Steam generation device

Abstract

To provide a steam generation device that uses outside air and hot waste water as heat source fluid for a heat pump, and generates steam of pressure and temperature suitable for a steam use device with high efficiency.SOLUTION: A steam generation device 100 comprises: a heat pump 200 in which a refrigerant compressor 2, a refrigerant condenser 3, a refrigerant expansion valve 4, and a refrigerant evaporator 5 are connected in a ring manner by a refrigerant circulation passage 1, and which generates steam in the refrigerant condenser 3 by driving the refrigerant compressor 2; a steam compressor 10 which compresses the steam discharged from the refrigerant condenser 3 to generate superheated steam; and a heat exchanger 20 which cools the superheated steam discharged from the steam compressor 10 with a cooling medium to generate saturated steam.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology disclosed in this specification relates to a steam generator.

Background Art

[0002] Conventionally, when steam is required in a factory or the like, a combustion-type boiler that generates steam by burning fossil fuels such as heavy oil, kerosene, and methane gas has been used. Since a combustion-type boiler emits a large amount of carbon dioxide by burning fossil fuels, it is not preferable from the viewpoint of preventing global warming.

[0003] Therefore, as disclosed in Patent Document 1 and Patent Document 2, a heat pump type steam generator that generates steam using a heat pump has been invented. However, the heat pump type steam generator is not as widespread as the combustion-type boiler.

[0004] The reasons why the heat pump type steam generator has not been widespread include that it is technically difficult to develop a high-temperature heat pump that can generate steam at a pressure and temperature equivalent to that of a boiler. In particular, the high-temperature durability of the refrigerant compressor and the difficulty in obtaining a refrigerant with a low global warming potential are mentioned. Furthermore, there are reasons to be considered as follows.

[0005] The advantage of a combustion boiler lies in the fact that the combustion gas temperature is very high compared to the steam temperature. Since the pressure of the boiler feed water can be easily increased by a pump or the like, if high-pressure boiler feed water is boiled at a high combustion gas temperature, high-temperature and high-pressure steam can be easily generated. In a combustion boiler used in many factories, the steam pressure (operating pressure) at the boiler outlet is set to about 0.8 MPa (about 170 °C), for example. To steam-using equipment that requires a temperature equivalent to that at the boiler outlet, steam is supplied while maintaining the pressure at the boiler outlet. To steam-using equipment that is suitable for a lower temperature than the boiler outlet, steam at a lower pressure is supplied through a pressure-reducing operation. The pressure lower than the boiler outlet is about 0.3 MPa (about 133 °C), for example. Thus, in the utilization of a combustion boiler, it is easy to change the pressure of the supplied steam or supply steam at multiple pressures.

[0006] A vapor-compression heat pump can exhibit a heating capacity several times the electric power input to the refrigerant compressor, so it is preferable from the viewpoints of energy saving and global warming prevention. Therefore, heat pumps are widely used for the generation of hot water. However, heat pumps are not much used for the generation of steam. Although the problems in the development of high-temperature heat pumps have already been described, there are also the following reasons.

[0007] As the first reason, when the pressure of the steam generated by a heat pump for a heat source fluid at a certain temperature is increased, the heat difference between the low-temperature heat source fluid and the high-temperature steam becomes large. A large heat difference reduces the coefficient of performance (COP) of the heat pump, so the advantages of using the heat pump are reduced.

[0008] As a second reason, when manufacturing a heat pump that generates steam at about 0.8 MPa, such as a combustion boiler, and obtaining high-pressure steam at 0.8 MPa (about 170°C) and low-pressure steam at 0.3 MPa (about 133°C) with that heat pump, the coefficient of performance (COP) is determined by the conditions for generating high-pressure steam. Therefore, even when the heat pump is used for generating low-pressure steam, more power will be consumed and it will operate under conditions where the coefficient of performance (COP) decreases, resulting in fewer merits in using the heat pump.

[0009] As disclosed in Patent Documents 1 and 2, a method has been conventionally proposed in which steam generated by utilizing heat lifted by a heat pump is adiabatically compressed by a steam compressor to increase the pressure. However, this method is not widely used. The reasons are as follows.

[0010] When low-pressure steam is adiabatically compressed to increase the pressure to the equivalent of the boiler outlet pressure (0.8 MPa) of a general combustion boiler, even in the most efficient isentropic compression, steam with a very high degree of superheat (i.e., steam with excessive enthalpy) is generated. This means an increase in the power input to the steam compressor, which is not preferable from the perspective of energy conservation.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0012] The technology disclosed in this specification aims to provide a steam generation device that utilizes outside air or warm wastewater as a heat source fluid for a heat pump and efficiently generates steam with a pressure and temperature suitable for steam-using equipment.

Means for Solving the Problems

[0013] This specification discloses a steam generation device. The steam generation device includes a heat pump in which a refrigerant compressor, a refrigerant condenser, a refrigerant expansion valve, and a refrigerant evaporator are annularly connected by a refrigerant circulation flow path, and steam is generated in the refrigerant condenser by driving the refrigerant compressor, a steam compressor that compresses the steam sent from the refrigerant condenser to generate superheated steam, and a heat exchanger that cools the superheated steam discharged from the steam compressor with a cooling medium to generate saturated steam.

Advantages of the Invention

[0014] According to the technology disclosed in this specification, there is provided a steam generation device that utilizes outside air or warm waste water as a heat source fluid for a heat pump and generates steam with suitable pressure and temperature for steam-using equipment with high efficiency.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments will be described with reference to the drawings. The components of the embodiments described below can be combined as appropriate. Also, there may be cases where some components are not used.

[0017] [First Embodiment] The first embodiment will be described.

[0018] <Configuration> FIG. 1 is a schematic diagram showing the equipment configuration of the steam generator 100 according to the first embodiment. FIG. 2 is a block diagram showing the control system of the steam generator 100 according to the first embodiment. As shown in FIGS. 1 and 2, the steam generator 100 includes a controller 190, a heat pump 200, a first steam supply line 102, a steam-water separator 101, a second steam supply line 105, a makeup water line 9, a water supply pump 6, a hardness component removal device 110, a flow control valve 7, a capacity control valve 106, a steam pressure sensor 107, a water level sensor 8, a steam compressor 10, a heat exchanger 20, a cooling water line 80, a flow regulator 30, an inlet temperature sensor 60, an inlet pressure sensor 70, a return line 109, a pressure reducing valve 40, a steam transport line 90, and an air supply control valve 50.

[0019] The controller 190 includes a computer system. The controller 190 controls the operation of the steam generator 100.

[0020] The heat pump 200 has a vapor compression type heat pump circuit and heats makeup water to generate steam. In this embodiment, the heat pump 200 is an air source heat pump. The heat pump 200 uses outside air as a heat source fluid.

[0021] The heat pump 200 includes a refrigerant compressor 2, a refrigerant condenser 3, a refrigerant expansion valve 4, and a refrigerant evaporator 5. The refrigerant compressor 2, the refrigerant condenser 3, the refrigerant expansion valve 4, and the refrigerant evaporator 5 are annularly connected by a refrigerant circulation flow path 1. The refrigerant circulates through the refrigerant circulation flow path 1 including the refrigerant compressor 2, the refrigerant condenser 3, the refrigerant expansion valve 4, and the refrigerant evaporator 5. The refrigerant flows through the refrigerant compressor 2, the refrigerant condenser 3, the refrigerant expansion valve 4, and the refrigerant evaporator 5 in this order in the refrigerant circulation flow path 1. The heat pump 200 generates steam in the refrigerant condenser 3 by driving the refrigerant compressor 2.

[0022] The refrigerant compressor 2 is a device that compresses gaseous refrigerant by a compression mechanism such as a centrifugal type, scroll type, rotary type, screw type, etc. Gaseous refrigerant is supplied to the refrigerant compressor 2. The refrigerant compressor 2 compresses the gaseous refrigerant to generate high-temperature and high-pressure gaseous refrigerant. The refrigerant compressor 2 is driven by an electric motor 191. The driving frequency (i.e., the rotational speed) of the electric motor 191 is controlled by a controller 190 via an inverter device (not shown). When the refrigerant compressor 2 is driven, the gaseous refrigerant is compressed, and the high-temperature and high-pressure gaseous refrigerant is supplied to the refrigerant condenser 3.

[0023] The refrigerant condenser 3 is a device that condenses the gaseous refrigerant from the refrigerant compressor 2. The gaseous refrigerant is condensed in the refrigerant condenser 3 to release heat, thereby heating the makeup water supplied to the refrigerant condenser 3. The refrigerant condenser 3 heats the makeup water by heat exchange between the high-temperature fluid, the gaseous refrigerant, and the low-temperature fluid, the makeup water, to generate steam. The gaseous refrigerant liquefies into a liquid refrigerant state by releasing heat in the refrigerant condenser 3. In the present embodiment, a plate type heat exchanger or a shell and tube type heat exchanger is used as the refrigerant condenser 3.

[0024] The refrigerant expansion valve 4 is a device that reduces the pressure of the liquid refrigerant from the refrigerant condenser 3. The refrigerant expansion valve 4 reduces the pressure of the liquid refrigerant from the refrigerant condenser 3.

[0025] The refrigerant evaporator 5 is a device that evaporates the liquid refrigerant from the refrigerant expansion valve 4. Outside air is supplied as a heat source fluid to the heat transfer surface of the refrigerant evaporator 5. The liquid refrigerant absorbs heat by evaporating in the refrigerant evaporator 5, thereby taking heat from the outside air. The liquid refrigerant vaporizes into a gaseous refrigerant state by absorbing heat in the refrigerant evaporator 5.

[0026] The steam-water separator 101 is a device that separates the moisture contained in the steam (wet steam or steam-water two-phase flow) sent from the refrigerant condenser 3 to obtain dry steam. The steam generated in the refrigerant condenser 3 is supplied to the steam-water separator 101 via the first supply steam line 102. Note that depending on the position of the steam-water interface in the refrigerant condenser 3, the dry steam obtained by the steam-water separator 101 may be saturated steam or superheated steam. Also, when the steam-using equipment has a steam separator, the steam-water separator 101 can be omitted.

[0027] The water separated from the dry steam in the steam-water separator 101 is stored in the steam-water separator 101. The bottom of the steam-water separator 101 is connected to the makeup water line 9 via the precipitation line 103. A check valve 108 is provided in the precipitation line 103 to restrict the inflow of makeup water from the makeup water line 9 into the steam-water separator 101.

[0028] The second supply steam line 105 connects the steam-water separator 101 and the steam compressor 10. The dry steam from which moisture has been separated in the steam-water separator 101 is supplied to the steam compressor 10 via the second supply steam line 105. The dry steam from the steam-water separator 101 to the steam compressor 10 flows through the second supply steam line 105.

[0029] The makeup water line 9 is connected to the water supply port of the refrigerant condenser 3. Makeup water is supplied to the refrigerant condenser 3 via the makeup water line 9. The makeup water to the refrigerant condenser 3 flows through the makeup water line 9 but does not flow into the steam-water separator 101 due to the presence of the check valve 108.

[0030] The water supply pump 6 is arranged in the makeup water line 9. The water supply pump 6 operates to supply makeup water to the refrigerant condenser 3 via the makeup water line 9. The water supply pump 6 may be a variable-capacity pump or a fixed-capacity pump.

[0031] The hardness component removal device 110 is a facility for removing hardness components (calcium ions and magnesium ions) from makeup water. As the hardness component removal device 110, a water softening device or a reverse osmosis membrane device is exemplified. The hardness component removal device 110 is provided in the makeup water line 9. The hardness component removal device 110 is arranged on the downstream side of the feed water pump 6. The softened water from which the hardness components have been removed by the hardness component removal device 110 is supplied to the refrigerant condenser 3.

[0032] The flow control valve 7 is provided in the makeup water line 9. The flow control valve 7 adjusts the flow rate of the makeup water supplied to the refrigerant condenser 3. The flow control valve 7 is a proportional control valve. The controller 190 can adjust the opening degree of the flow control valve 7 in the range of 0% to 100%.

[0033] The internal pressures of the refrigerant condenser 3 and the gas-liquid separator 101 are adjusted by the operation of the vapor compressor 10 and the operation of the capacity control valve 106. When the flow control valve 7 is opened in this state, the makeup water in the makeup water line 9 is automatically supplied to the refrigerant condenser 3. When the discharge pressure of the feed water pump 6 is high, the flow rate of the makeup water supplied to the refrigerant condenser 3 becomes too large. When the discharge pressure of the feed water pump 6 is high, the controller 190 can control to reduce the flow rate of the makeup water supplied to the refrigerant condenser 3 by reducing the opening degree of the flow control valve 7.

[0034] The capacity control valve 106 is provided in the second steam supply line 105. The capacity control valve 106 adjusts the pressure in the refrigerant condenser 3 and the gas-liquid separator 101 (that is, the suction pressure of the vapor compressor 10). The capacity control valve 106 is a proportional control valve. The controller 190 can adjust the opening degree of the capacity control valve 106 in the range of 0% to 100%.

[0035] The steam pressure sensor 107 detects the pressure of the steam generated in the refrigerant condenser 3. The steam pressure sensor 107 is arranged at the upper part (vapor phase part) of the gas-liquid separator 101 communicating with the refrigerant condenser 3. The detected pressure of the steam pressure sensor 107 is transmitted to the controller 190.

[0036] The refrigerant condenser 3 and the gas-liquid separator 101 are communicated via a part of the first supply steam line 102, the precipitation line 103, and the makeup water line 9. Thereby, the height of the water surface WS of the separated water stored in the gas-liquid separator 101 is approximately the same as the gas-liquid interface in the refrigerant condenser 3. Also, the height of the water surface WS is set to be lower than the steam outlet position of the refrigerant condenser 3.

[0037] The water level sensor 8 detects the water level in the gas-liquid separator 101. The water level in the gas-liquid separator 101 refers to the height of the water surface WS of the separated water stored in the gas-liquid separator 101. A water level detection cylinder 104 is connected to the gas-liquid separator 101. The water level detection cylinder 104 is arranged on the side of the gas-liquid separator 101. The upper part of the water level detection cylinder 104 communicates with the gas phase part of the gas-liquid separator 101. The lower part of the water level detection cylinder 104 communicates with the liquid phase part. The water level sensor 8 is inserted into the water level detection cylinder 104. As described above, the height of the water surface WS is approximately the same as the height of the gas-liquid interface in the refrigerant condenser 3. By detecting the water level in the water level detection cylinder 104, the water level sensor 8 can indirectly detect the gas-liquid interface in the refrigerant condenser 3. The water level sensor 8 is a capacitance type sensor and can continuously detect the water level of the gas-liquid separator 101. The detected water level of the water level sensor 8 is transmitted to the controller 190.

[0038] The steam compressor 10 is a device that compresses the dry steam sent from the gas-liquid separator 101 to generate superheated steam. The steam compressor 10 is driven by an electric motor 192. The driving frequency (i.e., the rotational speed) of the electric motor 192 is controlled by the controller 190 via an inverter device (not shown). When the steam compressor 10 is driven, the dry steam sent from the gas-liquid separator 101 is compressed to generate superheated steam.

[0039] The vapor compressor 10 includes a multi-stage vapor compressor 10. In this embodiment, the vapor compressor 10 is provided in four stages. The vapor compressor 10 includes a first-stage first vapor compressor 11, a second-stage second vapor compressor 12, a third-stage third vapor compressor 13, and a fourth-stage fourth vapor compressor 14. For the vapor compressor 10, a centrifugal compressor or a screw compressor, for example, is preferably used.

[0040] The heat exchanger 20 cools the superheated vapor discharged from the vapor compressor 10 with a cooling medium to generate saturated vapor.

[0041] The heat exchanger 20 includes a plurality of heat exchangers 20 that respectively cool the superheated vapor discharged from each stage of the vapor compressor 10 with a cooling medium. In this embodiment, the heat exchanger 20 includes four heat exchangers 20. The heat exchanger 20 includes a first heat exchanger 21 that cools the superheated vapor discharged from the first vapor compressor 11 with a cooling medium, a second heat exchanger 22 that cools the superheated vapor discharged from the second vapor compressor 12 with a cooling medium, a third heat exchanger 23 that cools the superheated vapor discharged from the third vapor compressor 13 with a cooling medium, and a fourth heat exchanger 24 that cools the superheated vapor discharged from the fourth vapor compressor 14 with a cooling medium.

[0042] At least a part of the saturated vapor generated in the first heat exchanger 21 is supplied to the second vapor compressor 12. At least a part of the saturated vapor generated in the second heat exchanger 22 is supplied to the third vapor compressor 13. At least a part of the saturated vapor generated in the third heat exchanger 23 is supplied to the fourth vapor compressor 14.

[0043] The cooling water line 80 connects the makeup water line 9 and the heat exchanger 20. A part of the makeup water flowing through the makeup water line 9 flows into the cooling water line 80 as a cooling medium. The cooling medium flowing through the cooling water line 80 is supplied to the heat exchanger 20.

[0044] The flow regulator 30 is a device that adjusts the flow rate of the cooling medium supplied to the heat exchanger 20, and is provided in the cooling water line 80. The flow regulator 30 is controlled by the controller 190. The cooling medium supplied to the heat exchanger 20 is the make-up water discharged from the water supply pump 6. In the following description, the cooling medium supplied to the heat exchanger 20 is appropriately referred to as "cooling water".

[0045] The cooling water line 80 includes a first cooling water line 81 that connects the first heat exchanger 21 and the make-up water line 9, a second cooling water line 82 that connects the second heat exchanger 22 and the make-up water line 9, a third cooling water line 83 that connects the third heat exchanger 23 and the make-up water line 9, and a fourth cooling water line 84 that connects the fourth heat exchanger 24 and the make-up water line 9.

[0046] The flow regulator 30 includes a first flow regulator 31 provided in the first cooling water line 81, a second flow regulator 32 provided in the second cooling water line 82, a third flow regulator 33 provided in the third cooling water line 83, and a fourth flow regulator 34 provided in the fourth cooling water line 84. The first flow regulator 31 adjusts the flow rate of the cooling water supplied to the first heat exchanger 21. The second flow regulator 32 adjusts the flow rate of the cooling water supplied to the second heat exchanger 22. The third flow regulator 33 adjusts the flow rate of the cooling water supplied to the third heat exchanger 23. The fourth flow regulator 34 adjusts the flow rate of the cooling water supplied to the fourth heat exchanger 24.

[0047] The heat exchanger 20 may be a direct heat exchanger or an indirect heat exchanger. In this embodiment, the heat exchanger 20 is a direct heat exchanger (gas-liquid contact tower) between superheated steam and cooling water. Inside the tower of the heat exchanger 20, a nozzle 111 is arranged. The nozzle 111 is connected to the cooling water line 80. Supplying cooling water to the heat exchanger 20 includes supplying cooling water to the nozzle 111. The nozzle 111 is a spray nozzle that sprays the cooling water supplied from the cooling water line 80 into the interior of the heat exchanger 20. In this embodiment, the nozzle 111 is arranged to spray the cooling water upward, but it may also be arranged to spray the cooling water downward.

[0048] When the heat exchanger 20 is a direct heat exchanger, the specific equipment used for the flow rate regulator 30 is selected based on the discharge pressure of the feed water pump 6 and the pressure of the superheated steam flowing into the heat exchanger 20. When the discharge pressure of the feed water pump 6 is higher than the pressure of the superheated steam flowing into the heat exchanger 20, a flow rate control valve is used as the flow rate regulator 30 to adjust the flow rate of the cooling water supplied from the nozzle 111 into the heat exchanger 20. When the discharge pressure of the feed water pump 6 is lower than the pressure of the superheated steam flowing into the heat exchanger 20, a booster pump is used as the flow rate regulator 30 to adjust the flow rate of the cooling water supplied from the nozzle 111 into the heat exchanger 20.

[0049] Inside the heat exchanger 20, the superheated steam discharged from the vapor compressor 10 comes into contact with the cooling water sprayed from the nozzle 111. The superheated steam discharged from the vapor compressor 10 is cooled by coming into contact with the cooling water sprayed from the nozzle 111 and returns to the state of saturated steam. On the other hand, the cooling water sprayed from the nozzle 111 is vaporized by coming into contact with the superheated steam discharged from the vapor compressor 10 and becomes saturated steam. In the following description, the saturated steam generated from the cooling water sprayed from the nozzle 111 is appropriately referred to as "additional steam".

[0050] The saturated steam generated in the heat exchanger 20 is the sum of at least a part of the steam generated in the refrigerant condenser 3 and the steam generated from the cooling water sprayed from the nozzle 111. The total amount of saturated steam obtained in the heat exchanger 20 is larger than the amount of dry steam obtained in the moisture separator 101. The additional steam generated in the heat exchanger 20 is added to the dry steam separated in the moisture separator 101.

[0051] The nozzle 111 is disposed inside each of the first heat exchanger 21, the second heat exchanger 22, the third heat exchanger 23, and the fourth heat exchanger 24. The nozzle 111 disposed inside the first heat exchanger 21 is connected to the first cooling water line 81. The nozzle 111 disposed inside the second heat exchanger 22 is connected to the second cooling water line 82. The nozzle 111 disposed inside the third heat exchanger 23 is connected to the third cooling water line 83. The nozzle 111 disposed inside the fourth heat exchanger 24 is connected to the fourth cooling water line 84. In each of the first heat exchanger 21, the second heat exchanger 22, the third heat exchanger 23, and the fourth heat exchanger 24, additional steam is generated from the cooling water. In each of the first heat exchanger 21, the second heat exchanger 22, the third heat exchanger 23, and the fourth heat exchanger 24, the additional steam is sequentially superposed on the dry steam generated in the gas-liquid separator 101.

[0052] The inlet temperature sensor 60 detects the inlet steam temperature of the heat exchanger 20. The inlet temperature sensor 60 includes a first inlet temperature sensor 61 that detects the inlet steam temperature of the first heat exchanger 21, a second inlet temperature sensor 62 that detects the inlet steam temperature of the second heat exchanger 22, a third inlet temperature sensor 63 that detects the inlet steam temperature of the third heat exchanger 23, and a fourth inlet temperature sensor 64 that detects the inlet steam temperature of the fourth heat exchanger 24. The detected temperature of the inlet temperature sensor 60 is transmitted to the controller 190.

[0053] The inlet pressure sensor 70 detects the inlet steam pressure of the heat exchanger 20. The inlet pressure sensor 70 includes a first inlet pressure sensor 71 that detects the inlet steam pressure of the first heat exchanger 21, a second inlet pressure sensor 72 that detects the inlet steam pressure of the second heat exchanger 22, a third inlet pressure sensor 73 that detects the inlet steam pressure of the third heat exchanger 23, and a fourth inlet pressure sensor 74 that detects the inlet steam pressure of the fourth heat exchanger 24. The detected temperature of the inlet pressure sensor 70 is transmitted to the controller 190.

[0054] The return line 109 has its starting end connected to the lower part of the heat exchanger 20. The return line 109 has its ending end connected to the makeup water line 9. The return line 109 returns the residual part of the cooling water supplied into the heat exchanger 20 from the cooling water line 80, which has not vaporized, to the makeup water line 9 as a part of the makeup water.

[0055] The pressure reducing valve 40 reduces the pressure of the cooling water flowing through the return line 109. The pressure reducing valve 40 includes a first pressure reducing valve 41 disposed between the first heat exchanger 21 and the return line 109, a second pressure reducing valve 42 disposed between the second heat exchanger 22 and the return line 109, a third pressure reducing valve 43 disposed between the third heat exchanger 23 and the return line 109, and a fourth pressure reducing valve 44 disposed between the fourth heat exchanger 24 and the return line 109. By the pressure reducing valve 40, the cooling water extruded from the heat exchanger 20 at the vapor pressure is depressurized, preventing the saturated vapor from leaking into the feed water together with the cooling water.

[0056] The steam transport line 90 is connected to the upper part of the heat exchanger 20. At least a part of the saturated steam generated in the heat exchanger 20 is sent to a steam header (not shown) after flowing through the steam transport line 90. The steam header is a pressure vessel that receives the saturated steam generated by the heat exchanger 20 and distributes this saturated steam to a plurality of steam-using devices. The steam transport line 90 includes a first steam transport line 91 connected to the upper part of the first heat exchanger 21, a second steam transport line 92 connected to the upper part of the second heat exchanger 22, a third steam transport line 93 connected to the upper part of the third heat exchanger 23, and a fourth steam transport line 94 connected to the upper part of the fourth heat exchanger 24. The steam header includes a first steam header that receives the saturated steam from the first steam transport line 91, a second steam header that receives the saturated steam from the second steam transport line 92, a third steam header that receives the saturated steam from the third steam transport line 93, and a fourth steam header that receives the saturated steam from the fourth steam transport line 94.

[0057] The second steam header has a second header pressure sensor for detecting the internal pressure. The third steam header has a third header pressure sensor for detecting the internal pressure. The fourth steam header has a fourth header pressure sensor for detecting the internal pressure. The detected pressures of the respective header pressure sensors are transmitted to the controller 190.

[0058] At least a part of the saturated steam generated in the first heat exchanger 21 flows into the first steam header while flowing through the first steam transport line 91. At least a part of the saturated steam generated in the second heat exchanger 22 flows into the second steam header while flowing through the second steam transport line 92. At least a part of the saturated steam generated in the third heat exchanger 23 flows into the third steam header while flowing through the third steam transport line 93. At least a part of the saturated steam generated in the fourth heat exchanger 24 flows into the fourth steam header while flowing through the fourth steam transport line 94.

[0059] The pressure of the saturated steam generated in a certain heat exchanger 20 is higher than the pressure of the saturated steam generated in the heat exchanger 20 upstream of that heat exchanger 20. That is, the pressure of the saturated steam generated in the second heat exchanger 22 is higher than the pressure of the saturated steam generated in the first heat exchanger 21. The pressure of the saturated steam generated in the third heat exchanger 23 is higher than the pressure of the saturated steam generated in the second heat exchanger 22. The pressure of the saturated steam generated in the fourth heat exchanger 24 is higher than the pressure of the saturated steam generated in the third heat exchanger 23.

[0060] The saturated vapor temperature is determined by the vapor pressure. Therefore, the temperature of the saturated vapor generated in a certain heat exchanger 20 is higher than the temperature of the saturated vapor generated in the heat exchanger 20 on the upstream side of that heat exchanger 20. That is, the temperature of the saturated vapor generated in the second heat exchanger 22 is higher than the temperature of the saturated vapor generated in the first heat exchanger 21. The temperature of the saturated vapor generated in the third heat exchanger 23 is higher than the temperature of the saturated vapor generated in the second heat exchanger 22. The temperature of the saturated vapor generated in the fourth heat exchanger 24 is higher than the temperature of the saturated vapor generated in the third heat exchanger 23.

[0061] The saturated vapor flowing into the first steam header is supplied to the first steam-using device through the steam distribution pipe. The saturated vapor flowing into the second steam header is supplied to the second steam-using device through the steam distribution pipe. The saturated vapor flowing into the third steam header is supplied to the third steam-using device through the steam distribution pipe. The saturated vapor flowing into the fourth steam header is supplied to the fourth steam-using device through the steam distribution pipe. Each of the first steam-using device, the second steam-using device, the third steam-using device, and the fourth steam-using device may be composed of a plurality of steam-using devices.

[0062] The air supply control valve 50 is provided in the steam transport line 90. The air supply control valve 50 controls the flow rate of the saturated vapor flowing out through the steam transport line 90. The air supply control valve 50 includes a first air supply control valve 51 provided in the first steam transport line 91, a second air supply control valve 52 provided in the second steam transport line 92, a third air supply control valve 53 provided in the third steam transport line 93, and a fourth air supply control valve 54 provided in the fourth steam transport line 94.

[0063] <Steam Pressure Control> In a state where the first vapor compressor 11 is operating (for example, in a state where the electric motor 192 is operating at a predetermined rotational speed), the controller 190 adjusts the opening degree of the capacity control valve 106 so that the detected pressure of the vapor pressure sensor 107 becomes the target vapor pressure. The target vapor pressure may be equal to or higher than the atmospheric pressure, or may be less than the atmospheric pressure. For example, when the heat pump 200 is multi-mode or multi-stage, the compression ratio of the refrigerant compressor 2 is increased, or a refrigerant resistant to thermal decomposition is selected, the target vapor pressure can be set to be equal to or higher than the atmospheric pressure. Also, when the heat pump 200 is single-stage and the heat drop between the heat source fluid and the vapor cannot be made large, the target vapor pressure can also be set to be equal to or higher than the atmospheric pressure. By controlling the pressures in the refrigerant condenser 3 and the gas-liquid separator 101, make-up water boils at the boiling point corresponding to the pressure in the refrigerant condenser 3, generating vapor (wet vapor or gas-water two-phase flow).

[0064] The target vapor pressure in vapor pressure control is preferably set based on the temperature of the heat source fluid used in the heat pump 200. For example, when the outside air temperature is low, such as in winter or at night, the target vapor pressure is set relatively low, and when the outside air temperature is high, such as in summer or during the day, the target vapor pressure is set relatively high, thereby adjusting the boiling point of the make-up water according to the temperature of the heat source fluid. As a result, it becomes possible to operate the heat pump 200 with a good COP throughout the year.

[0065] <Water level control> The controller 190 adjusts the opening degree of the flow control valve 7 so that the detected water level of the water level sensor 8 falls within the target range. The target range is a water level at which the height of the water surface WS in the gas-liquid separator 101 is lower than the vapor outlet position of the refrigerant condenser 3 and excessive superheat does not occur on the heat transfer surface of the refrigerant condenser 3. When the water level is too high, that is, when the height of the water surface WS in the gas-liquid separator 101 exceeds the vapor outlet position of the refrigerant condenser 3, only the vapor corresponding to the amount of flash of the warm water generated in the refrigerant condenser 3 in the gas-liquid separator 101 can be obtained, so the generated vapor amount extremely decreases. Also, when the water level is too low, that is, when the height of the water surface WS in the gas-liquid separator 101 is significantly lower than the vapor outlet position of the refrigerant condenser 3, superheat occurs on the heat transfer surface above the gas-liquid interface, and the heat amount of the superheat does not contribute to water evaporation, so as a result, the generated vapor amount decreases. Therefore, the controller 190 controls the flow rate of the makeup water supplied to the refrigerant condenser 3 via the makeup water line 9 so that the detected water level of the water level sensor 8 falls within the target range.

[0066] <Cooling water flow control> The controller 190 obtains the saturation temperature from the detected pressure of the inlet pressure sensor 70 and calculates the superheat degree of the vapor flowing into the heat exchanger 20 by subtracting the saturation temperature from the detected temperature of the inlet temperature sensor 60. The controller 190 controls the flow regulator 30 based on the calculated superheat degree. The controller 190 controls the flow regulator 30 so that saturated vapor with a superheat degree of almost zero is generated from the superheated vapor supplied from the vapor compressor 10 to the heat exchanger 20 based on the calculated superheat degree. The controller 190 controls the flow regulator 30 so that the cooling water with a flow rate that eliminates the superheat degree of the superheated vapor is sprayed from the nozzle 111. The higher the flow rate of the cooling water supplied from the nozzle 111 to the inside of the heat exchanger 20, the lower the superheat degree of the superheated vapor.

[0067] In addition, when the steam supplied from the heat exchanger 20 to the steam compressor 10 is wet steam, the inside of the steam compressor 10 may be damaged due to erosion by moisture or the like. When the steam supplied from the heat exchanger 20 to the steam compressor 10 is dry steam, damage to the steam compressor 10 is avoided. Therefore, the controller 190 may control the flow regulator 30 based on the calculated degree of superheat so that the steam supplied from the heat exchanger 20 to the steam compressor 10 becomes superheated steam at a temperature slightly higher than the saturation temperature (for example, about 1 to 5 °C).

[0068] <Output Control of Refrigerant Compressor> During the operation of the heat pump 200, the controller 190 may fix the rotation speed of the refrigerant compressor 2 (the rotation speed of the electric motor 191), or may vary the rotation speed. For example, a refrigerant pressure sensor for detecting the pressure of the refrigerant gas discharged from the refrigerant compressor 2 is provided, and the controller 190 adjusts the rotation speed of the refrigerant condenser 3 so that the detected pressure of the refrigerant pressure sensor becomes the target refrigerant pressure. Alternatively, a refrigerant temperature sensor for detecting the temperature of the refrigerant gas discharged from the refrigerant compressor 2 is provided, and the controller 190 adjusts the rotation speed of the refrigerant compressor 2 so that the detected temperature of the refrigerant temperature sensor becomes the target refrigerant temperature. By adopting such output control, the amount of heat given from the refrigerant gas to the make-up water becomes almost constant, so the amount of steam generation in the refrigerant condenser 3 is stabilized.

[0069] <Discharge Pressure Control of Steam Compressor> During the operation of the second and subsequent second steam compressor 12, third steam compressor 13, and fourth steam compressor 14, the controller 190 controls the discharge pressure of each steam compressor 12, 13, 14. Specifically, the controller 190 controls the rotational speed (rotational speed of the electric motor 192) of the second steam compressor 12, which is the source of the detected steam, so that the detected pressure of the second header pressure sensor becomes the second target header pressure. The controller 190 controls the rotational speed (rotational speed of the electric motor 192) of the third steam compressor 13, which is the source of the detected steam, so that the detected pressure of the third header pressure sensor becomes the third target header pressure. The controller 190 controls the rotational speed (rotational speed of the electric motor 192) of the fourth steam compressor 14, which is the source of the detected steam, so that the detected pressure of the fourth header pressure sensor becomes the fourth target header pressure. The third target header pressure is higher than the second target header pressure, and the fourth target header pressure is higher than the third target header pressure. By this control, the steam supply amount can be made to follow the steam consumption amount in the steam-using equipment. Note that when increasing the steam supply amount from the heat exchangers 22, 23, 24 to each steam header, the steam pressure in the refrigerant condenser 3 decreases, so the steam generation amount in the refrigerant condenser 3 is increased by the above-described steam pressure control and water level control.

[0070] <Control of the number of operating steam compressors> As described above, when it is possible to make the heat pump 200 multi-source or multi-stage, increase the compression ratio of the refrigerant compressor 2, or select a refrigerant resistant to thermal decomposition, the target steam pressure in the steam pressure control can be set to be equal to or higher than the atmospheric pressure. Also, as described above, when the temperature of the heat source fluid used in the heat pump 200 is high, the target steam pressure in the steam pressure control can be increased. Therefore, it may be possible to generate steam at the pressure required on the steam-using equipment side without operating all four steam compressors 11 to 14. Therefore, the number of operating units of the multi-stage steam compressor 10 may be set based on the target steam pressure.

[0071] <Function> FIG. 3 is a Mollier diagram of water for explaining the operation of the steam generator 100 according to the first embodiment.

[0072] In FIG. 3, the feed water a1 indicates the makeup water supplied to the refrigerant condenser 3. The temperature of the makeup water a1 is about 20°C. Also, the makeup water a1 flows into the refrigerant condenser 3 at a pressure lower than the atmospheric pressure due to the operation of the first steam compressor 11. The makeup water a1 heated by the heat pump 200 undergoes flashing boiling in the refrigerant condenser 3 and becomes saturated vapor b1.

[0073] The saturated vapor b1 sent out from the refrigerant condenser 3 is compressed by the first steam compressor 11 and becomes superheated vapor c1. In the case of an ideal reversible process, the saturated vapor b1 is compressed along the isentropic line in the first steam compressor 11. The superheated vapor c1 discharged from the first steam compressor 11 exchanges heat with the cooling water in the first heat exchanger 21 and becomes saturated vapor b2.

[0074] The saturated vapor b2 sent out from the first heat exchanger 21 is compressed by the second steam compressor 12 and becomes superheated vapor c2. The superheated vapor c2 discharged from the second steam compressor 12 exchanges heat with the cooling water in the second heat exchanger 22 and becomes saturated vapor b3.

[0075] The saturated vapor b3 sent out from the second heat exchanger 22 is compressed by the third steam compressor 13 and becomes superheated vapor c3. The superheated vapor c3 discharged from the third steam compressor 13 exchanges heat with the cooling water in the third heat exchanger 23 and becomes saturated vapor b4.

[0076] The saturated vapor b4 sent out from the third heat exchanger 23 is compressed by the fourth steam compressor 14 and becomes superheated vapor c4. The superheated vapor c4 discharged from the fourth steam compressor 14 exchanges heat with the cooling water in the fourth heat exchanger 24 and becomes saturated vapor b5.

[0077] The number of stages of the multi-stage vapor compression machine 10 is set such that saturated vapor at a pressure equal to or higher than atmospheric pressure is generated in at least the heat exchanger 20 located on the most downstream side. In the present embodiment, the number of stages of the vapor compression machine 10 is set to four so that saturated vapor at a pressure equal to or higher than atmospheric pressure is generated in at least the fourth heat exchanger 24 located on the most downstream side.

[0078] As described above, the pressure of the saturated vapor generated in a certain heat exchanger 20 is higher than the pressure of the saturated vapor generated in the heat exchanger 20 upstream of that heat exchanger 20. The temperature of the saturated vapor generated in a certain heat exchanger 20 is higher than the temperature of the saturated vapor generated in the heat exchanger 20 upstream of that heat exchanger 20.

[0079] Focusing on the vapor pressure when the vapor compression machine 10 is operated under predetermined pressure boosting conditions, as an example, the pressure of saturated vapor b1 is 0.01 MPa, the pressure of saturated vapor b2 is 0.03 MPa, the pressure of saturated vapor b3 is 0.1 MPa, the pressure of saturated vapor b4 is 0.3 MPa, and the pressure of saturated vapor b5 is 0.8 MPa.

[0080] Similarly, focusing on the vapor temperature, as an example, the temperature of saturated vapor b1 is 45.8 °C, the temperature of saturated vapor b2 is 69.1 °C, the temperature of saturated vapor b3 is 99.6 °C, the temperature of saturated vapor b4 is 133.5 °C, and the temperature of saturated vapor b5 is 170.4 °C.

[0081] The first-stage first vapor compressor 11 functions as a vacuum pump. By the operation of the first vapor compressor 11, the boiling point of the makeup water is lowered. In the present embodiment, since the vapor compression machine 10 is arranged in multiple stages, the temperature of the vapor can be increased to a level that can be utilized by the vapor-using equipment.

[0082] In this embodiment, the controller 190 obtains the saturation temperature from the detected pressure of the first inlet pressure sensor 71, subtracts the saturation temperature from the detected temperature of the first inlet temperature sensor 61, and calculates the superheat degree of the steam flowing into the first heat exchanger 21. Then, based on the calculated superheat degree, the first flow regulator 31 is controlled so that the state changes from superheated steam c1 to saturated steam b2, and the flow rate of the cooling water sprayed from the nozzle 111 into the first heat exchanger 21 is controlled.

[0083] The controller 190 obtains the saturation temperature from the detected pressure of the second inlet pressure sensor 72, subtracts the saturation temperature from the detected temperature of the second inlet temperature sensor 62, and calculates the superheat degree of the steam flowing into the second heat exchanger 22. Then, based on the calculated superheat degree, the second flow regulator 32 is controlled so that the state changes from superheated steam c2 to saturated steam b3, and the flow rate of the cooling water sprayed from the nozzle 111 into the second heat exchanger 22 is controlled.

[0084] The controller 190 obtains the saturation temperature from the detected pressure of the third inlet pressure sensor 73, subtracts the saturation temperature from the detected temperature of the third inlet temperature sensor 63, and calculates the superheat degree of the steam flowing into the third heat exchanger 23. Then, based on the calculated superheat degree, the third flow regulator 33 is controlled so that the state changes from superheated steam c3 to saturated steam b4, and the flow rate of the cooling water sprayed from the nozzle 111 into the third heat exchanger 23 is controlled.

[0085] The controller 190 obtains the saturation temperature from the detected pressure of the fourth inlet pressure sensor 74, subtracts the saturation temperature from the detected temperature of the fourth inlet temperature sensor 64, and calculates the superheat degree of the steam flowing into the fourth heat exchanger 24. Then, based on the calculated superheat degree, the fourth flow regulator 34 is controlled so that the state changes from superheated steam c4 to saturated steam b5, and the flow rate of the cooling water sprayed from the nozzle 111 into the fourth heat exchanger 24 is controlled.

[0086] The saturated vapor b2 is supplied to the first steam-using device via the first steam transport line 91. The saturated vapor b3 is supplied to the second steam-using device via the second steam transport line 92. The saturated vapor b4 is supplied to the third steam-using device via the third steam transport line 93. The saturated vapor b5 is supplied to the fourth steam-using device via the fourth steam transport line 94. When the steam generator 100 is used in a food factory, the saturated vapor b4 is used as, for example, the heat source of a steamer, and the saturated vapor b5 is used as, for example, the heat source of a fryer.

[0087] The line Lj shown in FIG. 3 shows an example in which the steam generated by utilizing the heat pumped up by the heat pump is compressed by the steam compressor to increase the pressure. When the low-pressure steam is compressed to rise to the operating pressure of a general steam boiler (about 0.8 MPa), even in the most efficient isentropic compression, as shown by the line Lj in FIG. 3, steam with a very high degree of superheat (that is, steam with excessive enthalpy) is generated. This means an increase in the electric power input to the steam compressor, which is not preferable from the viewpoint of energy saving. For example, it will be compressed from the state of the saturated vapor b1 to the state of the superheated steam c5. When the temperature of the saturated vapor b1 is 45.8 °C and the pressure of the saturated vapor b1 is 0.01 MPa, the temperature of the superheated steam c5 exceeds 600 °C, and the pressure of the superheated steam c5 exceeds 0.8 MPa. That is, generating such superheated steam c5 requires the steam compressor to operate at a high compression ratio and requires materials with high heat resistance, which is not practical.

[0088] <Effect> As described above, according to the present embodiment, for example, high-pressure saturated steam with a steam pressure of about 0.8 MPa (about 170 °C) can be efficiently generated and supplied. The meaning of "efficiently" is that the specific energy is lower compared to the case of generating high-pressure steam only by the heat pump cycle, and an operation with a higher coefficient of performance (COP) can be realized. Note that the specific energy in the present embodiment is the total power consumption of the entire device required to produce 1 m 3 / min of saturated steam in the state where the heat pump 200, the steam compressor 10, and the heat exchanger 20 are operating, and the unit is kW / (m3 is / min). Operating the heat exchanger 20 means operating the flow regulator 30 to supply cooling water to the heat exchanger 20.

[0089] The following reasons (Reason 1) to (Reason 3) can be cited as the reasons why steam can be generated efficiently. (Reason 1) The operation of depressurizing and boiling the makeup water in the refrigerant condenser 3 to generate low-pressure steam (e.g., 0.01 MPa) can take a smaller heat drop between the heat source fluid and the steam than when generating high-pressure steam (e.g., 0.8 MPa) in the refrigerant condenser 3. As a result, the coefficient of performance (COP) of the heat pump 200 is significantly improved. (Reason 2) The steam adiabatically compressed by the steam compressor 10 has superheat, but the amount of steam can be increased by using the sensible heat (compression heat) corresponding to the superheat to generate additional saturated steam. As a result, the power consumption required to produce saturated steam at the reference flow rate is reduced, and the specific energy of the entire device is significantly improved. (Reason 3) By connecting a plurality of steam compressors 10 in series and providing a heat exchanger 20 therebetween to cool the superheated steam to saturated steam before supplying it to the steam compressor 10, the specific volume of the suction steam can be reduced. As a result, the power consumption required for the adiabatic compression process is reduced, and the specific energy of the entire device is significantly improved.

[0090] In addition, since the intermediate-stage heat exchanger 20 among the multi-stage heat exchangers 20 is configured to be able to extract saturated steam, saturated steam at a lower pressure can also be extracted simultaneously, and saturated steam in different temperature ranges can be supplied simultaneously.

[0091] When the steam-using equipment does not require high-pressure saturated steam, the high-pressure-side steam compressor 10 may be stopped and only low-pressure saturated steam may be supplied. In this case, the steam generation device 100 can be operated under more efficient conditions.

[0092] The steam generator 100 according to the embodiment is an electric steam generator using a heat pump 200 and a steam compressor 10 as an alternative to the current combustion steam boiler (evaporation capacity in the range of 500 to 2000 kg / h). By using the heat pump 200 in a relatively low output temperature range, it is not necessary to develop a special high-pressure resistant heat pump, so hydrofluoroolefin or carbon dioxide can be selected as the refrigerant, and general-purpose products can be applied to the refrigerant compressor 2. If the steam compressor 10 is added in multiple stages, a considerable amount of high-pressure steam can also be generated.

[0093] [Second Embodiment] In the second embodiment, instead of the steam pressure control in the first embodiment, the following steam pressure control is executed. That is, with the first steam compressor 11 operating, the controller 190 adjusts the rotational speed of the first steam compressor 11 (the rotational speed of the electric motor 192) so that the detected pressure of the steam pressure sensor 107 becomes the target steam pressure. The target steam pressure is set in the same manner as in the first embodiment. Also by the steam pressure control according to the second embodiment, it is possible to boil the makeup water at the boiling point corresponding to the target steam pressure in the refrigerant condenser 3 and stably generate steam.

[0094] [Third Embodiment] In the third embodiment, instead of the steam pressure control in the first embodiment, the following steam pressure control is executed. That is, with the first steam compressor 11 operating, the controller 190 adjusts the rotational speed of the refrigerant compressor 2 (the rotational speed of the electric motor 191) so that the detected pressure of the steam pressure sensor 107 becomes the target steam pressure. The target steam pressure is set in the same manner as in the first embodiment. Also by the steam pressure control according to the third embodiment, it is possible to boil the makeup water at the boiling point corresponding to the target steam pressure in the refrigerant condenser 3 and stably generate steam.

[0095] [Fourth Embodiment] In the vapor pressure control of the fourth embodiment, the target vapor pressure is set based on the specific energy in the state where the heat pump 200, the vapor compressor 10, and the heat exchanger 20 are operating (i.e., the state where the vapor generator 100 is operating). Specifically, the target vapor pressure is set such that the specific energy in the state where the vapor generator 100 is operating becomes the lowest. For example, taking the target vapor pressure as the first variable and various operating conditions of the heat pump 200, the vapor compressor 10, and the heat exchanger 20 as the second variable to the nth variable, a table is created by experimentally obtaining the change in specific energy, and the target vapor pressure is set using this table.

[0096] [Fifth Embodiment] In the fifth embodiment, instead of the cooling water flow rate control of the first embodiment, the cooling water flow rate control is executed according to the following configuration and procedure. In this control, an outlet temperature sensor (not shown) that detects the outlet vapor temperature of the heat exchanger 20 is used instead of the aforementioned inlet temperature sensor 60. Then, the controller 190 obtains the saturation temperature from the detected pressure of the inlet pressure sensor 70, and controls the flow rate regulator 30 so that the detected temperature of the outlet temperature sensor (i.e., the vapor temperature after cooling) becomes the saturation temperature or a predetermined temperature (for example, a temperature about 1 to 5 °C higher) higher than the saturation temperature. Thereby, additional vapor is generated using the amount of heat corresponding to the superheat degree of the superheated vapor flowing into the heat exchanger 20.

[0097] The control of each stage will be described. The controller 190 obtains the saturation temperature from the detected pressure of the first inlet pressure sensor 71, and controls the first flow regulator 31 so that the detected temperature of the first outlet temperature sensor provided for the first heat exchanger 21 becomes the saturation temperature (or a predetermined temperature higher than the saturation temperature). The controller 190 obtains the saturation temperature from the detected pressure of the second inlet pressure sensor 72, and controls the second flow regulator 32 so that the detected temperature of the second outlet temperature sensor provided for the second heat exchanger 22 becomes the saturation temperature (or a predetermined temperature higher than the saturation temperature). The controller 190 obtains the saturation temperature from the detected pressure of the third inlet pressure sensor 73, and controls the third flow regulator 33 so that the detected temperature of the third outlet temperature sensor provided for the third heat exchanger 23 becomes the saturation temperature (or a predetermined temperature higher than the saturation temperature). The controller 190 obtains the saturation temperature from the detected pressure of the fourth inlet pressure sensor 74, and controls the fourth flow regulator 34 so that the detected temperature of the fourth outlet temperature sensor provided for the fourth heat exchanger 24 becomes the saturation temperature (or a predetermined temperature higher than the saturation temperature).

[0098] [Sixth Embodiment] FIG. 4 is a schematic diagram showing the heat exchanger 20B according to the sixth embodiment. In the first embodiment, the heat exchanger 20 is a direct heat exchanger between superheated steam and cooling water. As shown in FIG. 4, the heat exchanger 20B is an indirect heat exchanger between superheated steam and cooling water. The indirect heat exchanger may be a shell-and-tube heat exchanger or a plate heat exchanger.

[0099] In the example shown in FIG. 4, the heat exchanger 20B has a shell 113 to which the superheated steam discharged from the steam compressor 10 is supplied, and tubes 112 disposed inside the shell 113. The cooling water from the makeup water line 9 is supplied to the tubes 112 via the cooling water line 80. The cooling water flowing in from the cooling water line 80 flows through the tubes 112. The cooling water flowing through the tubes 112 is heated by the superheated steam and discharged from the tubes 112 in a warm water state.

[0100] The warm water discharged from the tube 112 may be supplied to the refrigerant condenser 3 via the makeup water line 9. When the warm water from the tube 112 is supplied as makeup water to the refrigerant condenser 3, the heating amount of the heat pump 200 decreases, and the coefficient of performance (COP) of the steam generator 100 improves. Further, the warm water discharged from the tube 112 may be supplied to warm water utilization equipment. Examples of the warm water utilization equipment include warm water washing machines and warm water sterilizers in food factories.

[0101] When the heat exchanger 20B is an indirect heat exchanger, the cooling water can flow at the discharge pressure of the feed water pump 6. Therefore, a flow control valve (flow rate control valve) can be used as the flow regulator 30. Further, cooling air may be supplied to the tube 112 as a cooling medium for the indirect heat exchanger. When the superheated steam is cooled by the cooling air, the cooling air is heated by the sensible heat of the superheated steam and becomes high-temperature air. The high-temperature air may be supplied to high-temperature air utilization equipment. Examples of the high-temperature air utilization equipment include a dryer for drying articles.

[0102] [Seventh Embodiment] FIG. 5 is a schematic diagram showing a refrigerant condenser 3C according to the seventh embodiment. In the example shown in FIG. 5, the refrigerant condenser 3C is a shell-and-tube heat exchanger and includes a shell 130, a plurality of water pipes 131 (tubes), a lower header 132, and an upper header 133.

[0103] The plurality of water pipes 131 are arranged to extend vertically inside the shell 130. That is, the shell 130 surrounds the plurality of water pipes 131. The lower header 132 is a container that distributes makeup water to the plurality of water pipes 131. The lower ends of the plurality of water pipes 131 are connected to the lower header 132. The upper header 133 is a container that collects steam from the plurality of water pipes 131. The upper ends of the plurality of water pipes 131 are connected to the upper header 133. It can also be said that the refrigerant condenser 3C has a structure similar to that of a small cross-flow boiler.

[0104] The upper header 133 in this embodiment is configured to be higher in height than the lower header 132. Inside this upper header 133, a steam-water separation space 101C is formed. The steam-water separation space 101C is a space for separating the steam generated in the water pipe 131 and the can water (make-up water) pushed up along with the steam from the water pipe 131.

[0105] A make-up water line 140 is connected to the lower header 132. An inlet steam line 141 is connected to the upper part of the steam-water separation space 101C in the upper header 133. In the shell 130 surrounding the plurality of water pipes 131, a refrigerant line 150 for introducing gas refrigerant is connected at a position close to the upper header 133. In the shell 130, a refrigerant line 151 for discharging liquid refrigerant is connected at a position close to the lower header 132.

[0106] When the heat pump 200 is operated, the gas refrigerant from the refrigerant compressor 2 is introduced into the shell 130 through the refrigerant line 150 and flows in the shell 130 in a downward flow. The liquid refrigerant flowing out of the shell 130 is led to the refrigerant expansion valve 4 through the refrigerant line 151. The make-up water is supplied to the lower header 132 through the make-up water line 140 and flows in the water pipe 131 in an upward flow. The make-up water is heated by the refrigerant in the shell 130 while flowing through the water pipe 131 and becomes steam. The steam generated in the water pipe 131 is collected in the upper header 133 together with the can water pushed up along with the steam, and the moisture and steam are separated in the steam-water separation space 101C. The moisture separated in the steam-water separation space 101C is returned to the water pipe 131 again. The dry steam obtained in the steam-water separation space 101C is supplied to the steam compressor 10 through the inlet steam line 141.

[0107] The refrigerant condenser 3C according to this embodiment does not include the moisture separator 101 as an additional element as in the first embodiment because the upper header 133 as described above is used to separate gas and water. For such a refrigerant condenser 3C, the controller 190 performs water level control while balancing maintaining the steam at a desired dryness and preventing heat loss due to superheating of the steam. Specifically, by performing water level control so that the gas-liquid interface is located at a predetermined height in the water pipe 131, both maintaining the dryness and preventing heat loss are achieved. As a result, in the refrigerant condenser 3C, saturated steam with a high dryness can be efficiently obtained.

[0108] [Other Embodiments] In the above-described embodiment, the heat pump 200 is assumed to be an air-source heat pump. When the heat pump 200 is an air-source heat pump, the refrigerant circulating in the refrigerant circulation flow path 1 exchanges heat with the outdoor air in the refrigerant evaporator 5. The heat pump 200 may be a water-source heat pump. When the heat pump 200 is a water-source heat pump, the refrigerant circulating in the refrigerant circulation flow path 1 exchanges heat with at least one of the circulating cooling water returned to the cooling tower, the warm wastewater from the factory, the groundwater, and the river water in the refrigerant evaporator 5.

[0109] In the above-described first embodiment, the heat exchanger 20 that functions as a saturated steam generator does not necessarily need to be provided for each stage of the steam compressor 10, and the heat exchanger 20 may be provided on the downstream side of several steam compressors 10. Further, the heat exchanger 20 may not necessarily be an independent device and may be installed in the space inside the casing of the steam compressor 10.

[0110] [Contribution to the Sustainable Development Goals (SDGs) Led by the United Nations] The steam generation device according to the present disclosure can contribute to the achievement of Goal 13 "Take urgent action to combat climate change and its impacts" and Goal 7 "Ensure access to affordable, reliable, sustainable and modern energy for all" of the SDGs (Sustainable Development Goals).

Description of Reference Numerals

[0111] 1… Refrigerant circulation flow path, 2… Refrigerant compressor, 3… Refrigerant condenser, 3C… Refrigerant condenser, 4… Refrigerant expansion valve, 5… Refrigerant evaporator, 6… Feed water pump, 7… Flow control valve, 8… Water level sensor, 9… Makeup water line, 10… Steam compressor, 11… First steam compressor, 12… Second steam compressor, 13… Third steam compressor, 14… Fourth steam compressor, 20… Heat exchanger, 20B… Heat exchanger, 21… First heat exchanger, 22… Second heat exchanger, 23… Third heat exchanger, 24… Fourth heat exchanger, 30… Flow regulator, 31… First flow regulator, 32… Second flow regulator, 33… Third flow regulator, 34… Fourth flow regulator, 40… Pressure reducing valve, 41… First pressure reducing valve, 42… Second pressure reducing valve, 43… Third pressure reducing valve, 44… Fourth pressure reducing valve, 50… Air supply control valve, 51… First air supply control valve, 52… Second air supply control valve, 53… Third air supply control valve, 54… Fourth air supply control valve, 60… Inlet temperature sensor, 61… First inlet temperature sensor, 62… Second inlet temperature sensor, 63… Third inlet temperature sensor, 64… Fourth inlet temperature sensor, 70… Inlet pressure sensor, 71… First inlet pressure sensor, 72… Second inlet pressure sensor, 73… Third inlet pressure sensor, 74… Fourth inlet pressure sensor, 80… Cooling water line, 81… First cooling water line, 82… Second cooling water line, 83… Third cooling water line, 84… Fourth cooling water line, 90… Steam transport line, 91… First steam transport line, 92… Second steam transport line, 93… Third steam transport line, 94… Fourth steam transport line, 100… Steam generator, 101… Steam-water separator, 101C… Steam-water separation space, 102… First steam supply line, 103… Precipitation line, 104… Water level detection cylinder, 105… Second steam supply line, 106… Capacity control valve, 107… Steam pressure sensor, 108… Check valve, 109… Return line, 110… Hardness component removal device, 111… Nozzle, 112… Tube, 113… Shell, 130… Shell, 131… Water pipe, 132… Lower header, 133… Upper header, 140… Makeup water line, 141… Steam supply line, 150… Refrigerant line, 151… Refrigerant line, 191… Electric motor, 192… Electric motor, 190… Controller, 200… Heat pump, WS… Water surface.

Claims

1. A heat pump in which a refrigerant compressor, a refrigerant condenser, a refrigerant expansion valve, and a refrigerant evaporator are annularly connected by a refrigerant circulation flow path, and steam is generated in the refrigerant condenser by driving the refrigerant compressor; A steam compressor that compresses the steam sent from the refrigerant condenser to generate superheated steam; A heat exchanger that cools the superheated steam discharged from the steam compressor with a cooling medium to generate saturated steam, and A steam generator.

2. The steam compressor includes a multi-stage steam compressor, The heat exchanger includes a plurality of heat exchangers that respectively cool the superheated steam discharged from each stage of the steam compressor with a cooling medium, The steam generator according to claim 1.

3. The number of stages of the multi-stage steam compressor is set such that saturated steam at atmospheric pressure or higher is generated in the heat exchanger located at least on the most downstream side, The steam generator according to claim 2.

4. The heat exchanger is a direct heat exchanger between superheated steam and cooling water, The steam generator according to any one of claims 1 to 3.

Images