Magnesium-based metal hydride hydrogen storage system with energy recovery function

Abstract

The magnesium-based metal hydride hydrogen storage system with the energy recovery function comprises an energy recovery device and a hydrogen storage tank, a first heat exchange pipe is installed in the energy recovery device, and the energy recovery device is filled with phase change heat storage materials; the hydrogen storage tank is filled with a magnesium-based hydrogen storage material, a second heat exchange pipe is arranged in the hydrogen storage tank, and heat conduction oil is filled in the second heat exchange pipe; an oil outlet of the second heat exchange pipe is connected with an oil inlet of the heating module through a first pipe set, an oil outlet of the heating module is connected with an oil inlet of the second heat exchange pipe through a second pipe set, and a circulating pump is installed on the second pipe set. The first pipe group is connected with an oil inlet of the first heat exchange pipe through a first branch pipe; the second pipe set is connected with an oil outlet of the first heat exchange pipe through a second branch pipe. By arranging the energy recovery device, energy released in the hydrogen absorption process can be recovered, energy is provided in the hydrogen desorption process, energy-saving and efficient hydrogen storage are achieved, and the operation stability of the hydrogen storage system is guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of metal oxide hydrogen storage, in particular to a magnesium-based metal hydride hydrogen storage system with an energy recovery function. Background Art

[0002] With the sharp rise in global energy demand, greenhouse gas emissions and global climate change are becoming increasingly serious. Compared with fossil fuels, hydrogen energy has the advantages of high energy conversion efficiency, no pollution products generated during use, and abundant hydrogen reserves. Therefore, hydrogen energy is considered to be the clean energy with the greatest development potential in the 21st century. For various applications of hydrogen energy, the storage of hydrogen is inevitably involved.

[0003] The current methods of hydrogen storage mainly include: high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage and metal hydride solid hydrogen storage. Among them, metal hydride solid hydrogen storage has the advantages of large volume storage density, low storage pressure and good safety, and is a very promising hydrogen storage technology. There are also many technical routes for metal hydride solid hydrogen storage, which are mainly related to the type of hydrogen storage material. Among them, magnesium-based metal hydride hydrogen storage has the advantages of high mass hydrogen storage density, abundant magnesium materials and low cost.

[0004] However, in the related art, magnesium-based metal hydride hydrogen storage has the characteristics of heat release during hydrogen absorption, heat absorption during hydrogen release, and reversible cycle. A large amount of heat will be generated during the hydrogen absorption process, and a large amount of heat will be absorbed during the hydrogen release. Both processes of hydrogen absorption and desorption need to be maintained within a relatively high temperature range. A large amount of energy will be consumed during its use, which has become a key issue limiting the application and promotion of magnesium-based metal hydride solid-state hydrogen storage technology. Therefore, it is urgent to design a hydrogen storage system to solve the problem of high energy consumption of magnesium-based metal hydride hydrogen storage systems during use. Utility Model Content

[0005] In view of the shortcomings of the above-mentioned existing production technologies, the applicant provides a magnesium-based metal hydride hydrogen storage system with energy recovery function. By setting up an energy recovery device, it is possible to recover the energy released during the hydrogen absorption process and provide energy during the hydrogen release process, thereby achieving energy-saving and efficient hydrogen storage and ensuring the operational stability of the hydrogen storage system. At the same time, the system is environmentally friendly, emission-free and pollution-free, has low requirements for the use environment, has strong adaptability and high safety.

[0006] The technical solution adopted by the utility model is as follows:

[0007] A magnesium-based metal hydride hydrogen storage system with energy recovery function, comprising an energy recovery device and a hydrogen storage tank, wherein a first heat exchange tube is installed in the energy recovery device, and the interior of the energy recovery device is filled with a phase-change heat storage material, and the phase-change heat storage material fills the gap between the inner wall surface of the energy recovery device and the outer wall surface of the first heat exchange tube; a gas port for hydrogen inlet and outlet is opened on the hydrogen storage tank, and the hydrogen storage tank is filled with magnesium-based hydrogen storage material, and hydrogen is absorbed or released through the magnesium-based hydrogen storage material; a second heat exchange tube is arranged in the hydrogen storage tank, and heat transfer oil is filled in the second heat exchange tube;

[0008] The oil outlet of the second heat exchange tube is connected to the oil inlet of the heating module through the first tube group, and the oil outlet of the heating module is connected to the oil inlet of the second heat exchange tube through the second tube group. A circulating pump is installed on the second tube group. The heating module is used to heat the heat transfer oil, and the circulating pump drives the heat transfer oil to flow;

[0009] The first tube group is provided with a first branch pipe, the end of which is connected to the oil inlet of the first heat exchange tube; the second tube group is provided with a second branch pipe, the end of which is connected to the oil outlet of the first heat exchange tube;

[0010] When the hydrogen storage system absorbs hydrogen and releases heat, the circulating pump drives the heat transfer oil to circulate between the second heat exchange tube and the energy recovery device, so that the phase change heat storage material in the energy recovery device absorbs heat and becomes molten, thereby recovering the energy released by the magnesium-based hydrogen storage material absorbing hydrogen;

[0011] When the hydrogen storage system releases hydrogen, the circulating pump drives the heat transfer oil to circulate between the second heat exchange tube and the energy recovery device, so that the phase change heat storage material in the energy recovery device releases heat and returns to a solid state, thereby allowing the magnesium-based hydrogen storage material to release hydrogen.

[0012] As a further improvement of the above technical solution:

[0013] The heating module adopts electric heating.

[0014] The heating module comprises an electric heater, an oil tank for storing heat transfer oil is arranged inside the electric heater, and the electric heater heats the heat transfer oil in the oil tank when powered on.

[0015] The exteriors of the hydrogen storage tank and the energy recovery device are both provided with insulation layers.

[0016] The gas port of the hydrogen storage tank is connected to the shell side outlet of the second heat exchanger through the third tube group, the shell side inlet of the second heat exchanger is connected to the fourth tube group, and cooling water is introduced into the tube side of the second heat exchanger, so that the second heat exchanger uses water cooling to cool the hydrogen released by the magnesium-based hydrogen storage material.

[0017] The third pipe group is provided with a first exhaust pipe.

[0018] The energy recovery device, the hydrogen storage tank, the first tube group, the second tube group, the first branch pipe and the second branch pipe are all equipped with temperature sensors.

[0019] The exhaust port of the energy recovery device is connected to a second exhaust pipe.

[0020] The energy recovery device and the hydrogen storage tank are both equipped with pressure measuring devices.

[0021] A first valve is installed at the oil inlet of the heating module, a second valve is installed at the oil outlet of the heating module, a third valve is installed on the first branch pipe, and a fourth valve is installed on the second branch pipe.

[0022] The beneficial effects of the utility model are as follows:

[0023] The utility model has a compact and reasonable structure and is easy to operate. By arranging an energy recovery device, the energy released when the magnesium-based hydrogen storage material absorbs hydrogen can be recovered and used for heating the magnesium-based hydrogen storage material when releasing hydrogen, thereby avoiding wasting the energy generated when absorbing hydrogen. The heat recovery efficiency of the hydrogen storage system can reach 90%, thereby reducing energy loss and improving energy utilization.

[0024] The utility model also has the following advantages:

[0025] (1) In the utility model, a heating module is provided to heat the heat transfer oil when the hydrogen storage system absorbs hydrogen for the first time, so that the temperature inside the hydrogen storage tank reaches the hydrogen absorption temperature; at the same time, since the heat stored in the phase change thermal storage material will decay over time, the provision of a heating module can also avoid the problem of insufficient heat supply that may be caused by the phase change thermal storage material when the magnesium-based hydrogen storage material releases hydrogen, thereby ensuring the stable operation of the hydrogen storage system.

[0026] (2) The utility model has an oil filling port on the oil tank, through which heat transfer oil can be added to the hydrogen storage system.

[0027] (3) In the present invention, by providing a second heat exchanger, the hydrogen released by the magnesium-based hydrogen storage material can be cooled.

[0028] (4) The utility model is provided with a safety valve and a pressure measuring device, so that the hydrogen state inside the hydrogen storage system can be detected. If overpressure occurs, it can be safely released to ensure the safe and stable operation of the hydrogen storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the utility model.

[0030] Figure 2 This is a schematic diagram of the heating module in the present invention heating the thermal oil.

[0031] Figure 3 It is a schematic diagram of the utility model when it is in a stable hydrogen absorption or hydrogen release state.

[0032] Among them: 1. Energy recovery device; 2. First heat exchange tube; 3. Hydrogen storage tank; 4. Second heat exchange tube; 5. Insulation layer; 6. Electric heater; 7. Oil tank; 8. Circulation pump; 9. Safety valve; 10. Pressure measuring device; 11. Temperature sensor; 12. First tube group; 13. Second tube group; 14. Third tube group; 15. Fourth tube group; 16. Fifth tube group; 17. First branch pipe; 18. Second branch pipe; 19. First exhaust pipe; 20. Second exhaust pipe; 21. First valve; 22. Second valve; 23. Third valve; 24. Fourth valve; 25. Fifth valve; 26. Sixth valve; 27. Heat exchanger. DETAILED DESCRIPTION

[0033] The specific implementation of the utility model is described below in conjunction with the accompanying drawings.

[0034] like Figure 1-Figure 3As shown, a magnesium-based metal hydride hydrogen storage system with energy recovery function includes an energy recovery device 1 and a hydrogen storage tank 3, wherein a first heat exchange tube 2 is installed in the energy recovery device 1, and the interior of the energy recovery device 1 is filled with a phase-change heat storage material, which fills the gap between the inner wall of the energy recovery device 1 and the outer wall of the first heat exchange tube 2; a gas port for hydrogen inlet and outlet is provided on the hydrogen storage tank 3, the hydrogen storage tank 3 is filled with a magnesium-based hydrogen storage material, and hydrogen is absorbed or released by the magnesium-based hydrogen storage material, a second heat exchange tube 4 is arranged in the hydrogen storage tank 3, and heat transfer oil is filled in the second heat exchange tube 4; the oil outlet of the second heat exchange tube 4 is connected to the oil inlet of the heating module through the first tube group 12, and the oil outlet of the heating module is connected to the oil inlet of the second heat exchange tube 4 through the second tube group 13, and a circulating pump 8 is installed on the second tube group 13, The heating module is used to heat the heat transfer oil, and the circulation pump 8 drives the heat transfer oil to flow; a first branch pipe 17 is installed on the first tube group 12, and the end of the first branch pipe 17 is connected to the oil inlet of the first heat exchange tube 2; a second branch pipe 18 is installed on the second tube group 13, and the end of the second branch pipe 18 is connected to the oil outlet of the first heat exchange tube 2; when the hydrogen storage system absorbs hydrogen and releases heat, the circulation pump 8 drives the heat transfer oil to circulate between the second heat exchange tube 4 and the energy recovery device 1, so that the phase change heat storage material in the energy recovery device 1 absorbs heat and becomes a molten state, thereby recovering the energy released by the magnesium-based hydrogen storage material absorbing hydrogen; when the hydrogen storage system releases hydrogen, the circulation pump 8 drives the heat transfer oil to circulate between the second heat exchange tube 4 and the energy recovery device 1, so that the phase change heat storage material in the energy recovery device 1 releases heat and returns to a solid state, thereby allowing the magnesium-based hydrogen storage material to release hydrogen. The hydrogen storage system of the utility model stores hydrogen based on magnesium-based hydrogen storage materials. Since the hydrogen absorption and release processes of the magnesium-based hydrogen storage materials are chemical reactions, heat is released when the magnesium-based hydrogen storage materials absorb hydrogen, and heat is absorbed when the magnesium-based hydrogen storage materials release hydrogen. The total amount of heat released during the hydrogen absorption process of the magnesium-based hydrogen storage materials is considerable. If it is directly released into the external environment, energy waste will be caused. In the utility model, by providing an energy recovery device 1, the heat released during the hydrogen absorption process of the magnesium-based hydrogen storage materials can be recovered, thereby reducing the energy loss of the hydrogen storage system and improving the energy utilization rate of the hydrogen storage system.

[0035] The specific structure and functions of the utility model are as follows:

[0036] The hydrogen storage system of the utility model comprises an energy recovery device 1, a hydrogen storage tank 3, a circulation pump 8, a first pipe group 12, a second pipe group 13, a first branch pipe 17, a second branch pipe 18, and a heating module; wherein,

[0037] The energy recovery device 1 adopts a closed container, which is filled with phase change heat storage material and is equipped with a first heat exchange tube 2. The oil inlet of the first heat exchange tube 2 is connected to the oil outlet of the second heat exchange tube 4 through the first branch tube 17 and the first tube group 12 in sequence; the oil outlet of the first heat exchange tube 2 is connected to the oil inlet of the second heat exchange tube 4 through the second branch tube 18 and the second tube group 13 in sequence. The circulation pump 8 is installed on the second tube group 13 to provide drive for the circulation of the heat transfer oil in the hydrogen storage system;

[0038] Phase change thermal storage materials are alloy materials that can collect or release energy within the temperature range of 300°C-400°C, and are suitable for the working environment of magnesium-based hydrogen storage materials, thereby realizing the reasonable recovery and reuse of energy generated by the hydrogenation reaction of magnesium-based hydrogen storage materials;

[0039] The hydrogen storage tank 3 and the energy recovery device 1 are both provided with a heat-insulating layer 5 on the outside, thereby preventing internal energy from being lost and further reducing energy loss;

[0040] The exhaust port of the energy recovery device 1 is connected to a second exhaust pipe 20, and the second exhaust pipe 20 is used to discharge the excess gas in the energy recovery device 1 to prevent the internal pressure of the energy recovery device 1 from being too high;

[0041] The energy recovery device 1 is also provided with a gas supply port, which is connected to an external argon gas source through a fifth tube group 16. A sixth valve 26 is installed on the fifth tube group 16. When the sixth valve is opened, the external argon gas source introduces argon into the energy recovery device 1 to protect the phase change heat storage material.

[0042] The energy recovery device 1 and the hydrogen storage tank 3 are both equipped with a pressure measuring device 10. The pressure measuring device 10 can be a pressure gauge or a pressure sensor. The pressure measuring device 10 installed on the energy recovery device 1 is used to measure the pressure inside the energy recovery device 1, and the pressure measuring device 10 installed on the hydrogen storage tank 3 is used to measure the pressure inside the hydrogen storage tank 3.

[0043] The energy recovery device 1, the hydrogen storage tank 3, the first tube group 12, the second tube group 13, the first branch pipe 17 and the second branch pipe 18 are all equipped with a temperature sensor 11, which is used for temperature measurement.

[0044] The gas port of the hydrogen storage tank 3 is connected to the shell side outlet of the heat exchanger 27 through the third tube group 14, and the shell side inlet of the heat exchanger 27 is connected to the fourth tube group 15. Cooling water is introduced into the tube side of the heat exchanger 27, so that the heat exchanger 27 uses water cooling to cool the hydrogen released by the magnesium-based hydrogen storage material; the third tube group 14 is installed with a fifth valve 25; the third tube group 14 is installed with a first exhaust pipe 19;

[0045] The first exhaust pipe 19 is used to discharge the excess gas in the hydrogen storage tank 3 to prevent the internal pressure of the hydrogen storage tank 3 from being too high; the first exhaust pipe 19 and the second exhaust pipe 20 are both equipped with a safety valve 9.

[0046] The heating module heats the heat transfer oil by electric heating, and can be used to heat the heat transfer oil to about 280°C when the hydrogen storage system absorbs hydrogen for the first time, so that the temperature inside the hydrogen storage tank 3 reaches the hydrogen absorption temperature; at the same time, since the heat stored in the phase change thermal storage material will decay over time, the setting of the heating module can also avoid the problem of insufficient heat supply that may be generated by the phase change thermal storage material when the magnesium-based hydrogen storage material releases hydrogen, thereby ensuring the stable operation of the hydrogen storage system;

[0047] The heating module includes an electric heater 6, and an oil tank 7 for storing heat transfer oil is arranged inside the electric heater 6. The electric heater 6 is powered on to heat the heat transfer oil in the oil tank 7;

[0048] The oil tank 7 is provided with an oil inlet, an oil outlet and an oil replenishing port, through which heat transfer oil can be replenished into the hydrogen storage system;

[0049] The oil inlet of the heating module corresponds to the oil inlet of the oil tank 7, and the oil outlet of the heating module corresponds to the oil outlet of the oil tank 7.

[0050] The oil inlet of the oil tank 7 is connected to the oil outlet of the second heat exchange tube 4 in the hydrogen storage tank 3 through the first tube group 12, and the oil outlet of the oil tank 7 is connected to the oil inlet of the second heat exchange tube 4 in the hydrogen storage tank 3 through the second tube group 13;

[0051] In addition, a first valve 21 is installed at the oil inlet of the heating module, a second valve 22 is installed at the oil outlet of the heating module, a third valve 23 is installed on the first branch pipe 17, and a fourth valve 24 is installed on the second branch pipe 18;

[0052] By setting valves, the on-off of corresponding pipelines can be controlled, so that the heat transfer oil can flow in the corresponding pipelines according to usage requirements.

[0053] The working process of the utility model is as follows:

[0054] like Figure 2 As shown, Figure 2 The middle arrow indicates the flow direction of the heat transfer oil inside the pipeline; when the hydrogen storage system absorbs hydrogen for the first time (the phase change heat storage material does not store heat), at this time, the third valve 23 and the fourth valve 24 are closed, and the first valve 21 and the second valve 22 are opened. Under the action of the circulation pump 8, the heat transfer oil circulates between the second heat exchange tube 4 and the oil tank 7 through the first tube group 12 and the second tube group 13, and the electric heater 6 heats the heat transfer oil in the oil tank 7, thereby raising the temperature of the heat transfer oil, and then the temperature inside the hydrogen storage tank 3 reaches the hydrogen absorption temperature;

[0055] Subsequently, the external hydrogen enters the hydrogen storage tank 3 through the fourth tube group 15, the shell side of the heat exchanger 27, the third tube group 14, and the gas supply port of the hydrogen storage tank 3 in sequence, and the magnesium-based hydrogen storage material in the hydrogen storage tank 3 absorbs hydrogen at the hydrogen absorption temperature;

[0056] Magnesium-based hydrogen storage materials release heat while absorbing hydrogen, such as Figure 3 As shown, Figure 3 The middle arrow indicates the flow direction of the heat transfer oil in the pipeline. When the hydrogen storage system is in a stable hydrogen absorption state or is not the first hydrogen absorption, at this time, the first valve 21 and the second valve 22 are closed, and the third valve 23 and the fourth valve 24 are opened. Under the action of the circulation pump 8, the heat transfer oil circulates between the second heat exchange tube 4 and the first heat exchange tube 2 through the first tube group 12, the first branch pipe 17, the second branch pipe 18, and the second tube group 13. The heat transfer oil transfers the energy released by the magnesium-based hydrogen storage material when absorbing hydrogen to the energy recovery device 1, so that the phase change heat storage material of the energy recovery device 1 absorbs heat and becomes a molten state, and the energy released by the magnesium-based hydrogen storage material when absorbing hydrogen is stored and recovered;

[0057] like Figure 3 As shown, Figure 3 The middle arrow indicates the flow direction of the heat transfer oil inside the pipeline. When the hydrogen storage system releases hydrogen, at this time, the first valve 21 and the second valve 22 are closed, and the third valve 23 and the fourth valve 24 are opened. The circulation pump 8 drives the heat transfer oil to circulate between the second heat exchange tube 4 and the first heat exchange tube 2. The shell side material of the energy recovery device 1 releases heat and returns to a solid state. The heat transfer oil transfers the heat released by the phase change heat storage material in the energy recovery device 1 to the hydrogen storage tank 3, so that the internal temperature of the hydrogen storage tank 3 reaches the hydrogen release temperature, and then the magnesium-based hydrogen storage material releases hydrogen.

[0058] When the energy released by the phase change heat storage material in the energy recovery device 1 is insufficient, the third valve 23 and the fourth valve 24 can be closed, and the first valve 21 and the second valve 22 can be opened, so that the heat transfer oil in the pipeline can be auxiliary heated by the heating module to ensure the stability of the hydrogen absorption and desorption process of the hydrogen storage system.

[0059] The above description is an explanation of the utility model, not a limitation of the utility model. The scope of the utility model is defined by the claims. Any form of modification can be made within the protection scope of the utility model.

Claims

1. A magnesium-based metal hydride hydrogen storage system with energy recovery function, characterized in that: The invention comprises an energy recovery device (1) and a hydrogen storage tank (3), wherein a first heat exchange tube (2) is installed in the energy recovery device (1), and the interior of the energy recovery device (1) is filled with a phase change heat storage material, and the phase change heat storage material fills the gap between the inner wall surface of the energy recovery device (1) and the outer wall surface of the first heat exchange tube (2); the hydrogen storage tank (3) is provided with a gas port for hydrogen inlet and outlet, and the hydrogen storage tank (3) is filled with a magnesium-based hydrogen storage material, and hydrogen is absorbed or released through the magnesium-based hydrogen storage material; a second heat exchange tube (4) is arranged in the hydrogen storage tank (3), and the second heat exchange tube (4) is filled with heat transfer oil; The oil outlet of the second heat exchange tube (4) is connected to the oil inlet of the heating module through a first tube group (12), and the oil outlet of the heating module is connected to the oil inlet of the second heat exchange tube (4) through a second tube group (13). A circulation pump (8) is installed on the second tube group (13). The heating module is used to heat the heat transfer oil, and the circulation pump (8) drives the heat transfer oil to flow. The first tube group (12) is provided with a first branch tube (17), the end of which is connected to the oil inlet of the first heat exchange tube (2); the second tube group (13) is provided with a second branch tube (18), the end of which is connected to the oil outlet of the first heat exchange tube (2); When the hydrogen storage system absorbs hydrogen and releases heat, the circulating pump (8) drives the heat transfer oil to circulate between the second heat exchange tube (4) and the energy recovery device (1), so that the phase change heat storage material in the energy recovery device (1) absorbs heat and becomes molten, thereby recovering the energy released by the magnesium-based hydrogen storage material when absorbing hydrogen; When the hydrogen storage system releases hydrogen, the circulation pump (8) drives the heat transfer oil to circulate between the second heat exchange tube (4) and the energy recovery device (1), so that the phase change heat storage material in the energy recovery device (1) releases heat and returns to a solid state, thereby allowing the magnesium-based hydrogen storage material to release hydrogen.

2. A magnesium-based metal hydride hydrogen storage system with energy recovery function as claimed in claim 1, characterized in that: The heating module adopts electric heating.

3. A magnesium-based metal hydride hydrogen storage system with energy recovery function as claimed in claim 2, characterized in that: The heating module comprises an electric heater (6), an oil tank (7) for storing heat transfer oil is arranged inside the electric heater (6), and the electric heater (6) heats the heat transfer oil in the oil tank (7) when powered on.

4. The magnesium-based metal hydride hydrogen storage system with energy recovery function as claimed in claim 1, characterized in that: The exteriors of the hydrogen storage tank (3) and the energy recovery device (1) are both provided with a thermal insulation layer (5).

5. The magnesium-based metal hydride hydrogen storage system with energy recovery function as claimed in claim 1, characterized in that: The gas port of the hydrogen storage tank (3) is connected to the shell side outlet of the heat exchanger (27) through the third tube group (14), the shell side inlet of the heat exchanger (27) is connected to the fourth tube group (15), and cooling water is introduced into the tube side of the heat exchanger (27), so that the heat exchanger (27) uses water cooling to cool the hydrogen released by the magnesium-based hydrogen storage material.

6. A magnesium-based metal hydride hydrogen storage system with energy recovery function as claimed in claim 5, characterized in that: The third pipe group (14) is provided with a first exhaust pipe (19).

7. A magnesium-based metal hydride hydrogen storage system with energy recovery function as claimed in claim 5, characterized in that: The energy recovery device (1), the hydrogen storage tank (3), the first tube group (12), the second tube group (13), the first branch pipe (17) and the second branch pipe (18) are all equipped with a temperature sensor (11).

8. The magnesium-based metal hydride hydrogen storage system with energy recovery function as claimed in claim 1, characterized in that: The exhaust port of the energy recovery device (1) is connected to a second exhaust pipe (20).

9. The magnesium-based metal hydride hydrogen storage system with energy recovery function as claimed in claim 1, characterized in that: The energy recovery device (1) and the hydrogen storage tank (3) are both equipped with a pressure measuring device (10).

10. The magnesium-based metal hydride hydrogen storage system with energy recovery function as claimed in claim 1, characterized in that: A first valve (21) is installed at the oil inlet of the heating module, a second valve (22) is installed at the oil outlet of the heating module, a third valve (23) is installed on the first branch pipe (17), and a fourth valve (24) is installed on the second branch pipe (18).

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