A LNG analysis sampling probe vacuum degree automatic maintaining device and a using method thereof

Abstract

The application provides a LNG analysis sampling probe vacuum degree automatic maintenance device and a use method thereof, which comprises a pneumatic vacuum generator, a pressure reducing valve, a vacuum degree setting and adjusting valve, a pneumatic switch and a pneumatic three-way joint. The sampling probe is connected with the pneumatic vacuum generator. The connecting pipeline between the sampling probe and the pneumatic vacuum generator is sequentially connected with the vacuum degree setting and adjusting valve and the pneumatic switch in sequence. The pneumatic vacuum generator is connected with an external instrument air pipeline. The external instrument air pipeline is connected with the pressure reducing valve and the pneumatic three-way joint respectively. The pressure reducing valve is connected with the vacuum degree setting and adjusting valve. The vacuum degree setting and adjusting valve is connected with the pneumatic three-way joint. The pneumatic three-way joint is connected with the pneumatic switch and the pneumatic vacuum generator respectively. The application realizes the effect of automatic vacuum extraction and vacuum degree maintenance by integrating the low air pressure generated by the pneumatic vacuum generator to automatically extract the vacuum cavity of the sampling probe.

Description

Technical Field

[0001] This invention relates to the field of online liquefied natural gas sampling technology, and in particular to an automatic vacuum maintenance device for an LNG analysis sampling probe and its usage method. Background Technology

[0002] During the unloading of liquefied natural gas (LNG) at the receiving terminal, continuous sampling and analysis of the LNG are necessary to obtain its composition. The accuracy of this sampling and analysis is extremely important. For component analysis, the LNG must first be vaporized. To ensure that all components of the vaporized LNG are completely vaporized, a cooling process is required between the LNG unloading manifold and the sampling probe entering the vaporizer. This is achieved by evacuating the sampling probe cavity to block heat conduction, preventing light components such as methane and nitrogen from prematurely vaporizing and escaping before entering the vaporizer, which would lead to inaccurate sampling and affect the final analysis results.

[0003] The sampling pipeline requires a high vacuum level, below 0.2 bar, to ensure adequate vacuum. Manual vacuuming is generally necessary. Manual vacuuming requires the operator to stand on the unloading main operating platform at least five meters above the ground. The vacuum generator is connected to both ends of the sampling probe and the instrument air duct. After connection, the instrument air switch is turned on. When the high-velocity instrument air (0.7 MPa) enters the vacuum generator, a negative pressure zone is created, drawing out the gas from the sampling probe cavity and expelling it with the instrument air. After approximately 15 minutes of vacuuming, the pressure in the sampling probe cavity decreases from an absolute pressure of 20 kPa to below 15 kPa, increasing the vacuum level. When the vacuum level in the sampling probe cavity drops below 15 kPa, the operator tightens the interface valve on the sampling probe, closes the instrument air switch, and disconnects the pipeline. Based on operational experience, this pressure can only be maintained for 3–5 days. Therefore, manual vacuuming is required by the operator before receiving the ship. Manual vacuuming operations are characterized by their simplicity, high repeatability, high labor consumption, high operational risk, and high wear rate of precision equipment parts.

[0004] Maintaining vacuum in sampling probes is a common challenge in liquefied natural gas (LNG) receiving terminals. Currently, most LNG receiving terminals use stainless steel hoses to directly connect the vacuum generator to the instrument air ducts and sampling probes. This method still requires manual operation by the operator in some parts, posing certain operational risks. Some LNG receiving terminals use a circulating LNG cooling method to maintain the supercooling of the sampling probes. This method involves installing a sleeve around the sampling probe, wrapping it with LNG, and injecting LNG into the sleeve for cooling circulation. This method is prone to leakage, and because the sleeve needs to be insulated, minor leaks are not easily detected. Furthermore, the cooling effect is not as ideal as vacuum cooling. Summary of the Invention

[0005] The purpose of this invention is to provide an automatic vacuum maintenance device for an LNG analysis sampling probe and its usage method, which can achieve the effect of automatically evacuating and maintaining the vacuum level.

[0006] According to one objective of the present invention, an automatic vacuum maintenance device for an LNG analysis sampling probe is provided, comprising a pneumatic vacuum generator, a pressure reducing valve, a vacuum setting and regulating valve, a pneumatic switch, and a pneumatic triplet. The sampling probe is connected to the pneumatic vacuum generator. The vacuum setting and regulating valve and the pneumatic switch are connected in series on the connecting pipeline between the sampling probe and the pneumatic vacuum generator. The pneumatic vacuum generator is connected to an external instrument air duct. The external instrument air duct is connected to the pressure reducing valve and the pneumatic triplet, respectively. The pressure reducing valve is connected to the vacuum setting and regulating valve, and the vacuum setting and regulating valve is connected to the pneumatic triplet. The pneumatic triplet is connected to the pneumatic switch and the pneumatic vacuum generator, respectively.

[0007] Furthermore, it also includes a housing, inside which the pneumatic vacuum generator, the pressure reducing valve, the vacuum setting and regulating valve, the pneumatic switch, and the pneumatic triplet are disposed.

[0008] Furthermore, the housing is equipped with a gas source power interface, an equipment gas source interface, and a vacuum interface. The pneumatic vacuum generator is connected to the external instrument air duct through the gas source power interface, the sampling probe is connected to the pneumatic vacuum generator through the vacuum interface, and the external instrument air duct is connected to the equipment gas source interface through a branch pipe.

[0009] Furthermore, the external instrument air duct is connected to the instrument air source, and a main switch is provided on the external instrument air duct.

[0010] Furthermore, it also includes a remote pressure gauge, which is installed on the pipeline between the vacuum setting and regulating valve and the pneumatic switch.

[0011] Furthermore, it also includes a local pressure display, which is connected in series in the connecting pipeline between the sampling probe and the vacuum setting regulating valve.

[0012] Furthermore, a vacuum switch is provided between the sampling probe and the vacuum interface, and a manual vacuum interface is provided at the front end of the vacuum switch.

[0013] Furthermore, a control switch is provided on the branch pipe, and the pipes located behind the control switch on the branch pipe are respectively connected to the pressure reducing valve and the pneumatic triplet.

[0014] According to another objective of the present invention, the present invention provides a method for using the above-mentioned automatic vacuum maintenance device for LNG analysis sampling probe, comprising the following steps:

[0015] S1, the external instrument air duct is connected to the pneumatic vacuum generator and provides power to the pneumatic vacuum generator. The external instrument air duct is connected to the pressure reducing valve and the pneumatic triplet respectively. The pressure reducing valve is connected to the vacuum setting and regulating valve and provides valve opening regulation pressure to the vacuum setting and regulating valve. The vacuum setting and regulating valve is connected to the pneumatic triplet and provides valve opening and closing gas signal to the pneumatic triplet. The pneumatic triplet is connected to the pneumatic switch and the pneumatic vacuum generator respectively and provides opening and closing signals to the pneumatic switch and the pneumatic vacuum generator.

[0016] S2, the vacuum setting and regulating valve is set to start vacuuming. When the vacuum level of the sampling probe is detected to be lower than the set value, the pneumatic switch and the pneumatic vacuum generator open after receiving the pneumatic signal from the pneumatic triplet. The pneumatic vacuum generator starts to work and uses the instrument air provided by the external instrument air duct to draw the gas in the vacuum chamber of the sampling probe to increase the vacuum level.

[0017] Furthermore, a remote pressure gauge is installed on the pipeline between the vacuum setting and regulating valve and the pneumatic switch. A high pressure alarm value is set, and the data transmitted to the central control unit through the remote pressure gauge is used for remote monitoring and alerts. At the same time, the pressure trend can be viewed.

[0018] The technical solution of this invention realizes the function of automatic vacuuming of the sampling probe by setting a pressure reducing valve, a vacuum setting and regulating valve, a pneumatic switch and a pneumatic triplet. The low air pressure generated by the integrated pneumatic vacuum generator is used to automatically evacuate the vacuum chamber of the sampling probe. When the vacuum degree of the sampling probe is lower than the set value of the pneumatic component, the vacuum degree of the sampling probe will be automatically and quickly increased until it is higher than the preset vacuum degree, and then the vacuuming operation will stop, thereby achieving the effect of automatic vacuuming and maintaining the vacuum degree. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0021] In the diagram: 1. Housing; 2. Pneumatic vacuum generator; 3. Pressure reducing valve; 4. Vacuum setting and regulating valve; 5. Pneumatic switch; 6. Pneumatic triplet; 7. Remote pressure gauge; 8. Air source power interface; 9. Equipment air source interface; 10. Vacuum interface; 11. External instrument air duct; 12. Instrument air source; 13. Main switch; 14. Branch pipe; 15. Control switch; 16. Sampling probe; 17. Vacuum switch; 18. Local pressure display. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] Example 1

[0026] like Figure 1 As shown,

[0027] An automatic vacuum maintenance device for an LNG analysis sampling probe includes a housing 1, a pneumatic vacuum generator 2, a pressure reducing valve 3, a vacuum setting and regulating valve 4, a pneumatic switch 5, a pneumatic triplet 6, and a remote pressure gauge 7. The housing 1 is provided with a gas source power interface 8, a device gas source interface 9, and a vacuum interface 10. The pneumatic vacuum generator 2, pressure reducing valve 3, vacuum setting and regulating valve 4, pneumatic switch 5, pneumatic triplet 6, and remote pressure gauge 7 are disposed inside the housing 1.

[0028] The pneumatic vacuum generator 2 is connected to the external instrument air duct 11 via the air source power interface 8. The external instrument air duct 11 is connected to the instrument air source 12, which provides power to the pneumatic vacuum generator 2. Meanwhile, a main switch 13 is provided on the external instrument air duct 11 to turn the instrument air duct on or off.

[0029] The sampling probe 16 is connected to the pneumatic vacuum generator 2 via the vacuum port 10. A local pressure display 18, a vacuum setting regulating valve 4, and a pneumatic switch 5 are connected in series on the connecting pipe between the sampling probe 16 and the pneumatic vacuum generator 2. A vacuum switch 17 is also provided between the sampling probe 16 and the vacuum port 10. A remote pressure gauge 7 is installed on the pipe between the vacuum setting regulating valve 4 and the pneumatic switch 5.

[0030] The present invention provides a vacuum switch 17 between the sampling probe 16 and the vacuum interface 10, and a manual vacuum interface is reserved at the front end of the vacuum switch 17 to ensure that manual vacuuming can be used to solve the problem when the automatic vacuuming fails.

[0031] The external instrument air duct 11 is connected to the equipment air source interface 9 through the branch pipe 14. A control switch 15 is provided on the branch pipe 14. The pipes of the branch pipe 14 located after the control switch 15 are connected to the pressure reducing valve 3 and the pneumatic triplet 6 respectively. The pressure reducing valve 3 is connected to the vacuum setting regulating valve 4. The vacuum setting regulating valve 4 is connected to the pneumatic triplet 6. The pneumatic triplet 6 is connected to the pneumatic switch 5 and the pneumatic vacuum generator 2 respectively.

[0032] Compared to a manual vacuum generator, the automatic vacuum maintaining device of this invention achieves the function of automatically evacuating the sampling probe by setting a pressure reducing valve 3, a vacuum setting regulating valve 4, a pneumatic switch 5, a pneumatic triplet 6, a local pressure display 18, and a remote pressure gauge 7.

[0033] The instrument air of this invention is connected to the housing 1 through the air source power interface 8 and the equipment air source interface 9, and is connected to the various components inside the housing 1. The instrument air entering through the air source power interface 8 is connected to the pneumatic vacuum generator 2 and provides power to the pneumatic vacuum generator. The instrument air entering through the equipment air source interface 9 is connected to the pressure reducing valve 3 and the pneumatic triplet 6 respectively. The pressure reducing valve 3 is connected to the vacuum setting regulating valve 4 and provides the valve opening regulating pressure for the vacuum setting regulating valve 4. The vacuum setting regulating valve 4 is connected to the pneumatic triplet 6 and provides it with the valve opening and closing gas signal. The pneumatic triplet 6 is connected to the pneumatic switch 5 and the pneumatic vacuum generator 2 respectively and provides the opening and closing signals for the pneumatic switch 5 and the pneumatic vacuum generator 2.

[0034] The working principle of this invention is as follows:

[0035] After the automatic vacuum maintenance device is installed, turn on the main switch 13 on the instrument air duct 11. During the initial commissioning phase, observe the pressure value on the local pressure display 18 to set the vacuum setting adjustment valve 4 for vacuuming. When the vacuum level of the sampling probe 16 is detected to be lower than the set value, the pneumatic switch 5 and the pneumatic vacuum generator 2 open after receiving the pneumatic signal from the pneumatic triplet 6. The pneumatic vacuum generator 2 starts working, using 0.7MPa instrument air to eject the gas in the vacuum chamber of the sampling probe 16, thereby increasing the vacuum level. Set a high pressure alarm value, and remotely monitor and alert via data transmitted to the central control unit through the remote pressure gauge 7. Simultaneously, the pressure trend can be viewed.

[0036] The automatic vacuuming device of the present invention uses the low air pressure generated by the integrated pneumatic vacuum generator 2 to automatically evacuate the vacuum chamber of the sampling probe 16. When the vacuum level of the sampling probe 16 is lower than the set value of the pneumatic component, it will automatically and quickly increase the vacuum level of the sampling probe until it is higher than the preset vacuum level, and then stop the vacuuming operation, thereby achieving the effect of automatic vacuuming and maintaining the vacuum level.

[0037] By analyzing and comparing liquefied natural gas (LNG) from the same source port loaded on the same LNG carrier, under the premise that the calorific value at the loading port is the same, the calorific value obtained by the sampling system using the LNG analysis sampling probe vacuum degree automatic maintenance device of this invention is closer to that at the loading port, and the calorific value is lower than the analysis results before the modification. Through the modification of automatic vacuuming, the vacuum degree of the sampling system is more stable during unloading sampling, and the gas quality analysis results are more accurate.

[0038] Routine inspections of this invention only require observing the vacuum level on the local instrument panel of the sampling system on the ground. Maintenance is only required if the vacuum level remains high or the automatic vacuum generator continues to pump vacuum without automatically stopping.

[0039] This invention's automatic vacuum maintenance device reduces manual operation; only manual activation is required while the system automatically maintains the vacuum level. This reduces operator time and risk. The device eliminates the need for frequent vacuum chamber connections, minimizing wear on precision components. Powered by instrument air, it poses no risk of leakage and offers high safety. It also provides excellent cold insulation. The automatic vacuum device can maintain the pressure within the sampling probe's cavity below 0.13 bar for extended periods, significantly meeting the vacuum requirements of the sampling system.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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 or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An automatic vacuum maintenance device for an LNG analysis sampling probe, characterized in that, The device includes a pneumatic vacuum generator, a pressure reducing valve, a vacuum setting and regulating valve, a pneumatic switch, and a pneumatic triplet. A sampling probe is connected to the pneumatic vacuum generator. The vacuum setting and regulating valve and the pneumatic switch are connected in series on the connecting pipe between the sampling probe and the pneumatic vacuum generator. The pneumatic vacuum generator is connected to an external instrument air duct. The external instrument air duct is connected to the pressure reducing valve and the pneumatic triplet. The pressure reducing valve is connected to the vacuum setting and regulating valve. The vacuum setting and regulating valve is connected to the pneumatic triplet. The pneumatic triplet is connected to the pneumatic switch and the pneumatic vacuum generator. The system also includes a housing, inside which are housed the pneumatic vacuum generator, the pressure reducing valve, the vacuum setting and regulating valve, the pneumatic switch, and the pneumatic triplet. The housing has a power supply interface, an equipment air supply interface, and a vacuuming interface. The pneumatic vacuum generator is connected to the external instrument air duct via the power supply interface, and the sampling probe is connected to the pneumatic vacuum generator via the vacuuming interface. The external instrument air duct is connected to the equipment air supply interface via a branch pipe. The system also includes a remote pressure gauge installed on the pipeline between the vacuum setting and regulating valve and the pneumatic switch. Finally, it includes a local pressure display connected in series on the connecting pipeline between the sampling probe and the vacuum setting and regulating valve.

2. The automatic vacuum maintenance device for the LNG analysis sampling probe according to claim 1, characterized in that, The external instrument air duct is connected to the instrument air source, and a main switch is provided on the external instrument air duct.

3. The automatic vacuum maintenance device for the LNG analysis sampling probe according to claim 1, characterized in that, A vacuum switch is also provided between the sampling probe and the vacuum interface, and a manual vacuum interface is provided at the front end of the vacuum switch.

4. The automatic vacuum maintenance device for the LNG analysis sampling probe according to claim 1, characterized in that, The branch pipe is equipped with a control switch, and the pipes located behind the control switch are connected to the pressure reducing valve and the pneumatic triplet respectively.

5. The method of using the automatic vacuum maintenance device for the LNG analysis sampling probe according to claim 1, characterized in that, Includes the following steps: S1, the external instrument air duct is connected to the pneumatic vacuum generator and provides power to the pneumatic vacuum generator. The external instrument air duct is connected to the pressure reducing valve and the pneumatic triplet respectively. The pressure reducing valve is connected to the vacuum setting and regulating valve and provides valve opening regulation pressure to the vacuum setting and regulating valve. The vacuum setting and regulating valve is connected to the pneumatic triplet and provides valve opening and closing gas signal to the pneumatic triplet. The pneumatic triplet is connected to the pneumatic switch and the pneumatic vacuum generator respectively and provides opening and closing signals to the pneumatic switch and the pneumatic vacuum generator. S2, the vacuum setting and regulating valve is set to start vacuuming. When the vacuum level of the sampling probe is detected to be lower than the set value, the pneumatic switch and the pneumatic vacuum generator open after receiving the pneumatic signal from the pneumatic triplet. The pneumatic vacuum generator starts to work and uses the instrument air provided by the external instrument air duct to draw the gas in the vacuum chamber of the sampling probe to increase the vacuum level.

6. The method of using the automatic vacuum maintenance device for the LNG analysis sampling probe according to claim 5, characterized in that, A remote pressure gauge is installed on the pipeline between the vacuum setting and regulating valve and the pneumatic switch. A high pressure alarm value is set, and the data transmitted to the central control unit through the remote pressure gauge is used for remote monitoring and alerts. At the same time, the pressure trend can be viewed.

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