CN103700221A - Oil and gas pipeline torrential flood disaster monitoring method - Google Patents

Abstract

The invention discloses a method for monitoring mountain torrents disasters of an oil-gas pipeline based on a fiber grating sensing technology, and relates to the technical fields of linear velocity measurement, liquid level measurement, mechanical vibration measurement, general safety devices and pipeline systems. The process comprises the following steps: respectively monitoring the water level, the flow rate and the vortex-induced vibration of the pipeline of the mountain torrents and the water regime; demodulating, collecting and preprocessing wavelength signals; remote transmission and reception of signals; further analysis and processing of the signals; dynamically displaying peak flow change and pipeline vortex-induced vibration frequency; forecasting the flood peak flow of the torrential flood and analyzing the fatigue state of the pipeline; mountain torrent forecast, pipeline safety precaution. The invention has high spatial resolution, low cost, safety and effectiveness.

Description

A kind of oil and gas pipes mountain flood monitoring method

Technical field

The present invention is a kind of oil and gas pipes mountain flood monitoring method based on fiber grating sensing technology, relates to the measurement of linear velocity, the measurement of the measurement of liquid level, mechanical vibration, general safety feature and piping system technical field.

Background technology

Mountain flood refers to flood, rubble flow and the landslide disaster that Mountainous Areas is caused by rainfall.Along with global warming in recent years causes extreme weather abnormal, do not meet heavy rain even not seen once in a hundred years decades and happen occasionally.China's middle and small river is numerous, and drainage area is at 100～1000km ²river have more than 50,000; China is located in Over East Asia Monsoon Area simultaneously, Mountain Area heavy rain takes place frequently, ravines and guillies criss-cross, topographic and geologic complicated condition, add increasingly sharpening of human engineering activity (indiscriminate felling of trees, cut into a mountain and cut slope, water conservancy irrigation), initial landform, landforms are formed larger disturbance and destroyed, cause mountain flood to occur frequent.

Long oil and gas pipeline is the same with railway, highway etc., is typical line-shape construction, and these line-shape constructions are inevitably subject to the impact of river, raceway groove, as wash away, riverbed incision, embankment are collapsed, bank erosion and river diversion; In the area of topographic relief, these engineerings are also subject to the impact of the erosion caused by sloping surfaces due to flowing water, as surface subsidence due to domatic soil erosion, pipe trench are emptied, domaticly collapsed, fort bank collapses etc.; Mountain area and in front of the mountains district's middle and small river, because the slope of river is large compared with the water catchment area causing greatly, current anxious, wash away acutely etc., make riverbed usually expose basement rock, ovum gravel and erratic boulder.In this class river course during roughing-in, if pipeline does not have build-in in stable basement rock or when buried depth is inadequate, once Freshets roar down from the mountains, next plays motion in high-velocity flow effect for these piece stones of top layer and erratic boulder, pipeline is very likely gone out by water, form the unsettled pipeline section directly not contacting with ground surface, i.e. tube span.Under certain condition, when current are flowed through pipeline, the wake zone of pipeline produces vortex, and vortex alternately discharges at pipeline rear side with certain frequency, make pipeline be subject to a following current to wave making resistance and perpendicular to the fluctuating force flowing to, cause pipeline vibration, this phenomenon is commonly referred to vortex-induced vibration, and it is one of the serviceable life that affects flood effect underground pipelines, the principal element that causes tube span fatigue failure.

Flood damage has brought huge risk and loss to China's oil and gas pipes industry.As the Ma Huining pipeline in loess plateau, after being constructed and put into operation, flood damage constantly occurs, unsettled, the disconnected event of running affairs once occurs for several times.The puckery peaceful blue gas pipe line mountain flood of the Northwest is also very frequent, often causes pipeline to expose with unsettled.In July, 2004, area, Ledu, Qinghai Province bust heavy rain, stone ditch breaks out mountain torrents, and surging flood is gone out pipeline, makes pipeline be the unsettled state of naked pipe, the large erratic boulder intense impact pipeline that flood is carried secretly.In July, 2010, area, the bulky level ground of loyal military pipeline meets with heavy showers and attacks.Heavy rain makes Lang Ping river, and the flood swelled in volume, and dangerous situation appears in the military pipeline of the loyalty many places of laying along river course, and wherein two place's pipe long-distances float pipe, and pipe is revealed at a place, separately has 30 many places water conservancy project protection barricades to be destroyed by rush of water.In August, 2010, the flood swelled in volume for Shi Ting river, Deyang, Sichuan, causes river levee to be destroyed by rush of water, and occurs that large area inrushes, and causes the unsettled 400m of blue Chengdu-Chongqing Products Pipeline branch line, is exposed under current scour completely.In March, 2011, there is flood in Hei Wa gully, the second west to east gas pipeline project Hutubi County, causes this section of coombe bottom incision, and about 140m pipeline is rushed out, and pipeline dew occurs empty floating, in critical condition.

In the face of numerous middle small watershed mountain floods; China's pipeline operator is often taked positive Hydraulic Protection Project safeguard procedures; but also there is the drawback of some in these measures; first be that cost is high; next is that protection works are not " putting things right once and for all " yet; the uncertain factor of design and construction is more, moreover cycle length and improvement that protection is administered are difficult for grasping opportunity.Monitoring be a kind of efficiently, prophylactico-therapeutic measures cheaply.

At present, China's middle and small river mountain torrent monitoring early warning technology is also in the starting stage, because most of middle and small river network density is less than normal, adds that the short stream in middle and small river source is anxious, mountain torrents have intensity large, last the features such as short, difficult forecast.Traditional mountain flood water regime monitoring adopts mechanical type or electromagnetic sensor more, for the former, its technology is relatively ripe, common are float type level meter, differential pressure water level gauge, mechanical rotor formula velocimeter etc., but owing to limited by physical construction self, its measuring error is large, precision is low; For the latter, common are radar type liquid-level gauge, ultrasonic current metre, acoustic Doppler velocimetry etc., measuring accuracy is higher, easy to use, but cost is high, and easy electromagnetic wave interference.In addition, the monitoring to body ess-strain is more paid close attention in safety monitoring for buried pipeline under the extensive soil body migration such as landslide, avalanche, surface collapse, frozen swell and melt settlement, movable causative fault, and the failure mode main manifestations of pipeline is that the vortex-induced vibration that Coupling effect of seepage rock deformation causes causes pipeline generation fatigue failure under mountain torrents effect, simple monitoring pipe body stress strain can not meet the requirement of pipe safety protection under mountain torrents effect.Vibration monitoring for hardware, traditional mechanical type, electric class vibration transducer (as piezoelectricity, magnetoelectricity and electric vortex type etc.) exist that sensitivity is low, measurement range is little, transmission range is near and the shortcoming such as fault in material, are not suitable for the long-term remote real time monitoring of heavy construction.The Distributed Optical Fiber Sensing Techniques (take BOTDR as representative) rising is in recent years existing certain application aspect mechanical vibration monitoring, but there is not yet the report that Fiber Bragg Grating technology is applied to the monitoring of mountain torrents effect underground pipelines vortex-induced vibration.

Current mountain flood monitoring and warning technology is applied to engineering and the urban flood defence System Constructions such as highway, railway, power station, dam more, also the buried oil and gas pipes under mountain torrents and impact thereof is not carried out the combined monitoring of system.Carry out pipeline mountain flood combined monitoring, can not only judge in advance water level, flow velocity and crest discharge before mountain torrents form, can also find out that current scour is to the influence mode of pipeline and degree, the more important thing is and can grasp condition and the Changing Pattern that vortex-induced vibration occurs steel pipe under flood percussive action, the safe condition of judgement pipeline is control definite foundation that provides on opportunity.Comprehensive above information, just can carry out safe early warning to the pipeline of valley floor, stream, mountain area section, forecasts in advance the precarious position of formation time, scale and the pipeline of mountain torrents, for the design of scheme of disaster reduction implements to provide foundation.

Fiber grating is fiber optic passive device with the fastest developing speed in recent years.It is a kind of space periodicity index distribution of utilizing the light sensitive characteristic of fiber optic materials to set up on the fibre core of optical fiber, its role is to change or controls light in the dissemination mode in this region.Except thering is the anti-electromagnetic interference (EMI) of ordinary optic fibre, size is little, lightweight, intensity is high, the feature such as high temperature resistant, corrosion-resistant, fiber grating also has its unique characteristic: be easy to little with optically-coupled, coupling loss, be easy to wavelength-division multiplex etc.Thereby make fiber grating have wide prospect in fields such as optical-fibre communications and Fibre Optical Sensors.As a kind of emerging technology of photon research field, the sensing technology that the fiber grating of take is pedestal sensor part is subject to common concern in recent years, and various countries researcher actively develops relevant research work.At present, the physical quantity that the fiber-optic grating sensor of having reported can be monitored has: temperature, strain, pressure, displacement, pressure, torsional angle, moment of torsion (twisting stress), acceleration, electric current, voltage, magnetic field, frequency, concentration, thermal expansivity, vibration etc., wherein practical application of a part of fiber grating sensing system.

Fiber Bragg Grating FBG (Fiber Bragg Grating) be the most simply, the most general a kind of fiber grating.It is that one section of refractive index is periodically variable optical fiber, and its index modulation degree of depth and grating cycle are all generally constants.The variation of temperature, strain can cause the cycle of Fiber Bragg Grating FBG and the variation of refractive index, thereby the reflectance spectrum of Fiber Bragg Grating FBG and transmission spectrum are changed.The variation of reflectance spectrum and transmission spectrum by detection fiber Bragg grating, just can obtain the information of corresponding temperature and strain, and Here it is measures the ultimate principle of temperature and strain with Fiber Bragg Grating FBG.

From coupled mode theory, Fiber Bragg Grating FBG can be coupled to a guided mode of wherein transmission another guided mode transmitting in opposite direction and form narrowband reflection, peak reflectance wavelength (bragg wavelength) λ uniformly _bfor:

λ _B＝2n _effΛ （1）

In formula: λ _bfor bragg wavelength; n _effeffective refractive index for spread fiber pattern; Λ is grating pitch.

To formula (1) differential, can obtain the centre wavelength of grating and the relation of temperature and strain:

$\frac{{\mathrm{\Δ\λ}}_B}{{\mathrm{\λ}}_B}=({\mathrm{\α}}_f+\mathrm{\ξ})\mathrm{\ΔT}+(1-P_e)\mathrm{\ϵ}---\left(2\right)$

In formula: α _fthermal expansivity for optical fiber; ξ is the thermo-optical coeffecient of fiber optic materials; P _eelasto-optical coefficient for fiber optic materials.From formula (2), strain stress is due to the flexible and elasto-optical effect in Fiber Bragg Grating FBG cycle, to cause the variation of bragg wavelength, and temperature T is due to Fiber Bragg Grating FBG thermal expansion effects and thermo-optic effect, to cause the variation of bragg wavelength.

Fiber grating can be made into various senser elements, at sensory field, is used widely.Compare with traditional electric transducer, fiber-optic grating sensor has advantages of own unique: (1) transducing head structure is simple, volume is little, lightweight, shape variable, be applicable to imbedding in various large scale structures, can measure stress, strain and the structural damage etc. of inside configuration, stability, reproducible; (2) and between optical fiber, have natural compatibility, be easily connected with optical fiber, light loss is low, spectral characteristic good, reliability is high; (3) have non-conducting, little on measured medium impact, there is again feature anticorrosive, anti-electromagnetic interference (EMI), be adapted at working in rugged surroundings; (4) lightly soft, can in an optical fiber, write a plurality of gratings, form sensor array, combine with wavelength-division multiplex and time division multiplex system, realize distributed sensing; (5) metrical information is with Wavelength-encoding, thereby fiber-optic grating sensor is not subject to the impact of the factors such as light-intensity variation, optical fiber connection and coupling loss, the optical polarization variation of light source, the antijamming capability that tool is stronger; (6) high sensitivity, high degree of resolution.

Compare with widely used Brillouin light domain reflectometer BOTDR, the advantage of fiber-optic grating sensor has: (1) can accurately locate measurement point, and resolution is high; (2) cost is low; (3) can process transducing part, encapsulate, make it be more suitable for on-the-spot rugged surroundings.

Due to these advantages, in Geotechnical Engineering field, fiber-optic grating sensor is easy to imbed in Rock And Soil the strain of its inside and temperature is carried out to high resolving power and large-range measuring, technical advantage is very obvious, especially be embodied in and can obtain long-term, reliable Rock And Soil deformation data, yet there are no fiber grating sensing technology for the report of mountain stream River Valley Region mountain torrents rainwater feelings and flood percussive action underground pipelines vortex-induced vibration frequency combined monitoring.

Summary of the invention

The object of the invention is to invent that a kind of spatial resolution is high, cost is low, the oil and gas pipes mountain flood monitoring method based on fiber grating safely and effectively.

The present invention proposes a kind of oil and gas pipes mountain flood monitoring and pre-alarming method based on fiber grating sensing technology.System adopts fiber grating sensing technology, and the pipeline under mountain stream River Valley Region mountain torrents regimen and flood percussive action is carried out to combined monitoring, and Contents for Monitoring comprises river water level, mountain torrents flow velocity and the monitoring of pipeline vortex-induced vibration.And built monitoring system, realized real-time automatic collecting, remote transmission and the automatic analysis of data.

The oil and gas pipes mountain flood monitoring method based on fiber grating sensing technology that the present invention proposes, its Contents for Monitoring comprises three parts: water level monitoring, flow monitoring and the monitoring of pipeline vortex-induced vibration, adopt respectively fiber-optic grating sensor real time on-line monitoring, fiber grating early warning content comprises the early warning to the crest discharge of mountain torrents and pipeline vortex-induced vibration frequency.

As shown in Figure 1, monitoring method as shown in Figure 2 for oil and gas pipes mountain flood monitoring method monitoring method principle flow chart based on fiber grating sensing technology.Metal plate 1 use bolt 2 is fixed on to bank, river course, protection cylinder 3 is installed on metal plate 1, and protection cylinder 3 is placed in to river course downwards, with bolt, fiber grating level sensor 4 is fixed in protection cylinder 3 walls, in bottom, river course reference for installation stake 5, fixed fiber grating flow sensor 6 in stake, installing optical fibres grating vibration sensor 8 on the monitoring cross section of oil and gas pipes 7, then by level sensor 4, flow sensor 6 is introduced optical Fiber Closure 9 in the lump with vibration transducer 8, be connected with the optical cable 10 that causes monitoring station, in monitoring station, optical cable 10 is connected with photoswitch 11, photoswitch 11 is connected with fiber Bragg grating (FBG) demodulator 12, (FBG) demodulator 12 is connected with slave computer 13, the pretreated data of slave computer 13 are transmitted by wireless communication module 14, wireless communication module 15 receives host computer 16, with said apparatus to oil and gas pipes mountain flood monitor.

Fiber grating level sensor 4, optical fiber optical grating flow speed sensor 6 and optical fiber raster vibration sensor 8 pass to photoswitch 11 by mountain torrents water level, flow velocity of river and pipeline vortex-induced vibration signal through optical cable I 10; photoswitch 11 reaches slave computer 13 by (FBG) demodulator 12 demodulation; slave computer 13 calls self-editing program; control photoswitch 11 and (FBG) demodulator 12, realize the collection of data and data are carried out to pre-service; Pretreated data receive host computer 16 by 14 transmission of wireless communication module I, wireless communication module II 15,16 pairs of data of host computer are carried out further analyzing and processing, by river water level and mountain torrents flow relocity calculation, obtain the crest discharge of mountain torrents, whether the crest discharge that judges this region has reached forecast warning value, and the comparative analysis of the natural vibration frequency of connecting pipe line vortex forcing frequency and pipeline self, the safe condition of pipeline under judgement mountain torrents percussive action.The processing of data is mainly completed by software, and software flow as shown in Figure 3.The pre-service of slave computer data is mainly that the optical wavelength data of fiber Bragg grating (FBG) demodulator collection are converted into strain data, host computer is after receiving data, first by Data classification, according to rainfall, water level and flow relocity calculation mountain torrents total amount and flood peak, and it is combined with pipeline vortex-induced vibration signal, the safety case of pipeline under time, scale and flood erosion effect that judgement mountain torrents form.

The flow process of the oil and gas pipes mountain flood monitoring method based on fiber grating sensing technology as shown in Figure 1, for:

Mountain torrents regimen and pipeline carry out respectively water level monitoring, flow monitoring and the monitoring of pipeline vortex-induced vibration;

The demodulation of wavelength signals, collection, pre-service;

The remote transmission of signal and reception;

Further analysis and the processing of signal;

Crest discharge changes dynamically demonstration, pipeline vortex-induced vibration frequency dynamic shows;

Mountain torrents Flood Peak Forecasting, pipeline Analysis of Mental Fatigue;

Mountain torrents forecast, pipe safety prewarning.

Wherein:

Water level monitoring method water level monitoring method adopts the fiber grating level sensor of designed, designed, and its structure as shown in Figure 4.A right cylinder 18 is fixed in center at upper and lower two end faces of the airtight casing 17 of stainless steel, a fiber Bragg grating strain sensor I 19 is pasted on to right cylinder 18 surfaces, and by optical cable II 20, signal is caused to monitoring station, and its principle is as follows:

According to hydrostatics principle, the hydrostatic pressure P at depth of water h place, river course is

P＝P ₀+γh (3）

Wherein: P ₀for atmospheric pressure, the unit weight that γ is water.

In Fig. 4, airtight casing 17, owing to deformed by the impact of outside surface hydraulic pressure P, causes inner connected right cylinder 18 to produce axial strain ε, according to Elasticity, has:

P＝Eε (4）

Wherein: E is the elastic modulus of right cylinder 18.

When river water level changes, outside under surface water pressure-acting, casing 17 and inner connected right cylinder 18 thereof deform, thereby cause that the temperature compensating type fiber Bragg grating strain sensor I 19 being pasted on right cylinder 18 produces axial strain ε, cause bragg wavelength to produce drift, its variation relation is shown in formula (2).

Association type (2), (3), (4), can obtain:

$\frac{{\mathrm{\Δ\λ}}_B}{{\mathrm{\λ}}_B}=(1-P_e)\frac{P_0+\mathrm{\γh}}{E}+({\mathrm{\α}}_f+\mathrm{\ξ})\mathrm{\ΔT}---\left(5\right)$

By formula (5), known the wavelength variations Δ λ of fiber grating _blinear with the variation of river water level h, fiber grating level sensor is measured river water level h indirectly based on formula (5), utilize airtight casing 17 and inner connected the stressed of right cylinder 18 thereof that hydrostatic pressure is converted into axial strain amount, and then the bragg wavelength that is converted into fiber grating changes, utilize (FBG) demodulator to detect the change amount Δ λ of wavelength _bjust can know water level height by inference.

Flow monitoring method flow monitoring method is to adopt optical fiber optical grating flow speed sensor, venturi-type choker-line 21, conduit I 22, conduit Ⅱ23He fiber bragg grating pressure sensing mechanism, consists of, and as shown in Figure 5, fluid flows through its structure from left to right.When flux density one timing, the Bernoulli equation of incompressible fluid is

${\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="HDA00002202185400021.png"\; state="\{\{state\}\}">P</figure-callout>}}_1+\frac{1}{2}{\mathrm{\&rho;v}}_1^2={\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HDA00002202185400021.png"\; state="\{\{state\}\}">P</figure-callout>}}_2+\frac{1}{2}{\mathrm{\&rho;v}}_2^2---\left(6\right)$

By fluid continuity equation,

$\mathrm{\&pi;}{\left(\frac{1}{2}{d}_1\right)}^2{v}_1=\mathrm{\&pi;}{\left(\frac{1}{2}{d}_2\right)}^2{v}_2---\left(7\right)$

The pressure difference that is obtained cross section I and cross section II by formula (6), (7) is

$\mathrm{\&Delta;P}=P_1-{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HDA00002202185400021.png"\; state="\{\{state\}\}">P</figure-callout>}}_2=\frac{\mathrm{\&rho;}}{2}[{\left(\frac{d_1}{d_2}\right)}^4-1]v_1^2=\frac{\mathrm{\&rho;}}{2}[{\left(\frac{d_1}{d_2}\right)}^4-1]v^2---\left(8\right)$

Wherein, d ₁, d ₂be respectively the large round tube inside diameter of venturi-type choker-line 21, little pipe (throat) internal diameter, (v ₁, P ₁) and (v ₂, P ₂) be respectively flow velocity and pressure on conduit I 22 and conduit II 23 midline cross sections.ρ is fluid density, v=v ₁flow velocity for liquid.From formula (8), can find out, the flow velocity of fluid is directly proportional to the pressure difference Δ P on conduit I 22 and conduit II 23 midline cross sections, and pressure difference Δ P can record by fiber bragg grating pressure sensing mechanism, and concrete grammar is as follows:

Fiber bragg grating pressure sensing mechanism is comprised of organic glass seal box 24, airtight aluminum foil pipe 25, steel pin 26, equi intensity cantilever 27, temperature compensating type fiber Bragg grating strain sensor II 28 and optical cable III 29 etc.Airtight aluminum foil pipe 25 is rigidly connected by steel pin 26 and the free end of semi-girder 27, and a temperature compensating type fiber Bragg grating strain sensor II 28 is sticked on to semi-girder 27 surfaces.

For semi-girder 27, according to the mechanics of materials, have

$\left\{\begin{array}{c}\mathrm{\&epsiv;}=\frac{\mathrm{Mh}}{2E{I}_y}\\ \frac{M}{I_y}=\frac{12\mathrm{Fl}}{{\mathrm{bh}}^3}\end{array}\right.---\left(9\right)$

In formula: E, h, l and b are respectively elastic modulus, thickness, length and the width of semi-girder 27, the strain that ε is beam, I _yfor the cross sectional moment of inertia of beam, M is semi-girder moment of flexure, and F is the pressure that semi-girder is subject to.

Because aluminum foil pipe can only stretch vertically, and elasticity coefficient is very little, and the relational expression of the pressure F that semi-girder is subject to is as follows

$F=\mathrm{\&Delta;PSg}=(P_1-P_2)\mathrm{\&pi;}{\left(\frac{d}{2}\right)}^{2}g---\left(10\right)$

In formula: Δ P is the inside and outside pressure difference of aluminum foil pipe 25, and S is the cross-sectional area of aluminum foil pipe 25, and g is acceleration of gravity, and d is the diameter of aluminum foil pipe 25,

The pressure of the unequal generation of inside and outside pressure of aluminum foil pipe 25 acts on semi-girder 27 by steel pin 26, caused the distortion of semi-girder 27, and then the bragg wavelength that causes temperature compensating type fiber Bragg grating strain sensor II 28 drifts about, its variation relation is shown in formula (2).

Association type (2), (8), (9), (10), have

$\frac{{\mathrm{\&Delta;\&lambda;}}_B}{{\mathrm{\&lambda;}}_B}=\frac{3(1-P_e)\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="ld"\; filenames="HDA00002202185400021.png"\; state="\{\{state\}\}">ld</figure-callout>}}^2\mathrm{\&rho;g}}{4E{\mathrm{bh}}^2}[{\left(\frac{d_1}{d_2}\right)}^4-1]{\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="HDA00002202185400021.png"\; state="\{\{state\}\}">v</figure-callout>}}^2+({\mathrm{\&alpha;}}_f+\mathrm{\&xi;})\mathrm{\&Delta;T}---\left(11\right)$

By formula (11), known the wavelength variations Δ λ of fiber grating _bwith the square of tested flow velocity v, utilize this optical fiber optical grating flow speed sensor to measure mountain torrents flow velocity v.

The computing method of crest discharge are according to knowledge of hydraulics, and the crest discharge in river course calculation formula is as follows

Q=ΔhLv （12）

In formula: the crest discharge that Q is river course, the changing value that Δ h is river water level, L are river width, v is mountain torrents flow velocity.Therefore, the river water level and the mountain torrents flow velocity that according to monitoring, obtain, utilize formula (12) can calculate the crest discharge of mountain torrents.

Pipeline vortex-induced vibration frequency monitoring method current are when washing pipe section, often being accompanied by periodic vortex discharges, cause washing pipe section periodic vibration, this washing pipe section periodic vibration evoking due to vortex shedding becomes vortex-induced vibration, the fatigue accumulation damage that this vibratory response causes is to cause pipe across the main cause of fatigue failure.The measurement of the pipeline vortex-induced vibration therefore flood erosion being caused can judge the safe condition of pipeline preferably.

Pipeline vortex-induced vibration frequency monitoring method adopts the optical fiber raster vibration sensor of designed, designed, and its structure as shown in Figure 6.On pedestal 30 1 side inwalls, fix a Metallic rod 31, the free end of bar is fixed a derby 32, a temperature compensating type fiber Bragg grating strain sensor III 33 is pasted on to Metallic rod 31 surfaces, and by optical cable IV 34, signal is caused to monitoring station, its principle is as follows:

In Fig. 6, as Metallic rod 31 is equivalent to a semi-girder, according to the mechanics of materials, have

$\left\{\begin{array}{c}\frac{\mathrm{\&sigma;}}{x\left(t\right)}=\frac{{\mathrm{Ebh}}^3}{6l^3}\\ \mathrm{\&sigma;}=\frac{{\mathrm{<figure-callout\; id="2"\; label="Ebh"\; filenames="HDA00002202185400021.png"\; state="\{\{state\}\}">Ebh</figure-callout>}}^2}{6l}\mathrm{\&epsiv;}\end{array}\right.---\left(13\right)$

In formula: E, h, l and b are respectively elastic modulus, thickness, length and the width of semi-girder, the stress that σ is beam, x (t) is the free-ended amount of deflection of beam, according to formula (13),

$x\left(t\right)=\frac{l^2}{h}\mathrm{\&epsiv;}---\left(14\right)$

When the derby 32 of installing when the free end of Metallic rod 31 vibrates together along with external environment condition, effect due to inertial force, make the temperature compensating type fiber Bragg grating strain sensor III 33 of pasting produce axial strain, cause bragg wavelength to produce drift, its variation relation is shown in formula (2).

Association type (2), (14), have

$\frac{{\mathrm{\&Delta;\&lambda;}}_B}{{\mathrm{\&lambda;}}_B}=(1-P_e)\frac{h}{l^2}x\left(t\right)+({\mathrm{\&alpha;}}_f+\mathrm{\&xi;})\mathrm{\&Delta;T}---\left(15\right)$

Optical fiber raster vibration sensor is measured member Vibration Parameter indirectly based on formula (15), utilize the stressed of Metallic rod that the parameters such as amplitude, acceleration are converted into axial strain amount, and then the bragg wavelength that is converted into fiber grating changes, the change amount of utilizing (FBG) demodulator to detect wavelength just can realize the vibration survey to member.

Suppose under external force, it is the simple harmonic oscillation that A, angular frequency are ω that pedestal 30 is done amplitude, and its vibration displacement can be expressed as

x(t)=A cos(ωt-θ) （16）

X (t) is asked to second derivative, can obtain vibration acceleration a (t)

a(t)＝x(t)″＝-Aω ² cos(ωt-θ) （17）

Association type (16), (17), have

a(t)=-ω ²x(t) （18）

Association type (15), (18), have

$\frac{{\mathrm{\&Delta;\&lambda;}}_B}{{\mathrm{\&lambda;}}_B}=-(1-P_e)\frac{h}{{\mathrm{\&omega;}}^2{l}^2}a\left(t\right)+({\mathrm{\&alpha;}}_f+\mathrm{\&xi;})\mathrm{\&Delta;T}---\left(19\right)$

The natural frequency that wherein ω is optical fiber raster vibration sensor, can be represented by the formula

$\mathrm{\&omega;}=\sqrt{\frac{{\mathrm{Ebh}}^3}{6m{l}^3}}---\left(20\right)$

Wherein m is the quality of derby 32, and association type (19), (20), have

$\frac{{\mathrm{\&Delta;\&lambda;}}_B}{{\mathrm{\&lambda;}}_B}=-(1-P_e)\frac{6\mathrm{ml}}{\mathrm{Eb}{h}^2}a\left(t\right)+({\mathrm{\&alpha;}}_f+\mathrm{\&xi;})\mathrm{\&Delta;T}---\left(21\right)$

By formula (21), known the wavelength variations Δ λ of fiber grating _bchange linear with the vibration acceleration a (t) of vibration source, the variation of the wavelength by measuring optical fiber grating just can realize the measurement to vibration acceleration, vibration acceleration a (t) is carried out to FFT(Fast Fourier Transform, fast fourier transform) after calculating, can obtain the rumble spectrum of member, thereby obtain the vibration period; By the wave number in 1/4th cycles, can obtain amplitude and the frequency at measuring point place, and can draw the amplitude-time-history curves of structural member.

Oil and gas pipes mountain flood monitoring system

Designed according to the method described above oil and gas pipes mountain flood monitoring system.As shown in Figure 7, this system is divided into collection in worksite emission coefficient and long-range receiving and analyzing system, specifically comprises the receiving terminal (host computer) of Level monitor, flow monitoring device, pipeline vortex-induced vibration monitoring device, field monitoring station, office.

The overall formation of oil and gas pipes mountain flood monitoring system as shown in Figure 2.Metal plate 1 use bolt 2 is fixed on to bank, river course, protection cylinder 3 is installed on metal plate 1, and protection cylinder 3 is placed in to river course downwards, with bolt, fiber grating level sensor 4 is fixed in barrel, in bottom, river course reference for installation stake 5, fixed fiber grating flow sensor 6 in stake, installing optical fibres grating vibration sensor 8 on the monitoring cross section of oil and gas pipes 7, then by level sensor 4, flow sensor 6 is introduced optical Fiber Closure 9 in the lump with vibration transducer 8, be connected with the optical cable I 10 that causes monitoring station, in monitoring station, optical cable I 10 is connected with photoswitch 11, photoswitch 11 is connected with fiber Bragg grating (FBG) demodulator 12, (FBG) demodulator 12 is connected with slave computer 13, the pretreated data of slave computer 13 are by 14 transmission of wireless communication module I, wireless communication module II 15 receives host computer 16, with said apparatus, oil and gas pipes mountain flood is carried out to combined monitoring.

Fiber grating level sensor 4, optical fiber optical grating flow speed sensor 6 and optical fiber raster vibration sensor 8 pass to photoswitch 11 by river water level, mountain torrents flow velocity and pipeline vortex-induced vibration signal through optical cable I 10; photoswitch 11 reaches slave computer 13 by (FBG) demodulator 12 demodulation; slave computer 13 calls self-editing program; control photoswitch 11 and (FBG) demodulator 12, realize the collection of data and data are carried out to pre-service; Pretreated data receive host computer 16 by 14 transmission of wireless communication module I, wireless communication module II 15,16 pairs of data of host computer are carried out further analyzing and processing, by river water level and mountain torrents flow relocity calculation, obtain the crest discharge of mountain torrents, whether the crest discharge that judges this region has reached forecast warning value, and connecting pipe line vortex forcing frequency and its natural frequency comparative analysis result, the safe condition of pipeline under judgement mountain torrents souring.

The electric principle of this system as shown in Figure 8, monitor respectively water level, three type optical fiber grating sensors--the fiber grating level sensor 4 of flow velocity and pipeline vortex-induced vibration, the PC joint of optical fiber optical grating flow speed sensor 6 and optical fiber raster vibration sensor 8 is connected with the PC joint of light switch 11 by optical cable I 10, the R232 of light switch 11 connects the R232 interface of slave computer 13, the PC joint of light switch 11 connects the CH1 end of fiber Bragg grating (FBG) demodulator 12SM125, the LAN port of fiber Bragg grating (FBG) demodulator 12SM125 connects the LAN port of slave computer 13, the R232 port of slave computer 13 connects the R232 port of GPRS wireless communication module I 14 Siemens MC 35i, GPRS wireless communication module I 14 is through antenna GSM, GPRS network, after being received by GPRS wireless communication module II 15 antenna GSM, by R232, received the R232 of host computer 16, the output of host computer 16 is held by the VGA of VGA termination display.

The output signal of three type optical fiber grating sensors of water level, flow velocity and pipeline vortex-induced vibration through photoswitch one by one conducting transfer to fiber Bragg grating (FBG) demodulator 12, the centre wavelength displacement that fiber Bragg grating (FBG) demodulator 12 demodulates each fiber-optic grating sensor transfers to slave computer 13, and the cycle of photoswitch 11 Continuity signals is controlled by slave computer 13.13 pairs of data of slave computer are carried out pre-service, and the data after processing are defeated by GPRS wireless communication module I 14, each monitoring variable that GPRS wireless communication module I 14 is calculated slave computer 13 is transferred to the host computer 16 that is positioned at office by public's cordless communication network, host computer carries out analyzing and processing by self-programmed software to data, by display, is shown.

Wherein:

River water level monitoring device as shown in Figure 4.A right cylinder 18 is fixed in center at upper and lower two end faces of the airtight casing 17 of stainless steel, a fiber Bragg grating strain sensor I 19 is pasted on to right cylinder 18 surfaces, and by optical cable II 20, signal is caused to optical Fiber Closure 9, optical Fiber Closure 9 is connected with optical cable I 10, and finally causes monitoring station.

Described fiber Bragg grating strain sensor I 19 is selected temperature compensating type fiber Bragg grating strain sensor.

Mountain torrents flow monitoring device as shown in Figure 5.Venturi-type choker-line 21, conduit I 22, conduit Ⅱ23He fiber bragg grating pressure sensing mechanism, consist of, fiber bragg grating pressure sensing mechanism is comprised of organic glass seal box 24, airtight aluminum foil pipe 25, steel pin 26, equi intensity cantilever 27, temperature compensating type fiber Bragg grating strain sensor II 28 and optical cable III 29 etc.Airtight aluminum foil pipe 25 is rigidly connected by steel pin 26 and the free end of semi-girder 27.A temperature compensating type fiber Bragg grating strain sensor II 28 is sticked on to semi-girder 27 surfaces, and by optical cable III 29, signal is caused to optical Fiber Closure 9, optical Fiber Closure 9 is connected with optical cable I 10, and finally causes monitoring station.

Described fiber Bragg grating strain sensor II 28 is selected temperature compensating type fiber Bragg grating strain sensor.

Pipeline vortex-induced vibration monitoring device as shown in Figure 6, on pedestal 30 1 side inwalls, fix a Metallic rod 31, the free end of bar is fixed a derby 32, a fiber Bragg grating strain sensor III 33 is pasted on to Metallic rod 31 surfaces, and by optical cable IV 34, signal is caused to optical Fiber Closure 9, optical Fiber Closure 9 is connected with optical cable I 10, and finally causes monitoring station.

Described fiber Bragg grating strain sensor III 33 is selected temperature compensating type fiber Bragg grating strain sensor.

Field monitoring station is arranged near valve chamber river course, comprises following a few part:

(1) optical Fiber Closure of monitoring station and each sensor be connected optical cable, for by water level, flow velocity and pipeline vortex-induced vibration sensor signal concentration of transmissions to monitoring station;

(2) light switch, due to pipeline mountain flood, to monitor sensor used a lot, and signalling channel is numerous, cannot once be connected on fiber Bragg grating (FBG) demodulator, with light switch, each channel signal is changed successively to (FBG) demodulator analysis;

(3) fiber Bragg grating (FBG) demodulator, for demodulating the centre wavelength displacement of each sensor;

(4) computing machine and program, for controlling the frequency of (FBG) demodulator demodulation, and the centre wavelength displacement that (FBG) demodulator is demodulated is calculated as each monitoring variable automatically, these monitoring variables are sent to GPRS wireless communication module, and the signal that receives GPRS wireless communication module is controlled;

(5) GPRS wireless communication module, is transferred to for each monitoring variable that computing machine is calculated the server that is positioned at office by cordless communication network, also can accept the signal of server, sends to computing machine.

The principle of work of this system is: when monitored region, mountain stream river valley occurs to continue rainfall, pipeline river water level, river flow along the line all changes, amount of increase by level sensor 4 monitoring river water levels changes, and by 6 pairs of mountain torrents flow velocitys of flow sensor, measures, based on river water level, mountain torrents flow velocity, can calculate the crest discharge of mountain torrents, meanwhile, mountain torrents continuous erosion effect meeting causes pipeline 7 and produces vortex-induced vibration, by the vibration transducer 8 on body, measures its vibration frequency, by connecting optical cable I 10, the sensor signal concentration of transmissions of each position in pipeline mountain torrent monitoring region is arrived to light switch 11, light switch 11 changes each channel signal successively to fiber Bragg grating (FBG) demodulator 12, fiber Bragg grating (FBG) demodulator 12 demodulates each sensor wavelength centre wavelength displacement sensing to on-site computer 13, the centre wavelength displacement that on-site computer 13 demodulates (FBG) demodulator is calculated as each monitoring variable automatically, and monitoring variable is sent to on-the-spot GPRS wireless communication module I 14, GPRS wireless communication module I 14 is by cordless communication network signal transmission, by GPRS wireless communication module II 15, send terminal server 16 to, terminal server 16 is by each crest discharge and pipeline vibration frequency and alarm threshold value contrast, in the time of necessary, provide warning.

The advantage of effect this method of invention shows:

(1) propose mountain stream river valley area Storm Flood and the lower oil and gas pipes of impact thereof to carry out the method for combined monitoring, disclosed river water level variation, mountain torrents change in flow with and flood erosion effect underground pipelines vortex-induced vibration and optic fiber grating wavelength variation between linked character; By many indexs, carry out the safe early warning of the lower oil and gas pipes of mountain stream river valley area Storm Flood impact;

(2) fiber grating sensing technology is applied to pipeline mountain flood monitoring, this technology is anti-interference, corrosion-resistant, it is with the obvious advantage to be easy to networking etc.; This technology is easy to realize automatic real time on-line monitoring, and cost is lower;

(3) water level monitoring, the fiber grating level sensor of employing designed, designed, changes by river water level the movement that the variation in water pressure causing is converted into sensor internal fiber bragg grating center wavelength; Test wavelength moves size, can know water level height by inference; Compare with traditional float-type, bubble type, differential pressure type liquid level sensor, the advantages such as that this monitoring method has is highly sensitive, measurement range wide, long transmission distance, the remote real time monitoring to long oil and gas pipeline mountain torrents water level along the line is realized in available minimum monitoring point;

(4) flow monitoring, the optical fiber optical grating flow speed sensor that adopts designed, designed, based on venturi-type choker-line, is converted into pressure change by mountain torrents change in flow, and by equi intensity cantilever, pressure difference is converted into the movement of sensor internal fiber bragg grating center wavelength; Test wavelength moves size, can calculate the size of mountain torrents flow velocity; This optical fiber optical grating flow speed sensor be take fiber grating as sensing primitive; without any rotary part; compare with traditional mechanical rotor formula velocimeter and ultrasonic current metre, acoustic Doppler velocimetry; the advantages such as this monitoring method has that precision is high, anti-electromagnetic wave disturbs, can multiple spot distributed, the remote real time monitoring to long oil and gas pipeline mountain torrents flow velocity along the line is realized in available minimum monitoring point;

(5) pipeline vortex-induced vibration monitoring, adopt the optical fiber raster vibration sensor of designed, designed, utilize the stressed of built-in metal bar that the parameters such as amplitude, acceleration are converted into axial strain amount, and then the bragg wavelength that is converted into fiber grating changes, the change amount of utilizing (FBG) demodulator to detect wavelength just can realize the measurement to mountain torrents effect underground pipelines vortex-induced vibration; Compare with traditional mechanical type, electric class vibration transducer, the advantages such as that this monitoring method has is highly sensitive, measurement range wide, long transmission distance, the remote real time monitoring to long oil/gas pipe line is realized in available minimum monitoring point, saved cost, also set-up time and the damage to body of equipment have been reduced, for the control of pipeline mountain flood provides effective foundation, guaranteed the safety of pipeline.

The present invention can extensively use the monitoring and warning of the common pipeline flood damages such as the damaged or destroyed by flood of road, stream, domatic damaged or destroyed by flood, raised fields ground damaged or destroyed by flood, has good application prospect.

Accompanying drawing explanation

Fig. 1 oil and gas pipes mountain flood monitoring method principle flow chart

Fig. 2 oil and gas pipes mountain flood monitoring method figure

Fig. 3 software flow pattern

Fig. 4 level sensor monitoring device pie graph

Fig. 5 flow sensor monitoring device pie graph

Fig. 6 vibration transducer monitoring device pie graph

Fig. 7 oil and gas pipes mountain flood Fundamentals of Supervisory Systems

Fig. 8 oil and gas pipes mountain flood monitoring system electrical schematic diagram

Wherein

1-metal plate, 2-bolt

3-protection cylinder, 4-fiber grating level sensor

5-spud pile, 6-optical fiber optical grating flow speed sensor

7-pipeline, 8-optical fiber raster vibration sensor

9-optical Fiber Closure, 10-optical cable I

11-photoswitch, 12-(FBG) demodulator

13-slave computer, 14-wireless communication module I

15-wireless communication module II, 16-host computer

The airtight casing 18-right cylinder of 17-stainless steel

19-fiber Bragg grating strain sensor I, 20-optical cable II

21-venturi-type choker-line, 22-conduit I

23-conduit II, 24-organic glass seal box

25-airtight aluminum foil pipe 26-steel pin

27-equi intensity cantilever, 28-fiber Bragg grating strain sensor II

29-optical cable III, 30-pedestal

31-Metallic rod, 32-derby

33-fiber Bragg grating strain sensor III, 34-optical cable IV

Embodiment

Embodiment. this example is a kind of monitoring method, and the formation of system for use in carrying is as Figure 1-Figure 8.And carried out respectively site test in blue Chengdu-Chongqing products pipeline Pu Bahe, loyal military natural gas line Lang Ping river; these two test sections all belong to road, Typical Small Watershed stream, mountain area mountain torrents; flood season Mountainous Heavy Rainfall intensity large, produce and conflux that speed is fast, river flood rises suddenly to fall suddenly, section stream in source, river is anxious; mountain torrents have the advantages that intensity is large, flood peak is high, magnanimity is concentrated; incision and lateral erosion ability are strong, to companion's walking along the street, pipeline, water conservancy project protection facility destructiveness by force.Wherein blue Chengdu-Chongqing Products Pipeline Pu Ba river is positioned at Tan He township, Cheng County, Longnan City, Gansu Province, the about 10km of influenced duct length, the about 25km2 of drainage area; Loyal military pipeline Lang Ping river is positioned at Lang Ping town, Changyang, hubei Province county, the about 16km of influenced duct length, the about 100km2 of drainage area.

Oil and gas pipes mountain flood monitoring system

This system is divided into collection in worksite emission coefficient and long-range receiving and analyzing system, specifically comprises the receiving terminal (host computer) of river water level monitoring device, mountain torrents flow monitoring device and pipeline vortex-induced vibration monitoring device, field monitoring station, office.

The overall formation of oil and gas pipes mountain flood monitoring system as shown in Figure 2.Metal plate 1 use bolt 2 is fixed on to bank, river course, protection cylinder 3 is installed on metal plate 1, and protection cylinder 3 is placed in to river course downwards, with bolt, fiber grating level sensor 4 is fixed in barrel, in bottom, river course reference for installation stake 5, fixed fiber grating flow sensor 6 in stake, installing optical fibres grating vibration sensor 8 on the monitoring cross section of oil and gas pipes 7, then by level sensor 4, flow sensor 6 is introduced optical Fiber Closure 9 in the lump with vibration transducer 8, be connected with the optical cable I 10 that causes monitoring station, in monitoring station, optical cable I 10 is connected with photoswitch 11, photoswitch 11 is connected with fiber Bragg grating (FBG) demodulator 12, (FBG) demodulator 12 is connected with slave computer 13, the pretreated data of slave computer 13 are by 14 transmission of wireless communication module I, wireless communication module 15 receives host computer 16, host computer carries out Treatment Analysis to pretreated data, the safe condition of comprehensive judgement pipeline.

The electric principle of this system as shown in Figure 8, monitor respectively river water level, three type optical fiber grating sensors--the fiber grating level sensor 4 of mountain torrents flow velocity and pipeline vortex-induced vibration, optical fiber optical grating flow speed sensor 6, the PC joint of optical fiber raster vibration sensor 8 is connected with the PC joint of light switch 11 by optical cable I 10, the R232 of light switch 11 connects the R232 interface of slave computer 13, the PC joint of light switch 11 connects the CH1 end of fiber Bragg grating (FBG) demodulator 12 SM125, the LAN port of fiber Bragg grating (FBG) demodulator 12 SM125 connects the LAN port of slave computer 13, the R232 port of slave computer 13 connects the R232 port of GPRS transport module I 14 Siemens MC 35i, GPRS transport module I 14 is through antenna GSM, GPRS network, after being received by GPRS wireless communication module I 15 antenna GSM, by R232, received the R232 of host computer 16, the output of host computer 16 is held by the VGA of VGA termination display.

The output signal of three type optical fiber grating sensors of river water level, mountain torrents flow velocity and pipeline vortex-induced vibration through photoswitch one by one conducting transfer to fiber Bragg grating (FBG) demodulator 12, the centre wavelength displacement that fiber Bragg grating (FBG) demodulator 12 demodulates each fiber-optic grating sensor transfers to slave computer 13, and the cycle of photoswitch 11 Continuity signals is controlled by slave computer 13.13 pairs of data of slave computer are carried out pre-service, and the data after processing are defeated by GPRS wireless communication module I 14, each monitoring variable that GPRS wireless communication module I 14 is calculated slave computer 13 is transferred to the host computer 16 that is positioned at office by public's cordless communication network, host computer carries out analyzing and processing by self-programmed software to data, by display, is shown.

Wherein:

Level monitor as shown in Figure 4, a right cylinder 18 is fixed in center at upper and lower two end faces of the airtight casing 17 of stainless steel, a temperature compensating type fiber Bragg grating strain sensor 19 is pasted on to right cylinder 18 surfaces, and by optical cable II 20, signal is caused to optical Fiber Closure 9, optical Fiber Closure 9 is connected with optical cable I 10, and finally causes monitoring station.

In above-mentioned monitoring device:

Fiber grating level sensor: the fiber-optic grating sensor of selecting designed, designed encapsulation;

Temperature compensating type fiber Bragg grating strain sensor: BGK-FBG-4150;

Light switch is selected the grand SUM-FSW of light;

Grating demodulation instrument is selected SM125.

Flow monitoring device as shown in Figure 5, on pedestal 30 1 side inwalls, fix a Metallic rod 31, the free end of bar is fixed a derby 32, a temperature compensating type fiber Bragg grating strain sensor III 33 is pasted on to Metallic rod 31 surfaces, and by optical cable IV 34, signal is caused to optical Fiber Closure 9, optical Fiber Closure 9 is connected with optical cable I 10, and finally causes monitoring station.

In above-mentioned monitoring device:

Optical fiber optical grating flow speed sensor: the fiber-optic grating sensor of selecting designed, designed encapsulation;

Temperature compensating type fiber Bragg grating strain sensor: BGK-FBG-4150;

Light switch is selected the grand SUM-FSW of light;

Grating demodulation instrument is selected SM125.

Pipeline vortex-induced vibration monitoring device as shown in Figure 6, on pedestal 17 1 side inwalls, fix a Metallic rod 18, the free end of bar is fixed a derby 19, a temperature compensating type fiber Bragg grating strain sensor I 19 is pasted on to Metallic rod 18 surfaces, and by optical cable II 20, signal is caused to monitoring station; The slave computer 13 of monitoring station calls self-editing program, controls fiber Bragg grating (FBG) demodulator 12, realizes the real-time automatic collecting of data.

In above-mentioned monitoring device:

Optical fiber raster vibration sensor: the fiber-optic grating sensor of selecting designed, designed encapsulation;

Temperature compensating type fiber Bragg grating strain sensor: BGK-FBG-4150;

Light switch is selected the grand SUM-FSW of light;

Grating demodulation instrument is selected SM125.

Field monitoring station is arranged on selected pipeline mountain stream along the line river valley monitoring field, as shown in Figure 2, comprises optical Fiber Closure 9, connects optical cable I 10, light switch 11, fiber Bragg grating (FBG) demodulator 12, lower seat in the plane 13, GPRS wireless communication module I 14; The signal of each fiber-optic grating sensor collection is received the photoswitch 11 of monitoring station by optical cable I 10, photoswitch 11 outputs connect fiber Bragg grating (FBG) demodulator 12, and fiber Bragg grating (FBG) demodulator 12 outputs connect lower seat in the plane 13, and 13 outputs of lower seat in the plane connect GPRS wireless communication module I 14.

The signal of each fiber-optic grating sensor collection is received the photoswitch 11 of monitoring station by optical cable 10, light switch 11 changes each channel signal successively to fiber Bragg grating (FBG) demodulator 12, fiber Bragg grating (FBG) demodulator 12 demodulates the centre wavelength displacement of each fiber-optic grating sensor to lower seat in the plane 13, lower seat in the plane 13 automatically calculates the signal that each monitoring variable is defeated by GPRS wireless communication module I 14 and accepts GPRS wireless communication module I 14 and controls, each monitoring variable that GPRS wireless communication module I 14 is calculated lower seat in the plane 13 is transferred to by the public's cordless communication network receiving terminal host computer 16 that is positioned at office and is further analyzed and processes, with seat in the plane 13 also can be by the signal of GPRS wireless communication module II 15 acceptance reception host computers 16 at present.

Wherein:

Light switch: select the grand scientific and technological SUM-FSW of light;

Fiber Bragg grating (FBG) demodulator: select SM125;

Host computer and program: select and grind magnificent IPC-610, program is self-editing;

GPRS transport module 14: Siemens MC 35i

The receiving terminal that is positioned at office comprises following 2 parts:

(1) GPRS receiver module 15, the monitoring variable sending for receiving field monitoring station GPRS wireless communication module I 14, and be transferred to host computer 16, send feedback command also can to on-the-spot GPRS wireless communication module I 14;

(2) host computer 16 and program, for the signal of download terminal GPRS wireless communication module II 15, and calling program carries out automatic analysis, and analysis result and alarm threshold value are contrasted, and implements to report to the police in the time of necessary.

The principle of work of this system is: when monitored region, mountain stream river valley occurs to continue rainfall, pipeline river water level, river flow along the line all changes, amount of increase by Level monitor 4 monitoring river water levels changes, by 6 pairs of mountain torrents flow velocitys of flow monitoring device, measure, then according to the crest discharge of water level and flow relocity calculation mountain torrents, once surpass mountain torrents warning value, report to the police; Simultaneously, mountain torrents continuous erosion effect meeting causes pipeline 7 and produces vortex-induced vibration, by the vibration transducer 8 on body, measure its vibration frequency, and contrast with the natural frequency of pipeline self, judgement pipeline washes away the possibility that fatigue failure occurs under continuous erosion effect at mountain torrents.

By connecting optical cable I 10, the sensor signal concentration of transmissions of each position in pipeline mountain torrent monitoring region is arrived to light switch 11, light switch 11 changes each channel signal successively to fiber Bragg grating (FBG) demodulator 12, fiber Bragg grating (FBG) demodulator 12 demodulates each sensor wavelength centre wavelength displacement sensing to on-site computer 13, the centre wavelength displacement that on-site computer 13 demodulates (FBG) demodulator is calculated as each monitoring variable automatically, and monitoring variable is sent to on-the-spot GPRS wireless communication module I 14, GPRS wireless communication module I 14 is by cordless communication network signal transmission, by GPRS wireless communication module II 15, send terminal server 16 to, terminal server 16 is by the crest discharge of mountain torrents and pipeline vortex-induced vibration frequency and alarm threshold value contrast, in the time of necessary, provide warning.

Wherein:

GPRS wireless communication module II 15: select Siemens MC 35i;

Host computer 16 and program: host computer is selected and ground magnificent IPC-610; Program is self-editing.

While monitoring with said method, when monitored area occurs to continue rainfall, adopt the river water level variation of 4 pairs of each monitoring points of fiber grating level sensor to measure, adopt the mountain torrents flow velocity of 6 pairs of each monitoring points of optical fiber optical grating flow speed sensor to measure, based on river water level and these two measured values of mountain torrents flow velocity, utilize formula (12) just can calculate the crest discharge of mountain torrents, and then forecast reaching the mountain torrents of warning value; Simultaneously, mountain area continues the mountain torrents of heavy showers initiation and buried pipeline can be gone out, form the unsettled pipeline section directly not contacting with ground surface, under the effect of current wave making resistance, cause pipeline generation vortex-induced vibration, by 8 pairs of pipeline vortex-induced vibration frequencies of body optical fiber raster vibration sensor, measure, and be analyzed the possibility of judgement pipeline generation fatigue failure with the natural frequency of pipeline self.

Through monitoring for a long time, this example is easy to build monitoring system, is easy to real-time automatic collecting analysis and the long-range issue of pipeline combined monitoring data under mountain area Typical Small Watershed regimen and mountain torrents souring, long-range real-time automatic alarm.Avoided loaded down with trivial details artificial image data, improved the precision of early warning, reduced time of fire alarming, can also accurately locate place of alarm simultaneously, this to pipeline emergency measure take most important.

Claims (6)

1. an oil and gas pipes mountain flood monitoring method, it is characterized in that monitoring equipment therefor is: metal plate (1) is fixed on to bank, river course with bolt (2), in the upper protection cylinder (3) of installing of metal plate (1), and protection cylinder (3) is placed in to river course downwards, with bolt, fiber grating level sensor (4) is fixed in protection cylinder (3) wall, in river course bottom reference for installation stake (5), fixed fiber grating flow sensor (6) in stake, installing optical fibres grating vibration sensor (8) on the monitoring cross section of oil and gas pipes (7), then by level sensor (4), flow sensor (6) is introduced optical Fiber Closure (9) in the lump with vibration transducer (8), be connected with the optical cable I (10) that causes monitoring station, in monitoring station, optical cable I (10) is connected with photoswitch (11), photoswitch (11) is connected with (FBG) demodulator (12), (FBG) demodulator (12) is connected with slave computer (13), the pretreated data of slave computer (13) are by wireless communication module I (14) transmission, wireless communication module II (15) receives host computer (16),

Fiber grating level sensor (4), optical fiber optical grating flow speed sensor (6) and optical fiber raster vibration sensor (8) pass to photoswitch (11) by mountain torrents water level, flow velocity of river and pipeline vortex-induced vibration signal through optical cable I (10); photoswitch (11) reaches slave computer (13) by (FBG) demodulator (12) demodulation; slave computer (13) calls self-editing program; control photoswitch (11) and (FBG) demodulator (12), realize the collection of data and data are carried out to pre-service; Pretreated data receive host computer (16) by wireless communication module I (14) transmission, wireless communication module II (15), host computer (16) carries out further analyzing and processing to data, by river water level and mountain torrents flow relocity calculation, obtain the crest discharge of mountain torrents, whether the crest discharge that judges this region has reached forecast warning value, and the comparative analysis of the natural vibration frequency of connecting pipe line vortex forcing frequency and pipeline self, the safe condition of pipeline under judgement mountain torrents percussive action; The pre-service of slave computer data is mainly that the optical wavelength data of fiber Bragg grating (FBG) demodulator collection are converted into strain data, host computer is after receiving data, first by Data classification, according to rainfall, water level and flow relocity calculation mountain torrents total amount and flood peak, and it is combined with pipeline vortex-induced vibration signal, the safety case of pipeline under time, scale and flood erosion effect that judgement mountain torrents form.

2. a kind of oil and gas pipes mountain flood monitoring method according to claim 1, is characterized in that idiographic flow is:

Mountain torrents regimen and pipeline carry out respectively water level monitoring, flow monitoring and the monitoring of pipeline vortex-induced vibration;

The demodulation of wavelength signals, collection, pre-service;

The remote transmission of signal and reception;

Further analysis and the processing of signal;

Crest discharge changes dynamically demonstration, pipeline vortex-induced vibration frequency dynamic shows;

Mountain torrents Flood Peak Forecasting, pipeline Analysis of Mental Fatigue;

Mountain torrents forecast, pipe safety prewarning.

3. a kind of oil and gas pipes mountain flood monitoring method according to claim 1, it is characterized in that described water level monitoring method adopts the fiber grating level sensor of designed, designed, a right cylinder (18) is fixed in center at upper and lower two end faces of the airtight casing of stainless steel (17), a fiber Bragg grating strain sensor I (19) is pasted on to right cylinder (18) surface, and by optical cable II (20), signal is caused to monitoring station; Its computing method are as follows:

The hydrostatic pressure P at depth of water h place, river course is

P=P ₀+γh 3)

Wherein: P ₀for atmospheric pressure, the unit weight that γ is water;

Airtight casing (17), owing to deformed by the impact of outside surface hydraulic pressure P, causes inner connected right cylinder (18) to produce axial strain ε, has:

P＝Eε 4)

Wherein: E is the elastic modulus of right cylinder 18;

When river water level changes, outside under surface water pressure-acting, casing (17) and inner connected right cylinder (18) thereof deform, thereby cause that the temperature compensating type fiber Bragg grating strain sensor I (19) being pasted on right cylinder (18) produces axial strain ε, cause bragg wavelength to produce drift, its variation relation is shown in formula 2);

Association type 2), 3), 4), can obtain:

$\frac{{\mathrm{\&Delta;\&lambda;}}_B}{{\mathrm{\&lambda;}}_B}=(1-P_e)\frac{P_0+\mathrm{\&gamma;h}}{E}+({\mathrm{\&alpha;}}_f+\mathrm{\&xi;})\mathrm{\&Delta;T}---5)$

By formula 5) know the wavelength variations Δ λ of fiber grating _blinear with the variation of river water level h, fiber grating level sensor is based on formula 5) indirectly measure river water level h, utilize airtight casing (17) and inner connected the stressed of right cylinder (18) thereof that hydrostatic pressure is converted into axial strain amount, and then the bragg wavelength that is converted into fiber grating changes, utilize (FBG) demodulator to detect the change amount Δ γ of wavelength _bjust can know water level height by inference.

4. a kind of oil and gas pipes mountain flood monitoring method according to claim 1, it is characterized in that described flow monitoring method is to adopt optical fiber optical grating flow speed sensor, venturi-type choker-line (21), conduit I (22), conduit II (23) and fiber bragg grating pressure sensing mechanism, consist of, fluid flows through from left to right; When flux density one timing, the Bernoulli equation of incompressible fluid is

$P_1+\frac{1}{2}{\mathrm{\&rho;v}}_1^2=P_2+\frac{1}{2}{\mathrm{\&rho;v}}_2^2---6)$

By fluid continuity equation,

$\mathrm{\&pi;}{\left(\frac{1}{2}{d}_1\right)}^2{v}_1=\mathrm{\&pi;}{\left(\frac{1}{2}{d}_2\right)}^2{v}_2---7)$

By formula 6), 7) the pressure difference of cross section I and cross section II is

$\mathrm{\&Delta;P}=P_1-P_2=\frac{\mathrm{\&rho;}}{2}[{\left(\frac{d_1}{d_2}\right)}^4-1]v_1^2=\frac{\mathrm{\&rho;}}{2}[{\left(\frac{d_1}{d_2}\right)}^4-1]v^2---8)$

Wherein, d ₁, d ₂be respectively large round tube inside diameter, the roundlet pipe throat of venturi-type choker-line (21)) internal diameter, (v ₁, P ₁) and (v ₂, P ₂) be respectively flow velocity and pressure on conduit I (22) and conduit II (23) midline cross section; ρ is fluid density, v=v ₁flow velocity for liquid; From formula 8) can find out, the flow velocity of fluid is directly proportional to the pressure difference Δ P on conduit I (22) and conduit II (23) midline cross section, and pressure difference Δ P can record by fiber bragg grating pressure sensing mechanism, and concrete grammar is as follows:

Fiber bragg grating pressure sensing mechanism is comprised of organic glass seal box (24), airtight aluminum foil pipe (25), steel pin (26), equi intensity cantilever (27), temperature compensating type fiber Bragg grating strain sensor II (28) and optical cable III (29) etc.; Airtight aluminum foil pipe (25) is rigidly connected by steel pin (26) and the free end of semi-girder (27), and a temperature compensating type fiber Bragg grating strain sensor II (28) is sticked on to semi-girder (27) surface;

For semi-girder (27), according to the mechanics of materials, have

$\left\{\begin{array}{c}\mathrm{\&epsiv;}=\frac{\mathrm{Mh}}{2E{I}_y}\\ \frac{M}{I_y}=\frac{12\mathrm{Fl}}{{\mathrm{bh}}^3}\end{array}\right.---9)$

In formula: E, h, l and b are respectively semi-girders 927) elastic modulus, thickness, length and width, the strain that ε is beam, I _yfor the cross sectional moment of inertia of beam, M is semi-girder moment of flexure, and F is the pressure that semi-girder is subject to;

Because aluminum foil pipe can only stretch vertically, and elasticity coefficient is very little, and the relational expression of the pressure F that semi-girder is subject to is as follows

$F=\mathrm{\&Delta;PSg}=(P_1-P_2)\mathrm{\&pi;}{\left(\frac{d}{2}\right)}^{2}g---10)$

In formula: Δ P is the inside and outside pressure difference of aluminum foil pipe (25), and S is the cross-sectional area of aluminum foil pipe (25), and g is acceleration of gravity, and d is the diameter of aluminum foil pipe (25);

The pressure of the unequal generation of inside and outside pressure of aluminum foil pipe (25) acts on semi-girder (27) by steel pin (26), caused the distortion of semi-girder (27), and then the bragg wavelength that causes temperature compensating type fiber Bragg grating strain sensor II (28) drifts about, its variation relation is shown in formula 2);

Association type 2), 8), 9), 10), have

$\frac{{\mathrm{\&Delta;\&lambda;}}_B}{{\mathrm{\&lambda;}}_B}=\frac{3(1-P_e)\mathrm{\&pi;}{\mathrm{ld}}^2\mathrm{\&rho;g}}{4E{\mathrm{bh}}^2}[{\left(\frac{d_1}{d_2}\right)}^4-1]v^2+({\mathrm{\&alpha;}}_f+\mathrm{\&xi;})\mathrm{\&Delta;T}---11)$

By formula 11) know the wavelength variations Δ λ of fiber grating _bwith the square of tested flow velocity v, utilize this optical fiber optical grating flow speed sensor to measure mountain torrents flow velocity v.

5. a kind of oil and gas pipes mountain flood monitoring method according to claim 1, is characterized in that the crest discharge calculation formula in described river course is as follows:

Q=ΔhLv 12）

In formula: the crest discharge that Q is river course, the changing value that Δ h is river water level, L are river width, v is mountain torrents flow velocity; Therefore, the river water level and the mountain torrents flow velocity that according to monitoring, obtain, utilize formula 12) can calculate the crest discharge of mountain torrents.

6. a kind of oil and gas pipes mountain flood monitoring method according to claim 1, is characterized in that described pipeline vortex-induced vibration frequency monitoring method adopts the optical fiber raster vibration sensor of designed, designed; On pedestal (30) one side inwalls, fix a Metallic rod (31), the free end of bar is fixed a derby (32), a temperature compensating type fiber Bragg grating strain sensor III (33) is pasted on to Metallic rod (31) surface, and by optical cable IV (34), signal is caused to monitoring station, its computing method are as follows:

As Metallic rod (31) is equivalent to a semi-girder, have

$\left\{\begin{array}{c}\frac{\mathrm{\&sigma;}}{x\left(t\right)}=\frac{{\mathrm{Ebh}}^3}{6l^3}\\ \mathrm{\&sigma;}=\frac{{\mathrm{Ebh}}^2}{6l}\mathrm{\&epsiv;}\end{array}\right.---13)$

In formula: E, h, l and b are respectively elastic modulus, thickness, length and the width of semi-girder, the stress that σ is beam, x (t) is the free-ended amount of deflection of beam, according to formula 13), have

$x\left(t\right)=\frac{l^2}{h}\mathrm{\&epsiv;}---14)$

When the derby (32) of installing when the free end of Metallic rod (31) vibrates together along with external environment condition, effect due to inertial force, make the temperature compensating type fiber Bragg grating strain sensor III (33) of pasting produce axial strain, cause bragg wavelength to produce drift, its variation relation is shown in formula 2);

Association type 2), 14), have

$\frac{{\mathrm{\&Delta;\&lambda;}}_B}{{\mathrm{\&lambda;}}_B}=(1-P_e)\frac{h}{l^2}x\left(t\right)+({\mathrm{\&alpha;}}_f+\mathrm{\&xi;})\mathrm{\&Delta;T}---15)$

Optical fiber raster vibration sensor is based on formula 15) indirectly measure member Vibration Parameter, utilize the stressed of Metallic rod that amplitude, acceleration parameter are converted into axial strain amount, and then the bragg wavelength that is converted into fiber grating changes, the change amount of utilizing (FBG) demodulator to detect wavelength realizes the vibration survey to member;

Suppose under external force, it is the simple harmonic oscillation that A, angular frequency are ω that pedestal (30) is done amplitude, and its vibration displacement is expressed as

x(t)=A cos(ωt-θ) 16）

X (t) is asked to second derivative, can obtain vibration acceleration a (t)

a(t)＝x(t)″＝-Aω ² cos(ωt-θ) 17）

Association type 16), 17), have

a(t)＝-ω ²x(t) 18）

Association type 15), 18), have

$\frac{{\mathrm{\&Delta;\&lambda;}}_B}{{\mathrm{\&lambda;}}_B}=-(1-P_e)\frac{h}{{\mathrm{\&omega;}}^2{l}^2}a\left(t\right)+({\mathrm{\&alpha;}}_f+\mathrm{\&xi;})\mathrm{\&Delta;T}---19)$

The natural frequency that wherein ω is optical fiber raster vibration sensor, can be represented by the formula

$\mathrm{\&omega;}=\sqrt{\frac{{\mathrm{Ebh}}^3}{6m{l}^3}}---20)$

Wherein m is the quality of derby 32, association type 19), 20), have

$\frac{{\mathrm{\&Delta;\&lambda;}}_B}{{\mathrm{\&lambda;}}_B}=-(1-P_e)\frac{6\mathrm{ml}}{\mathrm{Eb}{h}^2}a\left(t\right)+({\mathrm{\&alpha;}}_f+\mathrm{\&xi;})\mathrm{\&Delta;T}---21)$

By formula 21) know the wavelength variations Δ λ of fiber grating _bchange linear with the vibration acceleration a (t) of vibration source, the variation of the wavelength by measuring optical fiber grating realizes the measurement to vibration acceleration, vibration acceleration a (t) is carried out after the calculating of Fast Fourier Transform fast fourier transform, can obtain the rumble spectrum of member, thereby obtain the vibration period; By the wave number in 1/4th cycles, can obtain amplitude and the frequency at measuring point place, and can draw the amplitude-time-history curves of structural member.

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