Distributed oil leakage monitoring optical cable structure suitable for direct burial and net hanging installation

Abstract

The utility model discloses a distributed oil leakage monitoring optical cable structure suitable for direct burial and net hanging installation, which comprises a braided sheath layer, a spiral armor layer and a distributed optical fiber oil sensing cable core, the spiral armor layer is sleeved on the distributed optical fiber oil sensing cable core, the braided sheath layer is sleeved on the spiral armor layer, and the braided sheath layer is sleeved on the spiral armor layer. A gap is formed between the spiral armoring layer and the distributed optical fiber oil sensing cable core, the spiral armoring layer is arranged on the distributed optical fiber oil sensing cable core in a sleeving manner, the braided sheath layer is arranged on the spiral armoring layer in a sleeving manner, and a gap is formed between the spiral armoring layer and the distributed optical fiber oil sensing cable core. The gap ensures that even if the oil-sensitive optical cable is in a buried state, the distributed optical fiber oil-sensitive cable core in the oil-sensitive optical cable always has an oil absorption swelling space, even if the oil-sensitive optical cable is completely wrapped, when the oil-sensitive optical cable is in contact with leaked oil, swelling strain can still be generated, and optical fiber sensing is always effective.

Description

Technical Field

[0001] This utility model relates to the field of distributed optical fiber sensing technology, specifically to a distributed oil leak monitoring optical cable structure suitable for direct burial and grid-mounted installation. Background Technology

[0002] In the petrochemical industry, the leakage and handling of oil pipelines are critical issues affecting safety and economic efficiency. Rapid and effective operational intervention at pipeline leak points is a fundamental requirement of any safety operation and maintenance management system. Currently, relevant technologies for quickly detecting and locating leaks include video surveillance, gas sensors, oil-sensing cables, and manual inspections. However, these traditional technologies all have drawbacks, such as video surveillance being affected by weather, low sensitivity of gas sensors, high cost and safety of oil-sensing cable systems, and blind spots in manual inspections.

[0003] For example, patent CN202311270674.9 provides an oil-sensing optical cable based on a grating array and an oil spill monitoring system, including a grating array sensing fiber; an elastic layer wrapped around the grating array sensing fiber; and an oil-absorbing and swelling sheath wrapped around the elastic layer. The oil-absorbing and swelling sheath is used to deform upon contact with oil. In use, the grating array-based oil-sensing optical cable and the oil pipeline can be installed parallel to each other. When a leak occurs at any point in the pipeline, oil soaks into the oil-sensing optical cable laid along the pipeline. The oil-absorbing and swelling sheath absorbs and swells, causing the internal grating array sensing fiber to bend, thereby generating a grating wavelength drift, which enables the location of the leak. The elastic layer provides the entire grating array-based oil-sensing optical cable with a certain degree of compressive strength and elasticity for restoring its original position. Compared with the prior art, this invention is less affected by weather, has high fiber optic sensing sensitivity, and features a simple structure, low cost, and no blind spots, making it highly practical.

[0004] However, this solution has a problem: The working principle involves an outer sheath of the optical cable made of an oil-absorbing and swelling material. When it comes into contact with oil, it swells and deforms, providing axial driving stress to the inner sensing fiber. This causes a shift in the center wavelength of the grating, which is detected by the demodulation system and triggers an alarm signal. In reality, most oil pipelines are buried underground, requiring the oil-sensing optical cable to be laid in the same trench to function as a monitoring and alarm system. However, once the oil-sensing optical cable is buried in the soil structure, the coating completely encloses it. The compressive force from this encapsulation makes it difficult for the cable to generate effective swelling strain when it comes into contact with leaking oil, ultimately leading to sensor failure. Utility Model Content

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a distributed oil leak monitoring optical cable structure suitable for direct burial and grid-mounted installation, thereby solving the technical problems of insufficient swelling strain and sensor failure in the prior art.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0007] This utility model provides a distributed optical cable structure for oil leak monitoring suitable for direct burial and grid installation, comprising:

[0008] The cable comprises a braided sheath layer, a spiral armor layer, and a distributed optical fiber oil-sensitive cable core. The spiral armor layer is fitted over the distributed optical fiber oil-sensitive cable core, and the braided sheath layer is fitted over the spiral armor layer. A gap exists between the spiral armor layer and the distributed optical fiber oil-sensitive cable core.

[0009] In some embodiments, the distributed optical fiber oil-sensing cable core includes an oil-sensing sheath, a spiral armor elastic layer, an optical fiber tight-buffered layer, and a sensing optical fiber. The optical fiber tight-buffered layer is sleeved on the sensing optical fiber, the spiral armor elastic layer is sleeved on the optical fiber tight-buffered layer, the oil-sensing sheath is sleeved on the spiral armor elastic layer and is tightly fitted to the outer surface of the spiral armor elastic layer, and the oil-sensing sheath is partially embedded in the pitch gap of the spiral armor elastic layer.

[0010] In some embodiments, the space between the spiral armor elastic layer and the optical fiber tight sleeve is filled with fixing adhesive dots to fix the sensing optical fiber to the center of the spiral armor elastic layer and to put the sensing optical fiber in a pre-tensioned state.

[0011] In some embodiments, the spacing between the fixed adhesive dots is equal to the grating spacing of the sensing optical fiber.

[0012] In some embodiments, the spiral armor elastic layer is made of stainless steel or a high-modulus polymer.

[0013] In some embodiments, the oil-sensitive sheath is made of an oil-absorbing and swelling polymer material.

[0014] In some embodiments, the distributed optical fiber oil-sensing core includes an oil-sensing jacket, a coupling agent, an optical fiber tight-closing sleeve, and a distributed sensing optical fiber. The optical fiber tight-closing sleeve is fitted onto the distributed sensing optical fiber, the oil-sensing jacket is fitted onto the optical fiber tight-closing sleeve, and the coupling agent fills the gap between the oil-sensing jacket and the optical fiber tight-closing sleeve.

[0015] In some embodiments, the coupling agent is an anaerobic, one-component adhesive.

[0016] In some embodiments, the woven sheath layer is made of polymeric synthetic fibers.

[0017] In some embodiments, the spiral armor layer is made of stainless steel.

[0018] Compared with existing technologies, the distributed oil leak monitoring optical cable structure provided by this utility model, suitable for direct burial and grid-mounted installation, includes a braided sheath layer, a spiral armor layer, and a distributed optical fiber oil-sensing cable core. The spiral armor layer is fitted over the distributed optical fiber oil-sensing cable core, and the braided sheath layer is fitted over the spiral armor layer. A gap exists between the spiral armor layer and the distributed optical fiber oil-sensing cable core. This gap ensures that even when the oil-sensing optical cable is buried, the distributed optical fiber oil-sensing cable core inside always has space for oil absorption and swelling. Even if the oil-sensing optical cable is completely encased, it can still generate swelling strain when it comes into contact with leaked oil, ensuring that the optical fiber sensing remains effective.

[0019] The above description is merely an overview of the technical solution of this utility model. To better understand the technical means of this utility model and to enable its implementation according to the description, the preferred embodiments of this utility model are described in detail below with reference to the accompanying drawings. Specific implementation methods of this utility model are given in detail in the following embodiments and their accompanying drawings. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the distributed oil leak monitoring optical cable provided by this utility model, which is suitable for direct burial and grid-mounted installation.

[0021] Figure 2 This is a schematic cross-sectional view of a distributed optical fiber oil-sensing cable core in one embodiment:

[0022] Figure 3 This is a schematic cross-sectional view of the distributed optical fiber oil-sensing cable core in another embodiment.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1- Braided sheath layer, 2- Spiral armor layer, 3- Distributed optical fiber oil-sensitive cable core, 31- Oil-sensitive sheath, 32- Spiral armor elastic layer, 33- Optical fiber tight-buffer layer, 34- Sensing optical fiber, 35- Fixing adhesive dots, 36- Oil-sensitive outer jacket, 37- Coupling agent, 38- Optical fiber tight-buffer, 39- Distributed sensing optical fiber. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0026] Please see Figure 1 This utility model provides a distributed oil leak monitoring optical cable structure suitable for direct burial and grid-mounted installation, including a braided sheath layer 1, a spiral armor layer 2, and a distributed optical fiber oil-sensing cable core 3. The spiral armor layer 2 is sleeved on the distributed optical fiber oil-sensing cable core 3, and the braided sheath layer 1 is sleeved on the spiral armor layer 2. There is a gap between the spiral armor layer 2 and the distributed optical fiber oil-sensing cable core 3.

[0027] In this invention, the spiral armor layer 2 is fitted over the distributed optical fiber oil-sensing cable core 3, and the braided sheath layer 1 is fitted over the spiral armor layer 2. A gap exists between the spiral armor layer 2 and the distributed optical fiber oil-sensing cable core 3. This gap ensures that even when the oil-sensing optical cable is buried, the distributed optical fiber oil-sensing cable core 3 inside always has space to absorb oil and swell. Even if the oil-sensing optical cable is completely wrapped, it can still generate swelling strain when it comes into contact with leaked oil, ensuring that the optical fiber sensing remains effective.

[0028] Specifically, the braided sheath layer 1 is made of high-molecular synthetic fibers. High-molecular synthetic fibers possess excellent wear resistance, corrosion resistance, tensile strength, high and low temperature stability, and extremely low moisture absorption, exhibiting excellent adaptability for underground burial. A well-designed braiding density ensures oil permeability. The braided sheath layer 1 provides protective sheathing for the entire sensing optical cable. Its tensile strength depends on the material strength, wire diameter, and braiding method of the synthetic fibers, and can be designed according to different installation environments. Generally, for applications requiring higher tensile strength, higher-strength synthetic fibers with thicker wire diameters and a tighter braiding method are selected, and vice versa.

[0029] The spiral armor layer 2 is made of stainless steel to ensure the sensor cable's corrosion resistance during burial. The metal spiral armor structure has good resistance to lateral pressure, resisting the compressive force of the soil during installation; the spiral armor is an open structure, allowing for good oil permeability. The mechanical properties of the spiral armor layer 2 can be adjusted by changing its outer diameter D2, cross-sectional width b, cross-sectional thickness t, and pitch P: generally, a larger outer diameter D2 results in weaker compressive strength; a larger cross-sectional width b results in stronger compressive strength but decreased bending performance; a larger cross-sectional thickness t results in stronger compressive strength; and a larger pitch P results in weaker compressive strength and decreased bending performance.

[0030] The distributed optical fiber sensing cable core 3 has two main sensing principles: distributed optical fiber sensing based on the Brillouin signal demodulation principle and grating array optical fiber sensing based on the grating wavelength demodulation principle. This utility model combines these two demodulation principles and provides two distributed optical fiber sensing cable core structures, as shown in the attached figures. Figure 2 Appendix Figure 3 As shown.

[0031] Appendix Figure 2 In this design, the distributed optical fiber oil-sensing core 3 includes an oil-sensing sheath 31, a spiral armor elastic layer 32, an optical fiber tight-buffered layer 33, and a sensing optical fiber 34. The optical fiber tight-buffered layer 33 is sleeved on the sensing optical fiber 34, the spiral armor elastic layer 32 is sleeved on the optical fiber tight-buffered layer 33, and the oil-sensing sheath 31 is sleeved on the spiral armor elastic layer 32 and tightly adheres to the outer surface of the spiral armor elastic layer 32. The oil-sensing sheath 31 is partially embedded in the pitch gap of the spiral armor elastic layer 32. The purpose of this design is to enhance the coupling between the two, so that the oil absorption and swelling strain of the oil-sensing sheath 31 can be quickly and effectively transmitted to the spiral armor elastic layer 32 and its internal sensing elements.

[0032] Furthermore, the oil-sensitive sheath 31 is made of oil-absorbing and swelling polymer materials, such as TPE, TPV, and SBS. When the oil-sensitive sheath 31 comes into contact with petrochemical oil, it will rapidly expand in volume. The volume expansion ratio will vary for different petrochemical oils, but it is generally required to be greater than 50%. The oil-sensitive sheath 1 is formed by extrusion or extrusion sintering and is tightly attached to the surface of the spiral armor elastic layer 2.

[0033] Furthermore, the spiral armor elastic layer 32 is made of stainless steel or high-modulus polymer and has a certain elastic stiffness.

[0034] Furthermore, the optical fiber tight cladding layer 33 is made of polymer materials, such as Hytrel, PE, PVC, PA, etc.; the optical fiber tight cladding layer 33 is used to protect the sensing optical fiber 34, improve its mechanical strength, and further suppress the growth of internal cracks in the sensing optical fiber 34 to ensure its service life.

[0035] Furthermore, fixing adhesive dots 35 are spaced between the spiral armor elastic layer 32 and the optical fiber tight-buffered layer 33. The function of the fixing adhesive dots 35 is to fix the sensing optical fiber 34 to the center of the spiral armor elastic layer 32 and to keep the sensing optical fiber 34 in a pre-tensioned state.

[0036] Furthermore, for the grating array sensing fiber, the spacing of the fixing adhesive dots 35 is equal to the grating spacing of the sensing fiber 34. Since the sensing fiber 34 is in a pre-tightened state, any strain change occurring in any segment between adjacent fixing adhesive dots 35 can be detected by the gratings between the fixing adhesive dots 35, thus realizing the distributed continuous sensing function of the grating array sensing fiber. For ordinary communication fiber based on the Brillouin signal demodulation principle, the signal from a single point on the sensing fiber can be amplified to the area fixed by the fixing adhesive dots 35, resulting in enhanced spatial signal amplification and improved sensing sensitivity.

[0037] Appendix Figure 3 The present invention provides a distributed optical fiber oil-sensitive cable core 3 specifically designed based on the Brillouin signal demodulation principle. The distributed optical fiber oil-sensitive cable core 3 includes an oil-sensitive outer jacket 36, a coupling agent 37a, an optical fiber tight-closing sleeve 38, and a distributed sensing optical fiber 39. The optical fiber tight-closing sleeve 38 is sleeved on the distributed sensing optical fiber 39, the oil-sensitive outer jacket 36 is sleeved on the optical fiber tight-closing sleeve 38, and the coupling agent 37a fills the gap between the oil-sensitive outer jacket 36 and the optical fiber tight-closing sleeve 38.

[0038] The coupling agent 37a is an anaerobic, single-component adhesive. Its function is to enhance the bonding strength between the oil-sensitive jacket 36 and the optical fiber tight-fitting sleeve 38, so that when the oil-sensitive jacket 36 absorbs oil and expands, its strain energy is effectively transferred to the distributed sensing optical fiber 39 inside the optical fiber tight-fitting sleeve 38, thereby improving the sensing sensitivity.

[0039] The beneficial effects of this utility model are as follows: The distributed oil leak monitoring optical cable structure suitable for direct burial and grid installation provided by this utility model includes a braided sheath layer, a spiral armor layer, and a distributed optical fiber oil-sensing cable core. The spiral armor layer is fitted over the distributed optical fiber oil-sensing cable core, and the braided sheath layer is fitted over the spiral armor layer. A gap exists between the spiral armor layer and the distributed optical fiber oil-sensing cable core. This gap ensures that even when the oil-sensing optical cable is buried, the distributed optical fiber oil-sensing cable core inside always has space for oil absorption and swelling. Even if the oil-sensing optical cable is completely wrapped, it can still generate swelling strain when it comes into contact with leaked oil, ensuring that the optical fiber sensing remains effective.

[0040] The specific embodiments of this utility model described above do not constitute a limitation on the scope of protection of this utility model. Any other corresponding changes and modifications made based on the technical concept of this utility model should be included within the scope of protection of the claims of this utility model.

Claims

1. A distributed optical cable structure for oil leak monitoring suitable for direct burial and grid-mounted installation, characterized in that, It includes: The cable comprises a braided sheath layer, a spiral armor layer, and a distributed optical fiber oil-sensitive core. The spiral armor layer is fitted onto the distributed optical fiber oil-sensitive core, and the braided sheath layer is fitted onto the spiral armor layer. A gap exists between the spiral armor layer and the distributed optical fiber oil-sensitive core. The distributed optical fiber oil-sensitive core includes an oil-sensitive sheath, a spiral armor elastic layer, an optical fiber tight-buffered layer, and a sensing optical fiber. The optical fiber tight-buffered layer is fitted onto the sensing optical fiber, the spiral armor elastic layer is fitted onto the optical fiber tight-buffered layer, and the oil-sensitive sheath is fitted onto the spiral armor elastic layer and tightly adheres to the outer surface of the spiral armor elastic layer. The oil-sensitive sheath is partially embedded in the pitch gap of the spiral armor elastic layer.

2. The distributed oil leak monitoring optical cable structure applicable to direct burial and grid installation as described in claim 1, characterized in that, The space between the spiral armor elastic layer and the optical fiber tight sleeve is filled with fixing adhesive dots, which are used to fix the sensing optical fiber to the center of the spiral armor elastic layer and to put the sensing optical fiber in a pre-tensioned state.

3. The distributed oil leak monitoring optical cable structure applicable to direct burial and grid installation as described in claim 2, characterized in that, The spacing between the fixed adhesive dots is equal to the grating spacing of the sensing optical fiber.

4. The distributed oil leak monitoring optical cable structure applicable to direct burial and grid installation as described in claim 3, characterized in that, The spiral armor elastic layer is made of stainless steel or a high-modulus polymer.

5. The distributed oil leak monitoring optical cable structure applicable to direct burial and grid installation as described in claim 2, characterized in that, The oil-sensitive sheath is made of an oil-absorbing and swelling polymer material.

6. The distributed oil leak monitoring optical cable structure applicable to direct burial and grid installation as described in claim 1, characterized in that, The distributed optical fiber oil-sensing cable core includes an oil-sensing outer jacket, a coupling agent, an optical fiber tight-closing sleeve, and a distributed sensing optical fiber. The optical fiber tight-closing sleeve is fitted onto the distributed sensing optical fiber, the oil-sensing outer jacket is fitted onto the optical fiber tight-closing sleeve, and the coupling agent fills the gap between the oil-sensing outer jacket and the optical fiber tight-closing sleeve.

7. The distributed oil leak monitoring optical cable structure applicable to direct burial and grid installation as described in claim 6, characterized in that, The coupling agent is an anaerobic, single-component adhesive.

8. The distributed oil leak monitoring optical cable structure applicable to direct burial and grid installation as described in claim 1, characterized in that, The woven sheath layer is made of high-molecular synthetic fibers.

9. The distributed oil leak monitoring optical cable structure applicable to direct burial and grid-mounted installation as described in claim 1, characterized in that, The spiral armor layer is made of stainless steel.

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