Steam supply system and method for operating the same

Abstract

To provide a steam supply system capable of restarting a stopped steam compressor with a configuration that can save energy.SOLUTION: A steam supply system (1A) comprises: a flow regulator valve (3) that reduces the pressure of water to a negative pressure to generate negative-pressure water; a heat exchanger (5) that heats the negative-pressure water to generate negative-pressure steam; a steam compressor (7) that compresses the negative-pressure steam generated by the heat exchanger (5); an inlet steam pipe (11) that connects the heat exchanger (5) and the steam compressor (7); an outlet steam pipe (13) that is connected to the discharge side of the steam compressor (7); and a negative pressure generation unit (19) that sets the inlet steam pipe (11), the steam compressor (7), and the outlet steam pipe (13) to a negative pressure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a steam supply system and a method of operating the same. [Background technology]

[0002] Patent Document 1 discloses a steam generation system in which water introduced from a water source is decompressed using a pressure reducing valve to produce negative pressure water, and the negative pressure water is heated using a heat source supplied from a heat pump unit to generate negative pressure steam in a steam generation unit. The negative pressure steam generated in the steam generation unit is then pressurized to above atmospheric pressure in a steam compressor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6086712 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have conducted extensive research into the above-described configuration of Patent Document 1 and have found that the following problems occur when restarting a steam compressor after it has been stopped.

[0005] That is, in the above configuration of Patent Document 1, when the steam compressor is stopped, it is not possible to maintain negative pressure on the suction side of the steam compressor, and the water supplied to the steam generating unit becomes at atmospheric pressure or higher. If the heat source for generating steam in the steam generating unit is 100°C or lower, the water (liquid phase) supplied to the steam generating unit will not be able to evaporate unless the steam compressor starts operating.

[0006] On the other hand, in order to restart a steam compressor after it has been stopped, it is necessary to heat the inside of the steam compressor, because if the steam compressor is started with its inside cold, liquid compression may occur due to condensed water inside the steam compressor, which may result in damage to the compressor.

[0007] In order to avoid liquid compression, it is conceivable to preheat the liquid using an external heating means such as an electric heater or hot air, but this is not preferable from the viewpoint of energy saving.

[0008] The present disclosure has been made in consideration of the above circumstances, and aims to provide a steam supply system and an operating method thereof that are configured to save energy and are capable of restarting a steam compressor after it has been stopped. [Means for solving the problem]

[0009] A steam supply system according to one aspect of the present disclosure includes a pressure reduction unit that reduces water pressure to a negative pressure to generate negative pressure water, a heat exchanger that heats the negative pressure water to generate negative pressure steam, a steam compressor that compresses the negative pressure steam generated by the heat exchanger, an inlet flow path that connects the heat exchanger and the steam compressor, an outlet flow path connected to the discharge side of the steam compressor, and a negative pressure generation unit that generates negative pressure in the inlet flow path, the steam compressor, and the outlet flow path.

[0010] A method for operating a steam supply system according to one aspect of the present disclosure is a method for operating a steam supply system including a pressure reduction section that reduces water pressure to a negative pressure to generate negative pressure water, a heat exchanger that heats the negative pressure water to generate negative pressure steam, a steam compressor that compresses the negative pressure steam generated by the heat exchanger, an inlet flow path that connects the heat exchanger and the steam compressor, and an outlet flow path that is connected to the discharge side of the steam compressor, wherein when the steam compressor is stopped, the inlet flow path, the steam compressor, and the outlet flow path are brought to negative pressure. [Effects of the Invention]

[0011] The energy-saving configuration allows the steam compressor to be restarted properly after being stopped. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram showing a steam supply system according to a first embodiment of the present disclosure. [Figure 2]FIG. 4 is a schematic configuration diagram showing a steam supply system according to a second embodiment of the present disclosure. [Figure 3] FIG. 10 is a schematic configuration diagram showing a steam supply system according to a third embodiment of the present disclosure. [Figure 4] FIG. 10 is a schematic configuration diagram showing a steam supply system according to a fourth embodiment of the present disclosure. [Figure 5] FIG. 10 is a schematic configuration diagram showing a steam supply system according to a fifth embodiment of the present disclosure. [Figure 6] FIG. 10 is a schematic configuration diagram showing a steam supply system according to a sixth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. [First embodiment] Hereinafter, a first embodiment of the present disclosure will be described with reference to FIG. The steam supply system 1A includes a flow rate adjustment valve (pressure reduction unit) 3 provided in a water supply flow path 2 through which water flows, a heat exchanger 5, and a steam compressor .

[0014] Water is supplied to the water supply flow path 2 from a water supply source (not shown). The supplied water is, for example, under positive pressure. The flow rate adjustment valve 3 is controlled by a control unit (not shown) to adjust the flow rate of the water sent from the water supply source and reduce the pressure. By reducing the pressure with the flow rate adjustment valve 3, the water becomes negatively pressurized, for example, at about 30 to 70 kPa. The negatively pressurized water generated by the flow rate adjustment valve 3 is supplied to the heat exchanger 5 via the water supply flow path 2.

[0015] In the heat exchanger 5, heat is exchanged between the negative pressure water supplied from the flow rate adjustment valve 3 and the hot water flowing through the hot water flow path 9. In the heat exchanger 5, the negative pressure water is heated by the hot water and vaporized to generate negative pressure steam. The temperature of the hot water supplied to the heat exchanger 5 is set to less than 100°C, for example, 95°C.

[0016] As the heat exchanger 5, a non-contact heat exchanger is used in which negative pressure water and hot water exchange heat without contact, and 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.

[0017] The steam compressor 7 is provided downstream of the heat exchanger 5. For example, a claw compressor or a centrifugal compressor is used as the steam compressor 7. An inlet steam pipe (inlet flow path) 11 is provided between the steam compressor 7 and the heat exchanger 5, and an outlet steam pipe (outlet flow path) 13 is provided on the discharge side of the steam compressor 7. The negative pressure steam generated in the heat exchanger 5 is compressed by the steam compressor 7 and raised to a positive pressure. The raised positive pressure steam is supplied to a heat utilization destination (not shown).

[0018] A negative pressure generating unit 19 is connected to the inlet steam pipe 11 via a connecting pipe (negative pressure connecting flow path) 17. The negative pressure generating unit 19 is, for example, a vacuum pump that generates a negative pressure lower than atmospheric pressure.

[0019] An electromagnetic valve 21 serving as an on-off valve is provided on the connecting pipe 17. The on-off of the electromagnetic valve 21 is controlled by a control unit.

[0020] A check valve (backflow prevention means) 23 is provided in the outlet steam pipe 13. The check valve 23 allows the steam discharged from the steam compressor 7 to flow toward the heat utilization side, and prevents the steam from flowing toward the steam compressor 7.

[0021] The control unit (not shown) is composed of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium, for example, in the form of a program. The CPU reads this program into RAM and executes information processing and arithmetic operations to realize various functions. The program may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0022] The steam supply system 1A having the above configuration operates as follows. <Normal operation> In normal operation, in which steam is generated and supplied to a heat utilization destination, water flowing through water supply flow path 2 is throttled by flow control valve 3 to become negative pressure water, which is then supplied to heat exchanger 5. In heat exchanger 5, the negative pressure water is heated by hot water supplied through hot water flow path 9, generating negative pressure steam at a temperature below 100°C. The generated negative pressure steam is sucked into the suction side of steam compressor 7 through inlet steam pipe 11 and is pressurized to positive pressure by steam compressor 7. Steam compressed by steam compressor 7 is supplied to the heat utilization destination through outlet steam pipe 13.

[0023] During normal operation, the solenoid valve 21 is closed by a command from the control unit, and therefore the inlet steam pipe 11 is not put into a negative pressure state by the negative pressure generating unit 19. However, the suction pressure of the steam compressor 7 creates a negative pressure between the inlet steam pipe 11 and the heat exchanger 5.

[0024] <When stopped> When steam is not supplied to the heat utilization destination, the steam compressor 7 is stopped by a command from the control unit. However, even when the steam compressor 7 is stopped, hot water is supplied to the heat exchanger 5 through the hot water flow path 9.

[0025] The control unit operates negative pressure generating unit 19 to generate negative pressure and opens solenoid valve 21. As a result, inlet steam pipe 11 connected via connecting pipe 17 and steam compressor 7 connected to inlet steam pipe 11 are maintained at negative pressure. Negative pressure is maintained in outlet steam pipe 13 from the discharge port of steam compressor 7 to check valve 23. Heat exchanger 5 is filled up to a midpoint with water supplied via water supply flow path 2. In FIG. 1, region A maintained at negative pressure is indicated by hatching.

[0026] In this way, the inlet steam pipe 11, the steam compressor 7, and the outlet steam pipe 13 (up to the check valve 23) are maintained at negative pressure. While the negative pressure is maintained, the negative pressure steam condenses, and the heat of condensation generated thereby keeps the inlet steam pipe 11, the steam compressor 7, and the outlet steam pipe 13 (up to the check valve 23) warm. If the negative pressure steam condenses and there is a shortage of steam, the flow control valve 3 is opened more widely by a command from the control unit, and water is supplied to the heat exchanger 5.

[0027] In this embodiment, the solenoid valve 21 may be kept open when the steam compressor 7 is stopped, or the opening and closing of the solenoid valve 21 may be controlled as appropriate. For example, when the steam compressor 7 is stopped, the solenoid valve 21 is opened, and after the pressure in one or more of the inlet steam pipe 11, the steam compressor 7, and the outlet steam pipe 13 (up to the check valve 23) drops to a predetermined first pressure, the solenoid valve 21 is closed to stop the operation of the negative pressure generating unit 19. The solenoid valve 21 may then be opened and the negative pressure generating unit may be activated or deactivated depending on the pressure in one or more of the inlet steam pipe 11, the steam compressor 7, and the outlet steam pipe 13 (up to the check valve 23). For example, after the solenoid valve 21 is closed to stop the operation of the negative pressure generating unit 19, if the pressure in one or more of the inlet steam pipe 11, the steam compressor 7, and the outlet steam pipe 13 (up to the check valve 23) rises to a predetermined second pressure, the solenoid valve 21 may be opened to activate the negative pressure generating unit 19. By performing such control, it is possible to control the pressure of any one or more of the inlet steam pipe 11, the steam compressor 7, and the outlet steam pipe 13 (up to the check valve 23) to within a predetermined pressure value.

[0028] <When restarting> When a request from a heat user makes it necessary to supply steam again, the steam compressor 7 is restarted. At the time of restart, the solenoid valve 21 is closed by a command from the control unit, and the steam compressor 7 is started. At this time, the inlet steam pipe 11, the steam compressor 7, and the outlet steam pipe 13 (up to the check valve 23) are maintained in a negative pressure state, and the steam compressor 7 is preheated, so that the start-up of the steam compressor 7 is carried out smoothly.

[0029] The above-described embodiment has the following advantages. A negative pressure generating unit 19 is connected to the inlet steam pipe 11, the steam compressor 7, and the outlet steam pipe 13 (up to the check valve 23) to create a negative pressure. This allows negative-pressure steam generated in the heat exchanger 5 to be guided to the inlet steam pipe 11, the steam compressor 7, and the outlet steam pipe 13 (up to the check valve 23) even when the steam compressor 7 is stopped. Therefore, even when the steam compressor 7 is stopped, the inlet steam pipe 11, the steam compressor 7, and the outlet steam pipe 13 (up to the check valve 23) can be heated using the condensation heat of the negative-pressure steam. Heating using the negative pressure generating unit 19 in this way is more efficient than using external heating means such as an electric heater or hot air. Furthermore, the negative pressure generating unit 19 can maintain a negative pressure inside the steam compressor 7, allowing the steam compressor 7 to be smoothly restarted after being stopped.

[0030] When the steam compressor 7 is stopped, the solenoid valve 21 is kept open, or the opening and closing of the solenoid valve 21 is controlled as appropriate. This not only keeps the on-off valve 21 open and the negative pressure generating unit 19 running when the steam compressor 7 is stopped, but also controls the opening and closing of the on-off valve 21 and the starting and stopping of the negative pressure generating unit 19 so that the pressure in the inlet steam pipe 11, and / or the steam compressor 7, and / or the outlet steam pipe 13 (up to the check valve 23) is maintained within a predetermined range. This allows the negative pressure generating unit 19 to be started when necessary, thereby saving energy.

[0031] Although the check valve 23 is provided in this embodiment, any means for preventing backflow may be used, for example, a solenoid valve that is controlled to close when stopped may be provided.

[0032] Furthermore, the connection position of the connecting pipe 17 is not limited to the inlet steam pipe 11 as in this embodiment, as long as the inlet steam pipe 11, the steam compressor 7, and the outlet steam pipe 13 (up to the check valve 23) can be placed in a negative pressure state, but may be connected to the steam compressor 7, the outlet steam pipe 13 (up to the check valve 23), or the heat exchanger 5.

[0033] [Second embodiment] A second embodiment of the present disclosure will be described below with reference to Fig. 2. A steam supply system 1B of this embodiment differs from the first embodiment in that an aspirator 25 is used as a negative pressure generating unit 19. Since the other configurations are similar, the same reference numerals are used and descriptions thereof will be omitted.

[0034] A water branch pipe 27 is provided branching off from the water supply flow path 2. The water branch pipe 27 is provided with an aspirator solenoid valve 29 and an aspirator 25. The opening and closing of the aspirator solenoid valve 29 is controlled by a control unit. Water guided through the water branch pipe 27 passes through the aspirator solenoid valve 29 and is then introduced into the aspirator 25. In the aspirator 25, the connecting pipe 17 becomes negative pressure due to the low pressure generated by the Venturi effect. Water that has passed through the aspirator 25 is discharged from an aspirator outlet pipe 31. Note that the water flowing through the aspirator outlet pipe 31 may be returned to the upstream side of the water supply flow path 2 to be recovered.

[0035] According to this embodiment, the following advantageous effects are achieved. An aspirator 25 is used as the negative pressure generating unit 19. This allows negative pressure to be generated with a simple configuration without using a vacuum pump, etc. Furthermore, by using water supplied to the flow rate adjusting valve 3, the device configuration becomes even simpler.

[0036] [Third embodiment] A third embodiment of the present disclosure will be described below with reference to Fig. 3. A steam supply system 1C of this embodiment differs from the first embodiment in that an ejector 33 is used as a negative pressure generating unit 19. Since the other configurations are similar, the same reference numerals are used and descriptions thereof will be omitted.

[0037] A high-pressure air pipe 35 is connected to the ejector 33. High-pressure air is supplied to the high-pressure air pipe 35 from a high-pressure air source (not shown). The high-pressure air pipe 35 is provided with an ejector solenoid valve 37. The opening and closing of the ejector solenoid valve 37 is controlled by a control unit. The high-pressure air supplied via the high-pressure air pipe 35 passes through the ejector solenoid valve 37 and then is introduced into the ejector 33. In the ejector 33, the connecting pipe 17 becomes negative pressure due to the low pressure generated by the Venturi effect. The air that has passed through the ejector 33 and has its pressure reduced is discharged from an air outlet pipe 39.

[0038] According to this embodiment, the following advantageous effects are achieved. An ejector 33 that generates negative pressure by high-pressure air is used as the negative pressure generating unit 19. This makes it possible to generate negative pressure with a simple configuration without using a vacuum pump or the like.

[0039] [Fourth embodiment] A fourth embodiment of the present disclosure will be described below with reference to Fig. 4. A steam supply system 1D of this embodiment differs from the first embodiment in that it is provided with a bypass flow path 41 that bypasses the steam compressor 7. Since the other configurations are similar, the same reference numerals are used and descriptions thereof will be omitted. Note that this embodiment can also be combined with the second or third embodiment described above.

[0040] As shown in Fig. 4, a bypass flow path 41 is provided so as to bypass the steam compressor 7. The upstream end of the bypass flow path 41 is connected to the inlet steam pipe 11, and the downstream end is connected to the outlet steam pipe 13. A bypass valve 43 is provided in the bypass flow path 41. The bypass valve 43 is an electromagnetic valve that is an on-off valve, and opening and closing thereof is controlled by a control unit.

[0041] The bypass valve 43 is opened when the steam compressor 7 is stopped and the negative pressure generating unit 19 preheats the inlet flow path, the steam compressor, and the outlet flow path by creating a negative pressure. The bypass valve 43 is closed when the steam compressor 7 is restarted or during normal operation.

[0042] According to this embodiment, the following advantageous effects are achieved. By providing a bypass flow path 41 that bypasses the steam compressor 7, negative pressure steam can be easily guided to the inlet steam pipe 11 and the outlet steam pipe 13 that sandwich the steam compressor 7. This allows the inlet steam pipe 11, the steam compressor 7, and the outlet steam pipe 13 to quickly become negative pressure regardless of the flow path resistance of the steam compressor 7.

[0043] [Fifth embodiment] A fifth embodiment of the present disclosure will be described below with reference to Fig. 5. A steam supply system 1E of this embodiment differs from the first embodiment in that a liquid discharge valve 45 is provided in the steam compressor 7. Since the other configurations are similar, the same reference numerals are used and their description will be omitted. This embodiment can also be combined with the second to fourth embodiments described above.

[0044] The upstream end of a liquid discharge pipe (liquid discharge means) 47 is connected to a position midway through the compression stroke of the steam compressor 7. The downstream end of the liquid discharge pipe 47 is connected to the outlet steam pipe 13. A liquid discharge valve (liquid discharge means) 45 is provided on the liquid discharge pipe 47. The liquid discharge valve 45 is an electromagnetic valve that is configured as an on-off valve, and its opening and closing is controlled by the control unit.

[0045] The liquid discharge valve 45 is opened by the control unit when the steam compressor 7 is restarted after being stopped. Specifically, the control unit opens the liquid discharge valve 45 to avoid liquid compression when condensed water (liquid) accumulates midway through the compression stroke of the steam compressor 7. By opening the liquid discharge valve 45, the condensed water accumulated in the steam compressor 7 is discharged to the outlet steam pipe 13 through the liquid discharge pipe 47. The opening operation of the liquid discharge valve 45 may be programmed to open at a predetermined timing when the steam compressor 7 is restarted, or may be set to open when the detected pressure of a pressure sensor (not shown) provided midway through the compression stroke of the steam compressor 7 or in the liquid discharge pipe 47 exceeds a predetermined value.

[0046] According to this embodiment, the following advantageous effects are achieved. When the steam compressor 7 is stopped, the negative pressure steam may condense, causing condensed water to accumulate inside the steam compressor 7. By opening the liquid discharge valve 45, the condensed water accumulated inside the steam compressor 7 is discharged to the outside through the liquid discharge pipe 47. This suppresses liquid compression in the steam compressor 7, and damage to the steam compressor 7 can be avoided.

[0047] As the liquid discharge means, instead of the liquid discharge valve which is an electromagnetic valve, for example, a relief valve which automatically opens when the pressure inside the steam compressor 7 becomes equal to or higher than a predetermined value than the pressure in the outlet steam pipe 13 (upstream of the check valve 23) may be used.

[0048] [Sixth embodiment] A sixth embodiment of the present disclosure will be described below with reference to Fig. 6. The steam supply system 1F of this embodiment differs from the first embodiment in that a heat pump 49 for heating hot water is provided. Since the other configurations are similar, the same reference numerals are used and the description thereof will be omitted. This embodiment can also be combined with the second to fifth embodiments described above.

[0049] As shown in Figure 6, a heat pump 49 is provided for heating hot water. The heat pump 49 is an air-source heat pump that uses outdoor air (external air) as a heat source. The heat pump 49 includes an evaporator that obtains heat from the outdoor air and evaporates a refrigerant, a refrigerant compressor that compresses the refrigerant evaporated in the evaporator, a condenser that condenses the refrigerant compressed in the refrigerant compressor, an expansion valve that expands the refrigerant condensed in the condenser, and refrigerant piping that connects these components and through which the refrigerant circulates. The condenser of the heat pump 49 is provided in a hot water heating unit 51, and in the hot water heating unit 51, the heat of condensation of the refrigerant in the condenser heats the hot water circulating in a hot water circuit 53 to a desired temperature.

[0050] A hot water pump 55 for circulating hot water is provided in the hot water circuit 53. The hot water pump 55 circulates the hot water between the hot water heating unit 51 and the heat exchanger 5.

[0051] According to this embodiment, the following advantageous effects are achieved. The heat generated by the heat pump 49 is used to heat hot water, which in turn heats the negative pressure water supplied to the heat exchanger 5. Because the heat pump 49 uses air as its heat source, it can effectively use the heat of outdoor air to preheat the steam compressor 7 when the system is not in operation, thereby saving energy. During normal operation, the heat pump 49 supplies hot water at a constant temperature, enabling stable steam generation.

[0052] The steam supply system and the operating method thereof described in each of the above-described embodiments can be understood, for example, as follows.

[0053] A steam supply system (1A, 1B, 1C, 1D, 1E, 1F) according to a first aspect of the present disclosure includes a pressure reduction section (3) that reduces water pressure to a negative pressure to generate negative pressure water, a heat exchanger (5) that heats the negative pressure water to generate negative pressure steam, a steam compressor (7) that compresses the negative pressure steam generated by the heat exchanger, an inlet flow path (11) that connects the heat exchanger and the steam compressor, an outlet flow path (13) that is connected to the discharge side of the steam compressor, and a negative pressure generating section (19) that generates negative pressure in the inlet flow path, the steam compressor, and the outlet flow path.

[0054] The negative pressure water reduced in pressure by the pressure reducing section is heated in a heat exchanger to become negative pressure steam, which is then supplied to the steam compressor via an inlet flow path. The steam compressor compresses the negative pressure steam, for example, to a pressure above atmospheric pressure, and discharges the compressed steam to an outlet flow path. A negative pressure generator is connected to the inlet flow path, the steam compressor, and the outlet flow path to create a negative pressure therein. This allows negative pressure steam generated in the heat exchanger to be guided to the inlet flow path, the steam compressor, and the outlet flow path even when the steam compressor is stopped. Therefore, even when the steam compressor is stopped, the inlet flow path, the steam compressor, and the outlet flow path can be heated using the condensation heat of the negative pressure steam. Because heating is performed by the negative pressure generator in this way, it is more efficient than using external heating means such as an electric heater or hot air. Furthermore, because the negative pressure generator can maintain a negative pressure inside the steam compressor, the steam compressor can be smoothly restarted after being stopped.

[0055] The steam supply system according to the second aspect of the present disclosure is the first aspect, and includes a negative pressure connection flow path (17) that connects the inlet flow path, the steam compressor, or the outlet flow path to the negative pressure generating unit, an on-off valve (21) provided in the negative pressure connection flow path, and a control unit that opens the on-off valve when the steam compressor is stopped.

[0056] When the steam compressor is stopped, the on-off valve provided in the negative pressure connection passage is opened to create negative pressure in the inlet passage, the steam compressor, and the outlet passage. This allows the steam compressor to be preheated using negative pressure steam even when the steam compressor is stopped.

[0057] In the steam supply system according to the third aspect of the present disclosure, in the second aspect, the control unit controls the operation of the on-off valve and the negative pressure generating unit based on the pressure of the inlet flow path, and / or the steam compressor, and / or the outlet flow path.

[0058] The opening and closing of the on-off valve and the on-off of the negative pressure generator are controlled based on the pressure in the inlet flow path, and / or the steam compressor, and / or the outlet flow path. This not only keeps the on-off valve open and the negative pressure generator running when the steam compressor is stopped, but also controls the opening and closing of the on-off valve and the on-off of the negative pressure generator so that the pressure in the inlet flow path, and / or the steam compressor, and / or the outlet flow path is maintained within a predetermined range. This allows the negative pressure generator to be started only when necessary, thereby saving energy.

[0059] A steam supply system according to a fourth aspect of the present disclosure is any one of the first to third aspects, wherein the outlet flow path is provided with backflow prevention means (23) that opens when the pressure downstream is lower than the upstream side and closes when the pressure downstream is higher than the upstream side.

[0060] When the negative pressure generating unit creates a negative pressure in the inlet flow path, the steam compressor, and the outlet flow path, the pressure downstream of the backflow prevention means becomes higher than the pressure upstream of the backflow prevention means, causing the backflow prevention means to close. This prevents fluid from flowing into the inlet flow path, the steam compressor, and the outlet flow path from downstream of the backflow prevention means, and maintains a negative pressure in the inlet flow path, the steam compressor, and the outlet flow path. When the steam compressor is operating normally, the compressed steam is discharged from the steam compressor into the outlet flow path, so the pressure downstream of the backflow prevention means is lower than the upstream side, the backflow prevention means is opened, and the compressed steam is directed to the downstream demand destination.

[0061] A steam supply system according to a fifth aspect of the present disclosure is the steam supply system according to any one of the first to fourth aspects, wherein the negative pressure generating unit includes an aspirator (25) that generates negative pressure using water supplied to the pressure reducing unit.

[0062] An aspirator is used as the negative pressure generating unit. This allows negative pressure to be generated with a simple configuration without using a vacuum pump, etc. Furthermore, by using water supplied to the pressure reducing unit, the device configuration becomes even simpler.

[0063] A steam supply system according to a sixth aspect of the present disclosure is the steam supply system according to any one of the first to fourth aspects, wherein the negative pressure generating unit includes an ejector (33) that generates negative pressure using air.

[0064] The negative pressure generating unit uses an ejector that generates negative pressure using air, which allows negative pressure to be generated with a simple configuration without using a vacuum pump or the like.

[0065] A steam supply system according to a seventh aspect of the present disclosure is in any one of the first to sixth aspects, and further includes a bypass flow path (41) that bypasses the steam compressor and connects the inlet flow path and the outlet flow path, and a bypass valve (43) provided in the bypass flow path.

[0066] By providing a bypass flow path that bypasses the steam compressor, negative pressure steam can be easily introduced into the inlet flow path and the outlet flow path that sandwich the steam compressor, thereby quickly creating negative pressure in the inlet flow path, the steam compressor, and the outlet flow path regardless of the flow path resistance of the steam compressor. The bypass valve is opened when the negative pressure generating unit applies negative pressure to the inlet flow path, the steam compressor, and the outlet flow path for preheating, and is closed when the steam compressor is operating for normal operation. The bypass valve may be controlled by the control unit.

[0067] The steam supply system according to an eighth aspect of the present disclosure is in any one of the first to seventh aspects, and further includes a liquid discharge means (45, 47) that discharges liquid from the steam compressor when the steam compressor is restarted after being stopped.

[0068] When the steam compressor is stopped, negative pressure steam condenses, and condensed water may accumulate inside the steam compressor. The liquid discharge means discharges the condensed water (liquid) accumulated inside the steam compressor to the outside. This suppresses liquid compression in the steam compressor and prevents damage to the steam compressor. As the liquid discharge means, for example, a relief valve that automatically opens when the pressure inside the steam compressor exceeds the pressure in the outlet flow path by a predetermined value, or an electromagnetic valve that opens and closes at any timing can be used.

[0069] A steam supply system according to a ninth aspect of the present disclosure is in any one of the first to eighth aspects, wherein a heat pump (49) is used as a heat source supplied to the heat exchanger.

[0070] The heat generated by the heat pump can be used to heat the negative pressure water supplied to the heat exchanger. For example, when using a heat pump that uses air as a heat source, the heat from the outdoor air can be effectively used to preheat the steam compressor when the system is not in operation, thereby saving energy. Furthermore, during normal operation, the heat pump supplies hot water at a constant temperature, enabling stable steam generation.

[0071] A method for operating a steam supply system according to a first aspect of the present disclosure is a method for operating a steam supply system including a pressure reduction section that reduces water pressure to a negative pressure to generate negative pressure water, a heat exchanger that heats the negative pressure water to generate negative pressure steam, a steam compressor that compresses the negative pressure steam generated by the heat exchanger, an inlet flow path that connects the heat exchanger and the steam compressor, and an outlet flow path that is connected to the discharge side of the steam compressor, wherein when the steam compressor is stopped, the inlet flow path, the steam compressor, and the outlet flow path are brought to negative pressure. [Explanation of symbols]

[0072] 1A, 1B, 1C, 1D, 1E, 1F Steam supply system 2 Water supply channel 3 Flow control valve (pressure reducing section) 5 Heat exchanger 7. Steam Compressor 9 Hot water flow path 11 Inlet steam pipe (inlet flow path) 13. Outlet steam pipe (outlet flow path) 17 Connecting pipe (negative pressure connecting flow path) 19 Negative pressure generating section 21 Solenoid valve (on-off valve) 23 Check valve (backflow prevention means) 25 Aspirator 27 Water branch pipe 29 Aspirator solenoid valve 31 Aspirator outlet tube 33 Ejector 35 High-pressure air piping 37 Ejector solenoid valve 39 Air outlet pipe 41 Bypass flow path 43 Bypass valve 45 Liquid discharge valve (liquid discharge means) 47 Liquid discharge pipe (liquid discharge means) 49 Heat Pump 51 Hot water heating unit 53 Hot water circuit 55 Hot water pump A Negative pressure area

Claims

1. a pressure reducing unit that reduces the pressure of water to a negative pressure to generate negative pressure water; a heat exchanger that heats the negative pressure water to generate negative pressure steam; a steam compressor that compresses the negative pressure steam generated in the heat exchanger; an inlet flow path connecting the heat exchanger and the vapor compressor; an outlet flow path connected to a discharge side of the steam compressor; a negative pressure generating unit that generates negative pressure in the inlet flow path, the steam compressor, and the outlet flow path; A steam supply system comprising:

2. a negative pressure connection flow path connecting the inlet flow path, the steam compressor, or the outlet flow path to the negative pressure generating unit; an on-off valve provided in the negative pressure connection flow path; a control unit that opens the on-off valve when the steam compressor is stopped; The steam supply system of claim 1 , comprising:

3. The steam supply system according to claim 2, wherein the control unit controls the operation of the on-off valve and the negative pressure generating unit based on the pressure of the inlet flow path, and / or the steam compressor, and / or the outlet flow path.

4. The steam supply system according to claim 1 or 2, wherein the outlet flow path is provided with a backflow prevention means that opens when the pressure downstream is lower than the upstream side and closes when the pressure downstream is higher than the upstream side.

5. 2. The steam supply system according to claim 1, wherein the negative pressure generating unit includes an aspirator that generates negative pressure using water supplied to the pressure reducing unit.

6. The steam supply system according to claim 1 , wherein the negative pressure generating unit includes an ejector that generates negative pressure using air.

7. a bypass flow path that bypasses the steam compressor and connects the inlet flow path and the outlet flow path; a bypass valve provided in the bypass flow path; The steam supply system of claim 1 , comprising:

8. 2. The steam supply system according to claim 1, further comprising a liquid discharge means for discharging liquid from the steam compressor when the steam compressor is restarted after being stopped.

9. The steam supply system according to claim 1 , wherein a heat pump is used as a heat source supplied to the heat exchanger.

10. a pressure reducing unit that reduces the pressure of water to a negative pressure to generate negative pressure water; a heat exchanger that heats the negative pressure water to generate negative pressure steam; a steam compressor that compresses the negative pressure steam generated in the heat exchanger; an inlet flow path connecting the heat exchanger and the vapor compressor; an outlet flow path connected to a discharge side of the steam compressor; A method of operating a steam supply system comprising: A method for operating a steam supply system, wherein the inlet flow path, the steam compressor, and the outlet flow path are brought into negative pressure when the steam compressor is stopped.

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