Technical Field
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The present disclosure relates to a steam supply system and a steam supply method.
Background Art
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In recent years, initiatives toward carbon neutrality have been actively pursued in the industrial field. In the industrial field, about 85% of the consumed energy used for thermal applications. As a main heat source for performing heat supply, a fuel-burning boiler has been used in the related art. On the other hand, substituting heat pumps for decarbonization is being keenly studied.
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As steam generation using a heat pump, it is known to generate negative pressure steam (for example, PTL 1). Since steam can be generated by heating at a low temperature of less than 100°C, it is advantageous in terms of energy saving.
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In addition, in a case where steam is supplied to each process of a plant, a centralized disposition method in which a fuel-burning boiler of about 650 kW is installed at one location in the plant and steam is distributed to each process through a header is widely used.
Citation List
Patent Literature
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[PTL 1]
Japanese Unexamined Patent Application Publication No. 2014-102062 Summary of Invention
Technical Problem
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In PTL 1, in a case where negative pressure steam is generated by a heat exchanger, heating using a refrigerant is performed.. However, a heat exchanger having a path through which water (negative pressure steam) flows and a path through which a refrigerant flows is required, and the heat exchanger may be difficult to replace.
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In addition, instead of the above-described centralized disposition method, in a case where a distributed disposition is adopted in which the capacity of a steam utilization side and the capacity of a steam supply side are matched one-to-one corresponded to each other and the equipment is installed in the vicinity of each process, a steam transportation loss as in the centralized disposition method can be reduced.
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The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide a steam supply system and a steam supply method in which a heat exchanger is easily replaceable.
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Another object of the present disclosure is to provide the steam supply system and the steam supply method in which a distributed disposition is realizable.
Solution to Problem
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A steam supply system according to an aspect of the present disclosure includes a decompression unit that depressurizes water supplied from a water supply unit to generate negative pressure water, and a first heat exchanger that exchange heat between the negative pressure water and hot water to generate negative pressure steam.
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A steam supply method according to an aspect of the present disclosure includes a decompression step of decompressing water to a negative pressure to generate negative pressure water in a decompression unit; and a first heat exchange step of exchanging heat between the negative pressure water and hot water to generate negative pressure steam.
Advantageous Effects of Invention
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Since a heat exchanger exchanges heat between negative pressure water and hot water is provided, and since water flows in both flow passages, the heat exchanger can be easily exchanged.
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In addition, since it is sufficient to install equipment having a capacity of supplying a heating medium to the extent of generating negative pressure steam, the equipment can be disposed in the distributed disposition.
Brief Description of Drawings
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- Fig. 1 is a schematic configuration diagram showing a steam supply system according to a first embodiment of the present disclosure.
- Fig. 2 is a schematic configuration diagram showing a steam supply system according to a second embodiment of the present disclosure.
- Fig. 3 is a schematic configuration diagram showing a steam supply system according to a third embodiment of the present disclosure.
- Fig. 4 is a schematic configuration diagram showing a steam supply system according to a fourth embodiment of the present disclosure.
- Fig. 5 is a schematic configuration diagram showing a steam supply system according to a fifth embodiment of the present disclosure.
- Fig. 6 is a schematic configuration diagram showing a steam supply system according to a sixth embodiment of the present disclosure.
- Fig. 7 is a schematic configuration diagram showing a steam supply system according to a seventh embodiment of the present disclosure.
- Fig. 8 is a schematic configuration diagram showing a steam supply system according to an eighth embodiment of the present disclosure.
Description of Embodiments
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Embodiments according to the present disclosure will be described below with reference to the drawings.
[First Embodiment]
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Hereinafter, a first embodiment of the present disclosure will be described with reference to Fig. 1.
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The steam supply system 1A includes a water flow passage 2 through which water flows. A flow rate control valve (decompression unit) 7 and a first heat exchanger 9 are provided in the water flow passage 2.
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Water is supplied to the flow rate control valve 7 from a water supply unit (not shown). The supplied water is, for example, positive pressure. The flow rate control valve 7 is controlled by a control unit (not shown), and adjusts a flow rate of the water sent from the water supply unit and depressurizes the water. The pressure is reduced by the flow rate control valve 7 to make the negative pressure water about 30~70 kPa, for example.
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The control unit (not shown) includes, for example, a central processing unit (CPU), a random-access memory (RAM), a read-only memory (ROM), a computer-readable storage medium, and the like. A series of pieces of processing for achieving various functions is stored in, for example, a storage medium or the like in the form of a program, and the CPU reads out the program to the RAM or the like, and executes processing for information processing and arithmetic processing of information, to achieve various functions. The program may adopt a form in which the program is installed in advance in the ROM or another storage medium, a form in which the program is provided in a stored state in the computer-readable storage medium, or a form in which the program is distributed via wired or wireless communication means. The computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.
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In the first heat exchanger 9, the negative pressure water supplied from the flow rate control valve 7 and the hot water flowing through the hot water flow passage 13 exchange the heat. In the first heat exchanger 9, the negative pressure water is heated by the hot water and vaporized to generate negative pressure steam. For example, in a case where the temperature of the negative pressure water flowing into the first heat exchanger 9 is 80°C, for example, hot water of 95 °C, which is lower than 100 °C, is used.
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As the first heat exchanger 9, a non-contact heat exchanger in which the negative pressure water and the hot water exchange the heat without contact is used, and for example, a partitioned heat exchanger such as a plate-type heat exchanger, a shell and plate heat exchanger, and a shell and tube heat exchanger can be used.
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The negative pressure steam is supplied to a heat use destination 15 by the first heat exchanger 9. The heat use destination 15 is, for example, a pressure lower than the negative pressure steam.
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The operation and effects of the present embodiment described above are as follows.
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The negative pressure steam of less than 100°C is generated by exchanging the heat with hot water in the first heat exchanger 9 after water is made to be negative pressure by the flow rate control valve 7. As a result, the hot water supplied to the first heat exchanger 9 can be set to less than 100°C.
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By supplying the negative pressure steam of lower than 100°C generated by the first heat exchanger 9 to the heat use destination 15, the heat of less than 100°C can be supplied to the heat utilization destination 15. Thus, it is possible to meet the demand of the heat use destination 15 requiring heat of less than 100°C.
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Since the first heat exchanger exchanges heat between the negative pressure water and the hot water, and water is allowed to flow through any flow passage, the heat exchanger can be easily exchanged as compared with a heat exchanger in which the water and the refrigerant exchange the heat.
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In order to supply the hot water for generating the negative pressure steam in the first heat exchanger 9, for example, a heat pump of about several tens to several hundreds of kW can be used. By using the heat pump of this capacity, the capacity of the heat use destination 15 and the capacity of the supply side (heat pump) can be matched one-to-one corresponded to each other, so that the steam supply system 1A can be disposed in the distributed disposition at each position in the plant. As a result, the steam transportation loss can be reduced as compared with a centralized disposition method in which a boiler is installed at one location in the plant and steam is distributed to each process through a header, and heat efficiency can be improved.
[Second Embodiment]
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Hereinafter, a second embodiment of the present disclosure will be described with reference to Fig. 2. The steam supply system 1B of the present embodiment is different from the first embodiment in that a steam compressor 10 is provided. Since the other configurations are the same, the same reference numerals are given to the same components, and the description thereof will not be repeated.
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The steam compressor 10 is provided on a downstream side of the first heat exchanger 9 and on an upstream side of the heat use destination 15. As the steam compressor 10, for example, a centrifugal compressor or the like is used. The negative pressure steam generated by the first heat exchanger is compressed by the steam compressor 10 and is pressurized to the positive pressure. The pressurized positive pressure steam is supplied to the heat use destination 15.
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According to the present embodiment, since the steam compressor 10 that compresses the negative pressure steam generated by the first heat exchanger 9 is provided, the positive pressure steam having the increased pressure can be supplied to the heat use destination. As a result, it is possible to supply heat to the heat use destination 15 that is not set to be the negative pressure.
[Third Embodiment]
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Hereinafter, a third embodiment of the present disclosure will be described with reference to Fig. 3. In the present embodiment, a path of water and the like are different from those in the first embodiment. In the following description, a configuration different from that of the first embodiment will be described, and the same configuration will be designated by the same reference numerals, and the description thereof will not be repeated.
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The steam supply system 1C includes a water circulation passage 3 that is closed. The water pump (water supply unit) 5, the flow rate control valve (decompression unit) 7, the first heat exchanger 9, and the second heat exchanger 11 are provided in the water circulation passage 3.
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The water pump 5 is controlled by a control unit (not shown), and sucks the negative pressure water of the water circulation passage 3 and discharges the negative pressure water to the flow rate control valve 7. The water discharged at this time is pressurized and remains at the negative pressure or is the positive pressure. As the water pump 5, for example, a self-priming vortex pump, a gear pump, or the like can be used.
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The flow rate control valve 7 and the first heat exchanger 9 are the same as those in the first embodiment.
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The second heat exchanger 11 is installed at a heat use destination 15. The heat use destination 15 is heated through the heat medium (for example, water or air) that is heated by the negative pressure steam of lower than 100°C. A pressurization unit such as the steam compressor 10 (refer to reference numeral 10 in FIG. 2) is not provided between the second heat exchanger 11 and the first heat exchanger 9, and the negative pressure steam generated by the first heat exchanger 9 is directly led to the second heat exchanger.
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As the second heat exchanger 11, the non-contact heat exchanger in which the negative pressure steam and the heat medium of the heat use destination 15 exchange the heat without contact is used, and for example, the partition wall type heat exchanger such as the plate type heat exchanger, a fin and tube heat exchanger, or an immersion heat exchanger can be used.
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The negative pressure steam is condensed by releasing the heat to the heat medium of the heat use destination 15 by the second heat exchanger 11 to be the negative pressure water. The negative pressure water is led to the suction side of the water pump 5 through the water circulation passage 3. As described above, in the water circulation passage 3, the flow rate control valve (decompression unit) 7, the first heat exchanger 9, the second heat exchanger 11, and the water pump (water supply unit) 5 are provided in this order along a circulation direction of the water. The water circulation passage 3 comprises these configurations, and thus a passage from a downstream side of the decompression unit 7 to a suction side of the water pump 5 in the passage can be set to be negative pressure. Since the first heat exchanger 9 and the second heat exchanger 11 are provided in the section, the latent heat associated with a change in the state of water can be exchanged with another medium at a temperature lower than 100°C in the heat exchangers.
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The operation and the effects of the present embodiment described above are as follows in addition to the operation and the replacement of the first embodiment.
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The negative pressure water that is condensed by releasing the latent heat of condensation in the second heat exchanger 11 is supplied to the flow rate control valve 7 by the water pump 5 to form a circulation system of the water. As a result, the effective use of the water can be achieved.
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By using the water pump 5 that transfers the negative pressure water led from the second heat exchanger 11 to the flow rate control valve 7, the water circulation passage 3 having a simple configuration can be formed.
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In the present embodiment, the steam compressor 10 (see Fig. 2) may be provided as in the second embodiment.
[Fourth Embodiment]
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Next, a fourth embodiment of the present disclosure will be described with reference to Fig. 4. The present embodiment differs in that a different water supply unit is employed instead of the water pump 5 (see FIG. 3) of the third embodiment. The same configurations will be designated by the same reference numerals, and the description thereof will not be repeated.
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As shown in Fig. 4, a steam supply system 1D of the present embodiment comprises a water supply unit 17. The water supply unit 17 comprises a water pump 19, an aspirator 21, and a water tank 23. The water tank 23 is open to the atmosphere. Therefore, the water stored in the water tank 23 is atmospheric pressure. The water pump 19 is controlled by a control unit (not shown), and sucks up the water stored in the water tank 23 and supplies the water to the aspirator 21. The aspirator 21 sucks the negative pressure water led from the second heat exchanger 11 by the low pressure generated by the Venturi effect, and supplies the water to the water tank 23 from the discharge pipe 25 of the water circulation passage 3. The negative pressure water is atmospheric pressure by being led to the water tank 23.
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A water supply pipe 27 of the water circulation passage 3 is provided to be immersed in the water stored in the water tank 23. The water stored in the water tank 23 is led to the flow rate control valve 7 via the water supply pipe 27. As described above, in the water circulation passage 3 according to the present embodiment, the flow rate control valve (decompression unit) 7, the first heat exchanger 9, the second heat exchanger 11, and the aspirator 21 are provided in this order along the circulation direction of the water. By providing the water circulation passage 3 with these configurations, it is possible to create a negative pressure at least in the passage from the downstream side of the decompression unit 7 to the suction side of the aspirator 21. Since the first heat exchanger 9 and the second heat exchanger 11 are provided in the section, the latent heat associated with a change in the state of water can be exchanged with another medium at a temperature lower than 100°C in the heat exchangers.
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The operation and the effects of the present embodiment are as follows in addition to the third embodiment.
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Since the water flowing through the water circulation passage 3 or the steam is set to be negative pressure, in a case in which the water circulation passage 3 is closed, it is difficult to discharge the air that has entered. Therefore, the water tank 23 that opens the negative pressure water to the atmosphere is provided, and the stored water of the water tank 23 set to the atmospheric pressure is led to the flow rate control valve 7 using the water supply pipe 27. As a result, even in a case in which the air enters the water circulation passage 3, the entered air can be discharged.
[Fifth Embodiment]
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Next, a fifth embodiment of the present disclosure will be described with reference to Fig. 5. The present embodiment is different from the third embodiment in that a hot water circulation passage 52 and a heat pump 30 are provided. The same configurations will be designated by the same reference numerals, and the description thereof will not be repeated. The present embodiment can also be applied to the steam supply system comprising the water supply unit 17 (refer to Fig. 4) as in the fourth embodiment.
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As shown in Fig. 5, the steam supply system 1E according to the present embodiment includes a hot water circulation passage 52 through which hot water circulates and flows. The hot water circulation passage 52 is connected to the first heat exchanger 9 and corresponds to the hot water flow passage 13 in Fig. 1. A hot water pump 54 and a hot water-heating heat exchanger 58 are provided in the hot water circulation passage 52. The hot water pump 54 is controlled by a control unit (not shown), and transports the hot water in the hot water circulation passage 52. The hot water-heating heat exchanger 58 is heated by the heating medium (refrigerant) led from the heat pump 30.
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The heat pump 30 includes a refrigerant circulation passage 32 through which the refrigerant circulates. The refrigerant circulation passage 32 is connected to the hot water-heating heat exchanger 58.
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The refrigerant circulation passage 32 includes the compressor 34 that compresses the refrigerant to be supplied to the hot water-heating heat exchanger 58, the expansion valve 36 that decompresses the refrigerant that has been subjected to exchange the heat in the hot water-heating heat exchanger 58, and the evaporator 38 that exchanges the heat between the refrigerant decompressed by the expansion valve 36 and the heat source medium to evaporate the refrigerant.
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As the compressor, for example, a scroll compressor or a rotary compressor is used. As the refrigerant, a substitute for fluorocarbon refrigerant or a natural refrigerant such as CO2 is used. As the heat source medium led to the evaporator 38, water or air is used.
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According to the present embodiment, since the heating medium to be supplied to the hot water-heating heat exchanger 58 is generated by using the heat pump 30, the heating medium heated to the desired temperature can be generated from the heat source medium that is the low-temperature heat source such as water or air.
[Sixth Embodiment]
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Next, a sixth embodiment of the present disclosure will be described with reference to Fig. 6. In the present embodiment, the heat pump 30 of the fifth embodiment (see Fig. 5) can perform reverse cycle operation. The same configurations will be designated by the same reference numerals, and the description thereof will not be repeated. The present embodiment can also be applied to the first embodiment (see Fig. 1), the second embodiment (see Fig. 2), and the fourth embodiment (see Fig. 4).
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In the steam supply system 1F according to the present embodiment, a heat storage body 53 is provided in the hot water circulation passage 52. The heat storage body 53 is provided between the hot water-heating heat exchanger 58 and the first heat exchanger 9, and stores sensible heat of hot water. Examples of the heat storage body include a heat storage tank that stores heat by water heat storage, a sensible heat storage body that stores heat by a porous body (foamed metal, gold net, or the like), and a latent heat storage body by using a phase change of paraffin or molten salt.
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The heat pump 30 includes a four-way valve 33. The four-way valve 33 is controlled by a control unit (not shown), and by switching of the four-way valve 33 it is determined whether the refrigerant discharged from the compressor 34 is directed to the hot water-heating heat exchanger 58 (forward cycle) or to the evaporator 38 (reverse cycle). The refrigerant discharged from the compressor 34 by the reverse cycle is led to the evaporator 38, and defrosting operation (defrost cycle operation) can be performed.
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The operation and the effects of the present embodiment are as follows in addition to the fifth embodiment.
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In a case in which air is used as the heat source that absorbs heat in the evaporator 38, frost may be attached to the evaporator 38 while the heat pump is operated (forward cycle operation). In this case, the four-way valve 33 is switched to perform reverse cycle operation of the heat pump 30, and the discharged gas from the compressor 34 is guided to the evaporator 38 to remove the frost attached to the evaporator 38 (defrost operation). However, in a case in which the defrost operation is performed, the heat pump 30 cannot supply heat to the hot water in the hot water-heating heat exchanger 58. Therefore, the heat storage body 53 that stores sensible heat of hot water is provided in the hot water circulation passage 52. As a result, the heat stored in the heat storage body 53 can be used during the defrost operation, and the hot water can be continuously heated.
[Seventh Embodiment]
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Next, a seventh embodiment of the present disclosure will be described with reference to Fig. 7. The present embodiment is obtained by applying the heat pump 30 of the fifth embodiment (see Fig. 5) to the second embodiment (see Fig. 2). Therefore, the same reference numerals are designated for the same configurations.
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Even in a configuration including the steam compressor 10 as in the steam supply system 1G of the present embodiment, the heating medium heated to a desired temperature can be generated from the heat source medium that is a low-temperature heat source such as water or air, and the hot water can be heated by adding the hot water circulation passage 52 and the heat pump 30.
[Eighth Embodiment]
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Next, a eighth embodiment of the present disclosure will be described with reference to Fig. 8. The present embodiment is different from the seventh embodiment in that the heat pump 30 of the seventh embodiment (see Fig. 7) is of a cascade type. The same configurations will be designated by the same reference numerals, and the description thereof will not be repeated. The present embodiment can be applied to the first embodiment (see Fig. 1), the third embodiment (see Fig. 3), and the fourth embodiment (see Fig. 4).
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As shown in Fig. 8, a steam supply system 1H of the present embodiment includes a cascade-type heat pump 40. The cascade-type heat pump 40 includes a high-stage heat pump 40A and a low-stage heat pump 40B.
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The high-stage heat pump 40A includes the high-stage refrigerant circulation passage 42A through which the refrigerant circulates, the high-stage compressor 44A that compresses the refrigerant to be supplied to the hot water-heating heat exchanger 58, the high-stage expansion valve 46A that decompresses the refrigerant after the heat exchange in the first heat exchanger 9, and the high-stage evaporator 48A that evaporates the refrigerant decompressed by the high-stage expansion valve 46A.
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The low-stage heat pump 40B includes the low-stage refrigerant circulation passage 42B through which the refrigerant circulates, the low-stage compressor 44B that compresses the refrigerant to be supplied to the high-stage evaporator 48A, the low-stage expansion valve 46B that decompresses the refrigerant after the heat exchange in the high-stage evaporator 48A, and the low-stage evaporator 48B that exchanges heat between the refrigerant decompressed by the low-stage expansion valve 46B and the heat source medium to evaporate the refrigerant.
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As the high-stage compressor 44A and the low-stage compressor 44B, for example, a scroll compressor or a rotary compressor is used. Since the required pressure range is different between the high stage and the low stage, it is preferable to use a compressor having high efficiency in the operating pressure range.
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As the refrigerant, a substitute for fluorocarbon refrigerant or a natural refrigerant such as CO2 is used. It is preferable that the refrigerant is different between the high-stage refrigerant circulation passage 42A and the low-stage refrigerant circulation passage 42B. For example, the efficiency can be improved by using the high-pressure refrigerant and the low-pressure refrigerant in a divided manner.
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As the heat source medium led to the low-stage evaporator 48B, water or air is used. In a case in which air is used as the heat source medium, a commercially available air-source heat pump can be used as the low-stage heat pump 40B.
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According to the present embodiment, since the cascade-type heat pump 40 including the high-stage heat pump 40A and the low-stage heat pump 40B is used, the heating medium can be generated from the heat source medium that is a low-temperature heat source such as water or air. Since the heat can be extracted from the heat source medium by the heat pumps 40A and 40B of a plurality of stages as the cascade type, the heat pump 40 can be operated with high efficiency.
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One or a plurality of heat pumps may be provided between the high-stage heat pump 40A and the low-stage heat pump 40B to form a cascade type of three or more stages.
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The steam supply system and the steam supply method according to each embodiment described above are understood as follows.
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A first aspect of the present disclosure relates to a steam supply system including a decompression unit (7) that decompresses water supplied from a water supply unit to a negative pressure to generate negative pressure water, and a first heat exchanger (9) that exchange heat between the negative pressure water and hot water to generate negative pressure steam.
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After the water is decompressed to the negative pressure by the decompression unit, the water is subjected to exchange the heat with the heating medium is heated by the first heat exchanger in the first heat exchanger to generate negative pressure steam of less than 100°C. As a result, the hot water supplied to the first heat exchanger can be set to less than 100°C.
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The heat use destination can be supplied with heat of less than 100°C by supplying the negative pressure steam of less than 100°C generated by the first heat exchanger to the heat use destination. As a result, it is possible to meet the demand of the heat use destination that requires heat of less than 100°C.
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Since the heat exchanger in which the negative pressure water and the hot water exchange the heat is configured such that water flows through any of the flow passages, the heat exchanger can be easily replaced as compared with the heat exchanger in which the water and the refrigerant exchange the heat.
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In addition, since it is sufficient to install an apparatus having a capacity of supplying the hot water of less than 100°C for generating the negative pressure steam in the first heat exchanger, the apparatus can be disposed in the distributed disposition.
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The negative pressure steam of less than 100°C is generated by exchanging the heat with hot water in the first heat exchanger after the water is brought to the negative pressure in the decompression unit. As a result, the heating medium supplied to the first heat exchanger can be set to less than 100°C.
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As the first heat exchanger, for example, a partition type heat exchanger such as a plate-type heat exchanger, a shell and plate heat exchanger, or a shell and tube heat exchanger can be used such that the negative pressure water and the hot water can exchange the heat without contact.
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A second aspect of the present disclosure relates to the steam supply system according to the first aspect, further including a steam compressor (10) that compresses negative pressure steam generated in the first heat exchanger.
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Since the steam compressor that compresses the negative pressure steam generated by the first heat exchanger is provided, the heat use destination can be supplied with the pressurized positive pressure steam. As a result, the heat can be supplied to the heat use destination that is not set to the negative pressure.
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A third aspect of the present disclosure relates to the steam supply system according to the first or second aspect, further including a second heat exchanger (11) that is connected to the first heat exchanger and generates condensate of the negative pressure steam by heat-exchanging with a heat use destination, the water supply unit (5) that supplies the condensate led from the second heat exchanger to the decompression unit.
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The heat is supplied to a heat use side by the second heat exchanger connected to the first heat exchanger. The second heat exchanger may be supplied with the negative pressure steam generated by the first heat exchanger as it is, or may be supplied with the positive pressure steam that has been compressed by the steam compressor and has become the positive pressure.
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In a case where the negative pressure steam is used as it is in the second heat exchanger, it is not necessary to install the steam compressor for compressing the negative pressure steam supplied to the second heat exchanger, which is advantageous from the viewpoint of cost and maintenance.
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The condensate that is condensed by releasing the latent heat of condensation in the second heat exchanger is supplied to the decompression unit by the water supply unit to form a circulation system of water. As a result, the effective use of the water can be achieved.
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As the second heat exchanger, for example, a partition type heat exchanger such as a plate type heat exchanger, a fin-and-tube heat exchanger, or an immersion heat exchanger can be used such that the negative pressure steam and the heat use destination can perform heat exchange without contact.
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A fourth aspect of the present disclosure relates to the steam supply system according to the third aspect, in which the water supply unit includes a water pump (5) that transfers the condensate led from the second heat exchanger to the decompression unit.
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By using the water pump that transfers the condensate led from the second heat exchanger to the decompression unit, it is possible to form a water circulation passage having a simple configuration.
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As the water pump, for example, a self-priming spiral pump or a gear pump can be used.
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A fifth aspect of the present disclosure relates to the steam supply system according to the third aspect, in which the water supply unit (17) includes a water tank (23) that opens the condensate led from the second heat exchanger to an atmosphere, and a water supply pipe (27) that guides the condensate stored in the water tank and set to atmospheric pressure to the decompression unit.
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Since the water flowing through the water circulation passage or the steam is at a negative pressure, in a case in which the water circulation passage is closed, it is difficult to discharge the air that has entered. Therefore, the water tank that opens the condensate of negative pressure to the atmosphere is provided, and the condensate of the water tank set to the atmospheric pressure is led to the decompression unit using the water supply pipe. As a result, even in a case in which air enters the water circulation passage, the air can be discharged to the atmosphere.
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A sixth aspect of the present disclosure relates to the steam supply system according to any one of the first to fifth aspects, further including a hot water circulation passage through which hot water flowing through the first heat exchanger circulates, a hot water-heating heat exchanger that heats the hot water led from the first heat exchanger, and a heat pump (30) that supplies a refrigerant as a heating medium to the hot water-heating heat exchanger, in which the heat pump includes a refrigerant circulation passage (32) for circulating the refrigerant, a compressor (34) that compresses the refrigerant to be supplied to the hot water-heating heat exchanger, an expansion valve (36) that decompresses a refrigerant after the heat is exchanged in the hot water-heating heat exchanger, an evaporator (38) that exchanges heat between a refrigerant decompressed by the expansion valve and heat source medium to evaporate the refrigerant.
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Since the heat pump is used, the heating medium can be generated from the heat source medium that is a low-temperature heat source such as water or air.
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A seventh aspect of the present disclosure relates to the steam supply system according to any one of the first to fifth aspects, further comprising a hot water circulation passage through which hot water flowing through the first heat exchanger circulates, a hot water-heating heat exchanger that heats the hot water led from the first heat exchanger, and a heat pump that supplies a refrigerant as a heating medium to the hot water-heating heat exchanger, in which the heat pump includes a high-stage heat pump (40A) and a low-stage heat pump (40B), the high-stage heat pump includes a high-stage refrigerant circulation passage (42A) for circulating the refrigerant, a high-stage compressor (44A) that compresses the refrigerant to be supplied to the hot water-heating heat exchanger, a high-stage expansion valve (46A) that decompresses a refrigerant after the heat is exchanged in the hot water-heating heat exchanger, and a high-stage evaporator (48A) that evaporates a refrigerant decompressed by the high-stage expansion valve and the low-stage heat pump includes a low-stage refrigerant circulation passage (42B) for circulating the refrigerant, a low-stage compressor (44B) that compresses the refrigerant to be supplied to the high-stage evaporator, a low-stage expansion valve (46B) that decompresses a refrigerant after the heat is exchanged in the high-stage evaporator, a low-stage evaporator (48B) that exchanges heat between a refrigerant decompressed by the low-stage expansion valve and heat source medium to evaporate the refrigerant.
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The heating medium can be generated from the heat source medium that is the low-temperature heat source such as water or air by the cascade-type heat pump including the high-stage heat pump and the low-stage heat pump. Since the heat can be extracted from the heat source medium by a plurality of stages of heat pumps as the cascade type, the heat pump can be operated with high efficiency.
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It should be noted that one or a plurality of heat pumps may be provided between the high-stage heat pump and the low-stage heat pump to form a three-stage or more cascade type.
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A eighth aspect of the present disclosure relates to the steam supply system according to any one of the third to seventh aspects, in which a heat storage body (53) that stores sensible heat of the hot water is provided in the hot water circulation passage, and the heat pump is capable of reverse cycle operation for defrosting.
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In a case in which air is used as the heat source that absorbs heat in the evaporator, frost may be attached to the evaporator during operation of the heat pump. In this case, the heat pump is operated in reverse cycle to discharge the gas from the compressor to the evaporator to remove the frost attached to the evaporator (defrost operation). However, in a case in which the defrost operation is performed, the heat cannot be supplied from the heat pump to the hot water. Therefore, a heat storage body that stores sensible heat of hot water is provided in the hot water circulation passage. As a result, the heat stored in the heat storage body can be used during the defrost operation, and the hot water can be continuously heated.
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Examples of the heat storage body include a heat storage tank that stores heat by water heat storage, a sensible heat storage body that stores heat by a porous body (foamed metal, gold net, or the like), and a latent heat storage body by using a phase change of paraffin or molten salt.
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A first aspect of the present disclosure relates to a steam supply method including a decompression step of decompressing water to a negative pressure to generate negative pressure water in a decompression unit; and a first heat exchange step of exchanging heat between the negative pressure water and hot water to generate negative pressure steam.
Reference Signs List
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- 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H: steam supply system
- 2: water flow passage
- 3: water circulation passage
- 5: water pump (water supply unit)
- 7: flow rate control valve (decompression unit)
- 9: first heat exchanger
- 10: steam compressor
- 11: second heat exchanger
- 13: hot water flow passage
- 15: heat use destination
- 17: water supply unit
- 19: water pump
- 21: aspirator
- 23: water tank
- 25: discharge pipe
- 27: water supply pipe
- 30: heat pump
- 32: refrigerant circulation passage
- 33: four-way valve
- 34: compressor
- 36: expansion valve
- 38: evaporator
- 40: heat pump
- 40A: high-stage heat pump
- 40B: low-stage heat pump
- 42A: high-stage refrigerant circulation passage
- 42B: low-stage refrigerant circulation passage
- 44A: high-stage compressor
- 44B: low-stage compressor
- 46A: high-stage expansion valve
- 46B: low-stage expansion valve
- 48A: high-stage evaporator
- 48B: low-stage evaporator
- 52: hot water circulation passage
- 53: heat storage body
- 54: hot water pump
- 58: hot water-heating heat exchanger