CN110006851B - A kind of On-Line Monitor Device of Gas and method of fiber grating gas sensing - Google Patents
A kind of On-Line Monitor Device of Gas and method of fiber grating gas sensing Download PDFInfo
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- CN110006851B CN110006851B CN201910335251.8A CN201910335251A CN110006851B CN 110006851 B CN110006851 B CN 110006851B CN 201910335251 A CN201910335251 A CN 201910335251A CN 110006851 B CN110006851 B CN 110006851B
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- fiber grating
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- pipe
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/4738—Diffuse reflection, e.g. also for testing fluids, fibrous materials
- G01N21/474—Details of optical heads therefor, e.g. using optical fibres
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
- G01N21/53—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/4738—Diffuse reflection, e.g. also for testing fluids, fibrous materials
- G01N21/474—Details of optical heads therefor, e.g. using optical fibres
- G01N2021/4742—Details of optical heads therefor, e.g. using optical fibres comprising optical fibres
Abstract
The present invention relates to the On-Line Monitor Device of Gas and method of a kind of fiber grating gas sensing, comprising: optical fiber grating sensing element, testing tube, fiber grating support stabilizer, positioning pipe, sealing-plug, fiber Bragg grating (FBG) demodulator, computer processor；The optical fiber grating sensing element passes through fiber grating support stabilizer, is arranged in testing tube, and the optical fiber grating sensing element is sequentially connected with fiber Bragg grating (FBG) demodulator, computer processor.The small in size, at low cost of the device, appearance transparent, visuality are good, simultaneously not influencing to efficiently reduce the flutter of fiber grating in use under the premise of fiber grating axial strain, systematic error is significantly reduced, the Stability and veracity of testing result is increased.
Description
Technical field
The invention belongs to industrial sensor fields, and in particular to a kind of gas on-line monitoring dress of fiber grating gas sensing
It sets and method.
Background technique
Disclosing the information of the background technology part, it is only intended to increase understanding of the overall background of the invention, without certainty
It is considered as recognizing or implying in any form that information composition has become existing skill well known to persons skilled in the art
Art.
Current development in science and technology is maked rapid progress, and industrial productivity is advanced by leaps and bounds.Along with expanding economy, environmental issue is gradually
It attracts people's attention, for preferably pollution administration and protection environment, occurs more and more sensing devices on the market.With
For gas detection, most of gas sensor is the principle based on electricity currently on the market, these sensors can be by ring
The change that gas concentration is tested in border is converted into the electric signal that can be read and analyze, and such as resistance value, current strength, is analyzing
The concentration change information of available tested gas, provides Informational support for environmental improvement after signal.
The toxic and harmful gas of high concentration can be generated in industrial processes, the discharge of these exhaust gas is air environmental pollution
One of the main reason for, the supervision and management to it need to be reinforced；Many inflammable and explosive high-risk gases are also industrial simultaneously
Necessary raw material, these gases are careless slightly in storage, transport and use process to will result in explosion, to personnel safety and society
It can stablize and cause grave danger.Therefore people actively research and develop the good gas sensor of high sensitivity, safety, to ensure industrial life
It produces safety to carry out, guarantees people life property safety.
In gas sensing field, common detection method, as the methods of spectrum, gas-chromatography limitation are big.Usually need
It carries out a large amount of previous experiments preparation, and is similar to the instruments such as gas chromatograph there is also equipment volumes big, occupied area
Greatly, the problems such as expensive, once the expense of great number can be spent by being damaged or need replacing components, while can not be real-time
Detecting state and process inside observation instrument.Current gas sensor is chiefly used in environment monitoring, and there are man's activity degree
Big feature, such as observer can take specific monitoring point, be monitored in special time period collection gas.With efficient, safety
The working regions such as factory or mine for the purpose of production, the effect of gas sensor is primarily to exist for a long time and incessantly
Line monitoring, often have monitoring point is more, monitoring point be mostly it is outdoor, do not apply generally additional air pressure pumping gas transmission, monitoring result by
Weather influences the characteristics of serious (convective wind, rainwater etc. all become an important factor for influencing monitoring data).
Such as: patent CN108872086A discloses a kind of fiber grating air-sensitive of composite air-sensitive Intumescent polymer film
Element, the gas sensor are made by fiber grating and in the air-sensitive Intumescent polymer film that the grating region of optical fiber coats.
The fiber grating can detect millionth axial strain, so that its measurement accuracy is high.
But inventor's follow-up study is found: such fiber-optic grating sensor is based on the highly sensitive of elasto-optical effect at present
Degree, high-precision sensor, it is sensitive for the mechanical disturbances such as vibrating, impacting, if fiber grating to be only simple placed on to survey
In test tube, when being passed through gas to be monitored, the flow perturbation of generation can make fiber grating that violent flutter, while and testing tube occur
Wall collides friction, occurs more noise signal in final result, causes during result really can not intuitively show
The long offset of cardiac wave, will affect the Stability and veracity of fiber grating test result, to next artificial neural network
Pattern-recognition can produce bigger effect so that monitoring result differs larger with true value.
Summary of the invention
In order to overcome the above problem, the present invention provides a kind of On-Line Monitor Device of Gas of fiber grating gas sensing
And method, the small in size, at low cost of described device, visuality are good, while under the premise of not influencing fiber grating axial strain
Efficiently reduce the flutter of fiber grating in use, significantly reduce systematic error, increase testing result accuracy and
Stability.
To realize the above-mentioned technical purpose, The technical solution adopted by the invention is as follows:
A kind of On-Line Monitor Device of Gas of fiber grating gas sensing, comprising: optical fiber grating sensing element, test
Pipe, fiber grating support stabilizer, positioning pipe, sealing-plug, fiber Bragg grating (FBG) demodulator, computer processor；The testing tube
Both ends are sealed by sealing-plug, are provided with fiber grating support stabilizer in testing tube, the fiber grating support stabilizer is set
It is equipped with the through-hole passed through for optical fiber grating sensing element and positioning pipe, the positioning pipe passes through fiber grating support stabilizer, and
It is fixedly connected with the sealing-plug of at least one end；
The optical fiber grating sensing element has the response characteristic of axial strain, at fiber Bragg grating (FBG) demodulator, computer
Reason device is sequentially connected.
The fiber grating support stabilizer of the application refers to: for fiber grating to be fixed on specific position in testing tube
Device.
The application for the high sensitive of fiber grating, vulnerable to external disturbance the characteristics of, devise a kind of gas and supervise online
Fiber grating support stabilizer needed for surveying device reduces chatter phenomenon under the premise of not limiting fiber grating axial strain
And the collision friction of reduction and tube wall, efficiently reduce disturbance of the air-flow to fiber grating.Fiber grating support stabilizer material
For quartz glass, the problem strong to organic gas adsorption capacity using the device of other materials (such as rubber, plastics) is avoided,
Instrument is small in size simultaneously, and surface area is small, and the inner surface and air-sensitive polymeric membrane of avoiding device generate excessive competitive Adsorption,
Guarantee the Stability and veracity of online monitoring data.Its special shape and size can cater to well gas and exist simultaneously
The testing tube of line monitoring device, centre of gravity and the smooth feature in surface make that unexpected rotation occurs partially in On-Line Monitor Device of Gas
When shifting, the effect of support and stable fiber grating still can be functioned well as.
In some embodiments, the testing tube, fiber grating support stabilizer, positioning pipe, sealing-plug are quartzy glass
Glass.
The positioning pipe of bearing apparatus is very thin quartz glass tube, can fix the position of optical fiber support stabilizer, work as testing tube
It is vertical in use, support stabilizer can be fixed on to predetermined position without movement to need in certain circumstances.
Testing tube glass capsulation plug containing cushion rubber is quartz glass product, is avoided while guaranteeing test composite pipe tightness pure
The sealing-plug of rubber adsorbs excessive problem to organic gas.
Since testing tube, fiber grating support stabilizer, the positioning pipe of bearing apparatus, testing tube glass capsulation plug are quartz
Glass is made, and transparency is high, and visual good, experimenter can directly observe the fiber grating state inside device, for having
Color gas can more be clearly observed internal gas flowing and distribution situation, be based on artificial neural network technology with subsequent
Pattern analysis and fluid-flow analogy result based on FLUENT software contrast, further increase the standard of online monitoring data
True property and stability.
In some embodiments, the fiber grating support stabilizer is that there are two the cylinders of circular hole for setting in axial direction
Body, be provided with multiple groups through-hole in its axial parallel direction, optical fiber grid region two sides are fixed on by the positioning pipe of bearing apparatus.Generally
, fiber grating support stabilizer diameter is less than test bore 0.5-1.5mm.The material of the fiber grating support stabilizer
Matter is quartz glass and volume very little, it is ensured that fiber grating support stabilizer will not be with air-sensitive polymeric membrane generation having excessively
Machine gas competitive Adsorption.
In some embodiments, described two circular holes are tangent, and the shaft section about cylindrical body is symmetrical.
Currently, the mode for fixing fiber grating has very much, but for the axial strain optical fiber for gas detection
Grating, during fixation, it is necessary to while meeting the collision friction for reducing chatter phenomenon, reduction and tube wall, and guarantee gas
The multiple requirements such as body circulation so as not to hindering the gas flowing in testing tube, and make gas-sensitive sensing element ambient gas
Type and its concentration can and the synchronic gas of suspected location change, therefore in some embodiments, the application is by cylindrical body upper half
Part two sides respectively cut out the big small column such as two diameters and parent cylindrical radius, finally make the top of big cylinder that " mountain " word be presented
Shape, above-mentioned design both ensure that effective circulation of gas-sensitive sensing element ambient gas, meanwhile, fiber grating support stabilizer and survey
The contact area of test tube is bigger, and overall structure is more stable, significantly reduces chatter phenomenon, the collision that reduces with tube wall rubs
It wipes.
In some embodiments, logical for being passed through for fiber grating and positioning pipe on the fiber grating support stabilizer
Hole is located at the lower section at two circular hole point of contacts, and the through-hole that passes through of positioning pipe is located at the lower section for the through-hole that fiber grating passes through.Big
Cylinder middle section cuts out the cylinder that a diameter is greater than fibre diameter 0.5-1.5mm, the access as fiber-optic grating sensor.
Access of the 0.5-1.5mm cylinder as fiber grating positioning pipe is cut out at 2mm below the fiber grating access.Fiber grating support
Stabilizer center of gravity is low and material is smooth quartz glass, it is ensured that fiber grating support stabilizer rotates anyway all may be used
To keep vertical state, fiber grating can be carried out stablizing support.Simultaneously because the light among fiber grating support stabilizer
Fine passage diameters are slightly larger than fibre diameter, therefore without limitation on the axial strain of fiber-optic grating sensor, reach reduction air-sensitive light
The purpose of the collision friction and chatter phenomenon of fine grating and test tube wall, increases the Stability and veracity of experimental data.
In some embodiments, the positioning pipe of bearing apparatus is very thin quartz glass tube, and one end, which is fixed on, is having optical fiber logical
Beyond the Great Wall, the positioning pipe of the bearing apparatus in testing tube passes through all light that need to be used to the testing tube glass capsulation of road and positioning pipe access
The remaining gap of all through-holes is bonded using minute quantity glue, reaches fixed light by the positioning pipe through-hole of fine grating support stabilizer
The effect of fine grating support stabilizer.It is no matter horizontal, vertical or exist at any angle using gas after positioning pipe is installed
Line monitoring device can guarantee that fiber grating support stabilizer is fixed on predetermined position without movement.
In some embodiments, the glass capsulation plug of the positioning pipe access containing optical fibre channel and bearing apparatus is mounted on
One end of testing tube, and the other end of testing tube is solid glass sealing-plug.The optical fibre channel can make optical fiber thus through-hole
It is passed through inside testing tube, remaining gap glue is sealed to guarantee air-tightness.The positioning pipe access of the bearing apparatus seals remaining seam by glue
Gap can play the role of the positioning pipe of fixed bearing apparatus.The solid glass sealing-plug of the other end, after installation is complete should be apart from light
Fine end is not less than 20mm, to guarantee not limiting the axial strain of fiber grating.
In some embodiments, the both ends of the testing tube are respectively arranged with multiple air inlet pipe, exhaust pipe, in principle not
Intended distinction air inlet pipe and exhaust pipe, therefore vent branch hereinafter referred to as is i.e. for fingering tracheae and exhaust pipe.The quartz glass tube
And vent branch basic structure is four-way pipe.The quartz glass tube is testing tube, and the air inlet pipe and exhaust pipe are branch pipe, phase
Than in vent branch, the internal diameter of testing tube is larger.The testing tube is the placement space of fiber-optic grating sensor, the ventilation branch
Pipe is the channel of organic gas inlet and outlet testing tube, and material is quartz glass.The specific size foundation of the testing tube
Depending on the concrete condition of experiment, length is depending on the length in the grid region quantity of fiber grating and each grid region and interval, generally
, the grid region length about 10-30mm of fiber grating, the distance between adjacent grid region and grid region about 10-100mm, optical fiber end
Grid region and fiber grating support stabilizer interval 20-30mm.If the test bore is excessive, test inside pipe wall table will lead to
Area is excessive, by enhancing test inside pipe wall with air-sensitive polymeric membrane to the competitive Adsorption of organic gas, therefore in general testing tube
Diameter is no more than 20mm.The quartz glass tube and its air inlet pipe and exhaust pipe need to have certain intensity to cope with experimental field
Phenomena such as vibration, impact.In general, the glass wall thickness of the quartz glass tube and its vent branch is not less than 2mm.The air inlet
Pipe and exhaust pipe are distributed at left and right sides of testing tube, in general, the safety in utilization in order to guarantee vent branch, vent branch with
Reserve the safe distance of 40-50mm in testing tube left and right ends.The caliber of vent branch is according to the gas being connected with organic gas source
The outer diameter of input pipe and the gas output tube being connected with gas bottle determines, in general, being passed through quartz glass tube to reduce gas
Generated turbulent phenomenon, vent branch internal diameter are not less than 5mm.It, can be corresponding simultaneously when once monitoring a variety of organic gas
Ground increases vent branch quantity, while the length of testing tube is increase accordingly by the quantity of grating region.In order to guarantee in actual use
Convenient for operation, the distance between adjacent branch pipe and branch pipe are not less than 30mm.
In some embodiments, the testing tube, fiber grating support stabilizer, the positioning pipe of bearing apparatus, testing tube glass
Glass sealing-plug is all quartz glass product.It avoids and organic gas is inhaled using the device of other materials (such as rubber, plastics)
The strong problem of attached ability, while instrument is small in size, internal surface area is small, and the inner surface and air-sensitive polymeric membrane of avoiding device produce
Raw excessive competitive Adsorption, guarantees the Stability and veracity of online monitoring data.
In some embodiments, the glass wall thickness of the testing tube, air inlet pipe and exhaust pipe is not less than 2mm；Due to quartz
Glass tube and its air inlet pipe and exhaust pipe, fiber grating support stabilizer are simple quartz glass part, so cost of manufacture
Low, inexpensive mass production may be implemented in simple process.
In some embodiments, such as the using areas such as chemical plant, in order to which save the cost can not be provided in each monitoring point
Air pump or air delivery device, and monitoring point is often under open-air atmosphere, influence vulnerable to weather (such as influenced by rainwater or convection current
The disturbance of wind), therefore the testing tube with vent branch is adapted as the testing tube with venthole, concrete operations are as follows: cancelling ventilation
Branch pipe, and intensive venthole is opened up away from the bottom of the tube of two sides at the 50mm of both ends in testing tube.At this point, since venthole is provided with bottom
Portion, even if being still able to maintain in device and not soaked by rainwater under rainy day environment；Since venthole is in optical fiber support stabilizer
Between sealing-plug, optical fiber support stabilizer can reduce disturbance of the convective wind to optical fiber, and convective wind is avoided to act on optical fiber diameter
Upwards；The intensive venthole of bottom may make that gaseous species and its concentration are consistent with ambient atmos in testing tube simultaneously.Therefore
Under the conditions of no pressure, described device can still be perfectly suitable for actual field condition after the repacking.
In some embodiments, the optical fiber grating sensing element is the optical fiber grating sensing coated with air-sensitive polymeric membrane
Element.The application method of the On-Line Monitor Device of Gas of the fiber grating gas sensing is to utilize air-sensitive polymeric membrane pair
The absorption of organic gas or desorption make air-sensitive polymeric membrane expand or shrink deformation, pass through polymeric membrane and fiber grating
Interface to fiber grating transmit axial stress, make fiber grating generate axial strain, finally make in fiber grating reflected light
Cardiac wave length is drifted about, and is then carried out pattern-recognition by the knots modification to reflection center wavelength of light, is obtained the kind of organic gas
Class and its concentration.
In the optical fiber grating sensing element coated with air-sensitive polymeric membrane, the structure of the optical fiber includes fibre
Core, covering and coat, existing optical fiber has single mode optical fiber and multimode fibre on the market, due to single mode optical fiber long transmission distance and
Dispersion, reliable in quality will not occur, and multimode fibre dispersion is big, loss is also big, is adapted only to the optical fiber of short-distance and medium-distance and low capacity
Communication system, therefore preferred single mode optical fiber.The core diameter of single mode optical fiber is about 10 μm, and cladding diameter is about 125 μm.The gas
Quick polymeric membrane includes a variety of pairs of sensitive macromolecule membranes of organic gas, such as (sensitive gas has chloroform, four to polyurethane film
Chlorination carbon, acetone, n-hexane, ethyl alcohol etc.), polymethyl methacrylate film (sensitive gas have tetrahydrofuran, ethyl acetate,
Chloroform, benzene etc.), polystyrene film (sensitive gas has carbon tetrachloride, chloroform, acetone, tetrahydrofuran, benzene, toluene etc.).
In some embodiments, vent branch internal diameter is not less than 5mm.
In some embodiments, the vent branch is 40-50mm at a distance from testing tube left and right ends.
In some embodiments, the distance between described vent branch is not less than 30mm.
It is described to contain present invention also provides a kind of On-Line Monitor Device of Gas of modular fiber optic grating gas sensing
The glass capsulation plug of the positioning pipe access of optical fibre channel and bearing apparatus is mounted on the both ends of testing tube simultaneously, thus with same root light
Fine successively to pass through multiple testing tubes, i.e., the different gratings on available same root optical fiber realize the on-line monitoring of more spatial points.
The present invention also provides a kind of gas on-line monitoring methods of fiber grating gas sensing, using any above-mentioned
Device carries out on-line checking to gas.
The beneficial effects of the present invention are:
(1) present invention is utilized using the optical fiber grating sensing element for being coated with air-sensitive polymeric membrane as gas sensor
Air-sensitive polymeric membrane drives fiber grating to generate axial strain, leads to light to deformation caused by absorption/desorption of organic gas
The central wavelength of fine optical grating reflection light is drifted about, and the optical signalling demodulation of (FBG) demodulator, the data point of computer processor are passed through
Analysis is handled to obtain gaseous species and its concentration data.
(2) medium that the fiber-optic grating sensor that the present invention uses is propagated using light as information is based on elasto-optical effect, solves
Existing the problem of being easy as the sensor of major way by electromagnetic interference using electric signal, it can detect millionth axial direction and answer
Become, precision is high.
(3) On-Line Monitor Device of Gas in the present invention is small in size, flexibly and easily, solves spectrum analysis or chromatography
Instrument be not easy the problem of carrying and taking up a large area, can be directly applied for factory, mine etc. scene on-line monitoring.
(4) material of the quartz glass tube in the present invention and vent branch, fiber grating support stabilizer is quartzy glass
Glass, it is cheap, it is conveniently easy to get, only needs to change components without complicated specialized maintenance when being damaged, when saving
Between, convenient for maintenance repair, use.And the visuality of quartz glass is good, can observe directly inside in actual use
Instantaneous operating conditions more can be clearly seen that colored gas internal gas flowing and distribution situation.
(5) the fiber grating support stabilizer in the present invention is not under the premise of limiting fiber grating axial strain, to light
Fine grating plays support and positioning action, reduces chatter phenomenon and reduces the collision friction with tube wall, efficiently reduces air-flow pair
The disturbance of fiber grating, while when unexpected rotation or offset occur for On-Line Monitor Device of Gas, it still can be well
Stable and positioning action is played, guarantees the Stability and veracity of online monitoring data.
(6) positioning pipe of the bearing apparatus in the present invention can fix fiber grating support stabilizer, therefore no matter horizontal, vertical
Or at any angle using gas on-Line Monitor Device, fiber grating support stabilizer can be made to be fixed on predetermined position.
The position of fiber grating support stabilizer can be adjusted before installing simultaneously, for the light of different grid region quantity, different interval
Fibre can well adapt to.
(7) for without the outdoor on-line monitoring of long-time under additional air pressure conditions, since venthole is provided with testing tube
Bottom and between optical fiber support stabilizer and sealing-plug, even if being still able to maintain in device under rainy day environment not by rain
Water-soaked, optical fiber support stabilizer can reduce disturbance of the convective wind to optical fiber, avoid convective wind from acting on optical fiber radially, together
When bottom intensive venthole may make that gaseous species and its concentration are consistent with ambient atmos in testing tube.By to test
The minor adjustment of pipe can still be well adapted for actual field condition.
Detailed description of the invention
The accompanying drawings constituting a part of this application is used to provide further understanding of the present application, and the application's shows
Meaning property embodiment and its explanation are not constituted an undue limitation on the present application for explaining the application.
Fig. 1 is the structure subdivision schematic diagram of the optical fiber grating sensing element coated with air-sensitive polymeric membrane.Wherein, a- light
Fibre, b- air-sensitive polymeric membrane, c- grating, d- polymer protective film.
Fig. 2 is the schematic three dimensional views of branch cast On-Line Monitor Device of Gas.
Fig. 3 is the schematic three dimensional views of fiber grating support stabilizer.
Fig. 4 is the subdivision schematic diagram of fiber grating support stabilizer use state.
Fig. 5 (a) be " the positioning pipe access for having optical fibre channel and bearing apparatus " glass capsulation plug and testing tube one end three
Tie up schematic diagram.
Fig. 5 (b) is the schematic three dimensional views of solid glass sealing-plug and testing tube one end.
Fig. 6 is the schematic three dimensional views of through-hole type On-Line Monitor Device of Gas.
Fig. 7 is the two-dimensional representation of testing tube and vent branch.
Fig. 8 is on-line monitoring curve of the fiber-optic grating sensor coated with polyimide film to toluene gas.
Wherein, 1 for optical fiber grating sensing element, 2 fiber grating support stabilizers, 3 positioning pipes, 4 testing tubes, 5 air inlet pipe,
6 sealing-plugs, 7 exhaust pipes, 8 ventholes, the through-hole I that 2-1 is passed through for optical fiber grating sensing element, 2-2 pass through logical for positioning pipe
Hole II.
Specific embodiment
It is noted that following detailed description is all illustrative, it is intended to provide further instruction to the application.Unless another
It indicates, all technical and scientific terms used in this application have logical with the application person of an ordinary skill in the technical field
The identical meanings understood.
It should be noted that term used herein above is merely to describe specific embodiment, and be not intended to restricted root
According to the illustrative embodiments of the application.As used herein, unless the context clearly indicates otherwise, otherwise singular
Also it is intended to include plural form, additionally, it should be understood that, when in the present specification using term "comprising" and/or " packet
Include " when, indicate existing characteristics, step, operation, device, component and/or their combination.
As background technique is introduced, simply rested in testing tube for current fiber grating, it is to be checked being passed through
When surveying gas, the flow perturbation of generation can make fiber grating occur violent flutter, while collide friction with test tube wall, shadow
The problem of ringing the monitoring Stability and veracity of fiber grating.Therefore, the present invention proposes a kind of fiber grating gas sensing
On-Line Monitor Device of Gas, optical fiber grating sensing element, testing tube and vent branch, light including being coated with air-sensitive polymeric membrane
Fine grating support stabilizer, the positioning pipe of bearing apparatus, testing tube glass capsulation plug, fiber Bragg grating (FBG) demodulator and calculating containing cushion rubber
Machine processor.
In the optical fiber grating sensing element for being coated with air-sensitive polymeric membrane, polymeric membrane is combined on fiber grating
(as shown in Figure 1), using polymeric membrane to the absorption of organic gas, diffusion, desorption and generate the principle of deformation, pass through macromolecule
Power is transmitted to fiber grating by the deformation of film, is brought it about axial strain and is sent out so as to cause the central wavelength of fiber grating reflected light
Raw drift, by the optical signal prosessing of (FBG) demodulator and the mode identification technology of computer processor, analyzes, identifies organic gas
Type and its relevant informations such as concentration.Long distance transmission is suitble to due to single mode optical fiber and dispersion, while fiber grating does not occur
Diameter it is smaller, it is easier to be strained by the drive of air-sensitive polymeric membrane, therefore 125 μm of diameter of fiber grating of selection.It is organic high
Molecular film is with a thickness of 10-60 μm.It is common to have for the suitable effective air-sensitive polymeric membrane of the organic gas type to be detected selection
The corresponding polymeric membrane of machine gas pollutant is as follows: (sensitive gas has chloroform, carbon tetrachloride, acetone, just to polyurethane film
Hexane, ethyl alcohol etc.), polymethyl methacrylate film (sensitive gas has tetrahydrofuran, ethyl acetate, chloroform, benzene etc.), polyphenyl
Vinyl film (sensitive gas has carbon tetrachloride, chloroform, acetone, tetrahydrofuran, benzene, toluene etc.).
In On-Line Monitor Device of Gas, since fiber grating is the sensitive optical sensor based on elasto-optical effect, micro- vibration
It is dynamic to wait mechanical disturbances that all have an impact to fiber-optic grating sensor, if fiber grating is directly simply located at gas on-line monitoring
In device, the disturbance of air-flow or working site vibration can all be had an impact result.To solve the above problems, devising basic knot
Structure is the quartz glass tube and vent branch (as shown in Figure 2) of four-way pipe.The material of entire gas piping is quartz glass, is kept away
The problem strong to organic gas adsorption capacity using the device of other materials (such as rubber, plastics), while instrument are exempted from
Small in size, internal surface area is small, and the inner surface and air-sensitive polymeric membrane of avoiding device generate excessive competitive Adsorption, guarantees online prison
The Stability and veracity of measured data.Depending on the design size of the On-Line Monitor Device of Gas concrete condition that mainly foundation is tested,
The length of testing tube is depending on the grid region quantity of fiber grating, the length in grid region and its length at interval, in general, optical fiber light
The grid region length about 10-30mm of grid, the distance between adjacent grid region and grid region about 10-100mm, optical fiber end grid region and optical fiber
Grating support stabilizer interval 20-50mm.If test bore is excessive, it is excessive to will lead to testing tube inner wall surface area, can increase
Strong test inside pipe wall is with air-sensitive polymeric membrane to the competitive Adsorption of organic gas.In general, test bore is no more than 20mm.It surveys
Situations such as test tube and vent branch need to have certain intensity, vibration, impact to cope with experimental field guarantees whole not to occur
Phenomena such as cracking, destruction.In general, the glass wall thickness of testing tube and vent branch is not less than 2mm.In general, vent branch point
Cloth is at left and right sides of testing tube.In general, the safety in utilization in order to guarantee vent branch, vent branch and testing tube or so two
Side should reserve the safe distance of 40-50mm.Vent branch bore should be according to intake line and the decision of output pipe bore, generally
, it is passed through turbulent phenomenon caused by testing tube in order to reduce gas, vent branch internal diameter is not less than 6mm.When primary monitoring is more
When kind organic gas, it can correspondingly increase branch pipe quantity, while the length of testing tube is increase accordingly by the quantity of grating region.For
Ensure that, in actual use convenient for operation, the distance between adjacent branch pipe and branch pipe are not less than 30mm.There is fiber grating in testing tube
The material of support stabilizer (as shown in Figure 3), the fiber grating support stabilizer is quartz glass and small volume, can be protected
Card support stabilizer will not generate excessive organic gas competitive Adsorption to air-sensitive polymeric membrane.Fiber grating support stabilizer is former
Type is cylindrical body, is placed on inside testing tube, therefore its diameter is slightly less than test bore, in general, fiber grating support is stablized
Device diameter is less than test bore 0.5-1.5mm or so.For so that it will not hinder the gas in testing tube to flow, and guarantee air-sensitive
The type and its concentration of sensing element ambient gas can change with the synchronic gas of suspected location, therefore half part is dug on the cylinder
The big small column such as two diameters and parent cylindrical radius is removed, finally makes the top of big cylinder that " mountain " font be presented.In big cylinder
Middle section cuts out the cylinder that a diameter is greater than fibre diameter 0.5-1.5mm, the access as fiber-optic grating sensor.In light
Access of the 0.5-1.5mm cylinder as fiber grating positioning pipe is cut out at 2mm below fine grating access.Fiber grating support is stablized
Think highly of that the heart is low and material is smooth quartz glass, it is ensured that fiber grating support stabilizer is rotated anyway and can be protected
Hold vertical state.Simultaneously because the optical fibre channel diameter among fiber grating support stabilizer is slightly larger than fibre diameter, therefore will not
Limit the axial strain of fiber-optic grating sensor.It is no matter horizontal, vertical or at any that the presence of the positioning pipe of bearing apparatus makes
Angle using gas on-Line Monitor Device can make fiber grating support stabilizer be fixed on predetermined position；It is fixed in gluing
Before, the position of fiber grating support stabilizer is adjustable, can also be with for the optical fiber of different grid region quantity and its different interval
It well adapts to.Testing tube glass capsulation plug of the both ends containing cushion rubber constructs different, and side is " to have determining for optical fibre channel and bearing apparatus
Position pipe access " glass capsulation plug (shown in such as Fig. 5 (a)), side is solid glass sealing-plug (shown in such as Fig. 5 (b)).Containing cushion rubber
Testing tube glass capsulation plug be quartz glass product, only the part that glass stopper is contacted with testing tube installation cushion rubber, guaranteeing
The problem for avoiding absorption of the sealing-plug of pure rubber to organic gas excessive while testing composite pipe tightness.For there is optical fibre channel
With the glass capsulation plug of the positioning pipe access of bearing apparatus, glue is answered to seal to guarantee airtightness by the gap after optical fiber.
In addition, under certain ad hoc environment, such as chemical plant using area, in order to which save the cost can not be in each monitoring point
There is provided air pump or air delivery device, and monitoring point is often under open-air atmosphere, influence vulnerable to weather (such as will receive rainwater influence or
The disturbance of person's convective wind), therefore the testing tube with vent branch is adapted as the testing tube with venthole, concrete operations are as follows: taking
Disappear vent branch, and opens up intensive venthole away from the bottom of the tube of two sides at the 50mm of both ends in testing tube.At this point, since venthole is opened
It is located at test bottom of the tube, even if being still able to maintain in device and not soaked by rainwater under rainy day environment, optical fiber support stabilizer can
To reduce disturbance of the convective wind to optical fiber, at the same the intensive venthole of bottom may make in testing tube gaseous species and its concentration with
Ambient atmos are consistent.Therefore under the conditions of no pressure, this device can still be perfectly suitable for field condition by fine tuning,
As shown in Figure 6.
Embodiment 1
1. being coated with the optical fiber grating sensing element 1 of air-sensitive polymeric membrane
A small amount of polyamic acid solution is taken to instill in Teflon mould using dropper, the optical fiber for the use of diameter being 125 μm
Grating, held by both hands grid region two sides slowly immerse grid region section in polyamic acid solution, when grid region is completely immersed in solution,
It is rotating slowly optical fiber, so that grid region surface is entirely and uniformly adhered to polyamic acid solution, delays in grid region in the solution after 180s
It slowly lifts out, is put into baking oven, set oven temperature as 90 DEG C, imidizate simultaneously dries 300s, according to above-mentioned infiltration-rotation-
Lifting-baking step in triplicate, prevents the influence due to surface tension and leads to not form complete film on grid region surface
Structure.
2. the basic structure of testing tube 4 and vent branch 5,7
Its essential structure is four-way pipe, and the plan view of testing tube 4 and vent branch 5,7 is as shown in fig. 7, customize it as quartz
Glass structure.The horizontal overall length 450mm of pipe, testing tube (horizontal tube) internal diameter 15mm, outer diameter 19mm, quartz glass wall thickness 2mm.Air inlet
Mouthful: the tube center distance left end 20mm of air inlet 1, pipe range 40mm, internal diameter 6mm, outer diameter 9mm, wall thickness 1.5mm.In the pipe of air inlet 2
The heart is away from left end 50mm, pipe range 60mm, internal diameter 5mm, outer diameter 8mm, wall thickness 1.5mm.A, b exhaust outlet pipe range 50mm, internal diameter 5mm, outside
Diameter 8mm, wall thickness 1.5mm, a are vented 4 right end 75mm, b exhaust 4 right end 50mm of tube center distance testing tube of tube center distance testing tube.
3. fiber grating support stabilizer 2
Its essential structure is cylindrical body, customizes it as quartz glass structure, parent body diameter 14.5mm, top cuts out two
The small column of a diameter 7mm, small column center of circle horizontal direction distance parent cylinder center of circle 3.5mm, vertical direction is away from parent cylinder
Center of circle 3.0mm, center cut out the small column of diameter 1.2mm as optical fibre channel 2-1, and the center of circle is located above parent cylinder
At 0.5mm.The small column of diameter 1mm is cut out as 3 access 2-2 of bearing apparatus positioning pipe at 2mm below optical fibre channel.At top three
The radius of corner 0.2mm at edge.Integral planar stretches 20mm and forms fiber grating support stabilizer 2.
4. the positioning pipe 3 of bearing apparatus
Its essential structure is very thin quartz glass tube, and customizing it is quartz glass structure, diameter 2mm, length 300mm.
All fiber grating support stabilizers 2 in testing tube, end pass through the glass capsulation plug 6 for having 2 access of support stabilizer, and
It is fixed by gluing and guarantees air-tightness.
5. the testing tube glass capsulation plug 6 containing cushion rubber
Its material is quartz glass, and side is solid glass sealing-plug 6, and side is to have optical fibre channel and have determining for bearing apparatus
The glass capsulation plug 6 of position pipe access.After the positioning pipe 3 of optical fiber and bearing apparatus is installed, carries out glue envelope and guarantee in testing tube
Air-tightness.
6. experimental procedure
The air inlet pipe of toluene standard gas bottle and quartz glass tube, fiber grating support stabilizer 2 are connected by flowmeter
Its position in pipe should first be made a reservation for before being packed into testing tube 4, control fiber grating support stabilizer 2 and grid region away from
It at a distance from 4 end of testing tube, is fixed completely with the good simultaneously gluing of the string of bearing apparatus positioning pipe 3 from fiber grating support stabilizer 2
Afterwards, required fiber grating support stabilizer 2 is put into testing tube 4 by property again, then by the light of compound polyimide film
Fine grating gas-sensitive sensing element 1 is put into the optical fibre channel of fiber grating support stabilizer 2, and in 4 two sides of testing tube, installation contains glue
The testing tube glass capsulation plug 6 of circle draws optical fiber from 4 glass stopper optical fibre channel 2-1 of testing tube, and bearing apparatus positioning pipe is in support
3 access 2-2 of device positioning pipe is drawn, and remaining gap carries out glue envelope and guarantees air-tightness.Optical fiber is connected on (FBG) demodulator by wire jumper,
(FBG) demodulator is connect with computer processor simultaneously and is configured；Carry out 7 harmless treatment of exhaust of the exhaust pipe of quartz glass tube.
Gas cylinder valve and flowmeter are opened, 500ppm toluene calibrating gas 300s is passed through in testing tube, valve is closed and exists
600s is kept in the state that device is closed.The attainable maximum pressure of 1 institute of optical fiber grating sensing element known to after four circulations
Strain is about 22 μ ε, and repeatability is preferable, while curve noise-free signal, data are intuitive and with a high credibility.(as shown in Figure 8).
Embodiment 2
The On-Line Monitor Device of Gas of fiber grating gas sensing is substantially the same manner as Example 1, the difference is that band
The testing tube 4 of vent branch 5,7 is adapted as the testing tube 4 with venthole, and concrete operations are as follows: cancellation vent branch 5,7, and
Testing tube 4 opens up intensive venthole 8 away from the bottom of the tube of two sides at the 50mm of both ends, as shown in Figure 6.At this point, since venthole 8 opens up
In bottom, even if being still able to maintain in device and not soaked by rainwater under rainy day environment；Since to be in optical fiber support steady for venthole
Determine between device 2 and sealing-plug 6, optical fiber support stabilizer 2 can reduce disturbance of the convective wind to optical fiber, and convective wind is avoided to act on
Optical fiber is radially；The intensive venthole 8 of bottom may make that gaseous species and its concentration and ambient atmos are kept in testing tube 4 simultaneously
Unanimously.Therefore under the conditions of no pressure, described device can still be perfectly suitable for actual field condition after the repacking,
Such as the using areas such as chemical plant.Solve under above situation, in order to save the cost can not each monitoring point provide air pump or
Air delivery device, and monitoring point is often under open-air atmosphere, influence vulnerable to weather (such as influenced by rainwater or convective wind is disturbed
It is dynamic) the problem of.
Application method is the same as embodiment 1.
Embodiment 3
A kind of On-Line Monitor Device of Gas of fiber grating gas sensing, comprising: optical fiber grating sensing element 1, test
Pipe 4, fiber grating support stabilizer 2, positioning pipe 3, sealing-plug 6, fiber Bragg grating (FBG) demodulator, computer processor；The test
The both ends of pipe 4 are sealed by sealing-plug 6, and fiber grating support stabilizer 2, the fiber grating support are provided in testing tube 4
Stabilizer 2 is provided with through-hole 2-1, the 2-2 passed through for optical fiber grating sensing element 1 and positioning pipe 3, and the positioning pipe 3 passes through light
Fine grating support stabilizer 2, and be fixedly connected with the sealing-plug of at least one end 6；
The optical fiber grating sensing element 1 has the response characteristic of axial strain, at fiber Bragg grating (FBG) demodulator, computer
Reason device is sequentially connected.
Its application method is the same as embodiment 1.
Finally it should be noted that the foregoing is only a preferred embodiment of the present invention, it is not limited to this hair
It is bright, although the present invention is described in detail referring to the foregoing embodiments, for those skilled in the art, still
It can modify to technical solution documented by previous embodiment, or part is equivalently replaced.It is all in this hair
Within bright spirit and principle, any modification, equivalent replacement, improvement and so on should be included in protection scope of the present invention
Within.Above-mentioned, although the foregoing specific embodiments of the present invention is described with reference to the accompanying drawings, not to the scope of the present invention
Limitation, those skilled in the art should understand that, based on the technical solutions of the present invention, those skilled in the art are not required to
Make the creative labor the various modifications or changes that can be made still within protection scope of the present invention.
Claims (7)
1. a kind of On-Line Monitor Device of Gas of fiber grating gas sensing characterized by comprising optical fiber grating sensing member
Part, testing tube, fiber grating support stabilizer, positioning pipe, sealing-plug, fiber Bragg grating (FBG) demodulator, computer processor；The survey
The both ends of test tube are sealed by sealing-plug, are provided with fiber grating support stabilizer in testing tube, the fiber grating support is steady
Determine device and be provided with the through-hole passed through for optical fiber grating sensing element and positioning pipe, the positioning pipe is stablized across fiber grating support
Device, and be fixedly connected with the sealing-plug of at least one end；
The optical fiber grating sensing element has the response characteristic of axial strain, with fiber Bragg grating (FBG) demodulator, computer processor
It is sequentially connected；
The fiber grating support stabilizer is that there are two the cylindrical bodies of circular hole for setting in axial direction；
Described two circular holes are tangent, and the shaft section about cylindrical body is symmetrical；
For being located at two circular hole point of contacts for the through-hole that fiber grating and positioning pipe pass through on the fiber grating support stabilizer
Lower section, and the through-hole that passes through of positioning pipe is located at the lower section for the through-hole that fiber grating passes through.
2. device as described in claim 1, which is characterized in that the testing tube, fiber grating support stabilizer, positioning pipe,
Sealing-plug is quartz glass.
3. device as described in claim 1, which is characterized in that the both ends of the testing tube be respectively arranged with multiple air inlet pipe,
Exhaust pipe.
4. device as described in claim 1, which is characterized in that fiber grating support stabilizer diameter is less than test bore
0.5-1.5mm；
Or the optical fiber grating sensing element is the optical fiber grating sensing element coated with air-sensitive polymeric membrane；
Or the glass wall thickness of the testing tube, air inlet pipe and exhaust pipe is not less than 2mm；
Or air inlet bore is not less than 5mm.
5. device as claimed in claim 3, which is characterized in that the air inlet pipe or exhaust pipe and testing tube left and right ends away from
From for 40-50mm；
Or the air inlet pipe is not less than 30mm with air inlet pipe or the distance between exhaust pipe and exhaust pipe.
6. a kind of On-Line Monitor Device of Gas of modular fiber optic grating gas sensing, which is characterized in that by claim 1-5
The testing tube of described in any item devices is connected, and same root optical fiber successively passes through above-mentioned testing tube.
7. a kind of gas on-line monitoring method of fiber grating gas sensing, which is characterized in that any using claim 1-6
Device described in monitors gas on-line.
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| US8542955B2 (en) * | 2010-10-28 | 2013-09-24 | General Electric Company | Gas detection system incorporating fiber gas sensors having fiber bragg gratings |
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