LNG (Liquefied Natural Gas) sampling system for filling ship

Abstract

The utility model relates to the technical field of liquefied natural gas sampling analysis, and provides an LNG sampling system for a filling ship, the system comprises an LNG pipeline and a BOG pipeline, the LNG pipeline is communicated with an LNG sampling assembly, a vaporization assembly and a gas quality analysis assembly in sequence, the LNG sampling assembly is used for being connected to a liquid phase header pipe to take out an LNG sample in the liquid phase header pipe, and the BOG pipeline is used for being connected with the vaporization assembly. The vaporization assembly is used for vaporizing the LNG sample; the BOG pipeline is sequentially communicated with a BOG sampling assembly and a gas mass analysis assembly, and the BOG sampling assembly is used for being connected to a gas phase header pipe so as to take out a BOG sample in the gas phase header pipe; and the gas quality analysis assembly is used for respectively carrying out online analysis on the gasified LNG sample and BOG sample. According to the utility model, the BOG pipeline is arranged outside the LNG pipeline, so that the LNG sample and the BOG sample can be sampled and analyzed at the same time, and the metering error caused by only considering the single-state gas can be avoided.

Description

Technical Field

[0001] This utility model relates to the field of liquefied natural gas sampling and analysis technology, and in particular to an LNG sampling system for bunkering ships. Background Technology

[0002] Liquefied Natural Gas (LNG) shipping and trading are key links in the LNG industry chain. For international LNG trade, which is settled based on LNG energy, rapid and reliable determination of LNG calorific value is crucial.

[0003] Existing technology provides a land-based LNG sampling and analysis device, which includes an LNG sampling probe, a vaporization device, and an online analysis device. This device can be widely used in facilities for analyzing LNG composition and calculating LNG calorific value. However, in the energy-based trade settlement of LNG for marine bunkering, the composition and energy contribution of BOG (Boil-Off Gas, which refers to the cryogenic gas generated during LNG storage and transportation due to heat conduction and natural evaporation) are crucial factors in ensuring fair transactions and accurate measurement of energy value. Existing LNG sampling and analysis devices cannot effectively analyze the composition and energy of BOG, which significantly hinders the development of LNG shipping trade. Utility Model Content

[0004] This invention provides an LNG sampling system for bunkering vessels, which addresses the shortcomings of existing LNG sampling and analysis devices that cannot effectively analyze the composition and energy of BOG (Boiled Ocean Gas). By setting up a BOG pipeline outside the LNG pipeline, both LNG and BOG samples can be sampled and analyzed simultaneously. This avoids measurement errors caused by considering only a single state of gas and ensures fairness and accuracy for both trading parties when transferring LNG.

[0005] The LNG sampling system for ship bunkering provided by this utility model includes:

[0006] The LNG pipeline is connected in sequence to an LNG sampling unit, a vaporization unit, and a gas chromatography-mass spectrometry unit. The LNG sampling unit is used to connect to the liquid phase manifold to take out the LNG sample in the liquid phase manifold. The vaporization unit is used to vaporize the LNG sample.

[0007] The BOG pipeline is connected in sequence to a BOG sampling assembly and a gas chromatography-mass spectrometry (GC-MS) analysis assembly. The BOG sampling assembly is used to connect to the gas phase main pipe to facilitate the extraction of BOG samples from the gas phase main pipe. The GC-MS analysis assembly is used to perform online analysis on the vaporized LNG sample and the BOG sample, respectively.

[0008] According to the LNG sampling system for marine bunkering provided by this utility model, the vaporization component includes:

[0009] An electrically heated vaporizer has its inlet connected to the outlet of the LNG sampling assembly and its outlet connected to the inlet of the gas chromatography-mass spectrometry assembly. The electrically heated vaporizer is used to vaporize the LNG sample.

[0010] The first-stage temperature detection element is located between the inlet of the electric heating vaporizer and the outlet of the LNG sampling assembly, and is used to detect the temperature of the LNG sample at the inlet of the electric heating vaporizer;

[0011] A second-stage temperature detection element is installed in the electric heating vaporizer to detect the temperature of the LNG sample inside the electric heating vaporizer;

[0012] The third-stage temperature detection element is located between the outlet of the electric heating vaporizer and the inlet of the gas chromatography-mass spectrometry component, and is used to detect the temperature of the LNG sample at the outlet of the electric heating vaporizer.

[0013] The LNG sampling system for ship bunkering provided by this utility model also includes an LNG pretreatment component.

[0014] The LNG pretreatment assembly includes a first-stage LNG depressurization valve, a buffer tank, an LNG pressure indicator, and an LNG flow meter. The inlet of the first-stage LNG depressurization valve is connected to the outlet of the electrically heated vaporizer, the outlet of the first-stage LNG depressurization valve is connected to the inlet of the buffer tank, and the outlet of the buffer tank is connected to the inlet of the gas chromatography-mass spectrometry (GC-MS) assembly. The LNG pressure indicator and the LNG flow meter are sequentially located between the outlet of the buffer tank and the inlet of the GC-MS assembly.

[0015] According to the LNG sampling system for ship bunkering provided by this utility model, the LNG pretreatment component further includes a second-stage LNG depressurization valve, which is located between the LNG pressure indicating element and the LNG flow meter.

[0016] The LNG sampling system for ship refueling provided by this utility model also includes an LNG heating pipeline, and the outlet of the electric heating vaporizer is connected to the inlet of the first-stage LNG pressure reducing valve through the LNG heating pipeline.

[0017] The temperature of the LNG heat tracing pipeline is a, where a ≥ 65℃.

[0018] The LNG sampling system for marine bunkering provided by this utility model also includes a BOG pretreatment component.

[0019] The BOG pretreatment component includes a first-stage BOG pressure reducing valve, a BOG pressure indicating element, a second-stage BOG pressure reducing valve, and a BOG flow meter. The inlet of the first-stage BOG pressure reducing valve is connected to the outlet of the BOG sampling component, the outlet of the first-stage BOG pressure reducing valve is connected to the inlet of the second-stage BOG pressure reducing valve, and the outlet of the second-stage BOG pressure reducing valve is connected to the inlet of the gas chromatography-mass spectrometry component.

[0020] The BOG pressure indicator is located between the outlet of the first-stage BOG pressure reducing valve and the inlet of the second-stage BOG pressure reducing valve, and the BOG flow meter is located between the outlet of the second-stage BOG pressure reducing valve and the inlet of the gas analyzer.

[0021] The LNG sampling system for ship refueling provided by this utility model also includes a BOG heat tracing pipeline, and the outlet of the BOG sampling component is connected to the inlet of the first-stage BOG pressure reducing valve through the BOG heat tracing pipeline.

[0022] The temperature of the BOG heat tracing pipe is b, where b ≥ 65℃.

[0023] According to the LNG sampling system for bunkering provided by this utility model, the LNG sampling component includes an LNG sampling probe, a manual shut-off valve, and a pneumatic shut-off valve. The manual shut-off valve and the pneumatic shut-off valve are sequentially located between the outlet of the LNG sampling probe and the inlet of the vaporization component. The LNG sampling probe is used to connect to the liquid phase manifold to facilitate the extraction of the LNG sample from the liquid phase manifold.

[0024] According to the LNG sampling system for bunkering vessels provided by this utility model, the BOG sampling assembly includes a BOG sampling probe and a three-valve assembly. The three-valve assembly is located between the outlet of the BOG sampling probe and the inlet of the gas chromatography-mass spectrometry (GC-MS) assembly. The BOG sampling probe is used to connect to the gas phase manifold to facilitate the extraction of the BOG sample from the gas phase manifold.

[0025] The LNG sampling system for marine bunkering provided by this utility model also includes a sample return pipeline;

[0026] The sample return pipeline includes:

[0027] The manual sampling return branch has its inlet connected to the outlet of the vaporization component, and its outlet is used to connect to the sample return main pipe. The manual sampling return branch is used to sample the LNG sample.

[0028] The LNG sample return branch has its inlet connected to the outlet of the vaporization component, and its outlet connected to the sample return main pipe. The LNG sample return branch is used to transport the LNG sample to the sample return main pipe.

[0029] The BOG sample return branch has its inlet connected to the outlet of the BOG sampling group, and its outlet is used to connect to the sample return main pipe. The BOG sample return branch is used to transport the BOG sample to the sample return main pipe.

[0030] The LNG sampling system provided by this utility model, by setting up a BOG pipeline outside the LNG pipeline, can simultaneously sample and analyze LNG and BOG samples. This satisfies the needs of the two main samples involved in the bunkering process, accurately measures the composition, calorific value and other key parameters of LNG and BOG samples, and accurately calculates the total energy of LNG trade transactions. It avoids measurement errors caused by considering only a single state of gas, ensures fairness and accuracy for both trading parties when transferring LNG, provides reliable data support for energy transactions, and reduces commercial disputes caused by inaccurate measurement. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is one of the process flow diagrams of the LNG sampling system for ship refueling provided in this embodiment of the utility model.

[0033] Figure 2 This is the second process flow diagram of the LNG sampling system for ship refueling provided in this embodiment of the utility model.

[0034] Figure label:

[0035] 10: Liquid phase main; 20: Gas phase main; 30: Sample return main; 40: LNG line; 50: BOG line; 100: LNG sampling assembly; 110: LNG sampling probe; 120: Manual shut-off valve; 130: Pneumatic shut-off valve;

[0036] 200: Vaporization assembly; 210: Electric heating vaporizer; 220: First-stage temperature sensing element; 230: Second-stage temperature sensing element; 240: Third-stage temperature sensing element; 250: Safety valve;

[0037] 300: LNG pretreatment assembly; 310: First-stage LNG pressure reduction valve; 320: Buffer tank; 330: LNG pressure indicator; 340: LNG flow meter; 350: Second-stage LNG pressure reduction valve; 360: LNG heat tracing pipeline;

[0038] 400: BOG sampling assembly; 410: BOG sampling probe; 420: Three-valve manifold;

[0039] 500: BOG pretreatment assembly; 510: First-stage BOG pressure reducing valve; 520: BOG pressure indicating element; 530: Second-stage BOG pressure reducing valve; 540: BOG flow meter; 550: BOG heat tracing pipeline;

[0040] 600: Gas chromatography-mass spectrometry (GC-MS) unit; 700: Sample return line; 710: Manual sampling return branch; 720: LNG sample return branch; 730: BOG sample return branch. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0042] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0043] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0044] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0045] Figure 1 This is one of the process flow diagrams of the LNG sampling system for marine refueling provided in this embodiment of the utility model; Figure 2 This is the second process flow diagram of the LNG sampling system for ship refueling provided in this embodiment of the utility model.

[0046] See Figure 1 and Figure 2 This utility model provides an LNG sampling system for a bunkering vessel, hereinafter referred to as the LNG sampling system. The bunkering vessel is equipped with a liquid phase manifold 10 and a gas phase manifold 20. The liquid phase manifold 10 is used to transfer LNG, and the gas phase manifold 20 is used to transfer BOG. ​​The specific structures of the liquid phase manifold 10 and the gas phase manifold 20 can be found in the existing technology adaptation design, and will not be described in detail here.

[0047] The LNG sampling system includes an LNG pipeline 40 and a BOG pipeline 50. The LNG pipeline 40 is sequentially connected to an LNG sampling assembly 100, a vaporization assembly 200, and a gas chromatography-mass spectrometry (GC-MS) analysis assembly 600. When the LNG sampling system is used on a bunkering vessel, the LNG sampling assembly 100 is connected to the liquid phase manifold 10 to facilitate the extraction of LNG samples from the liquid phase manifold 10. The vaporization assembly 200 is used to vaporize the LNG samples.

[0048] The BOG pipeline 50 is sequentially connected to the BOG sampling assembly 400 and the gas chromatography-mass spectrometry (GC-MS) analysis assembly 600. The BOG sampling assembly 400 is used to connect to the gas phase main pipe 20 to facilitate the extraction of BOG samples from the gas phase main pipe 20. The GC-MS analysis assembly 600 is used to perform online analysis on the vaporized LNG sample and the BOG sample, respectively.

[0049] The gas chromatography-mass spectrometry (GC-MS) component 600 can be equipped with a chromatographic analyzer. When analyzing LNG and BOG samples, the chromatographic analyzer mainly relies on the principle of chromatographic separation and the corresponding detection technology to achieve qualitative and quantitative determination of each component in the sample. The specific process is as follows.

[0050] When an LNG or BOG sample enters the chromatographic column, propelled by a carrier gas (such as nitrogen or helium), the components in the LNG or BOG sample undergo repeated partitioning and equilibrium between the stationary and mobile phases within the column. Due to the different interactions between the components and the stationary phase, their migration speeds within the column also differ. For example, light components such as methane have weaker interactions with the stationary phase and migrate faster within the column, while heavier components such as propane have stronger interactions with the stationary phase and migrate slower. After a certain separation time, the components elute from the column sequentially according to their retention capacity on the stationary phase and are detected by the detector.

[0051] For the analysis of LNG and BOG samples, commonly used detectors include flame ionization detectors (FID) and thermal conductivity detectors (TCD). FID has a high sensitivity response to hydrocarbon compounds and is suitable for detecting the content of hydrocarbon components in LNG and BOG. ​​TCD can detect almost all substances and also responds to inorganic gases (such as nitrogen and oxygen), and can be used to analyze the content of impurity gases in samples or to perform comprehensive component analysis.

[0052] Taking FID (Fluorescent Ion Detector) as an example, when hydrocarbon components flowing from the chromatographic column enter the FID detector, they undergo ionization under the high temperature of the hydrogen flame, generating an ion current. The intensity of the ion current is directly proportional to the concentration of the component. By measuring the magnitude of the ion current, the content information of each hydrocarbon component can be obtained. TCD (Thermal Density Detector) utilizes the difference in thermal conductivity between different components and the carrier gas. When a component passes through the detector, it causes a temperature change in the thermistor element, which in turn leads to a change in the resistance value, generating an electrical signal. The component content is determined based on the magnitude of the electrical signal.

[0053] The electrical signal output by the detector is acquired and recorded in real time by the data processing system. The data processing system converts the electrical signal into a digital signal and plots a chromatogram with time on the x-axis and signal intensity on the y-axis. Each peak in the chromatogram represents a component. The position of the peak (retention time) can be used for qualitative analysis to determine the types of components present in the sample; the peak area or peak height is used for quantitative analysis to calculate the content of each component.

[0054] See Figure 1 and Figure 2It is understood that in the LNG sampling system provided by this utility model embodiment, by setting up a BOG pipeline 50 outside the LNG pipeline 40, both LNG and BOG samples can be sampled and analyzed simultaneously. This can meet the needs of the two main samples involved in the bunkering process, accurately measure the composition, calorific value and other key parameters of the LNG and BOG samples, accurately calculate the total energy of LNG trade transactions, avoid measurement errors caused by considering only a single state of gas, ensure fairness and accuracy for both trading parties when transferring LNG, provide reliable data support for energy transactions, and reduce commercial disputes caused by inaccurate measurement.

[0055] In an optional embodiment of this utility model, when the LNG sampling system is used on a bunkering vessel, the LNG sampling component 100 and the BOG sampling component 400 can be housed in a stainless steel enclosure on the bunkering vessel, thereby achieving a fixed connection between them and the bunkering vessel. It is understood that the space on the bunkering vessel is limited, and placing the LNG sampling component 100 and the BOG sampling component 400 in the stainless steel enclosure can achieve a compact layout, optimize space utilization, make the entire LNG sampling system more organized, facilitate installation and maintenance on the vessel, and at the same time, not affect the normal operation of other equipment, ensuring the efficient operation of the vessel.

[0056] Secondly, when the ship is sailing at sea, the bunkering vessel will be affected by factors such as waves and will sway. Stainless steel has high strength and toughness, which can effectively resist the external force generated by swaying. It can protect the LNG sampling assembly 100 and BOG sampling assembly 400 from damage and ensure that the LNG sampling assembly 100 and BOG sampling assembly 400 can still work normally under swaying conditions.

[0057] In addition, the marine environment is characterized by high humidity and high salinity, which is highly corrosive. Stainless steel has excellent corrosion resistance, which can prevent the LNG sampling assembly 100 and BOG sampling assembly 400 from being corroded due to long-term exposure to the harsh environment. This can extend the service life of the LNG sampling assembly 100 and BOG sampling assembly 400, reduce equipment maintenance costs, and ensure the reliability of the LNG sampling assembly 100 and BOG sampling assembly 400 throughout the entire refueling process.

[0058] In addition, the LNG sampling assembly 100 and BOG sampling assembly 400 are fixed to the hull of the bunkering vessel, which ensures that the LNG sampling assembly 100 and BOG sampling assembly 400 maintain a stable position during the operation of the vessel. This avoids the LNG sampling assembly 100 and BOG sampling assembly 400 from becoming loose or damaged due to vibration or displacement of the vessel, thus ensuring the continuity and accuracy of the sampling process and providing a stable basis for the accurate measurement of the composition and calorific value of LNG.

[0059] In an optional embodiment of this utility model, the LNG sampling assembly 100 can be flexibly connected to the LNG pipeline 40 via a corrugated pipe, and the BOG sampling assembly 400 can also be flexibly connected to the BOG pipeline 50 via a corrugated pipe. It is understood that during the operation of the bunkering vessel, due to factors such as wave impact and ship vibration, the hull may experience displacement or deformation, which will cause changes in the relative positions between the LNG sampling assembly 100 and the LNG pipeline 40, and also change the relative positions between the BOG sampling assembly 400 and the BOG pipeline 50. In this embodiment of the utility model, the corrugated pipe flexible connection has good flexibility and extensibility, thus effectively compensating for such displacement and deformation, avoiding stress concentration caused by rigid pipe connections, preventing pipe rupture and leakage, and ensuring the integrity and safety of the sampling system.

[0060] Secondly, the operation of equipment on board generates vibrations. Direct rigid connections would affect the stability and measurement accuracy of the LNG sampling assembly 100 and the BOG sampling assembly 400, and could even damage the precision components inside. In this embodiment, the bellows flexible connection acts as a buffer, reducing vibration transmission and allowing the LNG sampling assembly 100 and the BOG sampling assembly 400 to operate in a relatively stable environment, thus improving sampling accuracy and reliability.

[0061] In addition, the corrugated flexible connection has a relatively simple structure and is easy to install. Unlike rigid connections, it does not require precise alignment of the pipe interface, making it easier to operate within the limited space of the bunkering vessel. Furthermore, when maintenance, repair, or replacement of the LNG sampling assembly 100, BOG sampling assembly 400, liquid phase main 10, or gas phase main 20 is required, the corrugated flexible connection facilitates disassembly and reinstallation, reducing maintenance costs and time.

[0062] Continue reading Figure 1 In an optional embodiment of this utility model, the vaporization assembly 200 includes an electric heating vaporizer 210, a first-stage temperature detection element 220, a second-stage temperature detection element 230, and a third-stage temperature detection element 240. The inlet of the electric heating vaporizer 210 is connected to the outlet of the LNG sampling assembly 100, and the outlet of the electric heating vaporizer 210 is connected to the inlet of the gas chromatography-mass spectrometry analysis assembly 600. The electric heating vaporizer 210 is used to vaporize the LNG sample.

[0063] Specifically, after the LNG sample is collected by the LNG sampling assembly 100 connected to the liquid phase manifold 10, it enters the electrically heated vaporizer 210 under pipeline pressure. The electrically heated vaporizer 210 is equipped with an electric heating element. When the LNG sample enters, the electric heating element starts working, converting electrical energy into heat energy to heat the LNG sample. LNG is natural gas in a liquid state under low temperature and high pressure. Its main component is methane, and it also contains small amounts of hydrocarbons such as ethane and propane. In the electrically heated vaporizer 210, as heat is continuously input, the temperature of the LNG sample gradually rises. The liquid molecules gain enough energy to overcome intermolecular forces and gradually transform into a gaseous state.

[0064] The first-stage temperature sensing element 220 is located between the inlet of the electric heating vaporizer 210 and the outlet of the LNG sampling assembly 100. The first-stage temperature sensing element 220 is used to detect the temperature of the LNG sample at the inlet of the electric heating vaporizer 210. The second-stage temperature sensing element 230 is located in the electric heating vaporizer 210. The second-stage temperature sensing element 230 is used to detect the temperature of the LNG sample inside the electric heating vaporizer 210. The third-stage temperature sensing element 240 is located between the outlet of the electric heating vaporizer 210 and the inlet of the LNG pretreatment assembly 300. The third-stage temperature sensing element 240 is used to detect the temperature of the LNG sample at the outlet of the electric heating vaporizer 210. In an optional embodiment of this utility model, the power of the electric heating vaporizer 210 can be controlled to ensure that the temperature displayed by the third-stage temperature sensing element 240 is not lower than 50°C.

[0065] Understandably, during the vaporization process, in order to ensure vaporization effect and safety, the temperature changes of the LNG sample at different locations in the LNG pipeline 40 are detected by setting a first-stage temperature detection element 220, a second-stage temperature detection element 230, and a third-stage temperature detection element 240. Based on the monitored temperature data, the power of the electric heating vaporizer 210 can be adjusted in real time to maintain a suitable vaporization temperature. In this way, it can be ensured that the LNG sample can be completely vaporized, and it can also be ensured that the LNG sample will not cause other problems (such as component decomposition) due to excessive temperature.

[0066] In an optional embodiment of this utility model, the vaporization component 200 further includes a safety valve 250. The safety valve 250 is located between the third-stage temperature detection element 240 and the inlet of the LNG pretreatment component 300. The safety valve 250 can control the gas pressure in the LNG pipeline 40, and can prevent pipeline damage or damage to other components in the pipeline due to excessive pressure.

[0067] Continue reading Figure 2In an optional embodiment of this utility model, the LNG sampling system further includes an LNG pretreatment component 300. The LNG pretreatment component 300 includes a first-stage LNG pressure reducing valve 310, a buffer tank 320, an LNG pressure indicating element 330, and an LNG flow meter 340. The inlet of the first-stage LNG pressure reducing valve 310 is connected to the outlet of the electric heating vaporizer 210, the outlet of the first-stage LNG pressure reducing valve 310 is connected to the inlet of the buffer tank 320, and the outlet of the buffer tank 320 is connected to the inlet of the gas chromatography-mass spectrometry analysis component 600. The LNG pressure indicating element 330 and the LNG flow meter 340 are sequentially arranged between the outlet of the buffer tank 320 and the inlet of the gas chromatography-mass spectrometry analysis component 600.

[0068] Understandably, the vaporized LNG sample exiting the electric heating vaporizer 210 is typically under high pressure. Subsequent equipment such as the buffer tank 320 and the gas analysis unit 600 have specific requirements for gas pressure. The first-stage LNG pressure reducing valve 310 can initially reduce the pressure of the high-pressure gas to an intermediate pressure range, allowing it to smoothly enter the buffer tank 320 for further processing. This avoids excessive impact from the high-pressure gas on the buffer tank 320 and subsequent equipment, protects the equipment from damage, extends the service life of the equipment, and ensures that the entire system operates under appropriate pressure conditions.

[0069] It is also understandable that the composition of the LNG sample after vaporization and depressurization may exhibit some inhomogeneity. In this embodiment, the buffer tank 320 has a large internal space, allowing the vaporized LNG sample to flow, diffuse, and mix sufficiently. By allowing the vaporized LNG sample to undergo natural convection and diffusion within the buffer tank 320, LNG samples entering the buffer tank 320 at different locations and times can be fully contacted, promoting uniform mixing between components. This ensures that the vaporized LNG sample entering the gas chromatography-mass spectrometry (GC-MS) unit 600 is representative and consistent, thereby improving the reliability of the analytical results and providing a guarantee for accurately assessing the quality and energy value of LNG.

[0070] It is also understandable that excessively high or low pressure during LNG processing can lead to safety issues. For example, excessively high pressure may cause LNG pipeline 40 to rupture, leak, or even trigger serious accidents such as explosions; excessively low pressure may affect the normal flow of gas and the normal operation of subsequent analysis equipment. The LNG pressure indicator element 330 can promptly detect pressure anomalies, allowing operators to take appropriate measures (such as adjusting the pressure-reducing valve opening, checking equipment malfunctions, etc.) to restore the pressure to a safe range, ensuring the safe operation of the system and protecting the safety of personnel, ships, and equipment.

[0071] In the process of LNG bunkering vessel trade and handover, LNG flow rate is a key parameter. The flow rate data recorded by the LNG flow meter 340 can be directly used to calculate the LNG transport volume and is one of the important bases for trade settlement. The accuracy and reliability of the LNG flow meter 340 can ensure the fair interests of both trading parties, avoid economic disputes caused by flow measurement errors, and maintain the normal order of the LNG trade market.

[0072] It should be noted that the volume of the buffer tank 320 needs to be greater than or equal to 2L. This is primarily to ensure that the gas sample is fully mixed, the pressure is stably regulated, and the continuous operation requirements of the system are met during LNG sampling and analysis. Specifically, the gas sample exiting the vaporization assembly 200 may have uneven composition and concentration. A larger buffer tank 320 (not less than 2L) provides sufficient space for the gas to flow, diffuse, and mix fully, making the components of the gas sample more homogeneous. This ensures that subsequent analytical results accurately reflect the true properties of the LNG sample. If the buffer tank 320 is too small, insufficient gas mixing may lead to deviations in the analytical results, affecting the accuracy of the judgment of LNG quality and energy measurement.

[0073] Secondly, during the operation of the LNG sampling system, the pressure of the LNG sample may fluctuate due to the instability of the gasification process, changes in pipeline resistance, and other factors. The buffer tank 320 plays a role in buffering and stabilizing the pressure. Its larger volume can better accommodate the changes in gas volume caused by pressure fluctuations, avoid sudden pressure changes from impacting subsequent equipment, ensure that the system operates under stable pressure conditions, improve the reliability and service life of the equipment, and also ensure the accuracy of the analysis process.

[0074] Continue reading Figure 2 In an optional embodiment of the present invention, the LNG pretreatment component 300 further includes a second-stage LNG pressure reducing valve 350, which is located between the LNG pressure indicating element 330 and the LNG flow meter 340.

[0075] Understandably, gas chromatography-mass spectrometry (GC-MS) analyzers (such as chromatographs) have strict and precise requirements for the pressure of the incoming LNG sample, typically needing to control the pressure within a very narrow range to ensure the accuracy and repeatability of the analytical results. While the first-stage LNG pressure-reducing valve 310 can initially reduce the pressure of the vaporized LNG, it cannot directly achieve the high-precision pressure conditions required by the GC-MS analyzer 600. The second-stage LNG pressure-reducing valve 350 can perform more precise pressure regulation based on the first-stage pressure reduction, accurately adjusting the gas pressure to the optimal range suitable for GC-MS analysis, thereby ensuring the analyzer functions properly and provides accurate and reliable analytical data.

[0076] Secondly, relying solely on the first-stage LNG pressure-reducing valve 310 to control LNG sample pressure carries significant risks. If the first-stage LNG pressure-reducing valve 310 malfunctions (e.g., valve jamming, adjustment failure), it could lead to uncontrolled pressure, directly impacting the normal operation of downstream equipment and potentially damaging expensive equipment such as the gas chromatography-mass spectrometry (GC) analyzer 600, resulting in severe economic losses and system downtime. In this embodiment, the second-stage LNG pressure-reducing valve 350 serves as a redundancy design, working in conjunction with the first-stage LNG pressure-reducing valve 310 to form a two-stage pressure regulation mechanism. When the first-stage LNG pressure-reducing valve 310 malfunctions, the second-stage LNG pressure-reducing valve 350 can maintain pressure stability to a certain extent, or adjust the pressure promptly after a failure, mitigating the impact of the failure on the system and providing additional safety assurance. This two-stage pressure-reducing valve configuration significantly improves the stability and reliability of system pressure control, reduces the probability of system failure due to pressure issues, and ensures that the bunkering vessel can safely and stably conduct LNG sampling and analysis during long-term operation.

[0077] Continue reading Figure 1 In an optional embodiment of this utility model, the LNG sampling system further includes an LNG heat tracing pipeline 360, and the outlet of the electric heating vaporizer 210 is connected to the inlet of the first-stage LNG pressure reducing valve 310 through the LNG heat tracing pipeline 360; the temperature of the LNG heat tracing pipeline 360 ​​is a, where a≥65℃, for example, the temperature of the LNG heat tracing pipeline 360 ​​can be set to 65℃, 75℃ or 85℃.

[0078] It is understandable that the temperature of the LNG sample is still low after vaporization. During the pipeline transportation process, there is a risk of reliquefaction due to heat loss. In this embodiment, the LNG heating pipeline 360 ​​can maintain the temperature of the LNG sample in the pipeline by continuously providing heat, so that it always remains in a gaseous state. In other words, when the vaporized LNG sample flows out of the outlet of the electric heating vaporizer 210, during the transportation to the pretreatment component, the LNG heating pipeline 360 ​​can prevent the LNG sample from reliquefying due to low ambient temperature or heat dissipation from the pipeline.

[0079] It is also understood that in this embodiment, the LNG heat tracing pipeline 360 ​​maintains the temperature of the LNG sample above 65°C. Under stable temperature conditions, the changes in gas volume and pressure can be controlled within a small range, thereby avoiding adverse effects on the system caused by sudden pressure changes due to temperature fluctuations, such as pipeline rupture and equipment damage.

[0080] Continue reading Figure 2In an optional embodiment of this utility model, the LNG sampling system further includes a BOG pretreatment component 500; the BOG pretreatment component 500 includes a first-stage BOG pressure reducing valve 510, a BOG pressure indicating element 520, a second-stage BOG pressure reducing valve 530, and a BOG flow meter 540. The inlet of the first-stage BOG pressure reducing valve 510 is connected to the outlet of the BOG sampling component 400, the outlet of the first-stage BOG pressure reducing valve 510 is connected to the inlet of the second-stage BOG pressure reducing valve 530, and the outlet of the second-stage BOG pressure reducing valve 530 is connected to the inlet of the gas chromatography-mass spectrometry (GC-MS) analysis component 600; the BOG pressure indicating element 520 is located between the first-stage BOG pressure reducing valve 510 and the second-stage BOG pressure reducing valve 530, and the BOG flow meter 540 is located between the second-stage BOG pressure reducing valve 530 and the inlet of the GC-MS analysis component 600.

[0081] The first-stage BOG pressure reducing valve 510, BOG pressure indicating element 520, second-stage BOG pressure reducing valve 530 and BOG flow meter 540 are similar to the first-stage LNG pressure reducing valve 310, LNG pressure indicating element 330, LNG flow meter 340 and second-stage LNG pressure reducing valve 350 in the aforementioned embodiments. For specific technical effects, please refer to the above description, which will not be repeated here.

[0082] Continue reading Figure 1 In an optional embodiment of this utility model, the LNG sampling system further includes a BOG heat tracing pipe 550. The outlet of the BOG sampling component 400 is connected to the inlet of the first-stage BOG pressure reducing valve 510 through the BOG heat tracing pipe 550. The temperature of the BOG heat tracing pipe 550 is b, where b ≥ 65℃. For example, the temperature of the BOG heat tracing pipe 550 can be set to 65℃, 75℃, or 85℃. The technical effect of the BOG heat tracing pipe 550 is similar to that of the LNG heat tracing pipe 360 ​​in the aforementioned embodiment. For details, please refer to the above description, which will not be repeated here.

[0083] Continue reading Figure 1 In an optional embodiment of this invention, the LNG sampling assembly 100 includes an LNG sampling probe 110, a manual shut-off valve 120, and a pneumatic shut-off valve 130. The manual shut-off valve 120 and the pneumatic shut-off valve 130 are sequentially located between the outlet of the LNG sampling probe 110 and the inlet of the vaporization assembly 200. The LNG sampling probe 110 is connected to the liquid phase manifold 10 to facilitate the extraction of LNG samples from the liquid phase manifold 10. In an optional embodiment of this invention, when the LNG sampling system is used on a bunkering vessel, the pneumatic shut-off valve 130 can rely on the ship's instrument air supply or can be installed in a separate instrument air cylinder. Specifically, it can be adapted according to the actual situation.

[0084] Under normal circumstances, the manual shut-off valve 120 remains open. When equipment maintenance, repair, or emergencies are required, operators can manually close the valve to cut off the flow of LNG samples and ensure operational safety. The pneumatic shut-off valve 130 is pneumatically driven. In the event of system abnormalities (such as vaporizer malfunction, abnormal pressure or temperature, etc.), the pneumatic shut-off valve 130 can quickly respond to remote control signals and rapidly close the valve, preventing further damage to the system. The pneumatic shut-off valve 130 enhances the system's safety and reliability. Furthermore, the two valves can be designed as redundancies, further improving the safety and reliability of the LNG sampling assembly 100.

[0085] Secondly, the refueling vessel will be constantly rocking while sailing at sea, which poses a challenge to the operation and stability of the valve. The pneumatic shut-off valve 130 is relatively simple and reliable, and its operation performance is not easily affected by the ship's rocking. Compared with other driving methods, the pneumatic shut-off valve 130 can work more stably in this dynamic environment, ensuring that the valve can act accurately when needed and maintain the normal operation of the system.

[0086] Secondly, in the complex operating environment of a bunkering vessel, operators may not be able to directly operate the valves manually, especially in emergencies or when frequent valve opening and closing is required. In this embodiment of the invention, the pneumatic shut-off valve 130 allows for remote control. Operators can open or close the valve from a location far from the valve (such as a control room) by controlling the flow of instrument air. This setup improves the convenience and efficiency of operation while also reducing the potential risks faced by operators on-site.

[0087] Continue reading Figure 1 In an optional embodiment of the present invention, the BOG sampling assembly 400 includes a BOG sampling probe 410 and a three-valve assembly 420. The three-valve assembly 420 is located between the outlet of the BOG sampling probe 410 and the inlet of the gas chromatography-mass spectrometry assembly 600. The BOG sampling probe 410 is used to connect to the gas phase manifold 20 so as to remove the BOG sample in the gas phase manifold 20.

[0088] The three-valve manifold 420 typically consists of two shut-off valves (isolation valves) and one balancing valve, all integrated into a single valve body for a compact design. During normal BOG sampling, the two shut-off valves (isolation valves) in the manifold 420 are open, while the balancing valve is closed. This ensures that the BOG sample in the gas phase header 20 can smoothly enter the BOG pretreatment component 500 via the BOG sampling probe 410, and then flow to the gas chromatography-mass spectrometry (GC-MS) component 600 for analysis. During operation, the BOG sample flow rate can be adjusted by precisely controlling the opening degree of the three-valve manifold 420 to meet the system's requirements for different sample volumes.

[0089] Continue reading Figure 2 In an optional embodiment of this utility model, the LNG sampling system further includes a sample return pipeline 700; the sample return assembly includes a manual sampling return branch 710, an LNG sample return branch 720, and a BOG sample return branch 730; the inlet of the manual sampling return branch 710 is connected to the outlet of the buffer tank 320, the outlet of the manual sampling return branch 710 is used to connect to the sample return main pipe 30, and the manual sampling return branch 710 is used to sample LNG samples.

[0090] Specifically, the manual sampling return branch 710 is sequentially connected to a pressure indicator, a manual sampling device, and a check valve. When manual sampling is required, the operator first ensures that the manual sampling return branch 710 is properly connected. When manual sampling begins, the operator activates the manual sampling device. At this time, the LNG sample, after being processed by the vaporization component 200, enters the manual sampling container (such as a sampling cylinder) under pipeline pressure. During this process, the pressure indicator displays the pressure in the current branch in real time. The operator can control the sampling process based on the pressure reading and the capacity of the sampling container to ensure safe and accurate acquisition of sufficient sample.

[0091] Understandably, in some cases, offline analysis of LNG samples may be necessary. Manual sampling allows samples to be collected into suitable containers, facilitating their transport to laboratories or other analytical sites to meet these specific analytical needs. Secondly, when the gas chromatography-mass spectrometry (GC-MS) analyzer 600 malfunctions or when system interference is suspected, the manual sampling return branch 710 provides an alternative sampling method. Manual sampling isolates the sample from the automated system for independent analysis, aiding in troubleshooting, verifying system accuracy, and providing a basis for timely system repair.

[0092] The inlet of the LNG sample return branch 720 is connected to the outlet of the buffer tank 320, and the outlet of the LNG sample return branch 720 is used to connect to the sample return main pipe 30. The LNG sample return branch 720 is used to transport the LNG sample to the sample return main pipe 30. Specifically, the LNG sample return branch 720 is connected in sequence to a flow meter and a check valve. It can be understood that the LNG sample return branch 720 can enable the LNG sample to form a circulation within the system, which helps to ensure the consistency of the LNG sample within the system with the LNG sample in the liquid phase main pipe 10. This can avoid errors in the online analysis of the gas chromatography-mass spectrometry component 600 caused by the poor flowability of the LNG sample in the LNG pipeline 40, and can avoid the lag in the detection results caused by this reason.

[0093] The inlet of the BOG sample return branch 730 is connected to the outlet of the BOG sampling assembly, and the outlet of the BOG sample return branch 730 is used to connect to the sample return main pipe 30. The BOG sample return branch 730 is used to transport BOG samples to the sample return main pipe 30. The structure and function of the BOG sample return branch 730 are similar to those of the aforementioned LNG sample return branch 720, specifically as described above.

[0094] A second aspect of this utility model provides a bunkering vessel that includes the LNG sampling system described in any of the foregoing embodiments. It is understood that the bunkering vessel, because it includes the LNG sampling system described in any of the foregoing embodiments, also has the technical effects of the LNG sampling system described in any of the foregoing embodiments. For details, please refer to the foregoing description, which will not be repeated here.

[0095] It should be noted that the technical solutions in the various embodiments of this utility model can be combined with each other, but the basis for such combination is that they can be implemented by those skilled in the art. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist, that is, it is not within the protection scope of this utility model.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A LNG sampling system for bunkering vessels, characterized in that, The application relates to a LNG sampling device. The LNG sampling device comprises: An LNG pipeline (40) sequentially connected with an LNG sampling assembly (100), a vaporization assembly (200) and a gas quality analysis assembly (600), the LNG sampling assembly (100) is used for connecting to a liquid-phase main pipeline (10) to take out a LNG sample in the liquid-phase main pipeline (10), and the vaporization assembly (200) is used for vaporizing the LNG sample.

2. The LNG sampling system for a bunkering vessel according to claim 1, characterized in that, A BOG pipeline (50) sequentially connected with a BOG sampling assembly (400) and the gas quality analysis assembly (600), the BOG sampling assembly (400) is used for connecting to a gas-phase main pipeline (20) to take out a BOG sample in the gas-phase main pipeline (20), and the gas quality analysis assembly (600) is used for on-line analyzing the vaporized LNG sample and the BOG sample. The vaporization assembly (200) comprises: An electric heating vaporizer (210) with an inlet communicated with an outlet of the LNG sampling assembly (100) and an outlet communicated with an inlet of the gas quality analysis assembly (600), the electric heating vaporizer (210) is used for vaporizing the LNG sample; A first-stage temperature detecting element (220) arranged between the inlet of the electric heating vaporizer (210) and the outlet of the LNG sampling assembly (100) and used for detecting the temperature of the LNG sample at the inlet of the electric heating vaporizer (210); A second-stage temperature detecting element (230) arranged in the electric heating vaporizer (210) and used for detecting the temperature of the LNG sample in the electric heating vaporizer (210); 3. The LNG sampling system for a bunkering vessel according to claim 2, characterized in that, A third-stage temperature detecting element (240) arranged between the outlet of the electric heating vaporizer (210) and the inlet of the gas quality analysis assembly (600) and used for detecting the temperature of the LNG sample at the outlet of the electric heating vaporizer (210). The LNG sampling device further comprises an LNG pretreatment assembly (300).

4. The LNG sampling system for a bunkering vessel according to claim 3, characterized in that, The LNG pretreatment assembly (300) comprises a first-stage LNG pressure reducing valve (310), a buffer tank (320), an LNG pressure indicating element (330) and an LNG flowmeter (340), the inlet of the first-stage LNG pressure reducing valve (310) is communicated with the outlet of the electric heating vaporizer (210), the outlet of the first-stage LNG pressure reducing valve (310) is communicated with the inlet of the buffer tank (320), the outlet of the buffer tank (320) is communicated with the inlet of the gas quality analysis assembly (600), and the LNG pressure indicating element (330) and the LNG flowmeter (340) are sequentially arranged between the outlet of the buffer tank (320) and the inlet of the gas quality analysis assembly (600). The LNG pretreatment assembly (300) further comprises a second-stage LNG pressure reducing valve (350) arranged between the LNG pressure indicating element (330) and the LNG flowmeter (340).

5. The LNG sampling system for a bunkering vessel of claim 3, wherein, Further comprising an LNG heat tracing pipe (360), an outlet of the electric heating vaporizer (210) is communicated with an inlet of the first stage LNG pressure reducing valve (310) through the LNG heat tracing pipe (360); A temperature of the LNG heat tracing pipe (360) is a, wherein a≥65℃.

6. The LNG sampling system for a bunkering vessel of claim 1, wherein, Further comprising a BOG pretreatment assembly (500); The BOG pretreatment assembly (500) comprises a first stage BOG pressure reducing valve (510), a BOG pressure indicating element (520), a second stage BOG pressure reducing valve (530) and a BOG flowmeter (540), an inlet of the first stage BOG pressure reducing valve (510) is communicated with an outlet of the BOG sampling assembly (400), an outlet of the first stage BOG pressure reducing valve (510) is communicated with an inlet of the second stage BOG pressure reducing valve (530), an outlet of the second stage BOG pressure reducing valve (530) is communicated with an inlet of the gas quality analysis assembly (600); The BOG pressure indicating element (520) is arranged between the outlet of the first stage BOG pressure reducing valve (510) and the inlet of the second stage BOG pressure reducing valve (530), and the BOG flowmeter (540) is arranged between the outlet of the second stage BOG pressure reducing valve (530) and the inlet of the gas quality analysis assembly (600).

7. The LNG sampling system for a bunkering vessel according to claim 6, characterized in that, Further comprising a BOG heat tracing pipe (550), an outlet of the BOG sampling assembly (400) is communicated with an inlet of the first stage BOG pressure reducing valve (510) through the BOG heat tracing pipe (550); A temperature of the BOG heat tracing pipe (550) is b, wherein b≥65℃.

8. The LNG sampling system for a bunkering vessel according to any one of claims 1 to 7, characterized in that, The LNG sampling assembly (100) comprises an LNG sampling probe (110), a manual shut-off valve (120) and a pneumatic shut-off valve (130), the manual shut-off valve (120) and the pneumatic shut-off valve (130) are arranged in sequence between an outlet of the LNG sampling probe (110) and an inlet of the vaporization assembly (200), and the LNG sampling probe (110) is used to be connected to the liquid phase header (10) so as to take out the LNG sample in the liquid phase header (10).

9. The LNG sampling system for a bunkering vessel according to any one of claims 1 to 7, characterized in that, The BOG sampling assembly (400) comprises a BOG sampling probe (410) and a three-valve group (420), the three-valve group (420) is arranged between an outlet of the BOG sampling probe (410) and an inlet of the gas quality analysis assembly (600), and the BOG sampling probe (410) is used to be connected to the gas phase header (20) so as to take out the BOG sample in the gas phase header (20).

10. The LNG sampling system for a bunkering vessel according to any one of claims 1 to 7, characterized in that, Further comprising a sample return pipeline (700); The sample return pipeline (700) comprises: A manual sampling return branch (710), an inlet of which is communicated with an outlet of the vaporization assembly (200), and an outlet of which is used to be connected to a sample return header (30), the manual sampling return branch (710) is used to sample the LNG sample; - an LNG sample return branch (720) having an inlet in communication with the outlet of the vaporization assembly (200) and an outlet for connection to the sample return header (30), the LNG sample return branch (720) being configured to deliver the LNG sample to the sample return header (30); - a BOG sample return branch (730) having an inlet in communication with the outlet of the BOG sampling group and an outlet for connection to the sample return header (30), the BOG sample return branch (730) being configured to deliver the BOG sample to the sample return header (30).

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