Gas inspection method and gas inspection device

Abstract

One method of gas inspection in the present application is a gas inspection method implemented in a liquefied gas carrier. By installing a gas inspection unit containing a gas detector between the extractor of a flammable gas device and the waste pipeline connected to the waste gas treatment device, a gas inspection pipeline is formed between the flammable gas device and the waste gas treatment device. The gas to be inspected is introduced from the flammable gas device into the formed gas inspection pipeline, and the gas inspection of the gas to be inspected introduced into the gas inspection pipeline is carried out by the gas detector in the gas inspection pipeline. After the gas inspection of the gas to be inspected is carried out, by introducing an inert gas into the gas inspection pipeline, the gas to be inspected remaining in the gas inspection pipeline is discharged to the waste gas treatment device via the waste pipeline. After being inerted in the gas inspection pipeline, the gas inspection unit is removed between the extractor and the waste pipeline.

Description

Technical Field

[0001] The present application relates to a gas inspection method implemented in a liquefied gas carrier and a gas inspection device formed in a liquefied gas carrier. Background Art

[0002] A liquefied gas carrier is a ship that transports liquefied gas, which is obtained by liquefying a combustible gas, from one land base to another land base (see Patent Document 1). A liquefied gas carrier has equipment such as tanks and pipes inside that contain combustible gas (hereinafter referred to as "combustible gas equipment"). An extractor for extracting the gas inside is provided in the combustible gas equipment. The gas extracted via the extractor is inspected for properties, concentration of combustible gas, etc. (hereinafter referred to as "gas inspection") by a gas inspector.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-203106 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] Since there are multiple extractors provided in the combustible gas equipment in a liquefied gas carrier, it is not practical to install gas inspectors in all the extractors. Therefore, it is effective to install a detachable gas inspector on the corresponding extractor at the required time for gas inspection. However, in the case of using a detachable gas inspector, how to dispose of the gas extracted for gas inspection (hereinafter referred to as "inspection target gas") becomes a problem.

[0008] The present application has been completed in view of the above circumstances, and an object thereof is to provide a gas inspection method and a gas inspection device that can appropriately dispose of the inspection target gas extracted for gas inspection when performing gas inspection using a detachable gas inspection device in a liquefied gas carrier.

[0009] Means for Solving the Problems

[0010] One method of gas inspection according to the present application is implemented in a liquefied gas carrier. Among them, by installing a gas inspection unit including a gas detector between an extractor provided in a flammable gas device and a waste pipeline connected to an exhaust gas treatment device, a gas inspection pipeline is formed between the flammable gas device and the exhaust gas treatment device. The gas to be inspected is introduced from the flammable gas device into the formed gas inspection pipeline, and the gas inspection unit in the gas inspection pipeline performs gas inspection on the gas to be inspected introduced into the gas inspection pipeline. After the gas inspection on the gas to be inspected is completed, by introducing an inert gas into the gas inspection pipeline, the gas to be inspected remaining in the gas inspection pipeline is discharged to the exhaust gas treatment device via the waste pipeline. After being inerted in the gas inspection pipeline, the gas inspection unit is removed between the extractor and the waste pipeline.

[0011] One gas inspection device according to the present application is formed in a liquefied gas carrier. Among them, the gas inspection device has: an extractor provided in a flammable gas device; a waste pipeline connected to an exhaust gas treatment device; and a gas inspection unit detachably installed between the extractor and the waste pipeline to perform gas inspection on the gas to be inspected extracted from the flammable gas device.

[0012] Advantages of the Invention

[0013] According to the above structure, it is possible to provide a gas inspection method and a gas inspection device that can appropriately dispose of the gas to be inspected extracted for gas inspection when performing gas inspection using a detachable gas inspection device in a liquefied gas carrier. Brief Description of the Drawings

[0014] Figure 1 It is a schematic diagram of a gas inspection device.

[0015] Figure 2 It is a flowchart showing a gas inspection method.

[0016] Figure 3 It is a schematic diagram of a gas inspection device of a modified example. Detailed Embodiments

[0017] (Gas Inspection Device)

[0018] First, the gas inspection device 100 of the embodiment will be described. Figure 1 It is a schematic diagram of the gas inspection device 100. The gas inspection device 100 is formed in a liquefied gas carrier 101 that transports liquefied gas obtained by liquefying a flammable gas from one land base to another land base. Flammable gases such as hydrogen and natural gas are equivalent to the above-mentioned flammable gases.

[0019] The gas inspection device 100 includes an extractor 10, a waste pipeline 20, a gas inspection unit 30, and an inert gas supply unit 50. Hereinafter, these components will be described in sequence.

[0020] <Extractor>

[0021] The extractor 10 is a device that extracts gas from the combustible gas equipment 102. The combustible gas equipment 102 refers to equipment that has combustible gas inside. For example, a tank containing liquefied gas has combustible gas inside, so it is equivalent to the combustible gas equipment 102. In addition, when combustible gas temporarily flows, not only the pipeline through which combustible gas flows is equivalent to the combustible gas equipment 102, but also the pipeline through which liquefied gas flows is equivalent to the combustible gas equipment 102. Three combustible gas equipment 102 are illustrated in Figure 1 and the extractor 10 is provided for each combustible gas equipment 102.

[0022] The extractor 10 of the embodiment has an extraction pipeline 11 and an extraction valve 12 provided on the extraction pipeline 11. In Figure 1 , one extraction valve 12 is provided on each extraction pipeline 11, but two or more extraction valves 12 can also be provided on each extraction pipeline 11. The extraction valve 12 can be manually adjusted for the opening degree, can be automatically adjusted for the opening degree, or can be adjusted by both manual and automatic means. The same applies to each valve described later.

[0023] <Waste Pipeline>

[0024] The waste pipeline 20 is a pipeline connected to the waste gas treatment equipment. This waste gas treatment equipment includes a ship-side waste gas treatment equipment 110 provided on the liquefied gas carrier 101 and a land-side waste gas treatment equipment 111 provided on land. In addition, the ship-side waste gas treatment equipment 110 also includes a liquefied gas combustion device for treating liquefied gas and a ventilation mast for suppressing the pressure increase in the tank containing liquefied gas. The waste pipeline 20 of the embodiment is connected to both the ship-side waste gas treatment equipment 110 and the land-side waste gas treatment equipment 111. In addition, when the liquefied gas carrier 101 docks at the land base, the land-side waste gas treatment equipment 111 can be connected to the waste pipeline 20 via a pipeline extending from the land-side waste gas treatment equipment 111.

[0025] The waste pipeline 20 has a plurality of connection pipelines 21, a ship-side branch pipeline 22, and a land-side branch pipeline 23. The connection pipelines 21 are provided corresponding to each operation area 104 where the extractor 10 is provided. The operation area 104 can be either indoor or outdoor. A connection valve 24 is provided on each connection pipeline 21.

[0026] The respective connecting pipelines 21 converge, and the pipeline branches formed by the convergence are a ship-side branch pipeline 22 and a land-side branch pipeline 23. The ship-side branch pipeline 22 is a pipeline that connects the respective connecting pipelines 21 to the ship-side exhaust gas treatment device 110. In addition, the land-side branch pipeline 23 is a pipeline that connects the respective connecting pipelines 21 to the land-side exhaust gas treatment device 111. In addition, the respective connecting pipelines 21 may not converge but may be separately branched into a ship-side branch pipeline 22 and a land-side branch pipeline 23. A ship-side valve 25 is provided on the ship-side branch pipeline 22, and a land-side valve 26 is provided on the land-side branch pipeline 23.

[0027] <Gas inspection unit>

[0028] The gas inspection unit 30 is a unit that performs gas inspection on the gas (gas to be inspected) extracted from the combustible gas device 102 via the extractor 10. The gas inspection unit 30 can be carried and can be detachably connected to each extractor 10. In Figure 1 this case, in the operation area 104 located at the bottom of the drawing, the gas inspection unit 30 is connected to the extractor 10 via the inert gas supply unit 50 and the flexible pipe 61. In addition, the gas inspection unit 30 is connected to the connecting pipeline 21 of the waste pipeline 20 via the flexible pipe 62. That is, the gas inspection unit 30 is detachably installed between the extractor 10 and the waste pipeline 20.

[0029] The gas inspection unit 30 has a direct connection pipeline 31, an inlet pipeline 32, an outlet pipeline 33, a main pipeline 34, and a bypass pipeline 35.

[0030] The direct connection pipeline 31 is a pipeline that connects the inlet and outlet of the gas inspection unit 30. The inlet pipeline 32 is a pipeline that branches from a portion of the direct connection pipeline 31 near the inlet for the gas to be inspected to flow in. The outlet pipeline 33 is a pipeline that combines with a portion of the direct connection pipeline 31 near the outlet for the gas to be inspected to flow out. The main pipeline 34 is a pipeline that connects the inlet pipeline 32 and the outlet pipeline 33 and is provided with a gas inspector 37 described later. The bypass pipeline 35 is a pipeline that connects the inlet pipeline 32 and the outlet pipeline 33 and is arranged in parallel with the main pipeline 34.

[0031] The gas inspection unit 30 also has a gas inspector 37, a direct connection valve 38, a flow rate adjustment valve 39, a switching valve 40, a check valve 41, and a flow meter 42.

[0032] The gas detector 37 is a device that is installed in the main pipeline 34 and inspects the gas to be inspected extracted from the flammable gas equipment 102. The gas detector 37 in the embodiment is a concentration detector that inspects the proportion of the flammable gas in the gas to be inspected. However, the gas detector 37 can also be a device other than the concentration inspection device. In addition, the gas detector 37 can also be installed in the main pipeline 34 in a detachable manner. The direct connection valve 38 is installed in the direct connection pipeline 31, between the part where the inlet pipeline 32 of the direct connection pipeline 31 branches and the part where it combines with the outlet pipeline 33.

[0033] The flow rate adjustment valve 39 is installed in the inlet pipeline 32. The flow rate adjustment valve 39 can adjust the flow rate of the gas to be inspected in the inlet pipeline 32, and thus can adjust the flow rate of the gas to be inspected flowing into the gas detector 37. The switching valve 40 is installed at the boundary part of the inlet pipeline 32, the main pipeline 34, and the bypass pipeline 35. The switching valve 40 is a so-called three-way valve that can select which one of the main pipeline 34 and the bypass pipeline 35 to supply the gas to be inspected passing through the inlet pipeline 32.

[0034] The check valve 41 is installed in the main pipeline 34, downstream of the gas detector 37. The check valve 41 is a valve for preventing the gas to be inspected from flowing back to the gas detector 37. The flow meter 42 is installed in the inlet pipeline 32 and can measure the flow rate of the gas to be inspected flowing in the inlet pipeline 32. The flow meter 42 in the embodiment is located downstream of the flow rate adjustment valve 39. However, the flow meter 42 can also be located upstream of the flow rate adjustment valve 39.

[0035] <Inert gas supply unit>

[0036] The inert gas supply unit 50 is a unit that supplies inert gas between the extractor 10 and the gas inspection unit 30. For example, nitrogen, argon, etc. are equivalent to the above-mentioned inert gas. The inert gas supply unit 50 can be carried and can be detachably installed between the extractor 10 and the gas inspection unit 30. In the embodiment, the inert gas supply unit 50 is connected to the gas inspection unit 30 via a flexible pipe 61.

[0037] The inert gas supply unit 50 has: a direct connection pipeline 51 that connects the inlet and outlet of the inert gas supply unit 50; a supply pipeline 52 that is connected to the direct connection pipeline 51; and a supply valve 53 that is installed in the supply pipeline 52. In addition, the supply pipeline 52 can be detachably connected to the inert gas provider 105 via a flexible pipe 63.

[0038] An inert gas provider 105 is provided in each operation area 104. Each inert gas provider 105 is connected to an inert gas pipeline 106 laid on the liquefied gas carrier 101. The inert gas provider 105 can extract the inert gas in the inert gas pipeline 106. The inert gas provider 105 has an inert gas supply pipeline 107 and an inert gas supply valve 108 provided on the inert gas supply pipeline 107.

[0039] In addition, in the embodiment, the inert gas supply unit 50 is used to supply inert gas to the gas inspection pipeline 70, but inert gas can also be supplied to the gas inspection pipeline 70 by other methods. For example, inert gas can be supplied to the gas inspection pipeline 70 by supplying inert gas from the inert gas provider 105 to the combustible gas equipment 102.

[0040] (Gas inspection method)

[0041] Next, the gas inspection method of the embodiment will be described. Here, the proportion of combustible gas in the gas in the combustible gas equipment 102 is inspected. In addition, gas inspection is carried out in one of the multiple operation areas 104 (the operation area 104 at the bottom of the drawing in Figure 1 ). Figure 2 FIG. is a flowchart showing the gas inspection method. In addition, the gas inspection method described below can be implemented manually or automatically.

[0042] First, the gas inspection unit 30 and the inert gas supply unit 50 are installed between the extractor 10 and the waste pipeline 20 (step S1). Specifically, the gas inspection unit 30 is installed on the extractor 10 via the inert gas supply unit 50 and the flexible pipe 61. Then, the gas inspection unit 30 is installed on the waste pipeline 20 via the flexible pipe 62. At this time, the inert gas supply unit 50 is installed on the inert gas provider 105 via the flexible pipe 63.

[0043] Thus, the extractor 10, the inert gas supply unit 50, the flexible pipe 61, the gas inspection unit 30, the flexible pipe 62, and the waste pipeline 20 are connected in sequence from the upstream side, thereby forming the gas inspection pipeline 70. That is, a gas inspection pipeline 70 is formed between the combustible gas equipment 102 and the ship-side waste gas treatment equipment 110 and between the combustible gas equipment 102 and the land-side waste gas treatment equipment 111. In addition, when forming the gas inspection pipeline 70, all valves 12, 24, 25, 26, 38, 39, 53 except the switching valve 40 are in a closed state.

[0044] Next, the gas to be inspected is introduced from the flammable gas equipment 102 into the gas inspection pipeline 70 (step S2). Specifically, the extraction valve 12, the direct connection valve 38, the connection valve 24, and the ship side valve 25 are opened. As a result, the gas to be inspected extracted from the flammable gas equipment 102 flows through the gas inspection pipeline 70 toward the ship side exhaust gas treatment equipment 110. That is, the gas to be inspected passing through the gas inspection pipeline 70 is not discharged into the work area 104 but is discharged into the ship side exhaust gas treatment equipment 110.

[0045] Next, the flow rate of the gas to be inspected is adjusted (step S3). Specifically, the direct connection valve 38 is closed, the flow rate adjustment valve 39 is opened, and the switching valve 40 is operated so that the gas to be inspected passing through the inlet pipeline 32 flows into the bypass pipeline 35. As a result, the gas to be inspected flowing into the gas inspection unit 30 flows out of the gas inspection unit 30 through the bypass pipeline 35. In this state, while checking the flow meter 42, the flow rate adjustment valve 39 is adjusted so that the gas to be inspected becomes a predetermined flow rate.

[0046] Next, the gas inspection is performed on the gas to be inspected using the gas inspector 37 of the gas inspection unit 30 (step S4). Specifically, the switching valve 40 is operated so that the gas to be inspected passing through the inlet pipeline 32 flows into the main pipeline 34. As a result, the gas to be inspected passes through the gas inspector 37, and at this time, the gas inspection is performed by the gas inspector 37. In addition, as described above, the gas to be inspected is adjusted to a preset flow rate. Therefore, it is possible to prevent damage to the gas inspector 37 caused by a large amount of the gas to be inspected flowing into the gas inspector 37. The inspected gas to be inspected is discharged into the ship side exhaust gas treatment equipment 110 through the waste pipeline 20.

[0047] Next, after the gas inspection of the gas to be inspected is completed, an inert gas is introduced into the gas inspection pipeline 70 (step S5). Specifically, the extraction valve 12 is closed, and the inert gas supply valve 108 and the supply valve 53 are opened. As a result, the gas to be inspected remaining in the gas inspection pipeline 70 is extruded by the inert gas and discharged into the ship side exhaust gas treatment equipment 110.

[0048] In an embodiment, when introducing an inert gas into the gas inspection pipeline 70, the gas detector 37 checks the proportion of combustible gas in the gas within the gas inspection pipeline 70. Then, the inert gas is introduced into the gas inspection pipeline 70 until the proportion of combustible gas in the gas within the gas inspection pipeline 70 becomes below a certain value (specifically, until it reaches a proportion at which ignition is impossible). Thereby, the inside of the gas inspection pipeline 70 is inerted. In addition, the inert gas is also supplied to the direct connection pipeline 31 and the bypass pipeline 35 of the gas inspection unit 30, and the gas inside these pipelines is also discharged to the shipboard exhaust gas treatment equipment 110.

[0049] Finally, the gas inspection unit 30 and the inert gas supply unit 50 are removed between the extractor 10 and the waste pipeline 20 (step S6). At this time, all valves 12, 24, 25, 26, 38, 39, 53 except the switching valve 40 are in a closed state. By removing the respective units 30, 50, a part of the gas in the gas inspection unit 30, the inert gas supply unit 50, and the respective flexible pipes 61, 62, 63 is released into the work area 104. However, since the proportion of combustible gas in the gas released as described above is below a certain value, the combustible gas will not ignite in the work area.

[0050] In addition, in the above gas inspection method, the gas that has passed through the gas inspection pipeline 70 is discharged to the shipboard exhaust gas treatment equipment 110, but the shipboard valve 25 can be closed and the land-side valve 26 can be opened to discharge the gas that has passed through the gas inspection pipeline 70 to the land-side exhaust gas treatment equipment 111. Alternatively, both the shipboard valve 25 and the land-side valve 26 can be opened to discharge the gas that has passed through the gas inspection pipeline 70 to both the shipboard exhaust gas treatment equipment 110 and the land-side exhaust gas treatment equipment 111. The gas discharged to the shipboard exhaust gas treatment equipment 110 and the land-side exhaust gas treatment equipment 111 is appropriately treated such as by combustion.

[0051] (Modification example)

[0052] Next, the gas inspection device 200 of the modification example of the above embodiment will be described. Figure 3 It is a schematic diagram of the gas inspection device 200 of the modification example. The gas inspection device 200 of the modification example differs in structure from the gas inspection device 100 of the above embodiment in that the gas inspection unit 30 has a sampling balloon 45. Except for this point, it basically has the same structure as the gas inspection device 100 of the above embodiment.

[0053] The sampling balloon 45 is disposed on the upstream side of the flow rate adjustment valve 39 of the inlet pipeline 32 via the balloon pipeline 46. A balloon valve 47 is provided on the balloon pipeline 46. The sampling balloon 45 is formed of a material that can expand and contract, can temporarily store the gas to be inspected taken in from the inlet pipeline 32, and can discharge the stored gas to be inspected into the inlet pipeline 32. By opening and closing the balloon valve 47, the timing of storing gas in the sampling balloon 45 and the timing of discharging gas can be adjusted.

[0054] Thus, in the gas inspection device 200 of the modified example, the gas to be inspected can be temporarily stored in the sampling balloon 45, so that gas inspection can be performed in a state where the introduction of the gas to be inspected from the combustible gas device 102 into the gas inspection pipeline 70 is stopped. Therefore, according to the gas inspection device 200 of the modified example, the degree of freedom in gas inspection is improved.

[0055] (Function and effect)

[0056] As described above, the gas inspection method of the embodiment is a gas inspection method implemented in a liquefied gas carrier. By installing a gas inspection unit including a gas inspector between the extractor provided in the combustible gas device and the waste pipeline connected to the waste gas treatment device, a gas inspection pipeline is formed between the combustible gas device and the waste gas treatment device. The gas to be inspected is introduced from the combustible gas device into the formed gas inspection pipeline, and the gas inspector in the gas inspection pipeline performs gas inspection on the gas to be inspected introduced into the gas inspection pipeline. After the gas inspection on the gas to be inspected is performed, by introducing an inert gas into the gas inspection pipeline, the gas to be inspected remaining in the gas inspection pipeline is discharged into the waste gas treatment device via the waste pipeline. After the inside of the gas inspection pipeline is inerted, the gas inspection unit is removed between the extractor and the waste pipeline.

[0057] According to this method, both the gas to be inspected used in the gas inspection and the gas to be inspected remaining in the gas inspection pipeline are discharged into the waste gas treatment device. Therefore, according to the above method, the waste gas treatment of the gas to be inspected extracted for gas inspection can be appropriately performed.

[0058] In addition, in the gas inspection method of the embodiment, when introducing an inert gas into the gas inspection pipeline, the proportion of combustible gas in the gas in the gas inspection pipeline is inspected by the gas inspector, and the inert gas is introduced into the gas inspection pipeline until the proportion of combustible gas in the gas in the gas inspection pipeline becomes a certain value or less.

[0059] According to this method, the gas inspection unit can be removed after confirming that the inspection target gas extracted for gas inspection has been properly disposed of.

[0060] As described above, the gas inspection device of the embodiment is a gas inspection device formed on a liquefied gas carrier. The gas inspection device includes: an extractor provided in a combustible gas device; a waste pipeline connected to an exhaust gas treatment device; and a gas inspection unit detachably installed between the extractor and the waste pipeline to perform a gas inspection on the inspection target gas extracted from the combustible gas device.

[0061] According to this structure, the inspection target gas used in the gas inspection is discharged to the exhaust gas treatment device. Therefore, according to the above structure, the inspection target gas extracted for gas inspection can be properly disposed of.

[0062] In addition, in the gas inspection device of the embodiment, the waste pipeline is connected to an exhaust gas treatment device provided on the liquefied gas carrier and an exhaust gas treatment device provided on land. The waste pipeline includes: a connection pipeline connected to the gas inspection unit; a ship-side branch pipeline connecting the connection pipeline to the exhaust gas treatment device provided on the liquefied gas carrier; and a land-side branch pipeline connecting the connection pipeline to the exhaust gas treatment device provided on land.

[0063] According to this structure, the inspection target gas extracted for gas inspection can be discharged to either the exhaust gas treatment device provided on the liquefied gas carrier or the exhaust gas treatment device provided on land. Therefore, the degree of freedom in disposing of the inspection target gas is increased.

[0064] In addition, the gas inspection device of the embodiment further includes an inert gas supply unit detachably installed between the extractor and the gas inspection unit to supply inert gas between the extractor and the gas inspection unit.

[0065] According to this structure, inert gas can be easily supplied to the gas inspection pipeline.

[0066] In addition, in the gas inspection device according to the embodiment, the gas inspection unit includes: an inlet pipeline through which the gas to be inspected flows in; an outlet pipeline through which the gas to be inspected flows out; a main pipeline that connects the inlet pipeline and the outlet pipeline; a gas inspector that is provided in the main pipeline and inspects the gas to be inspected; a bypass pipeline that connects the inlet pipeline and the outlet pipeline and is provided in parallel with the main pipeline; a switching valve that can select which one of the main pipeline and the bypass pipeline to supply the gas to be inspected passing through the inlet pipeline; and a flow rate adjustment valve that is provided in the inlet pipeline and can adjust the flow rate of the gas to be inspected in the inlet pipeline.

[0067] According to this structure, it is possible to supply the gas to be inspected to the gas inspector after adjusting the flow rate of the gas to be inspected. Therefore, it is possible to prevent damage to the gas inspector caused by a large amount of the gas to be inspected flowing into the gas inspector.

[0068] In addition, in the gas inspection device according to the modified example, the gas inspection unit includes a sampling balloon that is provided at a position upstream of the flow rate adjustment valve in the inlet pipeline and temporarily stores and discharges the gas to be inspected.

[0069] According to this structure, it is possible to perform a gas inspection in a state where the supply of the gas to be inspected from the combustible gas device to the gas inspection pipeline is stopped. Therefore, according to this structure, the degree of freedom of the gas inspection is improved.

[0070] Reference Numeral Explanation

[0071] 10: Extractor; 20: Waste pipeline; 21: Connection pipeline; 22: Ship-side branch pipeline; 23: Land-side branch pipeline; 30: Gas inspection unit; 32: Inlet pipeline; 33: Outlet pipeline; 34: Main pipeline; 35: Bypass pipeline; 37: Gas inspector; 39: Flow rate adjustment valve; 40: Switching valve; 45: Sampling balloon; 50: Inert gas supply unit; 70: Gas inspection pipeline; 100: Gas inspection device; 101: Liquefied gas carrier; 102: Combustible gas device; 110: Ship-side exhaust gas treatment device (exhaust gas treatment device); 111: Land-side exhaust gas treatment device (exhaust gas treatment device); 200: Gas inspection device.

Claims

1. A gas inspection method, which is implemented in a liquefied gas carrier, wherein, by selectively installing a gas inspection unit including a gas detector in a detachable manner between any one of a plurality of extractors provided in a combustible gas device and an exhaust pipeline connected to an exhaust gas treatment device, a gas inspection pipeline to be inspected is formed between the selected one of the extractors of the combustible gas device and the exhaust gas treatment device; introduce a gas to be inspected from the combustible gas device into the formed gas inspection pipeline; perform a gas inspection on the gas to be inspected introduced into the gas inspection pipeline through the gas detector in the gas inspection pipeline; after performing the gas inspection on the gas to be inspected, introduce an inert gas into the gas inspection pipeline, and discharge the gas to be inspected remaining in the gas inspection pipeline to the exhaust gas treatment device via the exhaust pipeline; after the gas inspection pipeline is inerted, remove the gas inspection unit between the selected one of the extractors and the exhaust pipeline to disconnect the gas inspection pipeline, so that the gas inspection unit can be detachably installed between another one of the plurality of extractors and the exhaust pipeline connected to the exhaust gas treatment device to form another gas inspection pipeline to be inspected.

2. The gas inspection method according to claim 1, wherein, when introducing an inert gas into the gas inspection pipeline, use the gas detector to inspect the proportion of combustible gas in the gas in the gas inspection pipeline, and introduce an inert gas into the gas inspection pipeline until the proportion of combustible gas in the gas in the gas inspection pipeline becomes below a certain value.

3. A gas inspection device, which is formed in a liquefied gas carrier, wherein, the gas inspection device includes: a plurality of extractors provided in a combustible gas device; an exhaust pipeline connected to an exhaust gas treatment device; and a gas inspection unit selectively installed in a detachable manner between any one of the plurality of extractors and the exhaust pipeline, and perform a gas inspection on the gas to be inspected extracted from the combustible gas device; after removing the gas inspection unit between the selected one of the extractors and the exhaust pipeline, the gas inspection unit can be detachably installed between another one of the plurality of extractors and the exhaust pipeline connected to the exhaust gas treatment device.

4. The gas inspection device according to claim 3, wherein, the exhaust pipeline is connected to an exhaust gas treatment device provided on the liquefied gas carrier and an exhaust gas treatment device provided on land; the exhaust pipeline includes: a plurality of connection pipelines respectively corresponding to the plurality of extractors, and the plurality of connection pipelines can be respectively connected to the gas inspection unit; a ship-side branch pipeline connecting the plurality of connection pipelines to an exhaust gas treatment device provided on the liquefied gas carrier; and A land-side branch pipeline that connects the plurality of connecting pipelines to an exhaust gas treatment device provided on the land.

5. The gas inspection device according to claim 3 or 4, wherein the gas inspection device further has an inert gas supply unit that is detachably installed between the extractor and the gas inspection unit and supplies inert gas between the extractor and the gas inspection unit.

6. The gas inspection device according to claim 3 or 4, wherein the gas inspection unit has: an inlet pipeline through which the gas to be inspected flows in; an outlet pipeline through which the gas to be inspected flows out; a main pipeline that connects the inlet pipeline and the outlet pipeline; a gas inspector that is provided on the main pipeline and inspects the gas to be inspected; a bypass pipeline that connects the inlet pipeline and the outlet pipeline and is provided in parallel with the main pipeline; a switching valve that can select which one of the main pipeline and the bypass pipeline to supply the gas to be inspected that has passed through the inlet pipeline; and a flow rate adjustment valve that is provided on the inlet pipeline and can adjust the flow rate of the gas to be inspected in the inlet pipeline.

7. The gas inspection device according to claim 6, wherein the gas inspection unit has a sampling balloon that is provided at a position upstream of the flow rate adjustment valve in the inlet pipeline and temporarily stores and discharges the gas to be inspected.

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