Refueling water tank hydrogen removal system and method

Abstract

The invention provides a hydrogen removal system and method for a refueling water tank, the system comprises a pressure stabilizer, the top end of the pressure stabilizer is connected with the refueling water tank through a first connecting pipeline, one end of the first connecting pipeline is inserted below the liquid level of the refueling water tank, and a pressure release valve is arranged on the first connecting pipeline; the first connecting pipeline is connected to a downstream treatment system through a second connecting pipeline at the upstream of the pressure release valve, and an exhaust valve is arranged on the second connecting pipeline; the refueling water tank is further provided with a nitrogen filling pipeline, the nitrogen filling pipeline comprises a main pipeline and a branch pipeline, one end of the main pipeline is connected to the downstream treatment system, one end of the branch pipeline is connected with the main pipeline, and the other end of the branch pipeline is inserted into the gas space of the refueling water tank; wherein a vacuum ejector is arranged on the main pipeline, an exhaust pipeline is further arranged on the refueling water tank, one end of the exhaust pipeline is communicated with the gas space of the refueling water tank, and the other end of the exhaust pipeline is connected to the vacuum ejector.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power unit safety control, and in particular to a hydrogen removal system and method for a refueling water tank. Background Art

[0002] During normal operation of a nuclear power unit, the oxygen content in the water is suppressed by adding hydrogen to the reactor coolant circuit to ensure that the water chemistry meets the operating requirements, thereby greatly reducing the possibility of corrosion.

[0003] During the shutdown period, the hydrogen in the reactor coolant loop needs to be released and discharged reliably and safely, and necessary measures must be taken to avoid the risk of hydrogen accumulation and combustion.

[0004] Currently, when designing the containment structure of a nuclear power plant, flow optimization is typically performed in local compartments to improve hydrogen diffusion conditions and reduce the possibility of hydrogen accumulation. The refueling tank within the containment, a crucial pressure relief and exhaust device during normal operation and after an accident, is typically semi-enclosed to prevent the release of radioactive gases into the containment atmosphere. However, if hydrogen is released into the containment refueling tank's air space and cannot be promptly dispersed or discharged, it could cause local hydrogen concentrations to exceed combustion limits, resulting in the risk of combustion and a significant safety hazard.

[0005] Based on this, the inventors of the present application propose a system and method for removing hydrogen from a refueling water tank in order to solve one or more of the above-mentioned technical problems. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defect in the prior art that hydrogen easily accumulates in the gas space of the refueling water tank and cannot be discharged in time, which causes safety risks, and to provide a refueling water tank hydrogen removal system and method.

[0007] The present invention solves the above technical problems through the following technical solutions:

[0008] The present invention provides a hydrogen removal system for a refueling water tank, comprising:

[0009] A pressure stabilizer, the top end of which is connected to the refueling water tank through a first connecting pipe, one end of which is inserted below the liquid level of the refueling water tank, and a pressure relief valve is provided on the first connecting pipe;

[0010] The first connecting pipeline is connected to the downstream processing system upstream of the pressure relief valve through a second connecting pipeline, and the second connecting pipeline is provided with an exhaust valve;

[0011] The refueling water tank is further provided with a nitrogen filling pipeline, which includes a main pipeline and a branch pipeline. One end of the main pipeline is connected to the downstream processing system, one end of the branch pipeline is connected to the main pipeline, and the other end is inserted into the air space of the refueling water tank; wherein,

[0012] A vacuum ejector is provided on the main pipeline, and an air extraction pipeline is also provided on the refueling water tank. One end of the air extraction pipeline is communicated with the air space of the refueling water tank, and the other end is connected to the vacuum ejector.

[0013] According to one embodiment of the present invention, a diffuser is provided at one end of the first connecting pipe inserted below the liquid level of the refueling water tank, and the diffuser is arranged close to the bottom wall of the refueling water tank.

[0014] According to one embodiment of the present invention, a nitrogen isolation valve is provided on the main line, and the nitrogen isolation valve is located upstream of the connection position between the branch line and the main line.

[0015] According to one embodiment of the present invention, a hydrogen detector is further provided on the top of the refueling water tank, and the hydrogen detector is used to detect whether hydrogen exists in the refueling water tank.

[0016] According to one embodiment of the present invention, the hydrogen detector is communicatively connected to the nitrogen isolation valve.

[0017] According to one embodiment of the present invention, a first check valve is provided on one end of the second connecting pipeline close to the downstream processing system;

[0018] The main pipe is provided with a second check valve at one end close to the downstream processing system;

[0019] The second connecting pipeline merges with the main pipeline at one end close to the downstream processing system and is connected to the downstream processing system.

[0020] According to one embodiment of the present invention, an anti-external pressure panel and an anti-internal pressure panel are respectively provided on opposite sides of the top of the refueling water tank, and the anti-external pressure panel and the anti-internal pressure panel are used to cooperate to balance the pressure balance of the air space of the refueling water tank.

[0021] According to one embodiment of the present invention, the downstream treatment system includes a drain tank, a liquid level gauge and a water supply pipeline, one end of the liquid level gauge is inserted into and installed on the drain tank, and one end of the water supply pipeline is connected to the bottom of the drain tank;

[0022] An exhaust pipe is also provided on the top of the drain tank, and one end of the exhaust pipe is inserted into the air space on the top of the drain tank.

[0023] The present invention also provides a method for removing hydrogen from a refueling water tank, using the refueling water tank hydrogen removal system as described above, the method comprising:

[0024] Step 1: Install a hydrogen detector and nitrogen filling pipeline on the top of the refueling water tank;

[0025] Step 2: When the hydrogen detector detects the presence of hydrogen in the refueling water tank, the nitrogen filling pipeline is opened to extract the hydrogen in the refueling water tank and transport it to the downstream processing system.

[0026] According to one embodiment of the present invention, a vacuum ejector is provided on the nitrogen filling pipeline, and the vacuum ejector is connected to the air space of the refueling water tank through one end of the air extraction pipeline.

[0027] The positive progress effect of the present invention is:

[0028] The hydrogen removal system for the refueling water tank of the present invention discharges non-condensable gas and hydrogen to the downstream processing system through the first connecting pipeline and the second connecting pipeline during normal operation and shutdown, thereby reducing the hydrogen content at the top of the pressurizer. In order to avoid the residual hydrogen entering the refueling water tank and causing local accumulation after the pressure relief valve is opened before the shutdown and refueling water supply, or the hydrogen at the top of the pressurizer entering the air space of the refueling water tank and causing local accumulation due to erroneous opening of the pressure relief valve, a nitrogen charging pipeline is provided, and the gas in the air space of the refueling water tank is extracted by an exhaust pipeline through a vacuum ejector provided on the nitrogen charging pipeline, and the gas is mixed with nitrogen and then enters the downstream processing system. With this arrangement, the risk of hydrogen accumulation in the refueling water tank can be avoided, thereby greatly improving the operating safety of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which:

[0030] Figure 1 This is a three-dimensional diagram of the hydrogen removal system for the refueling water tank of the present invention.

[0031] 1. Pressure stabilizer; 11. First connecting pipeline; 111. Pressure relief valve; 12. Diffuser;

[0032] 2. Second connecting pipeline; 21. Exhaust valve; 22. First check valve;

[0033] 3. Refueling water tank; 31. Air extraction pipeline; 32. Hydrogen detector; 33. External pressure protection panel; 34. Internal pressure protection panel;

[0034] 4. Nitrogen filling pipeline; 41. Main pipeline; 411. Vacuum ejector; 42. Branch pipeline; 43. Second check valve; 44. Nitrogen isolation valve;

[0035] 5. Downstream treatment system; 51. Drain tank; 52. Liquid level gauge; 53. Water supply pipeline; 54. Exhaust pipeline. DETAILED DESCRIPTION

[0036] The present invention is further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from the description herein. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0038] Please refer to Figure 1 The present invention provides a refueling water tank hydrogen removal system, comprising a pressurizer 1, the top end of which is connected to the refueling water tank 3 via a first connecting pipe 11. One end of the first connecting pipe 11 is inserted below the liquid level of the refueling water tank 3. The first connecting pipe 11 is provided with a pressure relief valve 111, which is used to control the flow between the pressurizer 1 and the refueling water tank 3. The first connecting pipe 11 is connected to the downstream treatment system 5 upstream of the pressure relief valve 111 via a second connecting pipe 2, which is provided with a vent valve 21.

[0039] The refueling water tank 3 is also equipped with a nitrogen charging pipeline 4, which includes a main pipeline 41 and a branch pipeline 42. The main pipeline 41 is connected to the downstream processing system 5 at one end, and the branch pipeline 42 is connected to the main pipeline 41 at one end and inserted into the air space of the refueling water tank 3 at the other end. The main pipeline 41 is equipped with a vacuum ejector 411. The refueling water tank 3 is also equipped with an air extraction pipeline 31. The air extraction pipeline 31 is connected to the air space of the refueling water tank 3 at one end and connected to the vacuum ejector 411 at the other end.

[0040] It should be noted that the vacuum ejector realizes the suction function by converting the kinetic energy of high-pressure nitrogen based on the ejection effect in fluid dynamics, thereby forming a suction effect on the air space of the refueling water tank 1 to suck the gas in the air space of the refueling water tank 1 into the main line 41.

[0041] It can be seen that during normal operation and shutdown, the pressure relief valve 111 is closed, and the second connecting pipeline 2 discharges the non-condensable gas and hydrogen at the top of the pressurizer 1 to the downstream processing system 5, thereby reducing the hydrogen content at the top of the pressurizer 1.

[0042] Furthermore, to prevent localized accumulation of residual hydrogen gas entering the refueling water tank 3 after the pressure relief valve 111 is opened before the reactor is shut down for refueling and water delivery, or localized accumulation of hydrogen gas in the gas space of the pressurizer 1 entering the refueling water tank 3 after the pressure relief valve 111 is mistakenly opened, a nitrogen charging line 4 is provided, and a vacuum ejector 411 is installed on the nitrogen charging line 4. The gas in the gas space of the refueling water tank 3 is promptly discharged using the vacuum ejector 411 and the exhaust line 31. Simultaneously, the nitrogen charging line 4 replenishes nitrogen gas into the gas space of the refueling water tank 3 through the branch line 42, maintaining its pressure stability and preventing pressure imbalance in the gas space of the refueling water tank 3, which could adversely affect its structural integrity.

[0043] Therefore, by setting up the nitrogen filling pipeline 4, the present application can avoid the risk of local hydrogen accumulation on the top of the refueling water tank 3, thereby greatly improving the safety of the unit.

[0044] In one embodiment, a diffuser 12 is provided at one end of the first connecting pipe 11 inserted below the liquid level of the refueling water tank 3 , and the diffuser 12 is arranged close to the bottom wall of the refueling water tank 3 .

[0045] like Figure 1 The diffuser 12 has a porous structure and is used to diffuse and slow down the hydrogen-containing gas flow discharged into the refueling water tank 3 through the first connecting pipe 11, so as to prevent the gas from impacting the inner wall or liquid surface of the refueling water tank 3 and thereby damaging the structure of the refueling water tank 3. At the same time, it can also prevent the gas from excessively stirring the water body to produce radioactive aerosols.

[0046] Regarding the shape of the diffuser 12 , the diffuser 12 may be in the shape of a long cylinder, and a plurality of evenly arranged diffusion holes are provided around the cylinder. The specific shape and structure of the diffuser 12 are merely examples and are not intended to be limiting.

[0047] The gas diffused by the diffuser 12 is more easily and evenly sucked by the vacuum ejector 411, thereby improving the inerting efficiency.

[0048] In one embodiment, a nitrogen isolation valve 44 is provided on the main line 41 , and the nitrogen isolation valve 44 is located upstream of the connection position between the branch line 42 and the main line 41 .

[0049] The nitrogen isolation valve 44 is used to control the on-off of the main line 41, so that when nitrogen needs to be charged into the refueling water tank 3, the nitrogen isolation valve 44 is opened. When there is no hydrogen in the gas space of the refueling water tank 3, the nitrogen isolation valve 44 is kept in a closed state.

[0050] Furthermore, a hydrogen detector 32 is provided on the top of the refueling water tank 3 , and the hydrogen detector 32 is used to detect whether hydrogen exists in the refueling water tank 3 .

[0051] When the pressure relief valve 111 is opened by mistake, or when the pressure relief valve 111 is opened before the reactor is shut down for refueling and water supply, the hydrogen at the top of the pressurizer 1 will still flow into the refueling water tank 3 through the first connecting pipe 11, and there is a risk of local accumulation.

[0052] Therefore, the present application sets a hydrogen detector 32 on the top of the refueling water tank 3. When the hydrogen detector 32 detects that there is hydrogen in the air space of the refueling water tank 3 or the hydrogen concentration reaches a predetermined value, the nitrogen filling pipeline 4 is opened to extract the hydrogen entering the refueling water tank 3, and the hydrogen is mixed with nitrogen and flows to the downstream processing system 5.

[0053] Optionally, the hydrogen detector 32 is in communication with the nitrogen isolation valve 44 .

[0054] That is, when the hydrogen detector 32 detects hydrogen, a signal is transmitted to the nitrogen isolation valve 44, thereby driving the nitrogen isolation valve 44 to automatically open, and the hydrogen in the refueling water tank 3 is extracted through the exhaust pipe 31. The specific structure and model of the hydrogen detector 32 are not limited here.

[0055] In one embodiment, a first check valve 22 is provided at one end of the second connecting pipeline 2 close to the downstream processing system 5; a second check valve 43 is provided at one end of the main pipeline 41 close to the downstream processing system 5; the second connecting pipeline 2 and the main pipeline 41 merge at one end close to the downstream processing system 5 and are connected to the downstream processing system 5.

[0056] The first check valve 22 and the second check valve 43 are provided to prevent the gas on the downstream processing system 5 side from flowing back to the first connecting pipeline 11 and the second connecting pipeline 2, thereby playing a one-way flow protection role.

[0057] Optionally, an external pressure prevention panel 33 and an internal pressure prevention panel 34 are respectively provided on opposite sides of the top of the refueling water tank 3 , and the external pressure prevention panel 33 and the internal pressure prevention panel 34 are used to cooperate in balancing the pressure balance of the air space of the refueling water tank 3 .

[0058] That is, when the air space of the refueling water tank 3 is over-pressured, the anti-internal pressure panel 34 opens; when the air space of the refueling water tank 3 is under-pressured, the anti-external pressure panel 33 opens, thereby avoiding pressure imbalance in the refueling water tank 3 and adversely affecting the structural integrity of the refueling water tank 3.

[0059] That is, the external pressure prevention panel 33 and the internal pressure prevention panel 34 can automatically balance the pressure of the air space in the refueling water tank 3 .

[0060] In one embodiment, the downstream treatment system 5 includes a drain tank 51, a liquid level gauge 52 and a water supply pipeline 53. One end of the liquid level gauge 52 is inserted into and installed on the drain tank 51, and one end of the water supply pipeline 53 is connected to the bottom of the drain tank 51; an exhaust pipeline 54 is also provided at the top of the drain tank 51, and one end of the exhaust pipeline 54 is inserted into the air space at the top of the drain tank 51.

[0061] The liquid level meter 52 is used to monitor the liquid level of the drain tank 51 , so that when the liquid level in the drain tank 51 is higher than a preset value, excess coolant is discharged through the water supply pipe 53 .

[0062] The operating principle of the hydrogen removal system for the refueling water tank of this application is described in detail as follows:

[0063] During normal operation and shutdown, the pressure relief valve 111, the exhaust valve 21 and the nitrogen isolation valve 44 are closed.

[0064] During normal shutdown, the exhaust valve 21 is opened, and non-condensable gases such as hydrogen in the air space above the pressurizer 1 are discharged through the second connecting pipe to the downstream processing system 5. The liquid level in the coolant drain tank 51 is monitored by a liquid level gauge 52. When the liquid level exceeds a preset value, the water supply pipe 53 is opened to discharge the coolant.

[0065] At the end of the shutdown, before the pressure relief valve 111 needs to be opened, the nitrogen filling pipeline 4 is started, the nitrogen isolation valve 44 is opened, and the high-pressure nitrogen enters the vacuum ejector 411 to extract the gas in the air space of the refueling water tank 3. The gas enters the drain tank 51 through the second check valve 43 and enters the exhaust pipeline 54 after water washing.

[0066] At the same time, a portion of the high-pressure nitrogen enters the air space of the refueling water tank 3 through the branch pipe 42. On the one hand, it is used to reduce the vacuum degree of the refueling water tank 3 and maintain a relatively stable pressure; on the other hand, the injection of nitrogen promotes the uniform diffusion of hydrogen, prevents local accumulation, and plays an inerting role.

[0067] Then the pressure relief valve 111 is opened, and the non-condensable gas containing hydrogen at the top of the pressurizer 1 flows into the refueling water tank 3 through the first connecting pipe 11 and the diffuser 12 and finally enters the air space of the refueling water tank 3, mixes with the nitrogen filled in the air space, is continuously inerted and simultaneously extracted by the exhaust pipe 31, avoiding the risk of hydrogen accumulation.

[0068] It should be noted that the top of the refueling water tank 3 is also equipped with an internal pressure prevention panel 34 and an external pressure prevention panel 33. When the air space of the refueling water tank 3 is overpressured, the internal pressure prevention panel 34 opens, and the gas in the air space of the refueling water tank 3 is discharged to the outside of the refueling water tank 3 through the internal pressure prevention panel 34 to balance the air pressure. If the refueling water tank 3 is under negative pressure, the external pressure prevention panel 33 opens, and external air is automatically drawn into the refueling water tank 3 to balance the air pressure. This arrangement can prevent pressure imbalances in the refueling water tank 3 and maintain the structural integrity of the refueling water tank 3.

[0069] When the pressure relief valve 111 is mistakenly opened, the non-condensable gas containing hydrogen flows into the refueling water tank 3 through the first connecting pipe and the diffuser 12 and finally reaches the air space of the refueling water tank 3. When the hydrogen detector 32 detects hydrogen or the hydrogen content exceeds the preset value, the nitrogen isolation valve 44 is opened, and the gas in the air space of the refueling water tank 3 is extracted through the vacuum ejector 411. At the same time, high-pressure nitrogen is replenished to the air space of the refueling water tank 3, which promotes uniform diffusion of hydrogen, prevents local accumulation, and plays an inerting role.

[0070] As configured above, the present application can avoid the risk of hydrogen accumulation in the gas space of the refueling water tank 3 during normal shutdown and after an accident. At the same time, an anti-external pressure panel 33 and an anti-internal pressure panel 34 are provided to prevent the pressure imbalance in the refueling water tank 3 from causing damage to the overall structure of the refueling water tank 3, thereby greatly improving the operating safety of the unit.

[0071] The present invention also provides a method for removing hydrogen from a refueling water tank, using the above refueling water tank hydrogen removal system, the method comprising:

[0072] Step 1: Install a hydrogen detector and nitrogen filling pipeline on the top of the refueling water tank;

[0073] Step 2: When the hydrogen detector detects the presence of hydrogen in the refueling water tank, open the nitrogen filling pipeline to extract the hydrogen in the refueling water tank and transport it to the downstream processing system.

[0074] By adopting the above method, the risk of hydrogen accumulation in the gas space of the nuclear power plant's refueling tank can be completely avoided, greatly improving the operating safety of the unit.

[0075] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "install", "connect", "connect", "fix" and so on should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can also be a mechanical connection. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0076] This application uses specific terms to describe the embodiments of this application. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a certain feature, structure, or characteristic associated with at least one embodiment of this application. Therefore, it should be emphasized and noted that "one embodiment," "an embodiment," or "an alternative embodiment" mentioned twice or multiple times in different locations in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application may be appropriately combined.

[0077] Although the present invention is disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modifications, equivalent variations, and modifications made to the above embodiments in accordance with the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A hydrogen removal system for a refueling water tank, characterized in that: include: A pressure stabilizer, the top end of which is connected to the refueling water tank through a first connecting pipe, one end of which is inserted below the liquid level of the refueling water tank, and a pressure relief valve is provided on the first connecting pipe; The first connecting pipeline is connected to the downstream processing system upstream of the pressure relief valve through a second connecting pipeline, and the second connecting pipeline is provided with an exhaust valve; The refueling water tank is further provided with a nitrogen filling pipeline, which includes a main pipeline and a branch pipeline. One end of the main pipeline is connected to the downstream processing system, one end of the branch pipeline is connected to the main pipeline, and the other end is inserted into the air space of the refueling water tank; wherein, A vacuum ejector is provided on the main pipeline, and an air extraction pipeline is also provided on the refueling water tank. One end of the air extraction pipeline is communicated with the air space of the refueling water tank, and the other end is connected to the vacuum ejector.

2. The hydrogen removal system for the refueling water tank according to claim 1, characterized in that: A diffuser is provided at one end of the first connecting pipe inserted below the liquid level of the refueling water tank, and the diffuser is arranged close to the bottom wall of the refueling water tank.

3. The hydrogen removal system for the refueling water tank according to claim 1, characterized in that: A nitrogen isolation valve is provided on the main line, and the nitrogen isolation valve is located upstream of the connection position between the branch line and the main line.

4. The refueling water tank hydrogen removal system according to claim 3, characterized in that: A hydrogen detector is also provided on the top of the refueling water tank, and the hydrogen detector is used to detect whether there is hydrogen in the refueling water tank.

5. The hydrogen removal system for the refueling water tank according to claim 4, characterized in that: The hydrogen detector is in communication connection with the nitrogen isolation valve.

6. The refueling water tank hydrogen removal system according to claim 1, characterized in that: The second connecting pipeline is provided with a first check valve at one end close to the downstream processing system; The main pipe is provided with a second check valve at one end close to the downstream processing system; The second connecting pipeline merges with the main pipeline at one end close to the downstream processing system and is connected to the downstream processing system.

7. The refueling water tank hydrogen removal system according to claim 1, characterized in that: An external pressure prevention panel and an internal pressure prevention panel are respectively provided on opposite sides of the top of the refueling water tank. The external pressure prevention panel and the internal pressure prevention panel are used to cooperate to balance the pressure balance of the air space of the refueling water tank.

8. The refueling water tank hydrogen removal system according to claim 1, characterized in that: The downstream treatment system includes a drain tank, a liquid level gauge and a water supply pipeline, wherein one end of the liquid level gauge is inserted into and installed on the drain tank, and one end of the water supply pipeline is connected to the bottom of the drain tank; An exhaust pipe is also provided on the top of the drain tank, and one end of the exhaust pipe is inserted into the air space on the top of the drain tank.

9. A method for removing hydrogen from a refueling water tank, characterized in that: The refueling water tank hydrogen removal system according to any one of claims 1 to 8 is used, wherein the method comprises: Step 1: Install a hydrogen detector and nitrogen filling pipeline on the top of the refueling water tank; Step 2: When the hydrogen detector detects the presence of hydrogen in the refueling water tank, the nitrogen filling pipeline is opened to extract the hydrogen in the refueling water tank and transport it to the downstream processing system.

10. The method for removing hydrogen from a refueling water tank according to claim 9, characterized in that: A vacuum ejector is provided on the nitrogen filling pipeline, and the vacuum ejector is communicated with the air space of the refueling water tank through one end of the air extraction pipeline.

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