A gas detection device, a gas detection method, and a gas detection system

Abstract

The application discloses a kind of gas detection device, gas detection method and gas detection system, gas detection device includes sampling tank, main pipeline, gas sensor, first flow path and second flow path.Main pipeline is fixedly arranged at the top of sampling tank and is communicated with sampling tank, in the direction from top to bottom, main pipeline is extended to sampling tank from sampling tank outside.In, gas sensor is connected with main pipeline, and is contacted with gas in main pipeline.First flow path includes the gas inlet end and gas outlet end respectively arranged on the side wall of main pipeline, gas flows along gas inlet end to gas outlet end, to form gas flow path.Second flow path includes the inlet pipe and outlet pipe respectively arranged on the side wall of sampling tank, liquid flows along inlet pipe to outlet pipe, to form liquid flow path.The application avoids that gas sensor is immersed in seawater and reduces life and causes detection failure, prolongs the life of sensor, improves detection effectiveness.

Description

Technical Field

[0001] This invention relates to the field of gas detection technology for liquefied gas carriers, specifically to a gas detection device, a gas detection method, and a gas detection system. Background Technology

[0002] Liquefied gas carriers are cargo ships specifically designed to transport liquefied gas. They can be divided into liquefied natural gas carriers (primarily composed of methane) and liquefied petroleum gas carriers (primarily composed of propane). On liquefied gas carriers, it is often necessary to heat the liquid cargo to evaporate it into gas. The most economical heating method is to use seawater as a heat medium, and to heat the incoming liquid cargo through a heat exchanger to evaporate it into gas.

[0003] According to the International Code for the Construction and Equipment of Liquefied Gas Carriers (IGC Code), liquefied gas carriers must be equipped with a gas detection system for any cargo heating or cooling medium. If a heat exchanger leaks, cargo vapors can mix with the seawater inside the heat exchanger. Typically, the gas detection system is located outside the liquefied cargo seawater outlet. This system can detect whether the liquefied cargo seawater contains leaked cargo gases to determine if the heat exchanger is leaking.

[0004] Currently, in liquefied gas carriers, a liquefied cargo seawater sampling tank (hereinafter referred to as the sampling tank) is installed at the gas detection point to meet gas detection requirements. Seawater flows from a branch pipe on the main liquefied cargo seawater system to the sampling tank and then returns to the downstream of the main liquefied cargo seawater system. The gas sensor is directly installed on top of the sampling tank. Due to the high pressure of the liquefied cargo seawater at this point, the seawater completely fills the sampling tank, causing the gas sensor to be constantly submerged in the seawater inside. Because seawater is highly corrosive, the constant immersion of the gas sensor in the seawater inside the sampling tank will corrode the sensor, significantly reducing its lifespan. Furthermore, gases escaping from the rapidly flowing seawater are difficult for the gas sensor to capture and detect. If a leak occurs in the heat exchanger and is not detected by the gas sensor, the seawater in the heat exchanger will leak into the cargo system, contaminating the cargo. Moreover, if the cargo gas mixed in with the liquefied cargo seawater is flammable or explosive, the heat exchanger leak will also cause gas leakage, which may then enter other systems, potentially causing greater danger. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a gas detection device, a gas detection method, and a gas detection system, so that the gas sensor is always in a gas environment, ensuring that the gas in the liquid cargo seawater can dissipate for easy sensor detection, while also ensuring continuous seawater flow. This not only solves the requirement of continuous monitoring of gas detection in the liquid cargo seawater system of liquefied gas carriers, but also improves the accuracy of gas detection and extends the service life of the sensor.

[0006] To achieve the above and other related objectives, the present invention provides a gas detection device, comprising:

[0007] A sampling container, including a top and bottom end that are positioned opposite each other;

[0008] The main pipeline is fixedly installed at the top of the sampling tank and connected to the sampling tank. In the direction from the top to the bottom, the main pipeline extends from the outside of the sampling tank to the inside of the sampling tank.

[0009] A gas sensor is connected to the main pipeline and comes into contact with the gas inside the main pipeline;

[0010] The first flow path includes an air inlet and an air outlet respectively disposed on the side wall of the main pipeline, and the gas flows from the air inlet to the air outlet to form a gas flow path.

[0011] The second flow path is located on the side of the sampling tank near the bottom and includes an inlet pipe and an outlet pipe respectively installed on the side wall of the sampling tank. The liquid flows along the inlet pipe to the outlet pipe to form a liquid flow path.

[0012] Optionally, the height of the inlet pipe is higher than the height of the outlet pipe along the direction from bottom to top.

[0013] Optionally, the height of the air inlet end is lower than the height of the air outlet end along the direction from the bottom to the top.

[0014] Optionally, the main pipeline extending into the sampling tank includes:

[0015] An extension pipeline extends from the top of the sampling container into the sampling container, and at least one first through hole is provided on the extension pipeline;

[0016] A pipe cap is installed at the port of the extension pipe, and a second through hole is provided on the pipe cap.

[0017] Optionally, the extension pipeline is provided with three first through holes, which are evenly arranged radially along the extension pipeline.

[0018] Optionally, a first viewing mirror is also provided on the side wall of the sampling container, and the height of the first viewing mirror along the direction from the bottom to the top is the same as the height of the cap along the direction from the bottom to the top.

[0019] Optionally, an inlet branch line is provided on the inlet pipeline, and an outlet branch line is provided on the outlet pipeline.

[0020] Optionally, a manual ball valve may be installed on the branch of the outlet pipeline.

[0021] Optionally, a venting pipe is provided at the bottom of the sampling container, and the venting pipe is connected to the sampling container.

[0022] Optionally, the inlet pipeline is connected to the heat exchange pipeline of the liquefied gas carrier's heat exchanger, and a liquid medium flows through the heat exchange pipeline.

[0023] This embodiment also provides a gas detection method, which uses the aforementioned gas detection device and includes the following:

[0024] Compressed air is introduced into the first flow path, and the compressed air enters the sampling tank through the main pipeline. Liquid medium is introduced into the second flow path, and the liquid medium enters the sampling tank through the inlet pipeline.

[0025] When the liquid level of the liquid medium rises to the port of the main pipeline inside the sampling tank, the pressure of the compressed air is controlled to be greater than the pressure of the liquid medium, so that the liquid level of the liquid medium is always below the port of the main pipeline inside the sampling tank.

[0026] After the internal pressure of the sampling tank reaches equilibrium, a gas sensor is used to detect the gas composition of the liquid medium in the sampling tank that is released into the main pipeline.

[0027] Optionally, after the step of the gas sensor detecting the gas composition emitted from the liquid in the sampling vessel into the main pipeline, the method further includes:

[0028] The gas sensor readings are used to determine whether the heat exchanger on the liquefied gas carrier is leaking.

[0029] The present invention also provides a gas detection system, comprising:

[0030] Heat exchange medium supply piping;

[0031] The liquid cargo tank contains liquid cargo. The liquid cargo tank is equipped with a heat exchange device, which is connected to the heat exchange medium supply pipeline and heats the liquid in the liquid cargo tank into gas through the heat exchange medium.

[0032] The heat exchange medium discharge pipeline is connected to the heat exchange device;

[0033] A gas detection device is provided, wherein the inlet pipe of the gas detection device is connected to the outlet pipe of the heat exchange medium, so that the gas sensor inside the gas detection device can detect the gas emitted from the heat exchange medium. The gas detection device is the aforementioned gas detection device.

[0034] Compared with the prior art, the gas detection device, gas detection method, and gas detection system described in this invention have at least the following beneficial effects:

[0035] The gas detection device of this invention includes a sampling tank, a main pipeline, a gas sensor, a first flow path, and a second flow path. The sampling tank includes a top end and a bottom end positioned opposite each other. The main pipeline is fixedly disposed at the top end of the sampling tank and communicates with it, extending from the top to the bottom end into the tank. The gas sensor is connected to the main pipeline and in contact with the gas within it. The first flow path includes an inlet end and an outlet end respectively disposed on the side wall of the main pipeline, through which gas flows to form a gas flow path. The second flow path is disposed on the side of the sampling tank near the bottom end and includes an inlet pipe and an outlet pipe respectively disposed on the side wall of the tank, through which liquid flows to form a liquid flow path. This invention, by providing an inlet end and an outlet end on the main pipeline, with the inlet end connected to a ship's compressed air system, allows compressed air to continuously enter the main pipeline through the inlet end and exit from the outlet end. The sampling tank has inlet and outlet pipes located near its bottom. Liquid discharged from the heat exchanger enters the sampling tank through the inlet pipe and exits through the outlet pipe. Compressed air pressurizes the sampling tank to maintain the liquid level at an appropriate position, ensuring the gas sensor connected to the main pipeline is always in a gaseous environment. When the compressed air and seawater reach pressure equilibrium within the sampling tank, gases escaping from the liquid seawater can pass smoothly through the internal pipes and be detected by the gas detection sensor. This avoids the sensor being submerged in seawater, which would reduce its lifespan and cause detection failure, thus extending the sensor's lifespan and improving detection effectiveness.

[0036] The gas detection method described in this invention uses the aforementioned gas detection device, and the gas detection system includes the aforementioned gas detection device, which can also achieve the aforementioned technical effects. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the gas detection device described in an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the main pipeline extending into the sampling tank in an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram showing the flow direction of gas or liquid passing through the gas detection device in an embodiment of the present invention.

[0040] List of reference numerals in the attached diagram:

[0041] 1 Sampling container

[0042] 11 Top

[0043] 12 Bottom

[0044] 2. Supervisor Road

[0045] 21 Extension Piping

[0046] 211 First Through Hole

[0047] 22 pipe cap

[0048] 221 Second Through Hole

[0049] 3 Gas Sensor

[0050] 4. First Distribution Path

[0051] 41. Intake end

[0052] 42. Air outlet end

[0053] 5 Second Distribution Path

[0054] 51 Inlet Pipeline

[0055] 511 Intake pipe branch

[0056] 52. Exhaust pipe

[0057] 521 Exhaust pipe branch

[0058] 61 First Stream Mirror

[0059] 62 Second Stream Mirror

[0060] 7. Drainage pipeline

[0061] 8. Tank base

[0062] 9. Blind flange Detailed Implementation

[0063] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0064] It should be understood that the illustrations provided in the embodiments of this invention are merely schematic representations of the basic concept of the invention. Although the illustrations only show components relevant to the invention and are not drawn according to the actual number, shape, and size of components in implementation, the shape, quantity, and proportion of each component can be arbitrarily changed in actual implementation, and the component layout may also be more complex. The structures, proportions, sizes, etc., shown in the accompanying drawings are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and objectives that the invention can produce, should still fall within the scope of the technical content disclosed in this application.

[0065] Example 1

[0066] This embodiment provides a gas detection device, while referring to... Figure 1 and 3 The gas detection device includes a sampling container 1, a main pipeline 2, a gas sensor 3, a first flow path 4, and a second flow path 5. The sampling container 1 includes a top end 11 and a bottom end 12 disposed opposite to each other. The main pipeline 2 is fixedly disposed at the top end 11 of the sampling container 1 and communicates with it. Along the direction from the top end 11 to the bottom end 12, the main pipeline 2 extends from the outside of the sampling container 1 into its interior. The gas sensor 3 is connected to the main pipeline 2 and is in contact with the gas inside the main pipeline 2. (Refer to...) Figure 3 The first flow path 4 includes an inlet end 41 and an outlet end 42 respectively disposed on the side wall of the main pipeline 2. Gas flows along the inlet end 41 to the outlet end 42 to form a gas flow path. The second flow path 5 is disposed on the side of the sampling tank 1 near the bottom end 12, and includes an inlet pipe 51 and an outlet pipe 52 respectively disposed on the side wall of the sampling tank 1. Liquid flows along the inlet pipe 51 to the outlet pipe 52 to form a liquid flow path.

[0067] Specifically, refer to Figure 1The sampling tank 1 is a sealed container, and the sidewalls of the tank can be made of welded steel pipes or rolled steel plates. The tank body can be welded to the sidewalls of the tank body using flanges and pipe caps of appropriate specifications to form a whole. Optionally, the tank body is cylindrical with a cross-sectional diameter of 300mm. The sampling tank 1 includes a top end 11 and a bottom end 12 arranged opposite to each other. In this embodiment, the top end 11 of the tank body is formed by bolting a flange (not shown in the figure) provided on the upper sidewall of the tank body to a blind flange 9. Optionally, a rubber gasket (not shown in the figure) is also provided between the flange of the tank body and the blind flange 9 to seal the tank body. Optionally, the diameter of the blind flange 9 is 300mm. Optionally, a drain pipe 7 is provided at the bottom end 12 of the sampling tank 1. The drain pipe 7 is connected to the sampling tank 1 and is used to drain the seawater inside the tank when the liquid cargo seawater system is not in use, to prevent the seawater inside the tank from freezing and damaging the tank structure when the ship is sailing in cold waters. Optionally, a tank base 8 is also provided on the tank body of sampling tank 1. The tank base 8 is located near the top 11 of the tank body, allowing the tank body to be positioned at a higher level to provide space for the discharge pipeline 7 below the tank body. Optionally, the tank base 8 can be formed by welding a 10mm thick steel plate onto the tank body, and the steel plate needs to be cut into a predetermined shape. The medium inside sampling tank 1 is seawater, which is highly corrosive. Therefore, after the entire tank body is welded, both the inner and outer surfaces need to be pickled and hot-dip galvanized.

[0068] Reference Figure 1 The main pipeline 2 is fixedly installed at the top 11 of the sampling tank 1 and communicates with the sampling tank 1. Along the direction from the top 11 to the bottom 12, the main pipeline 2 extends from the outside of the sampling tank 1 into the inside of the sampling tank 1. Optionally, a through hole is provided at the top 11 of the sampling tank 1, through which the main pipeline 2 extends into the sampling tank 1. In this embodiment, a through hole is provided in the middle of the blind flange 9 at the top 11 of the sampling tank 1, through which the main pipeline 2 extends into the sampling tank 1, and is fixed to the blind flange 9 by welding. Optionally, the main pipeline 2 is a seamless steel pipe with a diameter of 100 mm, and the diameter of the through hole is 114 mm.

[0069] In an optional embodiment, refer to Figure 1 and 2The main pipeline 2 extends into the sampling tank 1, including an extension pipeline 21 and a cap 22. The extension pipeline 21 and the cap 22 can be formed by welding. The extension pipeline 21 extends from the top 11 of the sampling tank 1 into the sampling tank 1, and at least one first through hole 211 is provided on the side wall of the extension pipeline 21. Compressed air enters the sampling tank 1 from the air inlet 41 and pressurizes the sampling tank 1 through the first through hole 211. The cap 22 is provided at the port of the extension pipeline 21, and a second through hole 221 is provided on the cap 22. The second through hole 221 can also pressurize the sampling tank 1 and discharge the liquid that has entered into the main pipeline 2. Optionally, the extension pipeline 21 is provided with three first through holes 211, and the three first through holes 211 are evenly arranged radially along the extension pipeline 21. On the radial plane of the extension pipe 21, the lines connecting the locations of the three first through holes 211 can form an equilateral triangle. The location of the three first through holes 211 is designed to rapidly and stably pressurize the tank. Optionally, the diameter of the first through hole 211 is 10 mm, and the diameter of the second through hole 221 is 6 mm.

[0070] Reference Figure 1 The gas sensor 3 is connected to the main pipeline 2 and is in contact with the gas inside the main pipeline 2. Optionally, the gas sensor 3 is located on the outside of the sampling tank 1 and is connected to the main pipeline 2 located on the outside of the sampling tank 1.

[0071] Reference Figure 1 and 3 The first flow path 4 includes an inlet end 41 and an outlet end 42 respectively disposed on the side wall of the main pipeline 2. Gas flows along the inlet end 41 to the outlet end 42 to form a gas flow path. Along the direction from the bottom end 12 to the top end 11, the height of the inlet end 41 is lower than the height of the outlet end 42. Optionally, the inlet end 41 can be connected to the ship's compressed air system. The port of the inlet end 41 can be configured as a threaded joint. Compressed air from the ship's compressed air system enters the interior of the main pipeline 2 through the threaded joint and flows out from the outlet end 42, forming a gaseous environment inside the main pipeline 2 to ensure that the gas sensor 3 installed on the top of the sampling tank 1 is not submerged in seawater. According to classification society specifications, the outlet end 42 of the compressed air pipeline must be located at least 3 meters away from the ventilation openings of passageways and compartments to prevent the outlet pipeline 52 from containing potentially hazardous gases. Optionally, a blind flange can be installed on the outlet end 42.

[0072] Reference Figure 1 and 3A second flow path 5 is located on the side of the sampling tank 1 near the bottom 12. This second flow path 5 includes an inlet pipe 51 and an outlet pipe 52 respectively installed on the side wall of the sampling tank 1. Liquid flows along the inlet pipe 51 to the outlet pipe 52 to form a liquid flow path. Along the direction from the bottom 12 to the top 11, the height of the inlet pipe 51 is higher than the height of the outlet pipe 52. Optionally, an inlet pipe branch 511 is also provided on the inlet pipe 51, which is equipped with a blind flange for purging and drying the internal liquid medium with compressed air during subsequent tank maintenance. An outlet pipe branch 521 is provided on the outlet pipe 52. A manual ball valve is provided on the outlet pipe branch 521 for venting the outlet pipe 52 during initial use.

[0073] Optionally, a first sight glass 61 and a second sight glass 62 are also provided on the side wall of the sampling tank 1. The height of the first sight glass 61 along the direction from the bottom end 12 to the top end 11 is the same as the height of the pipe cap 22 along the same direction. The second sight glass 62 is located below the inlet pipe 51. Compressed air enters the sampling tank 1 through the air inlet 41 and pressurizes the tank through the first through hole 211. By observing the first sight glass 61, the pressure of the compressed air flowing into the tank is adjusted to ensure that the liquid seawater in the sampling tank 1 reaches an appropriate liquid level.

[0074] Example 2

[0075] This embodiment also provides a gas detection method, which uses the gas detection device described in Embodiment 1. (Refer to...) Figures 1-3 The gas detection method includes:

[0076] S1: Compressed air is introduced into the first flow path 4, and the compressed air enters the sampling tank 1 through the main pipeline 2. Liquid medium is introduced into the second flow path 5, and the liquid medium enters the sampling tank 1 through the inlet pipeline 51.

[0077] Compressed air from the ship's compressed air system enters the main pipe 2 at the top of the sampling tank 1 through the inlet pipe 51 and is pressurized into the tank through the three first through holes 211. Seawater in the lower part of the sampling tank 1 flows into the tank body through the inlet pipe 51 and flows out through the outlet pipe 52.

[0078] S2: When the liquid level of the liquid medium rises to the port of the main pipeline 2 inside the sampling tank 1, control the incoming pressure of compressed air to be greater than the incoming pressure of the liquid medium, so that the liquid level of the liquid medium is always below the port of the main pipeline 2 inside the sampling tank 1.

[0079] Observe the liquid level in the first flow mirror 61 to determine whether the pressure balance between compressed air and liquefied seawater in the sampling tank 1 is met. When the liquid seawater level in the tank reaches the position of the first flow mirror 61, it indicates that the three first through holes 211 have been submerged by seawater, and the gas escaping from the seawater cannot be detected by the gas sensor 3. At this time, the pressure of the compressed air flowing in can be appropriately increased to lower the seawater level below the first flow mirror 61. Optionally, the pressure of the compressed air is 7 barg, and the pressure of the liquefied seawater is approximately 0.2 to 0.3 barg.

[0080] S3: After the internal pressure of sampling tank 1 reaches equilibrium, gas sensor 3 is used to detect the gas composition of the liquid medium in sampling tank 1 that is emitted into the main pipeline 2.

[0081] After the internal pressure of the tank reaches equilibrium, the gas escaping from the seawater enters the internal pipeline through the first through-hole 211 and is detected by the gas sensor 3. Based on the detection result of the gas sensor 3, it is determined whether the heat exchanger of the liquefied gas carrier has leaked. If the liquefied cargo seawater contains flammable gas, the gas sensor 3 will issue an audible and visual alarm through the cargo control system.

[0082] Example 3

[0083] This embodiment also provides a gas detection system installed inside a liquefied gas carrier. The gas detection system includes a heat exchange medium supply pipeline, a liquefied cargo tank, a heat exchange medium discharge pipeline, and a gas detection device. The liquefied cargo tank contains liquid cargo and is equipped with a heat exchange device. The inlet of the heat exchange device is connected to the heat exchange medium supply pipeline, and the heat exchange medium heats the liquid in the cargo tank into gas. The outlet of the heat exchange device is connected to the heat exchange medium discharge pipeline. The inlet pipeline of the gas detection device is connected to the heat exchange medium discharge pipeline, so that the gas sensor inside the gas detection device can detect the gas emitted from the heat exchange medium. The gas detection device is the same as the gas detection device described in Embodiment 1.

[0084] In summary, the gas detection device of the present invention, an inflatable liquid seawater sampling tank, achieves a balance between compressed air and liquid seawater within the sampling tank by filling it with compressed air. This avoids the gas sensor being submerged in seawater, which would reduce its lifespan and cause detection failure, thereby extending the sensor's lifespan and improving detection effectiveness.

[0085] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A gas detection device, characterized in that, include: A sampling container, including a top and bottom end that are positioned opposite each other; A main pipeline is fixedly installed at the top of the sampling container and connected to the sampling container. In the direction from the top to the bottom, the main pipeline extends from the outside of the sampling container to the inside of the sampling container. The pipeline extending into the sampling container includes an extension pipeline and a cap. The extension pipeline extends from the top of the sampling container to the inside of the sampling container and is provided with at least one first through hole. The cap is provided at the port of the extension pipeline and is provided with a second through hole. A gas sensor is connected to the main pipeline and comes into contact with the gas inside the main pipeline; The first flow path includes an air inlet and an air outlet respectively disposed on the side wall of the main pipeline, and the gas flows along the air inlet to the air outlet to form a gas flow path. The second flow path is located on the side of the sampling tank near the bottom end, and includes an inlet pipe and an outlet pipe respectively disposed on the side wall of the sampling tank. The liquid flows along the inlet pipe to the outlet pipe to form a liquid flow path. In the direction from the bottom end to the top end, the height of the inlet pipe is higher than the height of the outlet pipe. The air inlet is used to connect to a compressed air system so that compressed air enters the sampling tank through the first through hole on the extension pipe and the second through hole on the pipe cap. When the liquid medium enters the sampling tank through the inlet pipe, the inlet pressure of the compressed air is greater than the inlet pressure of the liquid medium, thereby keeping the liquid level of the liquid medium below the port of the extension pipe.

2. The gas detection device according to claim 1, characterized in that, Along the direction from the bottom to the top, the height of the air inlet is lower than the height of the air outlet.

3. The gas detection device according to claim 1, characterized in that, The extension pipeline is provided with three first through holes, which are evenly arranged along the radial direction of the extension pipeline.

4. The gas detection device according to claim 1, characterized in that, A first viewing mirror is also provided on the side wall of the sampling container. The height of the first viewing mirror along the direction from the bottom end to the top end is the same as the height of the cap along the direction from the bottom end to the top end.

5. The gas detection device according to claim 1, characterized in that, An inlet branch is provided on the inlet pipeline, and an outlet branch is provided on the outlet pipeline.

6. The gas detection device according to claim 5, characterized in that, A manual ball valve is installed on the branch of the outlet pipeline.

7. The gas detection device according to claim 1, characterized in that, A vent pipe is provided at the bottom of the sampling container, and the vent pipe is connected to the sampling container.

8. The gas detection device according to claim 1, characterized in that, The inlet pipeline is connected to the heat exchange pipeline of the liquefied gas carrier's heat exchanger, and a liquid medium flows through the heat exchange pipeline.

9. A gas detection method, characterized in that, The gas detection method is performed using the gas detection device as described in any one of claims 1 to 8, and the gas detection method includes: Compressed air is introduced into the first flow path and enters the sampling tank through the main pipeline. Liquid medium is introduced into the second flow path and enters the sampling tank through the inlet pipeline. When the liquid level of the liquid medium rises to the port of the extension pipe inside the sampling tank, the pressure of compressed air is controlled to be greater than the pressure of the liquid medium, so that the liquid level of the liquid medium is always below the port of the extension pipe inside the sampling tank. After the internal pressure of the sampling tank reaches equilibrium, a gas sensor is used to detect the gas composition of the liquid medium in the sampling tank that is released into the main pipeline.

10. The gas detection method according to claim 9, characterized in that, After the step of detecting the gas composition of the liquid in the sampling vessel dissipating into the main pipeline using a gas sensor, the process also includes: The gas sensor readings are used to determine whether the heat exchanger on the liquefied gas carrier is leaking.

11. A gas detection system, characterized in that, include: Heat exchange medium supply piping; A liquid cargo tank contains liquid cargo. The liquid cargo tank is equipped with a heat exchange device, which is connected to a heat exchange medium supply pipeline and heats the liquid in the liquid cargo tank into gas through the heat exchange medium. A heat exchange medium discharge pipeline is connected to the heat exchange device; A gas detection device, wherein the inlet pipe of the gas detection device is connected to the outlet pipe of the heat exchange medium, so that the gas sensor in the gas detection device can detect the gas emitted in the heat exchange medium, and the gas detection device is the gas detection device as described in any one of claims 1 to 8.

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