closed. Furthermore, when it is determined that the water level WL has risen and remained above the water level L for a predetermined time, the number of water heaters in operation may be switched from three to two. It is also possible to set similar status confirmation times for other water level thresholds.

[0069] By such control, it is possible to perform control such as changing the number of water heaters in operation based on the status confirmation time for the water level WL to continue falling or the status confirmation time for the water level WL to continue rising. The set value of the state check time is preferably adjustable. By making the set value of the state check time adjustable, it is possible to set a first predetermined time as a delay time corresponding to a water level width required to confirm that the water level continues to fall, taking into consideration the difference in the water level fall speed due to the cross-sectional area of ​​the hot water tank 40, when the water level falls below the water level threshold. Alternatively, it is possible to set a second predetermined time as a delay time corresponding to a water level width required to confirm that the water level continues to rise, taking into consideration the difference in the water level rise speed due to the cross-sectional area of ​​the hot water tank 40, when the water level exceeds the water level threshold. The setting value of the status check time can be adjusted manually or automatically, and can be set to a value greater than 0. The status check time is measured using an internal timer of the control unit 100 or the like.

[0070] The first water level sensor 42 is not limited to an electrode-type water level detector, and various water level detectors can be used. For example, five float-type water level detectors may be provided to detect each water level threshold. Also, an electrode-type water level detector and a float-type water level detector may be used in combination. Furthermore, multiple water level thresholds may be detected using a water level detection unit such as a pressure-type water level sensor that can measure continuous water levels. The number of water level thresholds to be detected is not limited to five.

[0071] Fig. 5 is a diagram showing the number of operating water heaters 11, 12, and 13 and the total amount of make-up water when the water level is rising. The horizontal axis represents the water level WL in the hot water tank 40, and the vertical axis represents the total amount of make-up water. In Fig. 5, the amount of hot water supplied from the first heat pump water heater 11 is represented as "HP1", the amount of hot water supplied from the second heat pump water heater 12 is represented as "HP2", and the amount of hot water supplied from the third heat pump water heater 13 is represented as "HP3".

[0072] When the water level WL rises after falling below the water level LL, as shown in Fig. 5, hot water W1 is supplied from the three water heaters 11, 12, and 13, and cold water W5 is supplied directly from the water supply tank 60, until the water level WL exceeds the water level L. The total amount of make-up water at this time is as shown on the vertical axis of Fig. 5.

[0073] Thereafter, when the water level WL exceeds the water level L, the bypass water supply valve 62 is closed. Therefore, the total amount of make-up water decreases as shown in FIG. Further thereafter, when the water level WL exceeds the water level M, the operation of the third water heater 13 is stopped, and only the operations of the first and second water heaters 11, 12 are continued. Therefore, the total amount of make-up water is further reduced as shown in FIG. Further, thereafter, when the water level WL exceeds the water level H, the operation of second water heater 12 is stopped and only the operation of first water heater 11 is continued. Therefore, the total amount of make-up water is further reduced as shown in FIG. Then, when the water level WL exceeds the water level HH, the operation of the first water heater 11 is also stopped, and the operation of all three water heaters is stopped.

[0074] In this embodiment, the hot water temperature from water heaters 11, 12, and 13 is controlled to be constant. For example, the target hot water temperature is set to 70° C. Water heaters 11, 12, and 13 supply hot water W1 at a first temperature that corresponds to the target hot water temperature.

[0075] Note that stopping the operation of the water heaters described above also includes actions to stop the supply of hot water from the water heaters, such as stopping the operation of water supply pumps 17, 18, and 19 and closing the flow control valves corresponding to each of the water heaters 11, 12, and 13. It also includes stopping the operation of refrigerant compressor 91 to stop the circulation of refrigerant in the heat pump circuit.

[0076] In addition, a configuration may be adopted in which which of the water heaters 11, 12, and 13 is to be given priority in stopping / resuming the operation of the water heater is appropriately determined based on the state and operation history of each water heater. Also, it may be determined in advance.

[0077] In this way, since the number of operating water heaters is controlled depending on the water level WL in the hot water tank 40, it is possible to appropriately manage the water level WL in the hot water tank 40. Also, power consumption can be reduced.

[0078] Figure 6 is a modified example of the hot water storage control shown in Figure 5. In this modified example, a configuration for detecting the water level threshold value in more detail may be adopted, as shown in Figure 6. Here, the water level LL, water level L, water level M1, water level M2, water level M3, water level M4, water level H, and water level HH are set as detectable water level threshold values, in order from the lowest water level. In this modification, in addition to changing the number of operating water heaters, the target hot water temperature of the water heater is changed. Specifically, the water heater is capable of switching the target hot water temperature between multiple stages within a temperature range higher than a first temperature and lower than a second temperature.

[0079] More specifically, in this modified example, when the water heater is operating with its target hot water temperature set to a first temperature, if the water level detected by first water level sensor 42 exceeds the water level threshold by one step, control is executed to increase the target hot water temperature of the water heater by one step while maintaining the number of operating water heaters, and when the water heater is operating with its target hot water temperature increased by one step, control is executed to reduce the number of operating water heaters by one and at the same time return the target hot water temperature to the first temperature. In addition, when the water heater is operating with the target hot water temperature set to the first temperature, if the water level detected by the first water level sensor 42 falls one step below the water level threshold, control is executed to increase the number of operating water heaters by one and at the same time raise the target hot water temperature of the water heater by one step, and when the water heater is operating with the target hot water temperature raised by one step, control is executed to lower the target hot water temperature of the water heater by one step while maintaining the number of operating water heaters.

[0080] FIG. 6 is a diagram showing the number of operating water heaters 11, 12, and 13, the hot water temperature, and the total amount of makeup water when the water level is rising. For example, consider a case where the water level WL falls below the water level LL, and then rises to a position between the water level L and the water level M1. At this time, the target hot water temperature of the three water heaters 11, 12, and 13 is set to 70° C. (first temperature). If the water level WL rises further from this state and exceeds the water level M1, control is executed to raise the target hot water temperature of water heaters 11, 12, 13 by one step to 80° C. while maintaining the number of operating water heaters 11, 12, 13. Here, the temperature when raised by one step is set to a temperature lower than the target hot water storage temperature (second temperature) of hot water tank 40.

[0081] Next, while the target hot water temperature of water heaters 11, 12, and 13 is being increased by one step to 80°C and the water level WL rises further and exceeds water level M2, the number of operating water heaters is reduced by one and control is executed to return the target hot water temperature to 70°C (first temperature). Even if the water level WL continues to rise, similarly, control is alternately executed between increasing the target hot water temperature of the water heater by one step while maintaining the number of operating water heaters, and decreasing the number of operating water heaters by one while simultaneously returning the target hot water temperature to its original state.

[0082] Next, we consider a situation in which the water level WL exceeds water level HH and then drops, for example, to a position between water level M4 and water level H, and the target hot water temperature of the water heater is set to 70°C (first temperature). In this example, we will use the above-mentioned status confirmation time method to explain the case where the number of operating water heaters in a given water level range is the same when the water level is rising and when the water level is falling. Therefore, we will also use Figure 6 to explain the case when the water level is falling. When the water level WL falls further from a state in which it is between water level M4 and water level H and falls below water level M4, the number of water heaters in operation is increased by one to operate as two, and at the same time, the target hot water temperature of the water heater is raised by one step to 80°C.

[0083] Next, when the water heater is operating with its target hot water temperature set to 80°C and the water level WL falls below water level M3, control is executed to lower the target hot water temperature of the water heater by one step back to 70°C while maintaining the number of operating water heaters. Even if the water level WL continues to drop, the control alternates between increasing the number of operating water heaters by one and raising the target hot water temperature of the water heaters by one step, and returning the target hot water temperature to its original state while maintaining the number of operating water heaters.

[0084] In this modified example, the method of status confirmation time is used, but this is not limited to this. As described in Figure 4, a method of shifting the number of operating water heaters in a specified water level range when the water level is rising and when the water level is falling may also be used.

[0085] In addition, when the water level rises, control may be performed to increase the target hot water temperature of the water heater by one step while maintaining the number of operating water heaters, and if the water level rises further, control may be performed to increase the target hot water temperature of the water heater by another step while maintaining the number of operating water heaters. For example, when the water level exceeds M1, control is executed to increase the target hot water temperature of water heaters 11, 12, 13 by one step to 75°C while maintaining the number of operating water heaters 11, 12, 13. Then, during operation in this state, when the water level WL rises further and exceeds water level M2, control is executed to increase the target hot water temperature of water heaters 11, 12, 13 by another step to 80°C while maintaining the number of operating water heaters 11, 12, 13. Furthermore, during operation in this state, when the water level WL rises further and exceeds water level M3, control is executed to reduce the number of operating water heaters by one and return the target hot water temperature to 70°C (first temperature). When the water level is decreasing, the control is executed so as to perform the reverse operation.

[0086] In other words, when the water heater is operating with its target hot water temperature set to a first temperature, and the water level detected by the first water level sensor 42 exceeds the water level threshold by one step, control is executed to increase the target hot water temperature of the water heater by one step while maintaining the number of operating water heaters, and when the water heater is operating with its target hot water temperature increased by one or more steps, and the water level detected by the first water level sensor 42 exceeds the water level threshold by one step, control is executed to reduce the number of operating water heaters by one and at the same time return the target hot water temperature to the first temperature, or control is executed to increase the target hot water temperature of the water heater by another step while maintaining the number of operating water heaters. In addition, when the water heater is operating with the target hot water temperature set to the first temperature, if the water level detected by the first water level sensor 42 falls one step below the water level threshold, control may be executed to increase the number of operating water heaters by one and at the same time raise the target hot water temperature of the water heater by one or more steps (e.g., two steps), and when the water heater is operating with the target hot water temperature raised by one or more steps (e.g., two steps), control may be executed to lower the target hot water temperature of the water heater by one step while maintaining the number of operating water heaters.

[0087] Generally, raising the target hot water supply temperature of the water heater reduces the amount of hot water that can be supplied, and lowering the target temperature of the water heater increases the amount of hot water that can be supplied. Taking this into consideration, by adopting the control shown in this modified example, it becomes possible to finely adjust the total amount of make-up water while maintaining the same number of operating heat pumps as much as possible. This makes it possible to appropriately manage the water level in the hot water tank. In addition, because it is possible to continue operating the heat pump as much as possible, it is possible to solve the problem of low-temperature water supply at the initial stage of restarting the operation of the heat pump.

[0088] As described above, the hot water production system 1 of this embodiment includes a first heating means 2 that heats the water W1 to a first temperature while circulating it through the condenser of the heat pump hot water supply system 10, and a second heating means 3 that uses steam S generated by the steam boiler device 30 to raise the temperature of the water W1 heated by the first heating means 2 to a second temperature higher than the first temperature. The effects of adopting this configuration will be described in detail with reference to FIGS.

[0089] FIG. 7 shows a first comparative example in which a hot water producing system is constructed using only steam S from a steam boiler device 30 as heating means. The temperature of hot water required by the hot water demand point varies depending on the purpose, but for example, when washing bottles for food or medicine, pasteurizing sterilization (sterilization of bottles), etc., hot water in the high temperature range of about 75°C to 95°C may be required. Here, a case will be described in which the hot water production system supplies hot water in the high temperature range, for example, hot water at 90°C, to the hot water demand point.

[0090] The hot water production system 5 in Fig. 7 uses only steam S from a steam boiler device 30 as a heating means. Here, the steam boiler has a gas-fired or oil-fired burner and generates steam using fossil fuels. Therefore, the CO2 emissions and running costs of this hot water production system 5 are relatively high, and there is a demand for significant reductions.

[0091] Therefore, as a heating means, it is conceivable to adopt a hot water production system using an electrically driven heat pump hot water supply system 10 that does not use fossil fuels and has a high COP (coefficient of performance). FIG. 8 shows a second comparative example in which a hot water production system 6 is constructed using only a heat pump hot water supply system 10 as a heating means. The CO2 emission coefficient of electricity (0.51 kg CO2 / kWh) is larger than the CO2 emission coefficient of city gas 13A (0.18 kg CO2 / kWh), but when comparing the amount of CO2 emissions per output, the heat pump with a higher COP has less CO2 emissions than the steam boiler. In addition, the unit price of electricity (about 15 yen / kWh) is higher than the fuel unit price of city gas 13A (about 6.2 yen / kWh), but when comparing the running cost per output, the heat pump with a higher COP has less CO2 emissions than the steam boiler. Therefore, the hot water production system 6 has lower CO2 emissions and running costs than the hot water production system 5 of FIG. 7.

[0092] However, while a heat pump has a relatively high COP and is highly effective in reducing CO2 emissions when the hot water temperature is low, when the hot water temperature is increased, the COP becomes relatively low and the effect of reducing CO2 emissions decreases. For example, the COP of a heat pump when supplying hot water at 90°C is equivalent to 2.8. Therefore, compared to hot water production system 5 that uses only steam from a steam boiler as a heating means, the reduction in CO2 emissions (CO2 emission reduction ratio) is only about 10%. In addition, the reduction in running costs (running cost reduction ratio) is also only about 20%.

[0093] Next, we will consider the hot water production system 1 of this embodiment, i.e., a hybrid hot water production system equipped with a first heating means 2 that heats the service water W1 to a first temperature while circulating it through a condenser of a heat pump type hot water supply system 10, and a second heating means 3 that heats the service water W1 heated by the first heating means 2 to a second temperature higher than the first temperature by using steam S generated by a steam boiler device 30.

[0094] In such a hot water production system 1, the heat pump type hot water supply system 10 as the first heating means 2 heats the water W1 to a temperature range where it can be operated with high efficiency, for example to 70°C, and this heated hot water W1 can be heated to a high temperature range, for example to 90°C, using steam S from the steam boiler device 30, making it possible to produce hot water in the high temperature range with high efficiency.

[0095] Here, the COP of the heat pump when the hot water supply temperature is 70° C. is, for example, equivalent to 4.2, which is very high. In the hot water producing system 1 of this embodiment, the heat pump is responsible for heating up to a temperature range where such a high COP can be maintained. For example, when it is desired to produce hot water at 90° C. using the hot water production system 1, the heat pump is responsible for heating up to 70° C. In this case, the heat pump is responsible for about 60% to 80% (load factor 60% to 80%) of the total heat output required to produce hot water at 90° C. The steam boiler is responsible for raising the temperature from 70° C. to 90° C. At this time, the steam boiler is responsible for about 20% to 40% (load factor 20% to 40%) of the total thermal output required to produce hot water at 90° C.

[0096] When the heat pump and steam boiler are used in this combination, the hot water production system 1 reduces CO2 emissions by about 30%, which is very effective, compared to the hot water production system 5 that uses only steam from a steam boiler as a heating means. In addition, the running costs are also reduced by about 35%, which is very effective.

[0097] In this way, by using the hot water producing system 1 of this embodiment, it is possible to reduce CO2 emissions and running costs extremely effectively, even when the outlet hot water temperature is increased. Furthermore, with the hot water production system 1 of this embodiment, by appropriately adjusting the load factors of the heat pump and steam boiler, i.e., the share of thermal output (output allocation) of each, according to the target hot water outlet temperature, it is possible to extremely effectively reduce CO2 emissions and running costs. It is preferable that the relationship between the heat pump and steam boiler output ratio according to the target hot water outlet temperature of the hot water production system 1 is stored as a table or a formula. For example, the target hot water outlet temperature can be configured to be set, and an appropriate heat pump and steam boiler output ratio is set according to the set target hot water outlet temperature.

[0098] FIG. 10 is a graph showing the CO2 emission reduction ratio and the running cost reduction ratio when hot water of, for example, 90° C. is produced and dispensed using the hot water producing system 1 of this embodiment.

[0099] The horizontal axis of the graph in Fig. 10 is the hot water temperature of the heat pump, and the vertical axis of the line graph in Fig. 10 is the CO2 emission reduction ratio and the running cost reduction ratio. Here, the CO2 emission reduction ratio indicates the proportion of CO2 emissions that can be reduced by the hot water producing system 1 of this embodiment, assuming that the CO2 emissions of the hot water producing system 5 that uses only steam from a steam boiler as heating means are 100%. In other words, if the CO2 emission reduction ratio is 25%, it means that by switching to the hot water producing system 1, 100% CO2 emissions can be reduced to 75%. Meanwhile, the running cost reduction ratio indicates the percentage of the running cost that can be reduced by the hot water producing system 1 of this embodiment, assuming that the running cost of the hot water producing system 5 that uses only steam from a steam boiler as heating means is 100%. In other words, if the running cost reduction ratio is 30%, it means that by switching to the hot water producing system 1, the running cost of 100% can be reduced to 70%. The vertical axis of the bar graph in FIG. 10 indicates the output ratio of the heat pump and the steam boiler, that is, the share of the thermal output (output allocation) of each. The bar graph showing the heat pump output ratio is accompanied by the COP for each heat pump at the hot water supply temperature. The higher the hot water supply temperature, the lower the COP.

[0100] In the line graph of Figure 10, comparing the data for heat pump hot water temperature = 90°C with the data for heat pump hot water temperature = 50°C to 80°C, it can be seen that compared to producing hot water at 90°C using only a heat pump (data for heat pump hot water temperature = 90°C), heating to 50-80°C with a heat pump and then using steam to raise the temperature to 90°C clearly has a greater effect in reducing CO2 emissions and running costs. For example, heating to 50-70°C with a heat pump and then using steam to raise the temperature to 90°C will have a greater effect in reducing CO2 emissions and running costs. Furthermore, from the trend of the line graph, it can be seen that the effects of the present invention can be obtained even if, for example, the temperature is raised to 85°C using a heat pump and then raised to 90°C using steam.

[0101] In this way, by using the hot water production system 1 of this embodiment, i.e., a hybrid hot water production system equipped with a first heating means 2 that heats the service water W1 to a first temperature while circulating it through the condenser of the heat pump hot water supply system 10, and a second heating means that uses steam S generated by the steam boiler device 30 to raise the temperature of the service water W1 heated by the first heating means 2 to a second temperature higher than the first temperature, it is possible to extremely effectively reduce CO2 emissions and running costs even when the outlet hot water temperature of the system is increased.

[0102] The first heating means 2 of the hot water producing system 1 of this embodiment heats the service water W1 to a first temperature while causing the service water W1 to flow through the condenser of the heat pump water heater. By adopting a configuration in which the hot water heated by the second heating means 3 does not return to the condenser but flows through it, i.e., passes through once, hot water W1 at the first temperature heated by the first heating means 2 is always additionally supplied, and this hot water is heated by the second heating means 3. Therefore, even when the hot water demand point requires a large amount of hot water to be discharged, it becomes easy to always supply hot water at a stable temperature. Furthermore, in the case where the hot water tank 40 is provided, even if the water level WL in the hot water tank 40 drops, hot water W1 at the first temperature heated by the first heating means 2 is always additionally supplied into the hot water tank 40 according to the level of the drop. Therefore, with this configuration, the frequency of occurrence of a situation in which cold water W5 must be supplied into the hot water tank 40 decreases. Therefore, the supply of cold water W5 rarely causes an extreme drop in the temperature of the stored water TW in the hot water tank 40.

[0103] The second heating means 3 of the hot water production system 1 of this embodiment indirectly exchanges heat between the water W1 heated by the first heating means 2 and the steam S generated by the steam boiler device 30, thereby raising the temperature of the water W1 to a second temperature higher than the first temperature. In this way, by adopting indirect heat exchange as the heat exchange method, the temperature of the water W1 can be raised without directly supplying the steam S to the water W1. In other words, since the steam S is not mixed with the water W1, it is possible to prevent boiler chemicals such as boiler compounds from being mixed into the hot water tank 40. This makes it possible to maintain the quality of the water W1. In addition, the hot water storage control of the hot water tank 40 is less susceptible to disturbances that may occur when the steam S is directly supplied.

[0104] In order to obtain such an effect, it is particularly preferable to use a heat pump type water heater having an electrically driven refrigerant compressor as the water heater and a steam boiler having a gas-fired or oil-fired burner as the steam boiler. The effects of the present invention can be appropriately obtained by setting the first temperature to 50 to 85°C and the second temperature to a temperature higher than the first temperature, 75 to 95°C. Preferably, the first temperature is set to 50 to 80°C and the second temperature is set to a temperature higher than the first temperature, 75 to 95°C. More preferably, the first temperature is set to 50 to 70°C and the second temperature is set to 75 to 95°C. In this way, by combining a heat pump water heater having an electrically driven refrigerant compressor with a steam boiler having a burner that burns fossil fuels, and appropriately setting the temperature range for heating by each, it is possible to achieve a greater reduction in CO2 emissions and a greater reduction in running costs than when high-temperature water is produced by a heat pump water heater alone or a steam boiler alone.

[0105] The hot water producing system 1 of this embodiment is preferably provided with a hot water tank 40 for storing the hot water W1 sent from the second heating means 3, but may be configured to directly supply the hot water W1 sent from the second heating means 3 to a hot water demand point (not shown) without providing the hot water tank 40. In this case, it is preferable to provide a second heating means outlet hot water temperature sensor in the hot water supply line L1 downstream of the heating heat exchanger 210 instead of the storage hot water temperature sensor 41, and to control the opening of the heating steam supply valve 54 based on this second heating means outlet hot water temperature sensor.

[0106] In order to perform appropriate hot water storage control, it is preferable to have multiple water heaters constituting the heat pump hot water supply system 10, but it may be one. In the case of one water heater, the control by multiple water heaters described in this embodiment is not performed, and the hot water supply amount is controlled based on the water level WL of the hot water tank 40, and the hot water supply is controlled on and off. In addition, if multiple water heaters are installed, the number can be any number greater than or equal to two.

[0107] Although it is preferable that the steam boiler device 30 has a plurality of boilers, it may have only one boiler. In the case of one boiler, the combustion rate may be controlled based on the measured steam pressure value and the target steam pressure value. When multiple boilers are used, any number greater than or equal to two may be used. Furthermore, the boiler constituting the steam boiler device 30 may be a boiler other than a once-through boiler.

[0108] The hot water produced can be used for a variety of purposes, including but not limited to washing bottles for food or medicine and sterilizing them in a pasteurizer. For example, hot water can be used in the food and beverage industry to heat raw materials and processed products, wash bottles, and clean in place (CIP) manufacturing equipment. In addition, in the case of steam utilization in the food and beverage industry, the steam S generated by the steam boiler device 30 can be used for high-temperature cooking (fried foods, steamed foods, stir-fried foods), retort sterilization (sterilization of pouches and canned foods), stationary in place sterilization (SIP) of manufacturing equipment, back-up of hot water production, and the like. In the field of machinery, hot water can be used for washing and degreasing. Even in these applications, hot water in the high temperature range of about 75° C. to 95° C. may be required, and in cases where hot water in such a high temperature range is required, the hot water producing system 1 of this embodiment can be particularly suitably used.

[0109] In addition, a configuration may be adopted in which a drain recovery line (not shown) is provided between the heating heat exchanger 210 and the water supply tank 60 to recover steam drain generated in the heating heat exchanger 210 in the water supply tank 60. This allows the steam drain generated in the heating heat exchanger 210 to be effectively utilized for preheating the service water supplied to the heat pump hot water supply system 10 and the feed water supplied to the steam boiler device 30, and for water conservation.

[0110] According to the hot water producing system 1 of the present embodiment described above, the following effects are achieved.

[0111] (1) The hot water production system 1 of this embodiment includes a first heating means 2 that heats service water W1 to a first temperature while flowing it through a condenser 92 of a heat pump water heater 11, 12, 13 of a heat pump water supply system 10, and a second heating means 3 that indirectly exchanges heat with the service water heated by the first heating means 2 with steam S generated in a steam boiler device 30 to heat the service water to a second temperature higher than the first temperature. In this way, the water is heated by the first heating means 2 up to a temperature that can be efficiently heated by the heat pump water heaters 11, 12, 13, and further heating is performed by indirect heat exchange with steam S, so that even if the outlet temperature is increased, a hot water production system can be provided that is highly effective in reducing CO2 emissions and running costs. In addition, since steam is used for heating, the temperature control responsiveness is also good. Furthermore, by adopting indirect heat exchange, it is possible to prevent boiler chemicals such as boiler compounds from being mixed into the hot water tank.

[0112] (2) The water heaters 11, 12, and 13 of the hot water production system 1 of this embodiment have an electrically driven refrigerant compressor 91, the steam boiler device 30 has a gas-fired or oil-fired burner, the first temperature is 50 to 70°C, and the second temperature is 75 to 95°C. In this way, by combining a heat pump water heater having an electrically driven refrigerant compressor with a steam boiler having a burner that burns fossil fuels, and appropriately setting the temperature range for heating by each, it is possible to achieve a greater reduction in CO2 emissions and a greater reduction in running costs than when high-temperature water is produced by a heat pump water heater alone or a steam boiler alone.

[0113] (3) The second heating means 3 of the hot water producing system 1 of this embodiment includes a heating heat exchanger 210 that indirectly exchanges heat between the hot water W1 heated by the water heaters 11, 12, 13 and the steam S generated by the steam boiler device 30, a hot water tank 40 that stores the hot water W1 heated by the heating heat exchanger 210, a heating steam supply line L2 that supplies the steam S generated by the steam boiler device 30 to the heating heat exchanger 210, and a heating steam supply valve 54 provided in the heating steam supply line L2. This allows effective indirect heat exchange between the hot water W1 and the steam S at an appropriate position before entering the hot water tank 40.

[0114] (4) The second heating means 3 of the hot water producing system 1 of this embodiment is equipped with a hot water storage temperature sensor 41 that detects the temperature of the hot water in the hot water tank 40, and controls the opening of the heating steam supply valve 54 so that the detected temperature of the hot water storage temperature sensor 41 becomes the target hot water storage temperature. This makes it possible to appropriately control the temperature of the hot water in the hot water tank 40.

[0115] (5) The hot water producing system 1 of this embodiment includes a first water level sensor 42 that detects the water level in the hot water tank 40, a bypass water supply line L5 that supplies water to the hot water tank 40 without going through a water heater, and a bypass water supply valve 62 provided in the bypass water supply line L5, and when the water level detected by the first water level sensor 42 falls below the set water level, the bypass water supply valve 62 is opened. This allows water to be replenished through the bypass water supply line L5 at an appropriate time when the hot water in the hot water tank 40 becomes low.

[0116] (6) The hot water producing system 1 of this embodiment is equipped with a first water level sensor 42 that detects the water level in the hot water tank 40, and the first heating means 2 includes multiple water heaters 11, 12, 13. The hot water tank 40 has multiple water level thresholds set therein for changing the number of operating water heaters 11, 12, 13. When the water level in the hot water tank 40 drops, number control is executed to increase the number of operating water heaters 11, 12, 13 by one each time the water level detected by the first water level sensor 42 falls below the water level threshold by one step, and when the water level in the hot water tank 40 rises, number control is executed to decrease the number of operating water heaters 11, 12, 13 by one each time the water level detected by the first water level sensor 42 exceeds the water level threshold by one step. In this way, the number of operating water heaters 11, 12, 13 is increased or decreased depending on the water level in hot water tank 40, so it is possible to appropriately manage the water level in hot water tank 40. Also, power consumption can be reduced.

[0117] (7) The hot water production system 1 of this embodiment is equipped with a first water level sensor 42 that detects the water level in the hot water tank 40, and the first heating means 2 includes multiple water heaters 11, 12, 13. Multiple water level thresholds are set in the hot water tank 40 for changing the number of operating water heaters 11, 12, 13 and / or the target hot water temperature. The water heaters 11, 12, 13 are capable of switching between multiple target hot water temperatures within a temperature range higher than a first temperature and lower than a second temperature. During operation with the target hot water temperature of the water heater set to the first temperature, when the water level detected by the first water level sensor 42 exceeds the water level threshold by one step, control is executed to increase the target hot water temperature of the water heater by one step while maintaining the number of operating water heaters, and the system is operated with the target hot water temperature of the water heater increased by one or more steps. During operation, when the water level detected by the first water level sensor 42 exceeds the water level threshold by one step, control is executed to reduce the number of operating water heaters by one and at the same time return the target hot water temperature to the first temperature, or to increase the target hot water temperature of the water heater by another step while maintaining the number of operating water heaters; during operation with the target hot water temperature of the water heater set to the first temperature, when the water level detected by the first water level sensor 42 falls below the water level threshold by one step, control is executed to increase the number of operating water heaters by one and at the same time raise the target hot water temperature of the water heater by one or more steps; during operation with the target hot water temperature of the water heater raised by one or more steps, when the water level detected by the first water level sensor 42 falls below the water level threshold by one step, control is executed to lower the target hot water temperature of the water heater by one step while maintaining the number of operating water heaters. This makes it possible to appropriately manage the water level in the hot water tank 40. Also, it becomes possible to continue operation of the heat pump as long as possible, and it is possible to solve the problem of low-temperature water supply at the initial stage of restarting the operation of the heat pump.

[0118] (8) Water heaters 11, 12, 13 of hot water production system 1 of this embodiment are equipped with a water line that circulates water to condenser 92, a flow control valve or water supply pump 17, 18, 19 provided on the water line, and water supply temperature sensors 14, 15, 16 that detect the hot water temperature of water heaters 11, 12, 13, and the opening of the flow control valve or the rotation speed of water supply pumps 17, 18, 19 is controlled so that the detected temperature of hot water temperature sensors 14, 15, 16 becomes the target hot water temperature. This allows the hot water temperatures of water heaters 11, 12, and 13 to be appropriately controlled.

[0119] (9) The hot water production system 1 of this embodiment includes a water supply tank 60 for storing water to be supplied to the water heaters 11, 12, 13 and / or feed water to be supplied to the steam boiler equipment 30, and a drain recovery line for recovering steam drain generated in the heating heat exchanger 210 in the water supply tank 60. This allows the steam drain generated in heating heat exchanger 210 to be effectively utilized for preheating the water supplied to water heaters 11, 12, 13 and / or the feed water supplied to steam boiler device 30, and for water conservation.

[0120] (10) The hot water production method of this embodiment includes a first heating step in which service water W1 is heated to a first temperature while being passed through condensers 92 of heat pump water heaters 11, 12, and 13 of the heat pump water supply system 10, and a second heating step in which the service water heated in the first heating step is indirectly heat exchanged with steam S generated in a steam boiler device 30 to heat the service water to a second temperature higher than the first temperature. In this way, the water is heated in the first heating process up to a temperature that can be efficiently heated by the heat pump water heaters 11, 12, and 13, and further heating is performed by indirect heat exchange with steam S, so that even if the outlet temperature is increased, a hot water production system can be provided that is highly effective in reducing CO2 emissions and running costs. In addition, since steam is used for heating, the temperature control responsiveness is also good. Furthermore, by adopting indirect heat exchange, it is possible to prevent boiler chemicals such as boiler compounds from being mixed into the hot water tank.

[0121] <Second embodiment> Next, a second embodiment will be described with reference to Fig. 11. Note that a description of the same configuration as the first embodiment will be omitted. The hot water producing system 1 of the second embodiment is equipped with a backup steam supply line L12 that supplies steam S generated by the steam boiler device 30 to the hot water tank 40 as an additional backup heating means, and a backup steam supply valve 212 provided on the backup steam supply line L12. FIG. 11 is a diagram showing a hot water producing system 1 according to a second embodiment of the present invention.

[0122] As shown in Fig. 11, in this embodiment, the steam supply line 53 (heating steam supply line L2) branches midway, one of which is connected to the heating heat exchanger 210 and the other of which is connected to the hot water tank 40. The line connected to the heating heat exchanger 210 is provided with a heating steam supply valve 54 similar to that of the first embodiment. On the other hand, the line connected to the hot water tank 40 constitutes a backup steam supply line L12, and this backup steam supply line L12 is provided with a backup steam supply valve 212. The backup steam supply line L12 and the backup steam supply valve 212 constitute an additional backup heating means, and use steam from the steam boiler device 30 to heat the water TW stored in the hot water tank 40.

[0123] In this embodiment, similarly to the first embodiment, the water W1 heated by the first heating means 2 is further heated by the heating heat exchanger 210 constituting the second heating means 3. At this time, the heating steam supply valve 54 is controlled based on the temperature detected by the hot water temperature sensor 41 so that the temperature of the stored water TW in the hot water tank 40 becomes the target hot water temperature. However, in cases such as when a sudden load fluctuation occurs at the hot water demand location and cold water W5 is supplied from the bypass water supply line L5, it may be difficult to maintain the target hot water temperature.

[0124] Therefore, in this embodiment, the temperature of the stored water TW stored in the hot water tank 40 is increased by using the additional backup heating means described above. Specifically, the hot water production system 1 of this embodiment is capable of supplying steam S from the steam boiler device 30 into the hot water tank 40 via the backup steam supply line L12. By blowing the steam S into the hot water tank 40, direct heat exchange is performed between the hot water TW stored in the hot water tank 40 and the steam S from the steam boiler device 30. In this way, by adopting direct heat exchange as the heat exchange method of the backup heating means, it becomes possible to utilize the total heat of the steam S from the steam boiler device 30, i.e., sensible heat and latent heat, and the hot water TW stored in the hot water tank 40 can be quickly heated.

[0125] In the hot water producing system of the present embodiment, the steam supply control unit 130 controls the backup steam supply valve 212 in addition to the steam supply control described in the first embodiment. For example, the steam supply control unit 130, in cooperation with the hot water storage control unit 140, performs control to open the backup steam supply valve 212 when opening the bypass water supply valve 62. Also, when closing the bypass water supply valve 62, the steam supply control unit 130 performs control to close the backup steam supply valve 212.

[0126] Specifically, when it is detected that the water level WL in the hot water tank 40 has dropped and fallen below the water level LL, it is determined that the hot water tank 40 is on the verge of a drought, and similarly to the first embodiment, all three water heaters 11, 12, 13 are put into operation to supply as much hot water W1 as possible to the hot water tank 40, and the bypass water supply valve 62 is opened to directly replenish the cold water W5 stored in the water supply tank 60 to the hot water tank 40 (see arrow A in FIG. 4). At this time, in this embodiment, in consideration of the fact that the temperature of the stored water TW in the hot water tank 40 drops due to the supply of cold water W5, the backup steam supply valve 212 is fully opened to supply as much steam S as possible to the hot water tank 40. In this manner, by fully opening the backup steam supply valve 212 and supplying steam S, the temperature of the stored water TW in the hot water tank 40, which has been lowered by the supply of cold water W5, is raised as quickly as possible.

[0127] Then, when it is detected that the water level WL in the hot water tank 40 has risen and exceeded the water level L (entered the range between water level L and water level M), it is determined that the hot water tank 40 has recovered from the state immediately before the drought, and as in the first embodiment, the bypass water supply valve 62 is closed (see arrow B in FIG. 4). At this time, in this embodiment, the backup steam supply valve 212 is also closed. During this time, the heating steam supply valve 54 is controlled based on the temperature detected by the hot water temperature sensor 41 so that the temperature of the stored water TW in the hot water tank 40 becomes the target hot water temperature.

[0128] With the above configuration, when the bypass water supply valve 62 is opened, the backup steam supply valve 212 is also opened at the same time, so it is possible to respond to a sudden load change that makes it difficult to maintain the temperature of the hot water TW in the hot water tank 40. Furthermore, since heat is directly exchanged between the hot water TW and the steam S, the temperature of the hot water TW can be raised quickly.

[0129] The steam supply control unit 130 may be configured to control the openings of the heating steam supply valve 54 and the backup steam supply valve 212 so that the temperature detected by the hot water temperature sensor 41 becomes the target hot water temperature. In this case, the temperature zone for controlling the opening degree of the backup steam supply valve 212 may be a temperature zone lower than the temperature zone for controlling the opening degree of the heating steam supply valve 54 .

[0130] For example, the heating steam supply valve 54 may be controlled so that the temperature of the stored water TW in the hot water tank 40 becomes a target hot water storage temperature (e.g., 90°C), while the backup steam supply valve 212 may be controlled when the temperature of the stored water TW in the hot water tank 40 falls below a predetermined temperature (e.g., 80°C) that is lower than the target hot water storage temperature.

[0131] Alternatively, the heating steam supply valve 54 and the backup steam supply valve 212 may be assumed to be a single steam supply valve, and an opening degree may be assigned to them, and feedback control may be performed using a PID algorithm or the like. For example, the opening degree of the heating steam supply valve 54 from 0% (fully closed) to 100% (fully open) is assigned to the opening degree of the virtual steam supply valve from 0% (fully closed) to 50%, and the opening degree of the backup steam supply valve 212 from 0% (fully closed) to 100% (fully open) is assigned to the opening degree of the virtual steam supply valve from 50% to 100% (fully open). Then, the operating amount for the virtual steam supply valve is calculated using a PID algorithm so that the detected temperature of the hot water storage temperature sensor 41 converges to the target hot water outlet temperature, and an opening degree designation signal is output from the steam supply control unit 130 to each of the actuator circuit of the heating steam supply valve 54 and the actuator circuit of the backup steam supply valve 212. As a result, when the temperature of the stored water TW in the hot water tank 40 is stable near the target hot water temperature, such as when the bypass water supply valve is closed, the backup steam supply valve 212 is fully closed and the opening degree of the heating steam supply valve 54 is adjusted. On the other hand, when the temperature of the stored hot water in the hot water tank 40 drops significantly, such as when the bypass water supply valve 62 is opened, the heating steam supply valve 54 is fully opened and the opening degree of the backup steam supply valve 212 is adjusted.

[0132] With this configuration, it is possible to supply steam to the hot water tank 40 only when the temperature of the stored water TW in the hot water tank 40 is low. Therefore, it is possible to prevent boiler chemicals such as boiler compound from being mixed into the hot water tank 40 as much as possible.

[0133] According to the hot water producing system 1 of the present embodiment described above, in addition to the effects (1) to (10), the following effects are achieved.

[0134] (11) The hot water production system 1 of this embodiment is equipped with a backup steam supply line L12 that supplies steam S generated by a steam boiler device 30 to the hot water tank 40, and a backup steam supply valve 212 provided on the backup steam supply line L12, and controls the opening degrees of the heating steam supply valve 54 and the backup steam supply valve 212 so that the detected temperature of the hot water storage temperature sensor 41 becomes the target hot water storage temperature. This makes it possible to perform heating by direct heat exchange between the hot water and the steam S. This makes it possible to cope with a sudden load change that makes it difficult to maintain the hot water temperature in the hot water tank 40.

[0135] (12) In the hot water producing system 1 of this embodiment, the temperature zone for controlling the aperture of the backup steam supply valve 212 is a lower temperature zone than the temperature zone for controlling the aperture of the heating steam supply valve 54. This makes it possible to supply steam to the hot water tank 40 only when the temperature of the hot water in the hot water tank 40 is low. This makes it possible to prevent boiler chemicals such as boiler compound from being mixed into the hot water tank 40 as much as possible.

[0136] <Third embodiment> Next, a third embodiment will be described with reference to Fig. 12. Note that a description of the same configuration as the first embodiment will be omitted. The hot water producing system 1 of the third embodiment further includes a stored water circulation line L13 through which hot water stored in the hot water tank 40 is circulated, and as a second heating means 3, in addition to the heating heat exchanger 210 shown in the first embodiment (hereinafter referred to as the first heating heat exchanger 210 in this embodiment), includes a second heating heat exchanger 220 that indirectly exchanges heat between the hot water circulating through the stored water circulation line L13 and steam S. FIG. 12 is a diagram showing a hot water producing system 1 according to a third embodiment of the present invention.

[0137] 12, in this embodiment, the hot water tank 40 is provided with a stored water circulation line L13 through which the hot water stored in the hot water tank 40 circulates. The stored water circulation line L13 is provided with a circulation pump 221 for circulating the hot water stored in the hot water tank 40, a second heating heat exchanger 220 for heating the hot water circulating through the stored water circulation line L13, and a return temperature sensor 222 for detecting the temperature of the hot water returning from the second heating heat exchanger 220 to the hot water tank 40. The second heating heat exchanger 220 is supplied with steam S from the steam boiler device 30, and indirect heat exchange is performed between the hot water circulating through the stored water circulation line L13 and the steam S from the steam boiler device 30.

[0138] In the present embodiment, the second heating heat exchanger 220 and the first heating heat exchanger 210 are arranged in series on the heating steam supply line L2 downstream of the heating steam supply valve 54. Therefore, the steam S flowing through the heating steam supply line L2 flows through the second heating heat exchanger 220 and then flows through the first heating heat exchanger 210. With this configuration, the hot water TW stored in the hot water tank 40 is given priority for keeping warm, and the water W1 heated by the steam S can be supplied to the hot water tank 40.

[0139] The steam supply control unit 130 of this embodiment controls the opening of the heating steam supply valve 54 so that the temperature detected by the reflux temperature sensor 222 becomes the target reflux temperature. Specifically, the operation amount for the heating steam supply valve 54 is calculated by a PID algorithm so that the temperature detected by the reflux temperature sensor 222 converges to the target reflux temperature, and an opening designation signal is output from the steam supply control unit 130 to the actuator circuit of the heating steam supply valve 54. This makes it possible to appropriately control the hot water temperature in the hot water tank.

[0140] As described above, the hot water production system 1 of this embodiment is equipped with, as the second heating means 3, a first heating heat exchanger 210, a hot water tank 40 for storing hot water heated by the first heating heat exchanger 210, a stored water circulation line L13 through which the hot water stored in the hot water tank 40 is circulated, a second heating heat exchanger 220 for indirect heat exchange between the hot water circulating through the stored water circulation line L13 and steam, a heating steam supply line L2 for supplying steam S generated in the steam boiler device 30 to the first heating heat exchanger 210 and the second heating heat exchanger 220, and a heating steam supply valve 54 provided in the heating steam supply line L2. This makes it possible to cope with a sudden load change that makes it difficult to maintain the hot water temperature in the hot water tank 40. In addition, since steam S is not mixed into the hot water tank 40, it is possible to prevent boiler chemicals such as boiler compound from being mixed into the hot water tank 40.

[0141] It is preferable that the second heating heat exchanger 220 and the first heating heat exchanger 210 are arranged in series so that the steam S flows through them in this order, but these heat exchangers may be arranged in the opposite order. The second heating heat exchanger 220 and the first heating heat exchanger 210 may be arranged in parallel. In this case, for example, the heating steam supply line L2 is branched midway so that steam S from the steam boiler device 30 can be supplied to each of the second heating heat exchanger 220 and the first heating heat exchanger 210. In this case, a heating steam supply valve may be provided on the line before the branching, or a heating steam supply valve may be provided on each of the lines after the branching. The heating steam supply valve is controlled based on the detection results of each sensor, such as the reflux temperature sensor 222, the hot water storage temperature sensor 41 (not shown), the first water level sensor, etc. For example, the heating steam supply valve corresponding to the second heating heat exchanger 220 may be controlled based on the temperature detected by the reflux temperature sensor 222. The heating steam supply valve corresponding to the first heating heat exchanger 210 may be controlled based on the temperature detected by the hot water storage temperature sensor 41.

[0142] The circulation pump 221 may also be controlled based on the detection results of each sensor, such as the reflux temperature sensor 222, the hot water storage temperature sensor 41 (not shown), and the first water level sensor 42. For example, the drive of the circulation pump 221 may be controlled based on the temperature detected by the hot water storage temperature sensor 41. Specifically, the circulation pump 221 may be driven when the hot water storage temperature sensor 41 is lower than a predetermined temperature. The control of the circulation pump 221 may also be linked to the control of the heating steam supply valve, so that the circulation pump 221 is driven when the heating steam supply valve opens.

[0143] In addition, a configuration may be adopted in which a drain recovery line (not shown) is provided between the first heating heat exchanger 210 and / or the second heating heat exchanger 220 and the water supply tank 60, and steam drain generated in the first heating heat exchanger 210 and / or the second heating heat exchanger 220 is recovered in the water supply tank 60. This allows the steam drain generated in the first heating heat exchanger 210 and / or the second heating heat exchanger 220 to be effectively utilized for preheating the service water supplied to the heat pump hot water supply system 10 and the feed water supplied to the steam boiler device 30, and for water conservation.

[0144] According to the hot water producing system 1 of the present embodiment described above, in addition to the effects (1) to (10), the following effects are achieved.

[0145] (13) In the hot water producing system 1 of this embodiment, the second heating means 3 includes a first heating heat exchanger 210 that indirectly exchanges heat between hot water W1 heated by the water heaters 11, 12, and 13 and steam S, a hot water tank 40 that stores the hot water W1 heated by the first heating heat exchanger 210, a stored water circulation line L13 through which the hot water TW stored in the hot water tank 40 is circulated, a second heating heat exchanger 220 that indirectly exchanges heat between the hot water TW circulating through the stored water circulation line L13 and steam S, a heating steam supply line L2 that supplies steam S generated in the steam boiler device 30 to the first heating heat exchanger 210 and the second heating heat exchanger 220, and a heating steam supply valve 54 provided in the heating steam supply line L2. This makes it possible to cope with a sudden load change that makes it difficult to maintain the hot water temperature in the hot water tank 40. Also, it is possible to prevent boiler chemicals such as boiler compound from being mixed into the hot water tank 40.

[0146] (14) The heating steam supply line L2 of the hot water producing system 1 of this embodiment circulates the steam S generated in the steam boiler device 20 to the second heating heat exchanger 220, and then to the first heating heat exchanger 210. This allows the water W1 heated by the steam S to be supplied to the hot water tank while giving priority to keeping the hot water TW stored in the hot water tank 40 warm.

[0147] (15) In the hot water producing system 1 of this embodiment, the second heating means 3 is provided with a return temperature sensor 222 that detects the temperature of the hot water TW returning from the second heating heat exchanger 220 to the hot water tank 40, and the opening of the heating steam supply valve 54 is controlled so that the detected temperature of the return temperature sensor 222 becomes the target return temperature. This makes it possible to appropriately control the hot water temperature in the hot water tank 40.

[0148] (16) The hot water producing system 1 of this embodiment includes a water supply tank 60 for storing water to be supplied to the water heaters 11, 12, 13 and / or feed water to be supplied to the steam boiler equipment 30, and a drain recovery line for recovering steam drain generated in the first heating heat exchanger 210 and / or the second heating heat exchanger 220 in the water supply tank 60. This allows the steam drain generated in the first heating heat exchanger 210 and / or the second heating heat exchanger 220 to be effectively utilized for preheating the water supplied to the water heaters 11, 12, 13 and / or the feed water supplied to the steam boiler device 30, and for water conservation.

[0149] <Fourth embodiment> Next, a fourth embodiment will be described with reference to Fig. 13. Note that a description of the same configuration as the first embodiment will be omitted. The hot water producing system 1 of the fourth embodiment further includes a preheating heat exchanger 75 that performs indirect heat exchange between the service water W5 flowing through the bypass water supply line L5 and the steam S from the steam boiler device 30. FIG. 13 is a diagram showing a hot water producing system 1 according to a fourth embodiment of the present invention.

[0150] 13, in this embodiment, a preheating heat exchanger 75 is provided in the bypass water supply line L5. The preheating heat exchanger 75 is an indirect heat exchanger, and performs indirect heat exchange between the service water (cold water) W5 from the water supply tank 60 supplied through the bypass water supply line L5 and the steam from the steam boiler device 30. The preheating heat exchanger 75 is provided downstream of the bypass water supply valve 62.

[0151] The steam supply line 53 (heating steam supply line L2) in this embodiment branches midway, one of which is connected to the heating heat exchanger 210 and the other of which is connected to the preheating heat exchanger 75. The line connected to the heating heat exchanger 210 is provided with a heating steam supply valve 54 similar to that of the first embodiment. On the other hand, the line connected to the preheating heat exchanger 75 constitutes the preheating steam supply line L10, and this preheating steam supply line L10 is provided with a preheating steam supply valve 76.

[0152] The preheating heat exchanger 75, the preheating steam supply line L10, and the preheating steam supply valve 76 constitute additional preheating heating means and have the function of heating the water W5 supplied through the bypass water supply line L5.

[0153] In this embodiment, the hot water storage control unit 140 controls the preheating steam supply valve 76 in addition to the hot water storage control described in the first embodiment. Specifically, when the bypass water supply valve 62 is opened, the preheating steam supply valve 76 is also opened. This makes it possible to prevent a sudden drop in the temperature of the stored water TW in the hot water tank 40 due to the service water W5 supplied through the bypass water supply line L5.

[0154] As in the first embodiment, the bypass water supply valve 62 is opened when it is detected that the water level WL in the hot water tank 40 has fallen below the water level LL, that is, when the hot water tank 40 is about to run out of water. As a result, the cold water W5 stored in the water supply tank 60 is directly supplied to the hot water tank 40, preventing the hot water tank 40 from running out of water; however, the temperature of the water TW stored in the hot water tank 40 naturally drops.

[0155] The preheating heat exchanger 75 in this embodiment is provided to prevent as much as possible a decrease in the temperature of the stored water TW in the hot water tank 40 due to the replenishment of the water W5 through such bypass water supply. That is, when the bypass water supply valve 62 is opened, the preheating steam supply valve 76 is also opened, thereby heating the water W5 supplied into the hot water tank 40 through the bypass water supply line L5. This makes it possible to increase the temperature of the water W5 when the water W5 is replenished to the hot water tank 40 from the bypass water supply line L5.

[0156] In addition, a configuration may be adopted in which a drain recovery line (not shown) is provided between the heating heat exchanger 210 and / or the preheating heat exchanger 75 and the water supply tank 60, and steam drain generated in the heating heat exchanger 210 and / or the preheating heat exchanger 75 is recovered in the water supply tank 60. This allows the steam drain generated in the heating heat exchanger 210 and / or the preheating heat exchanger 75 to be effectively utilized for preheating the service water supplied to the heat pump hot water supply system 10 and the feed water supplied to the steam boiler device 30, and for water conservation.

[0157] According to the hot water producing system 1 of the present embodiment described above, in addition to the effects (1) to (16), the following effects are achieved.

[0158] (17) The hot water production system 1 of this embodiment includes a preheating heat exchanger 75 that indirectly exchanges heat between steam and water W5 circulating through the bypass water supply line L5, a preheating steam supply line L10 that supplies steam S generated in the steam boiler apparatus 30 to the preheating heat exchanger 75, and a preheating steam supply valve 76 provided on the preheating steam supply line L10, and the preheating steam supply valve 76 is opened when the bypass water supply valve 62 is opened. This makes it possible to increase the temperature of the make-up water when supplying water to the hot water tank 40 from the bypass water supply line L5.

[0159] (18) The hot water producing system 1 of this embodiment includes a water supply tank 60 for storing water to be supplied to the water heaters 11, 12, 13 and / or feed water to be supplied to the steam boiler equipment 30, and a drain recovery line for recovering steam drain generated in the heating heat exchanger 210 and / or the preheating heat exchanger 75 in the water supply tank 60. This allows the steam drain generated in the heating heat exchanger 210 and / or the preheating heat exchanger 75 to be effectively utilized for preheating the water supplied to the water heaters 11, 12, 13 and / or the feed water supplied to the steam boiler device 30, and for water conservation.

[0160] <Fifth embodiment> Next, a fifth embodiment will be described with reference to Figures 14 to 15. Note that a description of the same configuration as the first embodiment will be omitted. The hot water producing system 1 of the fifth embodiment further includes a switching means 80 that switches the supply destination of the hot water W1 supplied from the water heaters 11, 12, and 13 to the hot water tank 40 or the water supply tank 60. FIG. 14 is a diagram showing a hot water producing system 1 according to a fifth embodiment of the present invention.

[0161] 14, in this embodiment, the hot water supply line L1 branches midway, with one branch being connected to the hot water tank 40 via the heating heat exchanger 210 and the other branch being connected to the water supply tank 60. The hot water supply line connected to the water supply tank 60 constitutes the water supply tank hot water supply line L11.

[0162] Switching valves 81, 82, and 83 are provided as switching means 80 at the branching portions of the hot water supply line L1 connected to each of the hot water heaters 11, 12, and 13. These switching valves 81, 82, and 83 function as switching means for switching the supply destination of the hot water supplied from each of the hot water heaters 11, 12, and 13 to the hot water tank 40 side or the water supply tank 60 side. By providing such a switching means, the supply direction of hot water from each water heater 11, 12, 13 can be switched between the hot water tank 40 side and the water supply tank 60 side as necessary. This also makes it possible to continue operation of the water heaters 11, 12, 13 as much as possible, and eliminates the problem of low-temperature water supply at the initial stage of restarting operation of the heat pump water heaters 11, 12, 13.

[0163] In this embodiment, a second water supply tank 65 that supplies water to the heat pump water heaters 11, 12, and 13 is provided separately from the water supply tank 60. Water W1 from the second water supply tank 65 is supplied to the water heaters 11, 12, and 13 via a heat pump water supply line L3.

[0164] Next, the specific control of the switching valve 81 will be described. The hot water storage control unit 140 controls the bypass water supply valve 62 and the switching valves 81, 82, and 83 based on the detection result of the first water level sensor . The hot water tank 40 includes a first water level sensor 42 shown in FIG. 4, similarly to the first embodiment.

[0165] In this embodiment, the hot water storage control unit 140 opens the bypass water supply valve 62 when the first water level sensor 42 detects that the water level has fallen below the water level LL. In addition, when the water level in the hot water tank 40 drops, the hot water storage control unit 140 controls the switching valves 81, 82, 83 to increase the number of hot water heaters 11, 12, 13 for the hot water tank 40 by one each time the water level detected by the first water level sensor 42 falls one step below the water level threshold, and at the same time to decrease the number of hot water heaters 11, 12, 13 for the water supply tank 60 by one; and when the water level in the hot water tank 40 rises, the hot water storage control unit 140 controls the switching valves 81, 82, 83 to decrease the number of hot water heaters 11, 12, 13 for the hot water tank 40 by one each time the water level detected by the first water level sensor 42 exceeds the water level threshold by one step, and at the same time to increase the number of hot water heaters 11, 12, 13 for the water supply tank 60 by one. This control is performed, for example, at water level H, water level M, and water level L when the water level is decreasing, and at water level M, water level H, and water level HH when the water level is increasing. The hot water storage control unit 140 may control the water heaters 11, 12, and 13 and the switching valves 81, 82, and 83 via the hot water supply control unit 110.

[0166] Here, for example, a case where the water level WL in the hot water tank 40 fluctuates will be described with reference to Fig. 15. Note that a description of the same control as that in Fig. 4 of the first embodiment will be omitted.

[0167] First, the control when the water level WL is recovering (see arrow B in FIG. 4) will be described. When the water level WL rises and the tip of the third electrode rod 423 is immersed in the water surface, the first water level sensor 42 detects that the water level WL has exceeded the water level M. At this time, it is determined that there is a little extra water stored in the hot water tank 40, and only one of the three switching valves is switched to the water supply tank 60 side. For example, of switching valves 81, 82, and 83, only switching valve 83 is switched to the water supply tank 60 side. In other words, the switching means 80 is controlled so as to decrease the number of hot water heaters for the hot water tank 40 by one and simultaneously increase the number of hot water heaters for the water supply tank 60 by one.

[0168] Next, when the water level WL rises further and the tip of the fourth electrode rod 424 is immersed in the water surface, the first water level sensor 42 detects that the water level WL has exceeded the water level H. At this time, it is determined that there is more water stored in the hot water tank 40, and two of the three changeover valves are switched to the water supply tank 60 side. For example, of the changeover valves 81, 82, and 83, the changeover valves 82 and 83 are switched to the water supply tank 60 side.

[0169] Next, when the water level WL rises further and the tip of the fifth electrode 425 is immersed in the water surface, the first water level sensor 42 detects that the water level WL has exceeded the water level HH. At this time, it is determined that the amount of water stored in the hot water tank 40 has reached a sufficient level, and all three changeover valves 81, 82, and 83 are switched to the water supply tank 60 side.

[0170] Next, a case where the water level WL starts to drop from this state will be described. When the water level WL drops (see arrow A in FIG. 4) and the lower end of the fourth electrode rod 424 is exposed above the water surface, the first water level sensor 42 detects that the water level WL has fallen below the water level H. When the hot water storage control unit 140 detects that the water level WL has fallen below the water level H, it switches one of the three switching valves to the hot water tank 40 side. For example, of the switching valves 81, 82, and 83, the switching valve 81 is switched to the hot water tank 40 side.

[0171] Here, if the water level WL rises after falling below the water level H and the tip of the fifth electrode rod 425 is submerged in the water surface, it is determined that the amount of water stored in the hot water tank 40 is sufficient again, and all of the switching valves 81, 82, 83 are switched to the water supply tank 60 side, as described above.

[0172] On the other hand, after the water level WL falls below the water level H, when the water level WL falls further (see arrow A in Figure 4) and the lower end of the third electrode rod 423 is exposed above the water surface, the first water level sensor 42 detects that the water level WL has fallen below the water level M. When the hot water storage control unit 140 detects that the water level WL has fallen below the water level H, it switches two of the three switching valves to the hot water tank 40 side. For example, of the switching valves 81, 82, and 83, the switching valves 81 and 82 are switched to the hot water tank 40 side.

[0173] From this state, when the water level WL further drops and the lower end of the second electrode rod 422 is exposed above the water surface, the first water level sensor 42 detects that the water level WL has fallen below the water level L. When the hot water storage control unit 140 detects that the water level WL has fallen below the water level L, it switches all three switching valves 81, 82, and 83 to the hot water tank 40 side.

[0174] As a result, the hot water W1 heated by the first heating means 2 can be switched to the hot water tank 40 or the water supply tank 60 depending on the need and supplied as hot water. That is, the hot water W1 heated by the first heating means 2 that does not need to be supplied to the hot water tank 40 can be supplied to the water supply tank 60 that stores water for boiler supply or bypass supply. Therefore, the hot water W1 heated by the first heating means 2 can be used effectively. In addition, by controlling the switching means 80, it is possible to continue the operation of the heat pump water heaters 11, 12, 13 as much as possible, and the problem of low-temperature water supply at the initial stage of restarting the operation of the heat pump can be solved.

[0175] In order to effectively heat the water for the boiler feed water and the bypass feed water, it is preferable to separate the water supply tank into a water supply tank 60 for storing the water for the boiler feed water and the bypass feed water, and a second water supply tank 65 for storing the water for supply to the heat pump hot water supply system 10, and to supply the hot water W1 heated by the first heating means 2 to the water supply tank 60, but as shown in the first embodiment, the second water supply tank 65 may be shared with the water supply tank 60. In this case, the water supplied to the heat pump hot water supply system 10 is also heated. The switching means 80 may be configured to be capable of switching the supply destination of the hot water W1 from the water heaters 11, 12, and 13 to the hot water tank 40 or the second water tank 65.

[0176] 10, the hot water storage control unit 140 shifts the number of operating water heaters in a predetermined water level band (for example, a water level band between water level L and water level M) between when the water level is rising and when the water level is falling, but instead of shifting the number of operating water heaters in a predetermined water level band between when the water level is rising and when the water level is falling, a status confirmation time may be provided, as in the first embodiment. In other words, the configuration may be such that control such as switching the switching valves 81, 82, 83 is executed when it is determined that the water level WL has remained above / below a predetermined water level threshold for a predetermined time.

[0177] Furthermore, in this embodiment, a second water level sensor (not shown) may be provided in the water supply tank 60 to detect the water level in the water supply tank 60, and when the detected water level by the second water level sensor reaches a water supply stop water level, one of the water heaters 11, 12, and 13 that is currently supplying hot water to the water supply tank 60 may be stopped, and when the detected water level reaches a water supply start water level, the water heater that is stopped may be operated. For example, when the water level WL is rising and exceeds the water level M, and one of the three water heaters, for example water heater 13, is supplying hot water to the water supply tank 60, when the water level detected by the second water level sensor of the water supply tank 60 reaches the water supply stop water level, the operation of water heater 13 is stopped. Then, when the water level detected by the second water level sensor reaches the water supply start water level, the operation of water heater 13 that had been stopped is resumed. This allows the water level in the water supply tank 60 to be appropriately managed.

[0178] According to the hot water producing system 1 of the present embodiment described above, in addition to the effects (1) to (18), the following effects are achieved.

[0179] (19) The hot water producing system 1 of this embodiment includes a water supply tank 60 for storing water to be supplied to the water heaters 11, 12, and 13 and / or feed water to be supplied to the steam boiler apparatus 30, and a switching means for switching the supply destination of the hot water W1 supplied from the water heaters 11, 12, and 13 to the hot water tank 40 or the water supply tank 60. This allows hot water W1 supplied from water heaters 11, 12, and 13 to be switched to hot water tank 40 or water supply tank 60 as needed. Also, by making the switchable, it is possible to continue operation of the heat pump as long as possible, and the problem of low-temperature water supply at the initial stage of restarting operation of the heat pump can be eliminated. (20) The hot water producing system 1 of this embodiment includes a first water level sensor 42 that detects the water level in the hot water tank 40, and the first heating means 2 includes a plurality of water heaters 11, 12, and 13. The hot water tank 40 has a plurality of water level thresholds set therein for changing the number of hot water heaters 11, 12, and 13. When the water level in the hot water tank 40 drops, the number of hot water heaters 11, 12, and 13 for the hot water tank 40 is reduced by one each time the water level detected by the first water level sensor 42 falls below the water level threshold by one step. When the water level in the hot water tank 40 rises, the switching means 80 is controlled so that the number of hot water heaters 11, 12, 13 for the hot water tank 40 is decreased by one each time the water level detected by the first water level sensor 42 exceeds the water level threshold by one step, and at the same time, the switching means 80 is controlled so that the number of hot water heaters 11, 12, 13 for the hot water tank 40 is increased by one each time the water level detected by the first water level sensor 42 exceeds the water level threshold by one step. This allows water to be supplied by switching between the hot water tank 40 and the water supply tank 60 as needed. In addition, by controlling the switching means 80, it is possible to continue operation of the heat pump as long as possible, and this makes it possible to solve the problem of low-temperature water supply at the initial stage of restarting the operation of the heat pump.

[0180] (21) The hot water producing system 1 of this embodiment is equipped with a second water level sensor that detects the water level in the water supply tank 60, and when the water level detected by the second water level sensor reaches the water supply stop water level, the water heater that is supplying hot water to the water supply tank 60 is stopped, and when the detected water level reaches the water supply start water level, the water heater that is stopped is operated. This allows the water level in the water supply tank 60 to be appropriately managed.

[0181] Although the preferred embodiments of the hot water producing system of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments and can be modified as appropriate. In addition, a plurality of embodiments can be combined. [Explanation of symbols]

[0182] 1. Hot water production system 2...First heating means 3...Second heating means 10. Heat pump hot water system 11…First heat pump water heater 12…Second heat pump water heater 13…Third heat pump water heater 14, 15, 16...Hot water temperature sensor 17, 18, 19…Water supply pump 30...Steam boiler equipment 31...Once-through boiler 40…Hot water tank 41…Hot water temperature sensor 42…First water level sensor 421...1st electrode rod 422...Second electrode rod 423...Third electrode rod 424…4th electrode rod 425...5th electrode rod 51…Steam header 52…Connecting line 53…Steam supply line 54... Steam supply valve for heating 55…Pressure gauge 60…Water tank 62...Bypass water supply valve 75…Preheating heat exchanger 76…Preheating steam supply valve 80...Switching means 81, 82, 83...Switching valve 90…Heat pump circuit 91...Refrigerant compressor 92…Condenser 93…Expansion valve 94…Evaporator 100...Control unit 110...Hot water supply control unit 120...Boiler control unit 130...Steam supply control unit 140...Hot water storage control unit 210...Heating heat exchanger (first heating heat exchanger) 212…Back-up steam supply valve 220…Second heating heat exchanger L1…Hot water supply line L2: Steam supply line for heating L3…Heat pump water supply line L4…Boiler feed water line L5…Bypass water supply line L6…Hot water outlet line L7…Refrigerant circulation line L8…Heat source water supply line L10: Preheating steam supply line L12: Backup steam supply line L13…Stored water circulation line W1…Water (warm water) W5…Water (cold water) W6…Hot water S: Steam R…Refrigerant TW: Hot water, stored water WL…Water level

Claims

1. A first heating means for heating the water to a target hot water temperature while passing the water through the heat pump type hot water heater; a second heating means for indirectly exchanging heat with the water heated to the target hot water supply temperature by the first heating means, the second heating means generating steam in a steam boiler and adjusting the steam pressure to a target hot water outlet temperature set higher than the target hot water supply temperature; A control means for controlling the first heating means and the second heating means, The second heating means is a heating heat exchanger for indirectly exchanging heat between the hot water heated by the water heater and the steam generated by the steam boiler; A hot water tank for storing hot water heated by the heating heat exchanger; a hot water temperature sensor for detecting the temperature of the hot water in the hot water tank; The control means adjusts the output sharing between the water heater and the steam boiler so that the temperature detected by the hot water storage temperature sensor becomes the set target hot water outlet temperature.

2. The second heating means is a steam header that collects steam generated in the steam boiler; a heating steam supply valve for adjusting the amount of steam supplied from the steam header, The control means a boiler control unit that controls the steam boiler so that a header pressure of the steam header becomes the target steam pressure; 2. The hot water producing system according to claim 1, further comprising a steam supply control unit that controls the heating steam supply valve so that the temperature detected by the hot water storage temperature sensor becomes the set target hot water outlet temperature.

3. The second heating means is a first water level sensor for detecting a water level in the hot water tank; a heating steam supply line for supplying steam generated in the steam boiler to the heating heat exchanger; A heating steam supply valve provided in the heating steam supply line, The first heating means is A water supply line for supplying water to the water heater; A hot water supply line that supplies hot water heated by the hot water heater to the heating heat exchanger; a hot water temperature sensor for detecting a hot water temperature of the hot water flowing through the hot water supply line; The control means when the water level detected by the first water level sensor falls below a first set water level during a drop in the water level in the hot water tank, the supply of water through the water supply line and the supply of hot water through the hot water supply line are started; when the water level detected by the first water level sensor exceeds a second set water level that is higher than the first set water level during a water level rise in the hot water tank, the supply of water through the water supply line and the supply of hot water through the hot water supply line are stopped; When the water supply is in progress, Controlling the water heater so that the temperature detected by the hot water temperature sensor becomes the target hot water temperature; 2. The hot water producing system according to claim 1, wherein an opening degree of the heating steam supply valve is controlled so that the temperature detected by the hot water storage temperature sensor becomes the target hot water outlet temperature.

4. a bypass water supply line for supplying water to the hot water tank without passing through the water heater; A bypass water supply valve provided in the bypass water supply line; a backup steam supply line for supplying steam generated by the steam boiler to the hot water tank; A backup steam supply valve provided in the backup steam supply line, The control means When the water level in the hot water tank drops and the detected water level of the first water level sensor falls below a third set water level that is lower than the first set water level, the bypass water supply valve is opened, and the opening degree of the heating steam supply valve and the backup steam supply valve is controlled so that the detected temperature of the hot water storage temperature sensor becomes the target hot water outlet temperature, 4. The hot water producing system according to claim 3, wherein when the water level in the hot water tank rises and the detected water level of the first water level sensor exceeds a fourth set water level that is higher than the third set water level, the bypass water supply valve is closed.

5. 5. The hot water producing system according to claim 4, wherein a temperature zone for controlling the opening degree of the backup steam supply valve is a temperature zone lower than a temperature zone for controlling the opening degree of the heating steam supply valve.

6. a bypass water supply line for supplying water to the hot water tank without passing through the water heater; A bypass water supply valve provided in the bypass water supply line; A circulation line through which the hot water stored in the hot water tank is circulated; an auxiliary heat exchanger for indirectly exchanging heat between the hot water and steam circulating through the circulation line; a return temperature sensor for detecting a temperature of the hot water returning from the auxiliary heat exchanger to the hot water tank; the heating-use steam supply line supplies steam generated in the steam boiler to the heating-use heat exchanger and the auxiliary heat exchanger, The control means When the water level in the hot water tank drops and the detected water level of the first water level sensor falls below a third set water level that is lower than the first set water level, the bypass water supply valve is opened, and the opening degree of the heating steam supply valve is controlled so that the detected temperature of the return flow temperature sensor becomes the target hot water outlet temperature.

4. The hot water producing system according to claim 3, wherein when the water level in the hot water tank rises and the detected water level of the first water level sensor exceeds a fourth set water level that is higher than the third set water level, the bypass water supply valve is closed.

7. 7. The hot water producing system according to claim 6, wherein the heating-use steam supply line circulates the steam generated in the steam boiler through the auxiliary heat exchanger, and then through the heating-use heat exchanger.

8. a bypass water supply line for supplying water to the hot water tank without passing through the water heater; A bypass water supply valve provided in the bypass water supply line; a preheating heat exchanger for indirectly exchanging heat between the water flowing through the bypass water supply line and steam; a preheating steam supply line for supplying steam generated in the steam boiler to the preheating heat exchanger; A preheating steam supply valve provided in the preheating steam supply line, The control means When the water level in the hot water tank drops, the detected water level of the first water level sensor falls below a third set water level that is lower than the first set water level, and the bypass water supply valve is opened and the preheating steam supply valve is opened.

4. The hot water producing system according to claim 3, wherein when the water level in the hot water tank rises and the detected water level of the first water level sensor exceeds a fourth set water level that is higher than the third set water level, the bypass water supply valve is closed.

9. The first heating means includes a plurality of the water heaters, A plurality of water level thresholds are set in the hot water tank for changing the number of the water heaters in operation; The control means When the water level in the hot water tank is decreasing, a number control is executed to increase the number of the water heaters in operation by one each time the water level detected by the first water level sensor falls below the water level threshold by one level; A hot water producing system as described in any one of claims 3 to 8, wherein when the water level in the hot water tank rises, a number control is performed to reduce the number of operating water heaters by one each time the detected water level of the first water level sensor exceeds the water level threshold by one step.

10. The first heating means includes a plurality of the water heaters, A plurality of water level thresholds are set in the hot water tank for changing the number of the hot water heaters in operation and / or the target hot water temperature; The water heater is capable of switching a target hot water supply temperature among a plurality of stages within a temperature range higher than a first temperature and lower than the target hot water outlet temperature, The control means When the target hot water temperature of the water heater is set to the first temperature and the detected water level of the first water level sensor exceeds the water level threshold by one step, control is executed to increase the target hot water temperature of the water heater by one step while maintaining the number of operating water heaters; when the target hot water temperature of the water heater is increased by one step or more and the detected water level of the first water level sensor exceeds the water level threshold by one step, control is executed to reduce the number of operating water heaters by one and at the same time return the target hot water temperature to the first temperature, or control is executed to increase the target hot water temperature of the water heater by another step while maintaining the number of operating water heaters; A hot water production system as described in any of claims 3 to 8, wherein, during operation with the target hot water temperature of the water heater set to the first temperature, when the water level detected by the first water level sensor falls one step below the water level threshold, control is executed to increase the number of operating water heaters by one and at the same time raise the target hot water temperature of the water heater by one or more steps, and, during operation with the target hot water temperature of the water heater raised by one or more steps, when the water level detected by the first water level sensor falls one step below the water level threshold, control is executed to lower the target hot water temperature of the water heater by one step while maintaining the number of operating water heaters.

11. a water supply tank for storing water to be supplied to the water heater and / or water to be supplied to the steam boiler; The hot water producing system according to any one of claims 3 to 10, further comprising a switching means for switching a supply destination of the hot water supplied from the water heater to the hot water tank or the water supply tank.

12. The first heating means includes a plurality of the water heaters, The hot water tank is provided with a plurality of water level thresholds for changing the number of hot water heaters; The control means When the water level in the hot water tank is decreasing, the switching means is controlled so that the number of hot water heaters for the hot water tank is increased by one each time the water level detected by the first water level sensor falls below the water level threshold by one step, and at the same time, the number of hot water heaters for the water supply tank is decreased by one each time; The hot water producing system of claim 11, wherein when the water level in the hot water tank rises, the switching means controls so as to reduce the number of hot water heaters for the hot water tank by one each time the detected water level of the first water level sensor exceeds the water level threshold by one step, while at the same time increasing the number of hot water heaters for the water supply tank by one.

13. a second water level sensor for detecting a water level in the water supply tank; The control means The hot water producing system of claim 11 or claim 12, wherein when the detected water level of the second water level sensor reaches a water supply stop water level, the water heater that is supplying hot water to the water tank is stopped, and when the detected water level reaches a water supply start water level, the water heater that is stopped is operated.

14. a water supply tank for storing water to be supplied to the water heater and / or water to be supplied to the steam boiler; The hot water producing system according to any one of claims 3 to 13, further comprising: a drain recovery line that recovers steam drain generated in the heating heat exchanger and returns it to the water supply tank.

15. A first heating step of heating the water to a target hot water temperature while passing the water through the heat pump water heater; a second heating step of indirectly exchanging heat with steam generated by a steam boiler and adjusted to a target steam pressure, the second heating step heating the water heated to the target hot water supply temperature in the first heating step to a target hot water outlet temperature set higher than the target hot water supply temperature; The second heating step includes storing the heated hot water in a hot water tank by indirect heat exchange between the hot water heated by the water heater and the steam generated by the steam boiler in a heating heat exchanger, and detecting the temperature of the hot water in the hot water tank with a hot water storage temperature sensor; A hot water production method that adjusts the output distribution of the water heater and the steam boiler so that the detected temperature of the hot water storage temperature sensor becomes the set target hot water outlet temperature when the first heating process and the second heating process are performed.

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