JP2009002676A - Optical fiber sensor cable and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber sensor cable which facilitates manufacturing and constructions with piping etc. , and stably senses distributional stains caused by wall reductions and shape changes in the piping under a high-temperature environment. <P>SOLUTION: The optical fiber sensor cable is equipped with: an elongated sensor substrate; at least one strain detecting fiber fixed to one surface of the sensor substrate along the longitudinal direction; and an insulating film disposed on the surface opposite to the one surface of the sensor substrate along the longitudinal direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention uses a high-resolution BOTDA (Brillouin Optical Time Domain Analysis) to shift the frequency of Brillouin scattered light by using a high resolution BOTDA (Brillouin Optical Time Domain Analysis). The present invention relates to an optical fiber sensor cable that is measured from a quantity and applied to prevent a leakage accident due to a pipe rupture.

As prior art considered to be related to the present invention, Patent Literatures 1 to 7 and Non-Patent Literature 1 are cited.
Patent Document 1 discloses a structure in which a metal tape is used for an optical fiber temperature sensor. The metal tape allows the sensor to be laid along the shape of the temperature object and plays a role in protecting the fiber. Further, a synthetic rubber is used for the adhesive layer with the temperature object.

  Patent Document 2 discloses a strain sensor having a structure in which an FBG (Fiber Bragg Grating) is fixed on a stainless metal substrate with a room temperature curing type two-component mixed epoxy adhesive.

  Patent Document 3 discloses an optical fiber sensor using solder because it is necessary to bond the fiber grating portion on the substrate more quickly and firmly than the adhesive. Further, it is disclosed that a polyimide coating is applied to protect the grating portion from the heat of the solder.

  Patent Document 4 discloses a strain amount measuring apparatus for a structure in which a metal having a high elastic modulus, metal plating, or polyimide is coated on an optical fiber in order to reliably transmit the strain generated in the structure to the optical fiber. . In this device, aluminum or stainless steel with good corrosion resistance is used for the gauge base.

  In Patent Document 5, the fiber grating portion is fixed to a base material composed of a low thermal expansion material and a high thermal expansion material, and the length of each thermal expansion material is adjusted, so that the temperature coefficient is equal to the temperature coefficient of the structure. A structure of a sensor that can have a coefficient is disclosed.

  Patent Document 6 discloses a sensor in which the carrier (gauge base) is made of metal or the carrier (gauge base) is made of polyimide for preventing galvanic corrosion.

  In Patent Document 7, a fiber grating portion is fixed to a base material made of a low thermal expansion agent and a high thermal expansion agent, and the temperature coefficient equal to the temperature coefficient of the structure is adjusted by adjusting the length of each thermal expansion material. A structure capable of having the structure is disclosed.

Non-Patent Document 1 discloses a heat-resistant strain gauge using polyimide as an adhesive.
Japanese Patent No. 2545127 Japanese Patent Laid-Open No. 11-173820 JP 2001-221615 A JP 2003-254723 A JP 2003-14491 A US Pat. No. 6,668,105 US Pat. No. 6,044,189 http://www.kyowa-ei.co.jp

However, the above-described prior art has the following problems.
In the sensor disclosed in Patent Document 1, the heat resistance temperature of the synthetic rubber system used for the adhesive layer is at most 130 ° C. Therefore, when applied to a higher temperature environment than this, the reliability of adhesion with the measurement object cannot be guaranteed. . Further, since the rubber of the adhesive layer is soft and sensitive to the unevenness of the laying surface, there is a problem of causing an increase in fiber bend loss.

  The room temperature curing type two-component mixed epoxy resin used as an adhesive in Patent Document 2 requires a curing time of about 0.5 to 48 hours depending on the blending and temperature. Complete curing generally requires a curing time of 4 to 6 days. Moreover, since the viscosity is high, it is difficult to apply uniformly, and it is very difficult to fix on the substrate without bending the fiber. When the fiber is fixed while being bent, there is a possibility that a loss increase that exceeds the dynamic range of the strain measuring device may occur, and there is a high possibility that the strain measurement becomes impossible. Moreover, the heat-resistant temperature of the room temperature curing type two-component mixed epoxy adhesive is about 200 ° C., and there is a problem that it cannot be applied to a place where the environmental temperature reaches 200 to 300 ° C. or more, such as a power plant.

  Since the optical fiber sensor disclosed in Patent Document 3 has a structure in which only the fiber grating portion is coated with polyimide, heat resistance cannot be guaranteed over the entire length of the fiber. In a distributed optical fiber sensor using Brillouin scattering, it is necessary to detect strain in the longitudinal direction, and the entire length of the installed sensor is exposed to a high temperature environment. However, the conventional technology of Patent Document 3 cannot guarantee the desired heat resistance over the entire length. In addition, when only the selected portion is coated, it is necessary to stop the line each time, and the manufacturing cost is higher than when batch coating is performed in the longitudinal direction.

  In the prior art of Patent Document 4, the main purpose is to surely transmit the strain generated in the structure to the optical fiber, and polyimide is coated on the optical fiber because of its high elastic modulus. This does not consider heat resistance. Also, aluminum or stainless steel with good corrosion resistance is used for the gauge base material, but if the gauge base material and the structure are dissimilar metals, either the sensor substrate or the structure will be electrically base due to galvanic corrosion. Rust is generated in the direction, and the sensor is peeled from the structure, which may reduce the strain detection sensitivity.

  In the prior art of Patent Document 5, when the low thermal expansion body that comes into contact with the structure and the structure are dissimilar metals, rust occurs on the base material or the structure that is electrically base due to galvanic corrosion, When the sensor is peeled from the structure, the strain detection sensitivity may be lowered.

  In the prior art of Patent Document 6, it is described that the carrier can be made of polyimide, but polyimide is softer than metal and easily affected by unevenness on the surface of the structure. When affected by irregularities, the fiber fixed on the base is bent, and there is a high possibility that the loss will increase.

  In Patent Document 7, when a low thermal expansion material that comes into contact with a structure and the structure are dissimilar metals, galvanic corrosion causes rust to occur on the base material or the structure that is electrically base, and from the structure. There is a possibility that the strain detection sensitivity is lowered by peeling the sensor.

  The measurement using the strain gauge disclosed in Non-Patent Document 1 requires one strain gauge per measurement point. In order to measure the strain applied to the structure as a whole, a huge number of strain gauges are required. Therefore, it is difficult to measure the entire facility substantially.

Further, in the conventional heat-resistant optical fiber sensor cable shown in FIG. 1, there is a problem that a great deal of time and cost are required for the attachment work. The conventional heat-resistant optical fiber sensor cable shown in FIG. 1 has a heat-resistant optical fiber core wire 1 formed by coating an optical fiber with a heat-resistant resin coating on a sensor base 2 made of a metal tape, and a heat-resistant adhesive 3. It has a structure that is fixed along the longitudinal direction with a cable.
FIG. 2 shows a schematic layout of a conventional sensor cable. The laying procedure is as follows, and roughly six steps are required before the sensor cable is laid.
(1) Application of the heat-resistant adhesive 6 to the pipe 7.
(2) Affixing the insulating film 5.
(3) Heat curing of the heat resistant adhesive 6.
(4) Application of the heat-resistant adhesive 4 on the insulating film 5.
(5) Affixing the sensor.
(6) Heat curing of the heat resistant adhesive 4.

  Further, if the installation of the sensor in the latter half fails, it is necessary to start over from the film attachment in the previous process, which requires enormous installation time and cost.

  The present invention has been made in view of the above circumstances, is easy to manufacture and apply to piping and the like, and can stably detect strain caused by deformation and thinning of piping even in a high temperature environment in a distributed manner. An object is to provide a possible optical fiber sensor cable.

  In order to achieve the above object, the present invention provides a long sensor substrate, at least one strain detection fiber fixed along the longitudinal direction on one surface of the sensor substrate, and a sensor substrate. And an insulating film disposed along the longitudinal direction on the surface opposite to the one surface of the optical fiber sensor cable.

  In the optical fiber sensor cable of the present invention, it is preferable that the insulating film width is equal to or greater than the width of the sensor substrate.

  In the present invention, a long sensor substrate, at least one strain detection fiber, and an insulating film are arranged in order, and are sent to the curable resin liquid application part while applying necessary tension in advance. A method for producing an optical fiber sensor cable, comprising: applying an optical fiber sensor cable according to the present invention in one step by applying a curable resin liquid at an adhesive resin liquid application unit and curing the resin liquid. .

The optical fiber sensor cable of the present invention includes a long sensor substrate, at least one strain detection fiber fixed along the longitudinal direction on one surface of the sensor substrate, and the sensor substrate. Since it has a structure having an insulating film arranged along the longitudinal direction on one surface and the opposite surface, distortion caused by deformation of pipes, thinning, etc. can be stably applied in a high temperature environment. Can be detected.
The optical fiber sensor cable of the present invention fixes the fiber on the metal substrate over the longitudinal direction, thereby reducing the side pressure applied to the fiber due to the unevenness or expansion of the structure surface, suppressing an increase in fiber loss, The strain measuring instrument is no longer disturbed. When an insulating film itself, for example, a polyimide film is used as a base material, it is softer than metal and may be deformed by irregularities on the pipe surface. In that case, the fiber on the substrate is bent, or the influence of the side pressure due to the expansion of the pipe is very large, which increases the possibility of increasing the loss.
In addition, by applying a thermosetting heat-resistant adhesive as an adhesive to fix the fiber to the substrate, it is possible to achieve a complete effect in a line shape, and curing is completed in about 30 seconds to fix the length of 1 m. It is possible to make it.

  In the optical fiber sensor cable of the present invention, the material of the measurement object and the sensor base material are different by pasting an insulating film across the longitudinal direction on the surface opposite to the optical fiber installation surface with respect to the sensor base material. Even in this case, it is possible to prevent galvanic corrosion due to contact with different metals. Since fixing to the measurement object is performed using an adhesive suitable for the installation environment, an insulating effect can be obtained only with the adhesive, but a minimum coating pressure cannot be guaranteed in the longitudinal direction. Therefore, there is a possibility that the substrate and the measurement object are partially in contact with each other, and it is difficult to completely prevent galvanic corrosion. On the other hand, the insulating film used in the present invention has a substantially uniform thickness in the longitudinal direction, and a minimum insulation thickness is ensured in the longitudinal direction by arranging the insulating film on the sensor substrate in advance. It becomes possible. The thickness of the film can also be adjusted to several tens of μm according to the purpose.

In the optical fiber sensor cable of the present invention, it is possible to attach an insulating film to a sensor base material at the same time as making a sensor on a production line, so that the adhesive spent on film attachment and sensor attachment at the time of actual installation The curing time is halved, and the number of process steps can be halved.
Further, according to the manufacturing method of the present invention, the pretension is determined by the laying (winding) pitch, the pipe diameter, and the environmental temperature range in the pipe, and the cable is manufactured by applying the tension in advance at the time of manufacturing the cable, thereby disconnecting This makes it possible to add the intended durability (lifetime).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
3A and 3B show an embodiment of the optical fiber sensor cable of the present invention, in which FIG. 3A is a perspective view of a main part of the optical fiber sensor cable 10 and FIG. In FIG. 3, reference numeral 10 is an optical fiber sensor cable, 11 is a strain detection fiber made of a heat-resistant optical fiber core wire, 12 is a sensor substrate made of a metal tape, 13 is a heat-resistant adhesive made of polyimide, and 14 is polyimide. An insulating film made of a film.

  The optical fiber sensor cable 10 according to the present embodiment includes a long sensor base 12 and a strain detection fiber core fixed on one surface of the sensor base 12 by a heat-resistant adhesive 13 along the longitudinal direction. It is comprised from the wire 11 and the film 14 for insulation arrange | positioned along the longitudinal direction in the surface on the opposite side to said one surface of the sensor base material 12. FIG.

  As the sensor substrate 12, a tape-shaped substrate made of a metal having excellent heat resistance and high rigidity, for example, a tape-shaped substrate made of stainless steel is used.

  As the strain detection fiber core 11, an optical fiber core having a structure in which a bare optical fiber made of quartz glass is covered with one or more layers of heat-resistant coating made of heat-resistant resin such as polyimide is preferable. By using this type of core wire, it is possible to obtain the optical fiber sensor cable 10 that can be attached to the measurement object for a long time in a high temperature atmosphere. The strain detection fiber core wire 11 is not limited to one, and a plurality of strain detection fiber core wires may be used. When using a plurality of fibers, a plurality of single-core fibers or tape cores can be used.

  In the present embodiment, polyimide is used as the heat resistant adhesive 13. Also, a polyimide film is used for the insulating film 14. In this embodiment, the laying environment temperature range to which the optical fiber sensor cable 10 is to be applied is assumed to be room temperature to 300 ° C. Since the polyimide constituting the heat-resistant adhesive 13 and the insulating film 14 has a glass transition point of 310 ° C., almost no weight reduction is observed at 300 ° C., and the insulation property is very high. It has sufficient resistance even at temperature. Of course, the material need not be limited to polyimide as long as the material can be used in the temperature range of the installation environment. Regarding the fixing adhesive 13, in addition to polyimide, thermosetting heat-resistant epoxy, ceramic-based heat-resistant adhesives, and the like can be given. As for the insulating film 14, polyethersulfone, polyarylate (long-term heat-resistant temperature 150 ° C), polyetherimide (long-term heat-resistant temperature 170 ° C), polyamideimide, polyetheretherketone and wholly aromatic polyester (long-term heat-resistant temperature 230). ˜240 ° C.).

The optical fiber sensor cable 10 of the present embodiment has three steps as follows when it is attached on a measurement object such as a pipe, and the laying is easily completed in half of the conventional steps.
(1) Application of heat-resistant adhesive to piping.
(2) Affixing the optical fiber sensor cable 10 of the present embodiment.
(3) Heat curing of the adhesive.

  Further, even when the laying fails, since there is no pre-process such as affixing the film in the conventional method shown in FIG. 2, the laying can be performed without requiring extra time.

  As described above, the optical fiber sensor cable 10 according to the present embodiment is attached to a desired part of a structure such as a pipe by a simple attachment work, and when an abnormality occurs in the structure, distortion caused by deformation is caused. By measuring the frequency shift amount of the Brillouin scattered light due to, it is possible to accurately detect the amount of distortion. In addition, measurement with high resolution BOTDA enables measurement with 10 cm distance resolution by sampling at intervals of 5 cm, and can realize distributed measurement in the longitudinal direction. Therefore, by laying the optical fiber sensor cable 10, it is possible to monitor the entire facility collectively, and there is no need to lay a sensor for each measurement point.

FIG. 4 is a configuration diagram for explaining an example of a method for manufacturing an optical fiber sensor cable according to the present invention.
In this example, the long liquid sensor substrate 12, one or a plurality of strain detection fiber cores 11, and the insulating film 14 are arranged in order, and a resin liquid application unit 15 is applied while applying necessary tension in advance. And applying the polyimide resin solution at the resin solution application unit 15, and then passing through the heating furnace 16 to cure the resin solution, thereby obtaining the optical fiber sensor cable 10 shown in FIG. 3 in one step. It is a feature.

  According to the manufacturing method of the optical fiber sensor cable 10, by determining the pretension according to the laying (winding) pitch to the pipe, the pipe diameter, and the environmental temperature range, by pre-tensioning the cable when manufacturing the cable, It is possible to prevent disconnection and to add the intended durability (service life).

It is a principal part perspective view which shows an example of the conventional optical fiber sensor cable. It is a principal part assembly perspective view for demonstrating the attachment method of the conventional optical fiber sensor cable. An embodiment of the optical fiber sensor cable of the present invention is shown, (a) is a perspective view of the main part, and (b) is a cross-sectional view. It is a block diagram which shows an example of the manufacturing method of the optical fiber sensor cable of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Optical fiber sensor cable, 11 ... Strain detection fiber core wire, 12 ... Sensor base material, 13 ... Heat-resistant adhesive, 14 ... Insulating film, 15 ... Resin liquid application part, 16 ... Heating furnace, 17 ... Take-off Roller, 18 ... take-up roller.

Claims (3)

  An elongated sensor substrate, at least one strain detection fiber fixed along the longitudinal direction on one surface of the sensor substrate, and a surface opposite to the one surface of the sensor substrate; An optical fiber sensor cable comprising an insulating film disposed along a longitudinal direction.   The optical fiber sensor cable according to claim 1, wherein the insulating film width is equal to or greater than the width of the sensor substrate.   A long sensor substrate, at least one strain detection fiber, and an insulating film are arranged in order, and are sent to the curable resin liquid application part while applying necessary tension in advance, and the curable resin liquid application part 3. A method for producing an optical fiber sensor cable, comprising: applying a curable resin liquid and curing the resin liquid to obtain the optical fiber sensor cable according to claim 1 or 2 in one step.

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