Push-pull all-fiber infrasonic wave sensor and pipeline leakage position detection method
Through push-pull all-fiber infrasonic sensor, the vibration-acoustic signal is converted into optical signals by using optical fiber and Michaelson interference systems, solving the problems of low sensitivity and susceptibility to electromagnetic interference in existing electrical sensors, achieving higher sensitivity and Wide adaptability, suitable for oil and gas pipeline monitoring in complex environments.
Patent Information
- Application Number
- CN202411720271.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-28
- Publication Date
- 2025-02-07
AI Technical Summary
In the existing acoustic inspection technology of oil and gas pipelines, electrical sensors have low sensitivity, narrow frequency bands and are easily affected by electromagnetic interference, making it difficult to work effectively in complex environments, especially in long-distance oil and gas pipeline monitoring.
A push-pull all-fiber infrasonic wave sensor is adopted. The sensor consists of a shell, a fixed base, an inertial mass and a compass cylinder. The sensor fiber and a Faraday rotary mirror form a Michaelson interference system. The optical signal is split and beam-typed through an optical fiber coupler. Form an interferometric optical signal to realize photoelectric conversion of vibration-acoustic signals.
It improves the sensitivity and bandwidth of the sensor, can work effectively in complex environments, eliminates electromagnetic interference, and enhances adaptability and safety in the field of subsea oil and gas pipelines.
Smart Images
Figure CN119394425A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of oil and gas pipeline acoustic inspection, and in particular to a push-pull all-optical fiber infrasonic wave sensor and a pipeline leakage position detection method. Background Art
[0002] With the growth of global oil and gas demand and the expansion of energy supply chain, oil and gas pipelines, as one of the main channels for energy transportation, have become the focus of industry attention due to the increasingly exposed safety issues such as oil leakage, corrosion, and pipeline damage. In response to such problems, oil and gas pipeline acoustic inspection technology provides technical support for oil and gas pipeline monitoring. Its basic principle is to locate the pipeline based on the time difference between the propagation of infrasound waves generated at the pipeline leakage point to the sensors at both ends of the pipeline. However, this technology requires highly sensitive and stable acoustic sensors as a basis. However, most of the current vibration-acoustic sensors are electrical sensors, which have low sensitivity, narrow frequency band, and are easily affected by electromagnetic interference. It is difficult for such sensors to work in complex environments such as the ocean, and there are also a series of safety issues in long-distance oil and gas pipeline monitoring conditions. Summary of the invention
[0003] In view of the problems of low sensitivity, narrow frequency band and susceptibility to electromagnetic interference of electrical sensors in the prior art, the present invention provides a push-pull all-optical fiber infrasonic sensor and a pipeline leakage position detection method.
[0004] The present invention provides the following technical solution: a push-pull all-fiber infrasonic wave sensor, comprising a housing, two fixed bases arranged in the housing, an inertial mass block between the two fixed bases, and two compliant cylinders respectively arranged between the inertial mass block and the two fixed bases, the outer surfaces of the two compliant cylinders are both wound with sensing optical fibers, one end of each sensing optical fiber close to the inertial mass block is provided with a Faraday rotation mirror, and one end of the two sensing optical fibers close to the fixed base is respectively connected to the second end and the third end of a one-to-two optical fiber coupler, and the first end of the one-to-two optical fiber coupler is also connected to an optical fiber interface.
[0005] The inertial mass block cooperates with the compliant cylinders on both sides to form a simple harmonic oscillator, which converts the kinetic energy generated by the vibration-acoustic signal into potential energy and stores it in the compliant cylinders. The side walls of the two compliant cylinders are provided with sensing optical fibers tightly and evenly wound into coils, and together with the corresponding Faraday rotator mirrors, they form the double interference arms of the Michelson interference system. The optical signal is introduced by the optical fiber interface, and is divided into two beams by a one-to-two optical fiber coupler and transmitted in the double interference arms respectively. The Faraday rotator can weaken the polarization attenuation caused by the polarization state in the optical fiber waveguide and reflect the light back to the one-to-two optical fiber coupler to generate interference, and the interference optical signal is output by the optical fiber interface. The outer shell is used to protect the internal structure and serve as the external support of the entire sensor; the two fixed bases are used to fix the simple harmonic oscillator composed of the inertial mass block and the two compliant cylinders to prevent the simple harmonic oscillator from being unstable and introducing noise. The one-to-two optical fiber coupler is fixed in the outer shell to avoid The output instability problem caused by fiber disturbance near the fiber coupler increases the stability of the sensor, and its fixing method can refer to the existing technology.
[0006] Please refer to Figure 3 In the right figure, when the sensor is subjected to external vibration-acoustic signals and performs simple harmonic vibration, the compliant column on one side of the inertial mass block is compressed. , and the other side of the progressive column stretches , forming a push-pull structure, while causing the deformation of the sensing optical fiber to cause the change of the light phase, thereby converting the acoustic signal generated by the pipeline leakage into the phase signal output of the optical fiber, and the phase change change of the two interfering arms is twice that of the single-arm Michelson interferometer system, so that the sensitivity of the present invention is also increased to twice that of the single-arm Michelson interferometer system. The two interfering arms are in the same environment, and this push-pull structure can eliminate the influence of environmental noise and temperature changes, etc., to achieve the effect of noise common mode suppression. At the same time, since there are no electronic devices inside the sensor and it is not subject to electromagnetic interference, it can better adapt to the field of oil and gas pipelines with extremely high requirements for fire and explosion protection, and it also has a broader prospect in the field of submarine oil and gas pipelines.
[0007] Preferably, grooves are provided at both ends of the compliant column, the fixed base is provided with a positioning column cooperating with the groove, the inertial mass block is provided with a convex column, the height of the convex column is the same as the depth of the groove, and the convex column is provided with a flange cooperating with the groove at one end facing the compliant column.
[0008] Preferably, the outer shell is tubular, the fixing base is connected to the outer shell by bolts, the outer surface of the fixing base is further provided with bolt holes, and a sealant is further provided between the outer shell and the fixing base.
[0009] Preferably, the shell and the fixed base are both made of aluminum, the inertial mass block is a solid copper block, copper has a relatively high density, and the compliant column is made of silicone.
[0010] Preferably, the two compliant bodies and the two sensing optical fibers are symmetrical about the central axis of the inertial mass block, and the two sensing optical fibers have the same length.
[0011] A pipeline leakage position detection method comprises the following steps: A pair of sensors is fixed to the pipeline to be tested, an optical signal is input to the sensors, and the optical signal fed back by the sensors is converted into an electrical signal and then demodulated to obtain a leakage signal; the sensor is a push-pull all-fiber infrasonic sensor; The time difference between a pair of sensors detecting the leakage signal is calculated to locate the leakage position.
[0012] Preferably, a detection system is also included, which includes a laser, and the laser is provided with piezoelectric ceramics. The laser is connected to a one-to-two fiber coupler through an optical fiber, and the two output ends of the one-to-two fiber coupler are respectively connected to the first ports of two circulators through optical fibers, and the second ports of the two circulators are respectively connected to a pair of sensors through optical fibers, and the third ports of the two circulators are connected to a photodetector through optical fibers, and the photodetector is electrically connected to a data acquisition system, and the data acquisition system is electrically connected to a control system, and the control system is also electrically connected to the piezoelectric ceramics.
[0013] Please refer to Figure 5 , the laser is used as the light source, and the piezoelectric ceramics produce a tiny deformation under the control of the control system to control the laser resonant cavity to change uniformly, change the wavelength of the output optical signal, and make its frequency uniform and stable. The one-to-two fiber coupler divides the optical signal from the laser into two beams and inputs them into the first port of the two circulators respectively, and then enters a pair of sensors from the second ports of the two circulators respectively. The interference optical signal output by the sensor enters from the second port of the circulator, and enters the photodetector through the third port of the circulator, and is converted into an electrical signal. After being collected by the data acquisition system, it is input into the control system. The control system can use the inverse tangent algorithm in the phase generation carrier technology to demodulate and obtain the pipeline leakage signal, and then use the cross-correlation algorithm to obtain the time difference of the leakage signal, so as to locate the leakage position of the oil and gas pipeline.
[0014] The invention has the following beneficial effects: the sensor uses a one-to-two optical fiber coupler to connect two sensing optical fibers wound on a compliant cylinder and a corresponding Faraday rotating mirror as double interference arms of a Michelson interference system, and an inertial mass block cooperates with the compliant cylinders on both sides thereof to form a simple harmonic oscillator; when the sensor is subjected to an external vibration-acoustic signal to perform simple harmonic vibration, the sensing optical fiber is deformed to cause a change in the light phase; the phase change variation of the two interference arms is twice that of a single-arm Michelson interference system, so that the sensitivity of the invention is also increased to twice that of a single-arm Michelson interference system; the theoretical frequency response range of the sensor fully meets the frequency range of 0-20 Hz of infrasound; the two interference arms are in the same environment, and the push-pull structure can eliminate the influence of environmental noise and temperature changes, etc., to achieve the effect of noise common mode suppression; at the same time, since there is no electronic device inside the sensor and it is not subject to electromagnetic interference, it can better adapt to the field of oil and gas pipelines with extremely high requirements for fire and explosion prevention, and also has a broader prospect in the field of submarine oil and gas pipelines. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 A schematic diagram of the structure of a sensor embodiment.
[0016] Figure 2 A cross-sectional view of an embodiment of a sensor.
[0017] Figure 3 A modal analysis diagram of a sensor embodiment.
[0018] Figure 4 FIG. 4 is a frequency response curve diagram of an embodiment of a sensor.
[0019] Figure 5 The figure is a schematic diagram of the working of one embodiment of the detection system.
[0020] Figure numerals: 10, sensor; 11, housing; 12, fixed base; 121, positioning column; 13, inertial mass block; 131, convex column; 132, flange; 14, compliant column; 141, groove; 15, sensing optical fiber; 16, Faraday rotation mirror; 17, one-to-two optical fiber coupler; 21, laser; 22, piezoelectric ceramics; 23, one-to-two optical fiber coupler; 24, circulator; 25, photodetector; 26, data acquisition system; 27, control system. DETAILED DESCRIPTION
[0021] The following is a more detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and the accompanying drawings so that a person skilled in the art can implement the embodiments after reading the description. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Example
[0022] The present invention provides a push-pull all-fiber infrasound sensor, the overall structure of which can be referred to Figure 1 .
[0023] The sensor includes a housing 11 , two fixed bases 12 arranged in the housing 11 , an inertial mass block 13 between the two fixed bases 12 , and two compliant columns 14 respectively arranged between the inertial mass block 13 and the two fixed bases 12 .
[0024] Please refer to Figure 2 The shell 11 is tubular, and the fixed base 12 is bolted to the shell 11; the outer surface of the fixed base 12 is also provided with bolt holes for fixing with the mounting platform on the pipeline by bolts; a sealant is also provided between the shell 11 and the fixed base 12 to enhance the sealing performance; grooves 141 are provided at both ends of the compliant column 14, and the fixed base 12 is provided with a positioning column 121 that cooperates with the groove 141, and the positioning column 121 is plugged into the groove 141; the inertial mass block 13 is provided with a boss 131, the height of the boss 131 is the same as the depth of the groove 141, and the boss 131 is provided with a flange 132 that cooperates with the groove 141 toward one end of the compliant column 14, and the boss 131 and the flange 132 are plugged into the groove 141.
[0025] In this embodiment, the shell 11 and the fixed base 12 are both made of aluminum, the inertial mass block 13 is a solid copper block, and the compliant column 14 is made of silicone.
[0026] Please refer to Figure 1 The outer surfaces of the two compliant cylinders 14 are both wound with sensing optical fibers 15. The sensing optical fibers 15 are wound into a coil shape and are wound as evenly and tightly as possible. A prestress of 5N can be applied to improve the service performance of the optical fiber. Each of the sensing optical fibers 15 close to the inertial mass block 13 is fused with a Faraday rotator mirror 16, and the ends of the two sensing optical fibers 15 close to the fixed base 12 are respectively connected to the second end and the third end of a one-to-two optical fiber coupler 17. The first end of the one-to-two optical fiber coupler 17 is also connected to a fiber interface to introduce an external light path. A through hole is provided on the side wall of the housing 11, and the fiber interface is fixed in the through hole. The one-to-two optical fiber coupler 17 is arranged in the housing 11.
[0027] Finite element analysis is performed on Example 1 to determine its appropriate operating frequency band: Soildworks can be used to draw the geometric model of Example 1 and set the material properties of each component; then the grid is divided, such as Figure 3 As shown in the left figure; finally, the two fixed bases 12 of Example 1 are subjected to a fixed constraint in the vertical direction, and the axial resonant vibration mode of the model of Example 1 is calculated as follows: Figure 3As shown in the figure on the right, the theoretical natural frequency corresponding to this vibration mode is the resonant frequency of Example 1, 153.31 Hz. Figure 4 The measured signal frequency and the resonant frequency of Example 1 must satisfy the formula ,in is the measured signal frequency, is the resonant frequency of Example 1, it can be calculated that the theoretical frequency response range of Example 1 is 0-30.662 Hz, which fully meets the frequency range of infrasound 0-20 Hz.
[0028] Example 2 The present invention provides a pipeline leakage position detection method based on a detection system including the push-pull all-optical fiber infrasonic wave sensor described in Example 1.
[0029] Please refer to Figure 5 The detection system uses a laser 21 as a light source. The laser 21 is also provided with a piezoelectric ceramic 22. The piezoelectric ceramic 22 is electrically connected to a control system 27. Under the control of the control system, a slight deformation is generated to control the uniform change of the laser resonant cavity, thereby changing the wavelength of the output optical signal and making its frequency uniform and stable.
[0030] The laser 21 is connected to a one-to-two fiber coupler 23 through an optical fiber, and the two output ends of the one-to-two fiber coupler 23 are respectively connected to the first ports of two circulators 24 through optical fibers, and the second ports of the two circulators 24 are respectively connected to a pair of sensors 10 through optical fibers. The third ports of the two circulators 24 are connected to a photodetector 25 through optical fibers, and the photodetector 25 is electrically connected to a data acquisition system 26, and the data acquisition system 26 is electrically connected to a control system 27, and the control system 27 is also electrically connected to the piezoelectric ceramic 22. Among them, the sensor 10 is a push-pull all-fiber infrasound sensor described in Example 1, and other components can refer to the relevant technology.
[0031] The pipeline leakage location detection method includes the following steps: A pair of sensors 10 are fixed to the pipeline to be tested, and the laser is started to input an optical signal to the sensor 10. The sensor 10 reflects the optical signal and forms an interference optical signal. The interference optical signal is transmitted to the photodetector 25 through the second port and the third port of the circulator and converted into an electrical signal. After being collected by the data acquisition system, it is input into the control system, and the inverse tangent algorithm in the phase generation carrier technology can be used for demodulation to obtain the pipeline leakage signal; the control system uses the cross-correlation algorithm to obtain the time difference of the leakage signal, thereby locating the leakage position of the oil and gas pipeline. The installation position of the sensor 10 and the method of positioning using the time difference can refer to the relevant technology.
[0032] The above are one or more embodiments of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.
Claims
1. A push-pull all-fiber infrasound sensor, characterized in that: The invention comprises a shell, two fixed bases arranged in the shell, an inertial mass block between the two fixed bases, and two compliant cylinders respectively arranged between the inertial mass block and the two fixed bases, wherein the outer surfaces of the two compliant cylinders are wound with sensing optical fibers, and a Faraday rotation mirror is arranged at one end of each sensing optical fiber close to the inertial mass block, and the ends of the two sensing optical fibers close to the fixed bases are respectively connected to the second end and the third end of a one-to-two optical fiber coupler, the first end of the one-to-two optical fiber coupler is also connected to an optical fiber interface, and the one-to-two optical fiber coupler is arranged in the shell.
2. A push-pull all-fiber infrasound sensor according to claim 1, characterized in that: Both ends of the compliant column are provided with grooves, the fixed base is provided with a positioning column matched with the groove, the inertial mass block is provided with a convex column, the height of the convex column is the same as the depth of the groove, and the convex column is provided with a flange matched with the groove at one end facing the compliant column.
3. A push-pull all-fiber infrasound sensor according to claim 1, characterized in that: The outer shell is tubular, the fixing base is connected to the outer shell by bolts, the outer surface of the fixing base is also provided with bolt holes, and a sealant is also provided between the outer shell and the fixing base.
4. A push-pull all-fiber infrasound sensor according to claim 1, characterized in that: The shell and the fixed base are both made of aluminum, the inertial mass block is a solid copper block, and the compliant column is made of silicone.
5. A push-pull all-fiber infrasound sensor according to claim 1, characterized in that: The two compliant bodies and the two sensing optical fibers are symmetrical about the central axis of the inertial mass block.
6. A pipeline leakage location detection method, characterized in that: The following steps are involved: A pair of sensors is fixed to the pipeline to be tested, an optical signal is input to the sensor, and the optical signal fed back by the sensor is converted into an electrical signal and then demodulated to obtain a leakage signal; the sensor is a push-pull all-fiber infrasonic sensor as described in any one of claims 1 to 5; The time difference between a pair of sensors detecting the leakage signal is calculated to locate the leakage position.
7. A pipeline leakage position detection method according to claim 6, characterized in that: It also includes a detection system, which includes a laser, and the laser is provided with piezoelectric ceramics. The laser is connected to a one-to-two fiber coupler through an optical fiber, and the two output ends of the one-to-two fiber coupler are respectively connected to the first ports of two circulators through optical fibers, and the second ports of the two circulators are respectively connected to a pair of sensors through optical fibers, and the third ports of the two circulators are connected to a photodetector through optical fibers, and the photodetector is electrically connected to a data acquisition system, and the data acquisition system is electrically connected to a control system, and the control system is also electrically connected to the piezoelectric ceramics.