CN102680150A - Nonlinear chirped fiber grating two-dimensional distributed strain sensing pipeline monitor device - Google Patents
Nonlinear chirped fiber grating two-dimensional distributed strain sensing pipeline monitor device Download PDFInfo
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- CN102680150A CN102680150A CN2012101677725A CN201210167772A CN102680150A CN 102680150 A CN102680150 A CN 102680150A CN 2012101677725 A CN2012101677725 A CN 2012101677725A CN 201210167772 A CN201210167772 A CN 201210167772A CN 102680150 A CN102680150 A CN 102680150A
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Abstract
The invention relates to a nonlinear chirped fiber grating two-dimensional distributed strain sensing pipeline monitor device, which belongs to the field of pipeline monitor technology. The nonlinear chirped fiber grating two-dimensional distributed strain sensing pipeline monitor device is characterized in that the monitor device comprises a fiber grating demodulator, chirped fiber gratings and a single-mode fiber; and the single-mode fiber is mounted in the chirped fiber gratings in two-dimensional distribution at the defect positions of the pipeline, and is connected with the fiber grating demodulator. The monitor device provided by the invention is stable in performance and flexible in design, and has the advantages of small sensor size, large measurement range, high resistance to corrosion and explosion, high long term stability and interchangeability, and high response speed. The monitor device is suitable for various kinds of severe environment, and can accurately monitor and evaluate the defect positions.
Description
Technical field
The invention belongs to the pipeline monitoring technical field, particularly relate to a kind of nonlinearly chirped fiber grating Two dimensional Distribution formula strain sensing pipeline monitoring device.
Background technology
At present, in petroleum industry, pipeline is a kind of extraordinary pressure-bearing and the oil gas conveying equipment that the height potential risk is arranged, in case take place to leak or blast, will cause serious environmental to pollute and enormous economic loss.Pipeline is under arms in the process; Inevitably can produce various damages and defective because improper, hazardous medium corrosion and third party's damage etc. are installed; The expansion of accurately following the tracks of and monitor these defectives changes the influence that pipeline strength, life-span are caused, and just can avoid unnecessary economic loss.Great number of statistic data shows, since weld defects, reasons such as corrosion default and mechanical injuries defective, and unavoidably there is local defect in pipeline, and then lowers the tube wall residual intensity.Local defect serious or key position to having found is implemented monitoring, is extremely necessary so that before pipeline lost efficacy, take the corresponding protection measure.
When local defect appears in pipeline, under the effect of pumped (conveying) medium pressure, the stress distribution of certain rule can occur meeting around the defective, and show the respective lines surface.Therefore can be through pipeline external wall be carried out the degree that real-time strain monitoring is known spot corrosion by inference.And theoretical and experiment shows that tangible Strain Distribution is only just arranged in the scope of the 3-5 times of diameter in spot corrosion center, and this strain is the distribution of quick decay, and near the strain the spot corrosion center is the highest.Traditional fiber Bragg grating strain sensor (FBG) though can carry out strain measurement, if when being applied to this type of and detecting, can be owing to can't accurately locate spot corrosion place and make measurement sensitivity weaken greatly even can't effectively detect.
Summary of the invention
The present invention provides a kind of nonlinearly chirped fiber grating Two dimensional Distribution formula strain sensing pipeline monitoring device for solving the problem that prior art exists.
The object of the invention provide a kind ofly have that sensor bulk is little, measurement range is big, the nonlinearly chirped fiber grating Two dimensional Distribution formula strain sensing pipeline monitoring device of corrosion-resistant and explosion-proof, stable performance, flexible design, long-time stability and characteristics such as interchangeability is good, response speed is fast.
The Bragg fiber grating that the present invention adopts several length to be about several centimetres to tens of centimetres constitutes.These long Bragg fiber gratings are arranged (like 3-5mm) with a determining deviation, are pasted on pipeline external wall.Thus, even the spot corrosion position can not accurately be measured, also can make sensitive zones cover the spot corrosion position through many combinations with long Bragg fiber grating.Simultaneously, when the distributed effects of strain of pipeline external wall during, can cause that this long Bragg fiber grating produces the local chirp, thereby make the width of this grating reflection/transmission peaks change in a certain sensing region of a certain long Bragg fiber grating.Through detecting the variation of peak width, can realize the maximum strain that this grating bears.Simultaneously, many long Bragg fiber gratings combine, and can realize the straining and sensing of Two dimensional Distribution formula.
When the present invention implements, on oil-gas pipeline, rely on the nondestructive examination instrument to confirm the position of pipeline inherent vice; After polishing is handled totally to defect area; According to defect area size, at known defective locations center along the pipeline circumferential direction with the fixing single chirped fiber grating of cyanoacrylate adhesive, lay the equidistantly several chirp gratings of about 5mm about vertically again; Can select identical or different grid region length according to actual conditions, grid region length is approximately got 2-5cm.The oil and gas pipes internal pressure can increase accordingly, and the unequal stress that defective position can produce big gradient distributes.The grid cycle that is bonded at the fiber grating of defective locations can be caused nonlinear effect by non-linear stretching, makes the grating reflection spectrum widening.Judge the accurate position and the two-dimensional stress distribution situation of oil and gas pipes defective according to the size of different grating reflection spectrum widenings.Chirp grating is compared FBG, because its grid region length is longer, and reflectance spectrum broadening when measuring non-linear stress, so it is bigger to measure the scope of nonlinear strain, many combinations just can realize the unequal stress distributed measurement of accurate two dimension.
Nonlinearly chirped fiber grating Two dimensional Distribution formula strain sensing pipeline monitoring device of the present invention adopts following technical scheme:
A kind of nonlinearly chirped fiber grating Two dimensional Distribution formula strain sensing pipeline monitoring device; Be characterized in: monitoring device comprises fiber Bragg grating (FBG) demodulator, chirped fiber grating and single-mode fiber; The chirped fiber grating that the Two dimensional Distribution formula of pipeline defective locations is arranged is equipped with single-mode fiber, and single-mode fiber and fiber Bragg grating (FBG) demodulator link together.
Nonlinearly chirped fiber grating Two dimensional Distribution formula strain sensing pipeline monitoring device of the present invention can also adopt following technical measures:
Described nonlinearly chirped fiber grating Two dimensional Distribution formula strain sensing pipeline monitoring device is characterized in: chirped fiber grating is the array way sensor of arranging, and the grid region length of chirped fiber grating is 2-5cm.
Described nonlinearly chirped fiber grating Two dimensional Distribution formula strain sensing pipeline monitoring device, be characterized in: the mode that chirped fiber grating is arranged is that 3-7mm is uniformly-spaced along the pipeline axial arranging.
Described nonlinearly chirped fiber grating Two dimensional Distribution formula strain sensing pipeline monitoring device, be characterized in: the quantity of chirped fiber grating is 6-20.
Advantage that the present invention has and good effect:
Nonlinearly chirped fiber grating Two dimensional Distribution formula strain sensing pipeline monitoring device; Owing to adopted brand-new technology scheme of the present invention; Compared with prior art; The present invention is based on the distributed two-dimentional strain measurement technique of oil-gas pipeline of chirped fiber grating, combination distribution that the chirped fiber grating that is about 2-5cm with several grid regions length uniformly-spaced (is about 5mm) as sensing element, causes the distribution situation of reflectance spectrum broadening degree reflection oil and gas pipes defect stress at the defective locations place of pipeline according to nonlinear effect; The center of accurate localization defective locations is monitored accurately and is assessed defective locations more.This sensor bulk is little, measurement range is big, corrosion-resistant and explosion-proof, stable performance, have the outstanding advantage that flexible design, long-time stability and interchangeability are good, response speed is fast.Be adapted at working under the various rugged surroundings.Therefore, the present invention has that cost is low, equipment is simple, the advantage that is easy to realize.
Description of drawings
Fig. 1 is a syndeton synoptic diagram of the present invention;
Fig. 2 is a grating syndeton of a present invention synoptic diagram.
Among the figure, 1. pipeline, 2. defective locations, 3. chirped fiber grating, 4. single-mode fiber, 5. fiber Bragg grating (FBG) demodulator, 6. coupling mechanism
Embodiment
For further understanding technology contents of the present invention, characteristics and effect, enumerate following instance now, and conjunction with figs. specifies as follows:
With reference to accompanying drawing 1 and Fig. 2.
A kind of nonlinearly chirped fiber grating Two dimensional Distribution formula strain sensing pipeline monitoring device; Comprise fiber Bragg grating (FBG) demodulator 5, chirped fiber grating 3 and single-mode fiber 4; The pipeline defective bit is equipped with the chirped fiber grating 3 of Two dimensional Distribution array way along pipeline 1 axial arranging; The grid region length of chirped fiber grating 3 is 2-5cm, and 11 chirped fiber gratings 3 are uniformly-spaced arranged by 5mm.Chirped fiber grating 3 links together through single-mode fiber 4 and fiber Bragg grating (FBG) demodulator 5.
The concrete structure of present embodiment and observation process thereof:
Combination realizes the strain measurement of pipeline Two dimensional Distribution formula based on many chirped fiber gratings, and monitoring device is as shown in the figure to have oil-gas pipeline 1, pipeline defective locations 2, chirped fiber grating 3, single-mode fiber 4 and spectral analysis device 5.Wherein, The chirped fiber grating 3 that the uniformly-spaced 5mm as shown in the figure of defective locations 2 places on oil-gas pipeline 1 lays 11 different length grid region 2-5cm is connected with fiber Bragg grating (FBG) demodulator 5 through single-mode fiber 4, and described chirped fiber grating 3 grid region length are identical or different.The grid region length of described chirped fiber grating 3 is approximately 2-5cm, lays with bonding agent along the pipeline hoop at defect area, and described 11 chirped fiber gratings 3 are uniformly-spaced arranged with 5mm vertically.
The oil-gas pipeline 1 of present embodiment is the steel construction material, and single-mode fiber 4 adopts the single-mode fiber of C-band.
Spectral analysis device--fiber Bragg grating (FBG) demodulator 5 contains the light source that service band is 1520～1570nm in employing.Adopting the reflectance spectrum scope of chirped fiber grating 3 is 1520nm～1570nm.Fiber Bragg grating (FBG) demodulator 5 adopts optical fiber grating regulating system.
The distributed two-dimentional strain measurement technique principle of oil-gas pipeline that the present invention is based on chirped fiber grating is:
When oil-gas pipeline 1 was carried oil gas, oil-gas pipeline 1 internal pressure can increase along with the increase of transmission range and transmission quantity, and pipeline begins to expand under pressure, and especially 2 places, defectiveness position can produce the unequal stress distribution of big gradient.Chirped fiber grating 3 grid cycle that are bonded at defect area can be caused nonlinear effect by non-linear stretching, make the reflectance spectrum broadening of chirped fiber grating 3.Change in shape from every grating reflection spectrum of fiber Bragg grating (FBG) demodulator 5 records; The size that changes according to the reflectance spectrum broadening of defect area diverse location place chirped fiber grating 3; Many chirped fiber grating 3 sensing data combinatory analyses just can obtain the accurate two-dimensional surface stress distribution situation of oil-gas pipeline 1 defective locations 2; Realization defective locations center is located more accurately and is assessed, so that the protection oil-gas pipeline that takes appropriate measures prevents to reveal.
Claims (4)
1. nonlinearly chirped fiber grating Two dimensional Distribution formula strain sensing pipeline monitoring device; It is characterized in that: monitoring device comprises fiber Bragg grating (FBG) demodulator (5), chirped fiber grating (3) and single-mode fiber (4); The chirped fiber grating (3) that the Two dimensional Distribution formula of pipeline defective locations is arranged is equipped with single-mode fiber (4), and single-mode fiber (4) links together with fiber Bragg grating (FBG) demodulator (5).
2. according to the described nonlinearly chirped fiber grating Two dimensional Distribution of claim 1 formula strain sensing pipeline monitoring device, it is characterized in that: chirped fiber grating (3) is the array way sensor of arranging, and the grid region length of chirped fiber grating (3) is 2-5cm.
3. according to the described nonlinearly chirped fiber grating Two dimensional Distribution of claim 1 formula strain sensing pipeline monitoring device, it is characterized in that: the mode that chirped fiber grating (3) is arranged is that 3-7mm is uniformly-spaced along pipeline (1) axial arranging.
4. according to claim 1,2 or 3 described nonlinearly chirped fiber grating Two dimensional Distribution formula strain sensing pipeline monitoring devices, it is characterized in that: the quantity of chirped fiber grating (3) is 6-20.
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| CN2012101677725A CN102680150A (en) | 2012-05-28 | 2012-05-28 | Nonlinear chirped fiber grating two-dimensional distributed strain sensing pipeline monitor device |
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| CN2012101677725A CN102680150A (en) | 2012-05-28 | 2012-05-28 | Nonlinear chirped fiber grating two-dimensional distributed strain sensing pipeline monitor device |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109799015A (en) * | 2019-01-30 | 2019-05-24 | 中国劳动关系学院 | Intensity modulated microstress sensor based on the weak chirp grating of outstanding core fibre |
| CN109932113A (en) * | 2019-02-20 | 2019-06-25 | 天津大学 | The chirped fiber measuring system of power tactile superelevation spatial resolution |
| CN109932112A (en) * | 2019-02-20 | 2019-06-25 | 天津大学 | Two-dimensional surface array power tactilely-perceptible method based on distributed fiber-optic sensor |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109799015A (en) * | 2019-01-30 | 2019-05-24 | 中国劳动关系学院 | Intensity modulated microstress sensor based on the weak chirp grating of outstanding core fibre |
| CN109932113A (en) * | 2019-02-20 | 2019-06-25 | 天津大学 | The chirped fiber measuring system of power tactile superelevation spatial resolution |
| CN109932112A (en) * | 2019-02-20 | 2019-06-25 | 天津大学 | Two-dimensional surface array power tactilely-perceptible method based on distributed fiber-optic sensor |
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Inventor after: Hu Xin Inventor after: Liu Haifeng Inventor before: Hu Xin Inventor before: Liu Haifeng Inventor before: Liu Bo |
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Application publication date: 20120919 |