Micro differential pressure sensing system and air tightness detection device

Abstract

The utility model discloses a micro differential pressure sensing system and an air tightness detection device, and relates to the technical field of air tightness detection. The micro differential pressure sensing system comprises an air pressure acquisition pipeline module, a differential pressure sensing module and a working environment maintenance module. When an enclosure system air pressure experiment starts, the air pressure collection pipeline module is used for controlling the first communication control pipeline to be opened to obtain the air pressure of the liquefied natural gas film type storage tank to the first air pressure tank; when an enclosure system air pressure experiment is finished, an air pressure collection pipeline module is used for controlling a second communication control pipeline to be opened to obtain air pressure of a liquefied natural gas film type storage tank to a second air pressure tank, so that an air pressure difference value in the first air pressure tank and the second air pressure tank is obtained through a pressure difference sensing module; and in a constant-temperature environment of the working environment maintenance module, micro-differential pressure leakage monitoring is performed on the internal air pressure of the LNG containment system in a marine environment, so that the accuracy of air pressure difference value detection is ensured.

Description

Technical Field

[0001] The present application relates to the technical field of air tightness detection, and in particular to a micro-pressure differential sensing system and an air tightness detection device. Background Art

[0002] Liquefied Natural Gas (LNG), whose main component is methane, is recognized as the cleanest fossil energy on earth. Membrane-type liquefied natural gas storage tanks, also known as LNG membrane-type storage tanks, use a containment system to ensure the overall tightness of the tank. Figure 1 As shown in the figure, the containment system of a liquefied natural gas (LNG) storage tank is divided into a primary shielded space, a secondary shielded space, and the space within the tank where LNG is stored. The containment system comprises a primary shielding layer, a secondary shielding layer, and an outer tank. The space between the primary and secondary shielding layers constitutes the primary shielded space, while the space between the secondary shielding layer and the outer tank constitutes the secondary shielded space. Both the primary and secondary shielding layers are constructed of 0.7mm thick Invar steel, and both the primary and secondary shielded spaces are filled with thermal insulation material. The shielding layer is welded using TIG welding, resulting in welds nearly 10,000 meters long, making weld defects unavoidable. However, due to plate thickness and structural limitations, conventional nondestructive testing techniques are limited in their application to tank wall weld defect detection. Therefore, tank wall seal testing is often used as a direct replacement for structural defect detection.

[0003] The containment system's airtightness testing is completed in multiple stages. The overall test phase involves verifying airtightness by comparing the rate of pressure rise before and after the 48-hour vacuum and pressure-maintaining period in the containment chamber. Due to the large volume of the containment chamber, the actual overall leakage rate is relatively low, necessitating the use of sensing equipment, primarily micro-differential pressure sensors, to monitor the internal pressure of the LNG containment system. However, existing equipment lacks micro-differential pressure sensors suitable for offshore environments. Utility Model Content

[0004] The embodiments of the present application provide a micro-pressure differential sensing system and an air tightness detection device, which can solve the technical problem that the current equipment does not have micro-pressure differential sensing equipment for offshore environments to realize micro-pressure differential leakage monitoring of the internal air pressure of the LNG containment system.

[0005] The present application provides a micro-differential pressure sensing system for monitoring the gas pressure of a liquefied natural gas membrane storage tank. The liquefied natural gas membrane storage tank is provided with a primary shielding layer, a secondary shielding layer, and an outer tank. The space between the primary shielding layer and the secondary shielding layer is a primary shielding space, and the space between the secondary shielding layer and the outer tank is a secondary shielding space.

[0006] The micro-pressure differential sensing system includes an air pressure collection pipeline module, a pressure differential sensing module and a working environment maintenance module;

[0007] The air pressure collection pipeline module includes a first communication control pipeline, a second communication control pipeline, a first air pressure tank and a second air pressure tank, wherein the first end of the first communication control pipeline is connected to the primary shielded space and the secondary shielded space, the second end of the first communication control pipeline is connected to the first air pressure tank, the first end of the second communication control pipeline is connected to the primary shielded space and the secondary shielded space, and the second end of the second communication control pipeline is connected to the second air pressure tank, and the first air pressure tank and the second air pressure tank have the same volume;

[0008] The pressure differential sensing module includes a micro-pressure differential sensor and a HART protocol acquisition module, the micro-pressure differential sensor is connected to the first air pressure tank and the second air pressure tank, and the HART protocol acquisition module is connected to the micro-pressure differential sensor to collect and transmit the sensing pressure data of the micro-pressure differential sensor in real time;

[0009] The working environment maintaining module includes a constant temperature box, in which the first air pressure tank, the second air pressure tank and the pressure difference sensing module are arranged.

[0010] Furthermore, the first connecting control pipeline and the second connecting control pipeline include a common main pipeline, the first connecting control pipeline also includes a first branch pipeline, the second connecting control pipeline also includes a second branch pipeline, the first branch pipeline is provided with a first connecting valve, the second branch pipeline is provided with a second connecting valve, and the common main pipeline is provided with a third connecting valve; the first air pressure tank is connected to the main shielding space and the secondary shielding space through the first branch pipeline and the common main pipeline, and the second air pressure tank is connected to the main shielding space and the secondary shielding space through the second branch pipeline and the common main pipeline.

[0011] Furthermore, the first connecting valve, the second connecting valve and the third connecting valve are all airtight ball valves; when the containment system air pressure test begins, the first connecting valve and the third connecting valve are opened, and the first air pressure in the first air pressure tank is obtained through the pressure differential sensing module; when the containment system air pressure test ends, the second connecting valve and the third connecting valve are opened, and the second air pressure in the second air pressure tank is obtained through the pressure differential sensing module; the micro-pressure differential sensor compares the difference between the first air pressure and the second air pressure, and the HART protocol acquisition module acquires the sensing pressure data of the micro-pressure differential sensor.

[0012] Furthermore, the pressure difference sensing module also includes a power supply in a constant temperature box, and the power supply in the constant temperature box is connected to the micro pressure difference sensor.

[0013] Furthermore, the working environment maintaining module also includes a temperature sensor, which is arranged in the constant temperature box to obtain the temperature in the constant temperature box in real time.

[0014] Furthermore, the system also includes a monitor and a data transmission line, the monitor is connected to the HART protocol acquisition module through the data transmission line to collect and record the sensor pressure data collected by the micro-pressure differential sensor, and the monitor is connected to the temperature sensor through the data transmission line to collect and record the temperature data collected by the temperature sensor.

[0015] Furthermore, the working environment maintenance module also includes an air conditioner, which is connected to the constant temperature box to maintain the temperature inside the constant temperature box. The air conditioner is connected to the monitor, and the monitor controls the air conditioner based on the temperature data collected by the temperature sensor.

[0016] Furthermore, the working environment maintaining module further includes a heater, which is disposed in the constant temperature box and is connected to the monitor, and the monitor controls the heater based on temperature data collected by the temperature sensor.

[0017] Furthermore, the working environment maintenance module also includes a humidifier and a humidity sensor, which are arranged in the constant temperature box. The humidifier and the humidity sensor are connected to the monitor, and the monitor controls the humidifier and the heater based on the humidity data collected by the humidity sensor.

[0018] An embodiment of the present application also provides an airtightness detection device, which includes the micro-pressure difference sensing system described above.

[0019] The micro-pressure differential sensing system and air tightness detection device provided in the embodiment of the present application use the air pressure collection pipeline module to control the opening of the first connecting control pipeline to obtain the air pressure of the liquefied natural gas membrane storage tank to the first air pressure tank at the beginning of the containment system air pressure test, and use the air pressure collection pipeline module to control the opening of the second connecting control pipeline to obtain the air pressure of the liquefied natural gas membrane storage tank to the second air pressure tank at the end of the containment system air pressure test, thereby obtaining the air pressure difference between the first air pressure tank and the second air pressure tank through the pressure differential sensing module, and performing micro-pressure differential leakage monitoring on the internal air pressure of the LNG containment system in a constant temperature environment suitable for the offshore environment under the working environment maintenance module, thereby ensuring the accuracy of the air pressure difference detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.

[0021] Figure 1This is a schematic diagram of the cross-sectional structure of an existing LNG membrane storage tank;

[0022] Figure 2 This is a schematic structural diagram of the micro-pressure differential sensing system of this application;

[0023] Figure 3 This is the external connection diagram of the micro differential pressure sensing system of this application;

[0024] Figure 4 This is a flow chart of the cabin pressure difference detection of the pressure difference sensing system of this application. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0026] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0028] An embodiment of the present application provides a micro-differential pressure sensing system for monitoring the gas pressure of a liquefied natural gas membrane storage tank.

[0029] like Figure 1 Figure 2 shows a schematic diagram of the LNG membrane storage tank structure, which primarily includes a primary shielding layer 1, a secondary shielding layer 2, and an outer wall 3. The enclosed space within the primary shielding layer 1 is the tank interior space 4, the enclosed space between the primary shielding layer 1 and the secondary shielding layer 2 is the primary shielding space 5, and the enclosed space between the secondary shielding layer 2 and the outer wall 3 is the secondary shielding space 6.

[0030] The micro-pressure differential sensing system includes an air pressure collection pipeline module, a pressure differential sensing module and a working environment maintenance module.

[0031] The air pressure collection pipeline module includes a first connecting control pipeline 11, a second connecting control pipeline 12, a first air pressure tank 13 and a second air pressure tank 14. The first end of the first connecting control pipeline 11 is connected to the main shielded space 5 and the secondary shielded space 6, the second end of the first connecting control pipeline 11 is connected to the first air pressure tank 13, the first end of the second connecting control pipeline 12 is connected to the main shielded space 5 and the secondary shielded space 6, the second end of the second connecting control pipeline 12 is connected to the second air pressure tank 14, and the volumes of the first air pressure tank 13 and the second air pressure tank 14 are the same.

[0032] The pressure differential sensing module includes a micro pressure differential sensor 21 and a HART protocol acquisition module 22. The micro pressure differential sensor 21 is connected to the first air pressure tank 13 and the second air pressure tank 14. The HART protocol acquisition module 22 is connected to the micro pressure differential sensor 21 to collect and transmit the sensing pressure data of the micro pressure differential sensor 21 in real time.

[0033] The working environment maintaining module includes a constant temperature box 31 , in which the first air pressure tank 13 , the second air pressure tank 14 and the pressure difference sensing module are arranged.

[0034] Furthermore, the first connecting control pipeline 11 and the second connecting control pipeline 12 include a common main pipeline, the first connecting control pipeline 11 also includes a first branch pipeline, the second connecting control pipeline 12 also includes a second branch pipeline, the first branch pipeline is provided with a first connecting valve 111, the second branch pipeline is provided with a second connecting valve 121, and the common main pipeline is provided with a third connecting valve 131; the first air pressure tank 13 is connected to the main shielding space 5 and the secondary shielding space 6 through the first branch pipeline and the common main pipeline, and the second air pressure tank 14 is connected to the main shielding space 5 and the secondary shielding space 6 through the second branch pipeline and the common main pipeline.

[0035] Among them, the first connecting control pipeline 11 and the second connecting control pipeline 12 are respectively connected to the first air pressure tank 13 and the second air pressure tank 14 by a common main pipeline. By adjusting the connecting valve switch on the first connecting control pipeline 11 and the second connecting control pipeline 12, at the beginning of the containment system air pressure test, the air pressure acquisition pipeline module is used to control the first connecting control pipeline 11 to open and obtain the air pressure of the liquefied natural gas membrane storage tank to the first air pressure tank 13. At the end of the containment system air pressure test, the air pressure acquisition pipeline module is used to control the second connecting control pipeline 12 to open and obtain the air pressure of the liquefied natural gas membrane storage tank to the second air pressure tank 14, so as to obtain the air pressure difference between the first air pressure tank 13 and the second air pressure tank 14 through the pressure differential sensing module, and perform micro-pressure differential leakage monitoring on the internal air pressure of the LNG containment system under the constant temperature environment of the working environment maintenance module suitable for the offshore environment to ensure the accuracy of the air pressure difference detection.

[0036] Furthermore, the first connecting valve 111, the second connecting valve 121 and the third connecting valve 131 are all airtight ball valves; when the containment system air pressure test begins, the first connecting valve 111 and the third connecting valve 131 are opened, and the first air pressure in the first air pressure tank 13 is obtained through the pressure difference sensing module; when the containment system air pressure test ends, the second connecting valve 121 and the third connecting valve 131 are opened, and the second air pressure in the second air pressure tank 14 is obtained through the pressure difference sensing module; the micro-pressure differential sensor 21 compares the difference between the first air pressure and the second air pressure, and the HART protocol acquisition module 22 acquires the sensing pressure data of the micro-pressure differential sensor 21.

[0037] The entire pipeline in the air pressure collection pipeline module ensures that the pressure leakage is less than two orders of magnitude below the pressure drop of the containment system under negative pressure maintenance conditions for 48 hours. To ensure the accuracy of the micro-differential pressure sensor 21 in comparing the difference between the first and second air pressures, the first and second air pressure tanks 13 and 14 have the same volume. The function of the first and second air pressure tanks 13 and 14 is to provide a certain buffer when the cabin pressure changes. Their volume is related to the volume of the cabin to be measured, and there are no requirements for their shape. Their airtightness must ensure that the pressure leakage is less than two orders of magnitude below the pressure drop of the containment system after maintaining the pressure under negative pressure conditions for 48 hours.

[0038] The HART protocol acquisition module 22 is placed in a constant temperature box 31 to prevent signal distortion or loss caused by long data transmission distance.

[0039] Furthermore, the pressure difference sensing module further includes a power supply 32 in the constant temperature box, which is connected to the micro-pressure difference sensor 21. The power supply 32 in the constant temperature box is provided with a power socket to directly power various systems in the constant temperature box 31.

[0040] Furthermore, the working environment maintaining module further includes a temperature sensor 33 , which is disposed in the constant temperature box 31 and is used to obtain the temperature in the constant temperature box 31 in real time.

[0041] Furthermore, the working environment maintenance module also includes a monitor 34 and a data transmission line 35. The monitor 34 is connected to the HART protocol acquisition module 22 through the data transmission line 35 to collect and record the sensor pressure data collected by the micro-pressure differential sensor 21. The monitor 34 is connected to the temperature sensor 33 through the data transmission line 35 to collect and record the temperature data collected by the temperature sensor 33.

[0042] Furthermore, the working environment maintenance module also includes an air conditioner, which is connected to the constant temperature box 31 to maintain the temperature inside the constant temperature box 31. The air conditioner is connected to the monitor 34, and the monitor 34 controls the air conditioner based on the temperature data collected by the temperature sensor 33.

[0043] Furthermore, the working environment maintaining module further includes a heater, which is disposed in the constant temperature box 31 and is connected to the monitor 34 . The monitor 34 controls the heater based on the temperature data collected by the temperature sensor 33 .

[0044] Furthermore, the working environment maintenance module also includes a humidifier and a humidity sensor, which are arranged in the constant temperature box 31. The humidifier and the humidity sensor are connected to the monitor 34, and the monitor 34 controls the humidifier and the heater based on the humidity data collected by the humidity sensor.

[0045] like Figure 3 As shown, Figure 3 This is the external connection diagram of the micro-pressure differential sensing system. The system's power supply is connected to the power supply inside the monitoring room of the test container. The system's pressure sampling port is connected to the pressure sampling port of the test chamber. The output signals of the temperature sensor 33 and HART protocol acquisition module 22 are then connected to a monitor 34 for signal acquisition and recording.

[0046] like Figure 4 As shown, Figure 4This is a flow chart for detecting cabin pressure differentials using the micro-pressure differential sensing system. During the entire test phase, third connecting valve 131 remains open. At the start of the experiment, first connecting valve 111 is opened to sample the initial cabin reference pressure. Once sampling is complete, first connecting valve 111 is closed. Throughout the test, second connecting valve 121 remains open to sample cabin pressure in real time. The micro-pressure differential sensor 21 collects and compares the pressures of the first and second air pressure tanks 13, 14 to implement pressure monitoring.

[0047] Combining all the above technical solutions, the advantages and positive effects of the present invention can be summarized as follows:

[0048] The present invention is based on a micro-pressure differential sensor, which can realize pressure monitoring during the overall testing phase of the LNG ship containment system and provide testing personnel with at least 48 hours of pressure change information.

[0049] An embodiment of the present application also provides an airtightness detection device, which includes the micro-pressure difference sensing system described above.

[0050] The micro-pressure differential sensing system and air tightness detection device provided in the embodiment of the present application use the air pressure collection pipeline module to control the opening of the first connecting control pipeline to obtain the air pressure of the liquefied natural gas membrane storage tank to the first air pressure tank at the beginning of the containment system air pressure test, and use the air pressure collection pipeline module to control the opening of the second connecting control pipeline to obtain the air pressure of the liquefied natural gas membrane storage tank to the second air pressure tank at the end of the containment system air pressure test, thereby obtaining the air pressure difference between the first air pressure tank and the second air pressure tank through the pressure differential sensing module, and performing micro-pressure differential leakage monitoring on the internal air pressure of the LNG containment system in a constant temperature environment suitable for the offshore environment under the working environment maintenance module, thereby ensuring the accuracy of the air pressure difference detection.

[0051] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0052] The above is a detailed introduction to a micro-pressure differential sensing system and an air tightness detection device provided in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application; ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements 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 application.

Claims

1. A micro differential pressure sensing system for monitoring the gas pressure of a liquefied natural gas membrane storage tank; characterized in that: The liquefied natural gas membrane storage tank is provided with a primary shielding layer, a secondary shielding layer and an outer tank, the space between the primary shielding layer and the secondary shielding layer is the primary shielding space, and the space between the secondary shielding layer and the outer tank is the secondary shielding space; The micro-pressure differential sensing system includes an air pressure collection pipeline module, a pressure differential sensing module and a working environment maintenance module; The air pressure collection pipeline module includes a first communication control pipeline, a second communication control pipeline, a first air pressure tank and a second air pressure tank, wherein the first end of the first communication control pipeline is connected to the primary shielded space and the secondary shielded space, the second end of the first communication control pipeline is connected to the first air pressure tank, the first end of the second communication control pipeline is connected to the primary shielded space and the secondary shielded space, and the second end of the second communication control pipeline is connected to the second air pressure tank, and the first air pressure tank and the second air pressure tank have the same volume; The pressure differential sensing module includes a micro-pressure differential sensor and a HART protocol acquisition module, the micro-pressure differential sensor is connected to the first air pressure tank and the second air pressure tank, and the HART protocol acquisition module is connected to the micro-pressure differential sensor to collect and transmit the sensing pressure data of the micro-pressure differential sensor in real time; The working environment maintaining module includes a constant temperature box, in which the first air pressure tank, the second air pressure tank and the pressure difference sensing module are arranged.

2. The micro differential pressure sensing system according to claim 1, wherein: The first connecting control pipeline and the second connecting control pipeline include a common main pipeline, the first connecting control pipeline also includes a first branch pipeline, the second connecting control pipeline also includes a second branch pipeline, the first branch pipeline is provided with a first connecting valve, the second branch pipeline is provided with a second connecting valve, and the common main pipeline is provided with a third connecting valve; the first air pressure tank is connected to the main shielding space and the secondary shielding space through the first branch pipeline and the common main pipeline, and the second air pressure tank is connected to the main shielding space and the secondary shielding space through the second branch pipeline and the common main pipeline.

3. The micro differential pressure sensing system according to claim 2, wherein: The first connecting valve, the second connecting valve and the third connecting valve are all airtight ball valves; when the containment system air pressure test begins, the first connecting valve and the third connecting valve are opened, and the first air pressure in the first air pressure tank is obtained through the pressure differential sensing module; when the containment system air pressure test ends, the second connecting valve and the third connecting valve are opened, and the second air pressure in the second air pressure tank is obtained through the pressure differential sensing module; the micro-pressure differential sensor compares the difference between the first air pressure and the second air pressure, and the HART protocol acquisition module acquires the sensing pressure data of the micro-pressure differential sensor.

4. The micro differential pressure sensing system according to claim 1, wherein: The pressure difference sensing module further includes a power supply in a constant temperature box, and the power supply in the constant temperature box is connected to the micro pressure difference sensor.

5. The micro differential pressure sensing system according to claim 1, wherein: The working environment maintaining module further includes a temperature sensor, which is disposed in the constant temperature box and is used to obtain the temperature in the constant temperature box in real time.

6. The micro differential pressure sensing system according to claim 5, characterized in that: The system also includes a monitor and a data transmission line. The monitor is connected to the HART protocol acquisition module through the data transmission line to collect and record the sensor pressure data collected by the micro-differential pressure sensor. The monitor is connected to the temperature sensor through the data transmission line to collect and record the temperature data collected by the temperature sensor.

7. The micro differential pressure sensing system according to claim 6, wherein: The working environment maintaining module further includes an air conditioner, which is connected to the constant temperature box to maintain the temperature inside the constant temperature box. The air conditioner is connected to the monitor, and the monitor controls the air conditioner based on temperature data collected by the temperature sensor.

8. The micro differential pressure sensing system according to claim 6, wherein: The working environment maintaining module further includes a heater, which is disposed in the constant temperature box and is connected to the monitor. The monitor controls the heater based on temperature data collected by the temperature sensor.

9. The micro differential pressure sensing system according to claim 8, wherein: The working environment maintenance module also includes a humidifier and a humidity sensor, which are arranged in the constant temperature box. The humidifier and the humidity sensor are connected to the monitor, and the monitor controls the humidifier and the heater based on humidity data collected by the humidity sensor.

10. An airtightness detection device, characterized in that: A micro-pressure differential sensing system comprising the micro-pressure differential sensing system according to any one of claims 1 to 9.

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