Gas Leak Detection System

Abstract

The invention discloses a gas leakage monitoring system, which belongs to the field of gas leakage monitoring. The gas leakage monitoring system comprises: a laser, an optical fiber sensor assembly, and a photoelectric conversion module connected in sequence; an electric signal acquisition module, an electric signal processing module, and an alarm signal output module connected in sequence, the electric signal acquisition module is connected to the photoelectric conversion module, and the electric signal processing module is connected to the laser; the laser is used to emit laser to the optical fiber sensor; the optical fiber sensor is used to make the laser generate a first interference light wave signal, and use the ultrasonic wave generated by the gas leakage to make the laser generate a second interference light wave signal; the photoelectric conversion module is used to convert the first interference light wave signal and the second interference light wave signal into a first electric signal and a second electric signal, and transmit them to the electric signal processing module through the electric signal acquisition module; the electric signal processing module is used to judge whether a gas leakage occurs in the monitored area, and output the judgment result through the alarm signal output module.

Description

Technical Field

[0001] The invention relates to the field of gas leakage monitoring, and in particular to a gas leakage monitoring system. Background Art

[0002] For pressure gas pipelines and containers on the ground, such as pipelines and containers in natural gas pipeline stations, shale gas production well platforms, etc., they are easily affected by factors such as welding construction quality, corrosion, and pipe quality, which may lead to gas (such as natural gas) leakage, which will not only cause economic losses, but also easily cause safety accidents. Therefore, it is necessary to monitor whether there is gas leakage in the above areas in a timely and effective manner.

[0003] The existing technology generally uses a flow pressure gauge and uses methods such as a pressure gradient method and a cross-correlation method to determine whether a gas leak occurs in a pressure gas pipeline or container in the area to be monitored.

[0004] The inventors found that the prior art has at least the following problems:

[0005] The existing technology can only monitor when a large amount of gas leakage occurs in the pressure gas pipeline or container in the monitored area, and has the characteristic of high false alarm rate. Summary of the invention

[0006] The embodiment of the present invention provides a gas leakage monitoring system, which can solve the above technical problems. The technical solution is as follows:

[0007] A gas leakage monitoring system, comprising: a laser, an optical fiber sensor assembly, and a photoelectric conversion module connected in sequence through optical fibers; and an electrical signal acquisition module, an electrical signal processing module, and an alarm signal output module connected in sequence through electrical wires, wherein the electrical signal acquisition module is connected to the photoelectric conversion module through electrical wires, and the electrical signal processing module is connected to the laser through electrical wires;

[0008] The laser is used to emit laser light to the optical fiber sensor;

[0009] The optical fiber sensor assembly is used to make the laser generate a first interference light wave signal when no gas leakage occurs in the area to be monitored, and to make the laser generate a second interference light wave signal using ultrasonic waves generated by the gas leakage when gas leakage occurs in the area to be monitored;

[0010] The photoelectric conversion module is used to receive the first interference light wave signal and the second interference light wave signal, and convert the first interference light wave signal and the second interference light wave signal into a first electrical signal and a second electrical signal respectively, and then transmit the first electrical signal and the second electrical signal to the electrical signal processing module through the electrical signal acquisition module;

[0011] The electrical signal processing module is used to adjust the frequency of the laser emitted by the laser, and judge whether a gas leak occurs in the monitored area according to the received electrical signal, and output the judgment result through the alarm signal output module;

[0012] Wherein, the optical fiber sensor assembly includes a plurality of optical fiber sensors;

[0013] The gas leakage monitoring system further comprises: an optical beam splitter disposed between the laser and the plurality of optical fiber sensors via optical fibers;

[0014] The optical beam splitter is used to split the laser beam into multiple first sub-lasers, and transmit each first sub-laser to the corresponding optical fiber sensor;

[0015] The optical fiber sensor comprises: an N×N type optical beam splitter / combiner, two Faraday reflectors, and a plurality of transmission optical fibers, where N is an integer greater than 2;

[0016] The input end of the optical beam splitter / combiner is connected to the optical beam splitter through an optical fiber, and the output end is connected to the photoelectric conversion module through an optical fiber;

[0017] Each of the Faraday reflectors is connected to the beam splitting / combining end of the optical beam splitter / combiner through the corresponding transmission optical fiber.

[0018] In a possible design, a sensitivity enhancement component is provided on at least one of the transmission optical fibers.

[0019] In a possible design, the sensitizing element includes: a sensitizing cylinder, and a sensitive optical fiber arranged on the sensitizing cylinder;

[0020] The first end and the second end of the sensitive optical fiber are both connected to the corresponding transmission optical fiber.

[0021] In a possible design, the sensitive optical fiber is a bend-insensitive single-mode optical fiber.

[0022] In a possible design, the optical fiber sensor further includes: a dust protection cover;

[0023] The sensitizing component is located in the dustproof protective cover.

[0024] In a possible design, at least one of the transmission optical fibers is provided with a delay optical fiber.

[0025] In a possible design, the alarm signal output module includes: an alarm and a management platform respectively connected to the electrical signal processing module via optical fibers.

[0026] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0027] The gas leakage monitoring system provided by the embodiment of the present invention, through the cooperation of the laser and the optical fiber sensor assembly, enables the laser to generate a first interference light wave signal when no gas leakage occurs in the monitored area, and utilizes the ultrasonic wave generated by the gas leakage to enable the laser to generate a second interference light wave signal; and, through the cooperation of the photoelectric conversion module, the electrical signal acquisition module, the electrical signal processing module and the alarm signal output module, it can be effectively judged whether a gas leakage occurs in the gas pressure pipeline or container in the monitored area based on the first electrical signal and the second electrical signal converted from the first interference light wave signal and the second interference light wave signal; in addition, by electrically connecting the electrical signal processing module 5 to the laser 1, the sensitivity of the gas leakage monitoring system can be improved.

[0028] In summary, the gas leakage monitoring system provided by the embodiment of the present invention utilizes the principle that the ultrasonic wave generated by the gas leakage of the pressure gas pipeline and container on the ground changes the laser phase to monitor whether the gas leakage occurs in the monitored area. It has the characteristics of high sensitivity, low false alarm rate, low missed alarm rate, and fast alarm speed, and can avoid being affected by the size of the gas leakage in the pressure gas pipeline and container. In addition, since the optical fiber sensor is a passive optical device, it can avoid electromagnetic interference and expand the scope of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 is a structural block diagram of a gas leakage monitoring system provided by an embodiment of the present invention;

[0031] Figure 2 It is a schematic diagram of the connection between a type of optical fiber sensor, a photoelectric conversion module, and an optical beam splitter provided by an embodiment of the present invention;

[0032] Figure 3 is a schematic structural diagram of a sensitizing component provided in an embodiment of the present invention;

[0033] Figure 4 is a schematic structural diagram of another type of optical fiber sensor provided by an embodiment of the present invention;

[0034] Figure 5 It is a schematic diagram of the structure of another type of optical fiber sensor provided by an embodiment of the present invention.

[0035] The descriptions of the various reference numerals in the accompanying drawings are as follows:

[0036] 1-Laser;

[0037] 2- Fiber optic sensor assembly;

[0038] 2a-Fiber optic sensor;

[0039] 21- optical beam splitter / combiner;

[0040] 22-Faraday mirror;

[0041] 23- transmission optical fiber;

[0042] 24-sensitizing component;

[0043] 241-sensitization cylinder;

[0044] 242-sensitive optical fiber;

[0045] 25- dust protection cover;

[0046] 26-delay fiber;

[0047] 3- Photoelectric conversion module;

[0048] 4-Electrical signal acquisition module;

[0049] 5-Electrical signal processing module;

[0050] 6- Alarm signal output module;

[0051] 61- alarm;

[0052] 62-Management platform;

[0053] 7- Beam splitter. DETAILED DESCRIPTION

[0054] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0055] The embodiment of the present invention provides a gas leakage monitoring system, as shown in the attached Figure 1As shown, the gas leakage monitoring system includes: a laser 1, an optical fiber sensor assembly 2, and a photoelectric conversion module 3 connected in sequence through optical fibers; and an electric signal acquisition module 4, an electric signal processing module 5, and an alarm signal output module 6 connected in sequence through electric wires, the electric signal acquisition module 4 is connected to the photoelectric conversion module 3 through electric wires, and the electric signal processing module 5 is connected to the laser 1 through electric wires; the laser 1 is used to emit laser light to the optical fiber sensor assembly 2; the optical fiber sensor assembly 2 is used to generate a first interference light wave signal by the laser when no gas leakage occurs in the area to be monitored, and to generate a second interference light wave signal by the laser using ultrasonic waves generated by the gas leakage when gas leakage occurs in the area to be monitored; the photoelectric conversion module 3 is used to receive the first interference light wave signal and the second interference light wave signal, and convert the first interference light wave signal and the second interference light wave signal into a first electric signal and a second electric signal respectively, and then transmit the first electric signal and the second electric signal to the electric signal processing module 5 through the electric signal acquisition module 4; the electric signal processing module 5 is used to adjust the frequency of the laser emitted by the laser 1, and judge whether gas leakage occurs in the area to be monitored according to the received electric signal, and output the judgment result through the alarm signal output module 6.

[0056] The working principle of the gas leakage monitoring system provided by the embodiment of the present invention is described below:

[0057] When used, the optical fiber sensor assembly 2 of the gas leakage monitoring system is first installed in the area to be monitored. Then, the frequency of the laser to be emitted by the laser 1 is adjusted by the electrical signal processing module 5, and the laser 1 is used to emit laser light to the optical fiber sensor assembly 2.

[0058] When there is no gas leakage in the gas pressure pipeline or container in the monitored area, the optical fiber sensor assembly 2 is used to generate a first interference light wave signal by the laser. When there is a gas leakage in the monitored area, the ultrasonic wave generated by the gas leakage is used to generate a second interference light wave signal by the laser. Afterwards, the optical fiber sensor assembly 2 transmits the first interference light wave signal and the second interference light wave signal to the photoelectric conversion module 3.

[0059] The photoelectric conversion module 3 is used to convert the first interference light wave signal into a first electrical signal, and the second interference light wave signal into a second electrical signal. Afterwards, the first electrical signal or the second electrical signal is transmitted to the electrical signal processing module 5 through the electrical signal acquisition module 4, and the electrical signal processing module 5 performs signal demodulation, filtering, spectrum analysis, and signal feature analysis on the first electrical signal or the second electrical signal, thereby determining whether a gas leak occurs in the pipeline, and outputting the processing result through the alarm signal output module 6 to generate an alarm.

[0060] It can be seen that the gas leakage monitoring system provided by the embodiment of the present invention, through the cooperation of the laser 1 and the optical fiber sensor assembly 2, when there is no gas leakage in the monitored area, the laser generates a first interference light wave signal, and when there is a gas leakage in the monitored area, the laser generates a second interference light wave signal by using the ultrasonic wave generated by the gas leakage; and, through the cooperation of the photoelectric conversion module 3, the electrical signal acquisition module 4, the electrical signal processing module 5 and the alarm signal output module 6, it can be effectively judged whether there is a gas leakage in the gas pressure pipeline or container in the monitored area according to the first electrical signal and the second electrical signal converted from the first interference light wave signal and the second interference light wave signal. In addition, by electrically connecting the electrical signal processing module 5 to the laser 1, the sensitivity of the gas leakage monitoring system can be improved.

[0061] In summary, the gas leakage monitoring system provided by the embodiment of the present invention utilizes the principle that the ultrasonic wave generated by the gas leakage of the pressure gas pipeline and container on the ground changes the phase of the laser to monitor whether the gas leakage occurs in the monitored area. It has the characteristics of high sensitivity, low false alarm rate, low missed alarm rate, and fast alarm speed, and can avoid being affected by the size of the gas leakage in the pressure gas pipeline and container. In addition, since the optical fiber sensor is a passive optical device, it can avoid electromagnetic interference and expand the scope of use.

[0062] In order to expand the area monitored by the gas leakage monitoring system, in the embodiment of the present invention, as shown in the attached Figure 1 As shown, the optical fiber sensor assembly 2 includes a plurality of optical fiber sensors 2a; the gas leakage monitoring system further includes: an optical beam splitter 7 arranged between the laser 1 and the plurality of optical fiber sensors 2a through optical fibers; the optical beam splitter 7 is used to split the laser into a plurality of first sub-lasers, and transmit each first sub-laser to a corresponding optical fiber sensor 2a (see the attached Figure 1 ).

[0063] It should be noted that the input end of each optical fiber sensor 2a is connected to the optical beam splitter 7 through an optical fiber, and the output end is connected to the photoelectric conversion module 3 through an optical fiber; in addition, each optical fiber sensor 2a corresponds to a first interference light wave signal or a second interference light wave signal.

[0064] It can be understood that, since each optical fiber sensor 2 a is installed at a different position, the interference light wave signal transmitted by each optical fiber sensor 2 a to the photoelectric conversion module 3 may also be different.

[0065] Through the above arrangement, during the normal operation of the gas leakage monitoring system, the laser emitted by the laser 1 is split into multiple first sub-lasers by the optical beam splitter 7, and each first sub-laser is transmitted to the corresponding optical fiber sensor 2a. When there is no gas leakage in the monitored area, each optical fiber sensor 2a is used to make the first sub-laser generate a first interference light wave signal; when there is a gas leakage in the monitored area, the ultrasonic wave generated by the gas leakage modulates the phase of the first interference light wave signal, so that the first interference light wave signal generates a second interference light wave signal. Afterwards, multiple optical fiber sensors 2a are used to transmit multiple first interference light wave signals or multiple second interference light wave signals to the photoelectric conversion module 3.

[0066] The number and location of the optical fiber sensors 2a can be set specifically according to the conditions of the area to be monitored.

[0067] In addition, regarding the structure of the optical fiber sensor 2a, in order to ensure that the optical fiber sensor 2a has a certain anti-polarization fading capability, an example is given in the attached figure. Figure 2 As shown, the optical fiber sensor 2a includes: an N×N type optical splitter / combiner 21, a plurality of Faraday reflectors 22, and two transmission optical fibers 23, where N is an integer greater than 2; the input end of the optical splitter / combiner 21 is connected to the optical splitter 7 through an optical fiber, and the output end is connected to the photoelectric conversion module 3 through an optical fiber; each Faraday reflector 22 is connected to the splitting / combining end of the optical splitter / combiner 21 through a corresponding transmission optical fiber 23.

[0068] Through the above arrangement, during the normal operation of the gas leakage monitoring system, the optical splitter / combiner 21 is used to split the first sub-laser split by the optical splitter 7 into multiple second sub-lasers, and each second sub-laser is transmitted to the corresponding Faraday reflector 22 through the corresponding transmission optical fiber 23.

[0069] Afterwards, when no gas leakage occurs in the monitored area, the Faraday reflector 22 is used to reflect the second sub-laser toward the optical splitter / combiner 21, so that the second sub-lasers reflected by the multiple Faraday reflectors 22 are combined in the optical splitter / combiner 21 and interfere, thereby forming a first interference light wave signal.

[0070] Similarly, when a gas leak occurs in the monitored area, multiple second sub-lasers first form a first interference light wave signal in the optical splitter / combiner 21, and then the ultrasonic wave generated by the gas leakage acts on the transmission optical fiber 23, causing the transmission optical fiber 23 to vibrate and modulate the phase of the first interference light wave signal, so that the first interference light wave signal forms a second interference light wave signal.

[0071] Finally, the optical beam splitter / combiner 21 is used to transmit the first interference light wave signal or the second interference light wave signal to the photoelectric conversion module 3 .

[0072] It should be noted that the input end and the output end of the optical beam splitter / combiner 21 are located on the same side (for example, Figure 1 The beam splitting / combining end is on the other side (e.g. Figure 2 on the right side of the image).

[0073] The number of the Faraday reflectors 22 is two, which can help the second sub-laser to form a first interference light wave signal and a second interference light wave signal in the optical beam splitter / combiner 21 .

[0074] It can be understood that the two second sub-lasers form a first interference light wave signal or a second interference light wave signal in the optical beam splitter / combiner 21 .

[0075] The Faraday reflector 22 can be purchased, for example, through Feibot Optoelectronics Technology (Shenzhen) Co., Ltd.

[0076] In addition, the above-mentioned optical splitter / combiner 21 can not only split the light source, but also combine multiple light paths. If the multiple light paths meet the conditions for interference, interference light waves can be formed in the optical splitter / combiner 21.

[0077] The optical beam splitter / combiner 21 can be purchased, for example, from Feibot Optoelectronics Technology (Shenzhen) Co., Ltd.

[0078] The optical splitter / combiner 21 may be an N×N type optical splitter / combiner 21, that is, the first end and the second end of the optical splitter / combiner 21 of this type are each provided with N optical fibers. In order to avoid the influence of phase fading, N is greater than 2, for example, set to 3, 4, 5, 6, etc.

[0079] Based on the above-mentioned type of optical splitter / combiner 21, as shown in the attached Figure 2 As shown, an optical fiber at the first end of the optical splitter / combiner 21 is connected to the optical splitter 7, and the remaining (N-1) optical fibers are connected to the photoelectric conversion module 3, wherein the above-mentioned N optical fibers are equivalent to the above-mentioned optical fibers located between the optical splitter / combiner 21 and the optical splitter 7, and between the optical splitter / combiner 21 and the photoelectric conversion module 3. In addition, the second end of the optical splitter / combiner 21 is respectively connected to the corresponding two Faraday reflectors 22 through two optical fibers, and the remaining (N-2) optical fibers do not need to be connected, wherein the two optical fibers are equivalent to the above-mentioned two transmission optical fibers 23 located between the two Faraday reflectors 22 and the optical splitter / combiner 21.

[0080] In order to improve the sensitivity of the optical fiber sensor 2a, in the embodiment of the present invention, as shown in the attached Figure 2 As shown, at least one transmission optical fiber 23 is provided with a sensitivity enhancement component 24 .

[0081] Regarding the number of the sensitizing elements 24 , multiple sensitizing elements 24 may be arranged at intervals on the same transmission optical fiber 23 to further improve the sensitivity of the optical fiber sensor 2a. For example, three sensitizing tubes may be arranged on each transmission optical fiber 23 .

[0082] Regarding the structure of the sensitivity enhancing member 24, based on the premise of simple structure, an example is given in the embodiment of the present invention, as shown in the attached Figure 3 As shown, the sensitivity enhancement component 24 includes: a sensitivity enhancement cylinder 241 and a sensitive optical fiber 242 arranged on the sensitivity enhancement cylinder 241; the first end and the second end of the sensitive optical fiber 242 are both connected to the corresponding transmission optical fiber 23.

[0083] The above-mentioned sensitizing cylinder 241 can be prepared by aluminum foil. This type of sensitizing cylinder 241 has the characteristic of being easily vibrated when subjected to ultrasonic waves, which can further improve the sensitivity of the sensitizing element 24 to ultrasonic waves.

[0084] Among them, the thickness of the sensitizing cylinder 241 can be set to 0.1mm~0.15mm. For example, it can be set to 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, etc. The embodiment of the present invention does not impose specific restrictions on the thickness of the sensitizing cylinder 241, as long as it can effectively increase the sensitivity of the sensitizing component 24.

[0085] In addition, the diameter of the sensitization cylinder 241 can be set to 5 cm to 6 cm, for example, 5 cm, 5.5 cm, 6 cm, etc. By setting in this way, the production of the sensitization cylinder 241 is facilitated, and the sensitization cylinder 241 can also be guaranteed to have a certain strength.

[0086] The above-mentioned sensitive optical fiber 242 can be arranged on the sensitizing cylinder 241 in a winding manner. By so arranging, the length of the sensitive optical fiber 242 can be increased, thereby increasing the area where the ultrasonic wave acts on the sensitive optical fiber 242, and further increasing the sensitivity of the sensitizing component 24 to the ultrasonic wave.

[0087] The sensitive optical fiber 242 and the transmission optical fiber 23 may be single-mode optical fibers. Such sensitive optical fibers 242 and transmission optical fibers 23 have the characteristics of low light attenuation and low noise.

[0088] Furthermore, the sensitive optical fiber 242 may be a bend-insensitive single-mode optical fiber, which can avoid light attenuation of the sensitive optical fiber 242 on the sensitivity-enhancing cylinder 241 .

[0089] In order to prevent the sensitizing element 24 from being damaged by the external environment, in the embodiment of the present invention, as shown in the attached Figure 2 , Attachment Figure 3As shown, the optical fiber sensor 2a further includes: a dustproof protective cover 25; and a sensitivity enhancement component 24 is located inside the dustproof protective cover 25.

[0090] By such an arrangement, the sensitizing component 24 can be prevented from being eroded by rain, snow, wind and sand, etc., so as to extend the service life of the sensitizing component 24.

[0091] In order for the ultrasonic wave generated by the gas leakage to act on the sensitizing element 24, a plurality of through holes are provided on the side wall of the dust protection cover 25 or the side wall is configured to be a mesh structure.

[0092] In addition, the dustproof protective cover 25 may be configured as a barrel-shaped structure, and the embodiment of the present invention does not limit the structure of the dustproof protective cover 25 .

[0093] Since the difference in arm lengths corresponding to each optical circuit in the optical fiber sensor 2a (i.e., the optical path between each Faraday reflector 22 and the optical beam splitter / combiner 21) is larger, the noise generated by the optical fiber sensor 1 is larger. Therefore, in the embodiment of the present invention, as shown in the attached Figure 2 As shown, at least one transmission optical fiber 23 is provided with a delay optical fiber 26 to reduce the arm error of the optical fiber sensor 1 .

[0094] Since the arm length corresponding to each optical circuit is related to the optical path of each optical circuit, the length of the delay optical fiber 26 can be set according to the total length of the optical fiber (including the transmission optical fiber 23 and the sensitive optical fiber 242) corresponding to each optical circuit.

[0095] For example, if Figure 4 As shown, the optical fiber sensor 2a includes two Faraday reflectors 22, that is, the optical fiber sensor 2a includes an optical circuit 1 and an optical circuit 2. Two sensitizers 24 are arranged on the optical circuit 1, and four sensitizers 24 are arranged on the optical circuit 2, and each sensitizer 24 is wound with a 50m sensitive optical fiber 242; in addition, the transmission optical fiber 23 on the optical circuit 1 and the optical circuit 2 is 100m long. Then, in order to compensate for the arm difference between the optical circuit 1 and the optical circuit 2, a delay optical fiber 26 with a length of 98m can be arranged on the optical circuit 1.

[0096] Based on the above-mentioned length of the delay optical fiber 26 , in order to facilitate the installation of the delay optical fiber 26 , the delay optical fiber 26 can be wound on a fiber coil.

[0097] In addition, the delay optical fiber 26 may be a single-mode optical fiber. This type of delay optical fiber 26 has the characteristics of low light attenuation and low noise.

[0098] Based on the above-mentioned optical fiber sensor 2a, in order to facilitate the installation and replacement of the optical fiber sensor 2a, in the embodiment of the present invention, as shown in the attached Figure 5As described above, a sensitive component 24 is disposed on the transmission optical fiber 23 corresponding to one Faraday reflector 22 , and a delay optical fiber 26 is disposed on the transmission optical fiber 23 corresponding to another Faraday reflector 22 .

[0099] By means of the above arrangement, when the sensitive component 24 or the delay optical fiber 26 is damaged, the optical fiber sensor 2a can be directly replaced under the premise of considering the cost.

[0100] In the embodiment of the present invention, as shown in the attached Figure 1 As shown, the alarm signal output module 6 includes: an alarm 61 and a management platform 62 which are respectively connected to the electrical signal processing module 5 through wires.

[0101] It can be seen that by setting up the alarm 61, the staff can be reminded in time that the pipeline is leaking, and through the management platform 62, the staff can quickly find the location of the gas leak in the pipeline, which can effectively prevent the dangers of pipeline rupture, explosion, etc., thereby avoiding harm to the environment around the pipeline and the safety of life and property.

[0102] The electrical signal processing module 5 can communicate with the alarm 61 and the management platform 62 through the network port, RS232 interface, RS485 interface, and USB (Universal Serial Bus) to transmit the judgment result.

[0103] In addition, the alarm 61 can be configured as a buzzer.

[0104] In the embodiment of the present invention, the laser 1 can emit a narrowband light beam with a central wavelength of 1309.5nm~1310.5nm or 1549.5nm~1550.5nm. Based on the characteristics of the latter with small light attenuation and easy acquisition, the embodiment of the present invention preferably adopts it.

[0105] The line width of the narrow-band light beam emitted by the laser 1 can be set to 10K Hz.

[0106] In addition, the laser 1 can be purchased, for example, from Han's Laser Technology Industry Group Co., Ltd.

[0107] In the embodiment of the present invention, the photoelectric conversion module 3 can be configured as a photoelectric conversion circuit, and the electrical signal acquisition module 4 can be configured as an electrical signal acquisition circuit.

[0108] In the embodiment of the present invention, at least one protective layer may be provided on each optical fiber involved in the gas leakage monitoring system (eg, transmission optical fiber 23, sensitive optical fiber 242, delay optical fiber 36) to prevent the optical fiber from being damaged by harsh environments such as rain and snow.

[0109] Regarding the installation of the above-mentioned gas leakage monitoring system, the optical fiber sensor 2a can be installed in the gas leakage monitoring area, specifically, the sensitizer 24 is hung on the pole, and the transmission optical fiber 23, the delay optical fiber 26 and the Faraday reflector 22 are packaged in the cable box. In addition, other components of the gas leakage monitoring system are installed in the industrial control room.

[0110] To sum up, the gas leakage monitoring system provided by the embodiment of the present invention has been actually used and tested in natural gas stations. It can effectively monitor pipeline leakage with a leakage level greater than 4MPa (pressure during leakage) and 2mm (leakage aperture) in a spherical area with the optical fiber sensor 2a as the center and a radius of 15m. It has high sensitivity, accurate alarm, and strong anti-interference ability against environmental noise.

[0111] All the above optional technical solutions can be arbitrarily combined to form optional embodiments of the present disclosure, and will not be described in detail here.

[0112] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A gas leakage monitoring system, characterized in that: The gas leakage monitoring system comprises: a laser (1), an optical fiber sensor assembly (2), and a photoelectric conversion module (3) connected in sequence via optical fibers; and an electrical signal acquisition module (4), an electrical signal processing module (5), and an alarm signal output module (6) connected in sequence via electrical wires, wherein the electrical signal acquisition module (4) is connected to the photoelectric conversion module (3) via electrical wires, and the electrical signal processing module (5) is connected to the laser (1) via electrical wires; The laser (1) is used to emit laser light to the optical fiber sensor component (2); The optical fiber sensor assembly (2) is used to enable the laser to generate a first interference light wave signal when no gas leakage occurs in the area to be monitored, and to modulate the phase of the first interference light wave signal using ultrasonic waves generated by the gas leakage when gas leakage occurs in the area to be monitored, so that the first interference light wave signal generates a second interference light wave signal; The photoelectric conversion module (3) is used to receive the first interference light wave signal and the second interference light wave signal, and convert the first interference light wave signal and the second interference light wave signal into a first electrical signal and a second electrical signal respectively, and then transmit the first electrical signal and the second electrical signal to the electrical signal processing module (5) through the electrical signal acquisition module (4); The electrical signal processing module (5) is used to adjust the frequency of the laser emitted by the laser (1), and to determine whether a gas leak occurs in the monitored area based on the received electrical signal, and to output the determination result through the alarm signal output module (6); Wherein, the optical fiber sensor assembly (2) comprises a plurality of optical fiber sensors (2a); The gas leakage monitoring system further comprises: an optical beam splitter (7) arranged between the laser (1) and the plurality of optical fiber sensors (2a) via optical fibers; The optical beam splitter (7) is used to split the laser beam into multiple first sub-lasers, and transmit each of the first sub-lasers to the corresponding optical fiber sensor (2a); The optical fiber sensor (2a) comprises: an N×N type optical beam splitter / combiner (21), two Faraday reflectors (22), and a plurality of transmission optical fibers (23), wherein N is an integer greater than 2; The input end of the optical beam splitter / combiner (21) is connected to the optical beam splitter (7) via an optical fiber, and the output end is connected to the photoelectric conversion module (3) via an optical fiber; Each of the Faraday reflectors (22) is connected to the beam splitting / combining end of the optical beam splitter / combiner (21) via the corresponding transmission optical fiber (23); a sensitivity enhancement component (24) is provided on the transmission optical fiber (23) corresponding to one of the Faraday reflectors (22), and a delay optical fiber (26) is provided on the transmission optical fiber (23) corresponding to another of the Faraday reflectors (22), and the length of the delay optical fiber (26) is set according to the total length of the transmission optical fiber (23) and the sensitive optical fiber (242) corresponding to each optical circuit; The sensitivity enhancing component (24) comprises: a sensitivity enhancing cylinder (241), and a sensitive optical fiber (242) arranged on the sensitivity enhancing cylinder (241); the first end and the second end of the sensitive optical fiber (242) are both connected to the corresponding transmission optical fiber (23), and the sensitive optical fiber (242) is arranged on the sensitivity enhancing cylinder (241) in a winding manner; The optical fiber sensor (2a) further comprises: a dustproof protective cover (25); the sensitivity enhancement component (24) is located inside the dustproof protective cover (25); and a plurality of through holes are provided on the side wall of the dustproof protective cover (25) or the side wall of the dustproof protective cover (25) is arranged to form a mesh structure.

2. The gas leakage monitoring system according to claim 1, characterized in that: At least one of the transmission optical fibers (23) is provided with a sensitivity enhancement component (24).

3. The gas leakage monitoring system according to claim 2, characterized in that: The sensitive optical fiber (242) is a bend-insensitive single-mode optical fiber.

4. The gas leakage monitoring system according to claim 1, characterized in that: At least one of the transmission optical fibers (23) is provided with a delay optical fiber (26).

5. The gas leakage monitoring system according to any one of claims 1 to 4, characterized in that: The alarm signal output module (6) comprises: an alarm (61) and a management platform (62) which are respectively connected to the electrical signal processing module (5) via electric wires.

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