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

Abstract

The invention 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] The present invention relates to the technical field of distributed optical fiber sensing, and in particular to a distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation. Background Art

[0002] In the field of petrochemicals, oil pipeline leakage and its treatment are important issues involving safe production and economic benefits. Rapid and effective operation and maintenance intervention at pipeline leakage points is a basic operational requirement of the safe operation and maintenance management system. At present, in terms of rapid monitoring and locating leakage points, relevant technical means include video monitoring, gas sensors, oil-sensing cables and manual inspections, but these traditional technologies have some drawbacks, such as video monitoring technology is affected by weather, gas sensors have low sensitivity, oil-sensing cable systems are expensive and unsafe, and manual inspections have blind spots.

[0003] For example, patent CN202311270674.9 provides an oil-sensing optical cable based on a grating array and an oil leak monitoring system, including a grating array sensing optical fiber; an elastic layer wrapped around the grating array sensing optical fiber; an oil-absorbing swelling sheath wrapped around the elastic layer, and the oil-absorbing swelling sheath is used to deform when in contact with oil. When in use, the oil-sensing optical cable based on the grating array and the oil pipeline can be arranged in parallel. When a leak occurs at any position of the pipeline, the oil product infiltrates the oil-sensing optical cable laid along the line, and the oil-absorbing swelling sheath absorbs oil and swells, and the internal grating array sensing optical fiber is bent, thereby generating a grating wavelength drift, and then the location of the leak can be realized. The elastic layer is used to make the entire oil-sensing optical cable based on the grating array have a certain degree of pressure resistance and a certain degree of elasticity for resetting. Compared with the prior art, the present invention is not easily affected by weather, has high optical fiber sensing sensitivity, and has a simple structure and low cost, and has no blind spots, and has good practicality.

[0004] But the problem is that the working principle of this scheme is that the outer sheath of the optical cable is an oil-absorbing and swelling material. When it comes into contact with oil, it will swell and deform, providing axial driving stress for the inner sensing optical fiber, causing the central wavelength of the grating to drift and be sensed by the demodulation system to send out an alarm signal. In fact, most oil pipelines are buried, and the oil-sensing optical cable needs to be laid in the same trench to play a monitoring and alarm role. However, when the oil-sensing optical cable of this scheme is buried in the soil structure, the coating structure will completely wrap the oil-sensing optical cable. The wrapping squeezing force will cause the oil-sensing optical cable to contact the leaking oil, and it is difficult to produce effective swelling strain, which eventually leads to sensor failure. Summary of the invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, propose a distributed oil leakage monitoring optical cable structure suitable for direct burial and hanging net installation, and solve the technical problems of insufficient swelling strain and sensor failure in the prior art.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: The present invention provides a distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation, comprising: A braided sheath layer, a spiral armor layer and a distributed optical fiber oil sensing cable core, wherein the spiral armor layer is sleeved on the distributed optical fiber oil sensing cable core, and the braided sheath layer is sleeved on the spiral armor layer, wherein a gap is provided between the spiral armor layer and the distributed optical fiber oil sensing cable core.

[0007] 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 sleeve layer, and a sensing optical fiber. The optical fiber tight sleeve layer is sleeved on the sensing optical fiber, the spiral armor elastic layer is sleeved on the optical fiber tight sleeve layer, the oil-sensing sheath is sleeved on the spiral armor elastic layer and fits tightly with 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.

[0008] In some embodiments, the interval between the spiral armor elastic layer and the optical fiber tight sleeve is filled with fixed glue dots for fixing the sensing optical fiber to the center of the spiral armor elastic layer and putting the sensing optical fiber in a pre-tensioned state.

[0009] In some embodiments, the spacing of the fixed glue dots is equal to the grating spacing of the sensing optical fiber.

[0010] In some embodiments, the spiral armor elastic layer is made of stainless steel or high modulus polymer.

[0011] In some embodiments, the oil-sensitive sheath is made of an oil-absorbing and swelling polymer material.

[0012] In some embodiments, the distributed optical fiber oil-sensing cable core comprises an oil-sensitive jacket, a coupling agent, an optical fiber tight sheath and a distributed sensing optical fiber, the optical fiber tight sheath is sleeved on the distributed sensing optical fiber, the oil-sensitive jacket is sleeved on the optical fiber tight sheath, and the coupling agent is filled in the gap between the oil-sensitive jacket and the optical fiber tight sheath.

[0013] In some embodiments, the coupling agent is an anaerobic one-component glue.

[0014] In some embodiments, the braided sheath layer is made of polymer synthetic fibers.

[0015] In some embodiments, the spiral armor layer is made of stainless steel.

[0016] Compared with the prior art, the distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation provided by the present invention includes a braided sheath layer, a spiral armor layer and a distributed optical fiber oil sensing cable core, wherein the spiral armor layer is sleeved on the distributed optical fiber oil sensing cable core, and the braided sheath layer is sleeved on the spiral armor layer, wherein there is a gap between the spiral armor layer and the distributed optical fiber oil sensing cable core, and the spiral armor layer is sleeved on the distributed optical fiber oil sensing cable core, and the braided sheath layer is sleeved on the spiral armor layer, wherein there is a gap between the spiral armor layer and the distributed optical fiber oil sensing cable core. The gap ensures that even if the oil sensing optical cable is in an underground state, the distributed optical fiber oil sensing cable core inside it always has space to absorb oil and swell, and even if the oil sensing optical cable is completely wrapped, it can still produce swelling strain when it contacts leaking oil, ensuring that the optical fiber sensing is always effective.

[0017] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail as follows with reference to the accompanying drawings. The specific implementation of the present invention is given in detail by the following embodiments and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation provided by the present invention; Figure 2 This is a schematic cross-sectional view of a distributed optical fiber oil sensing cable core in one embodiment: Figure 3 4 is a schematic cross-sectional view of a distributed optical fiber oil sensing cable core in another embodiment.

[0019] Description of reference numerals: 1-braided sheath layer, 2-spiral armor layer, 3-distributed optical fiber oil-sensing cable core, 31-oil-sensing sheath, 32-spiral armor elastic layer, 33-optical fiber tight jacket layer, 34-sensing optical fiber, 35-fixed glue point, 36-oil-sensing jacket, 37-coupling agent, 38-optical fiber tight jacket, 39-distributed sensing optical fiber. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] See also Figure 1The present invention provides a distributed oil leakage monitoring optical cable structure suitable for direct burial and mesh installation, comprising a braided sheath layer 1, a spiral armor layer 2 and a distributed optical fiber oil sensing cable core 3, wherein 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, wherein there is a gap between the spiral armor layer 2 and the distributed optical fiber oil sensing cable core 3.

[0022] In the present invention, 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, and there is a gap between the spiral armor layer 2 and the distributed optical fiber oil sensing cable core 3. The gap ensures that even if the oil sensing optical cable is in a buried state, the distributed optical fiber oil sensing cable core 3 inside it always has space to absorb oil and swell, and even if the oil sensing optical cable is completely wrapped, it can still produce swelling strain when it contacts leaked oil, ensuring that the optical fiber sensing is always effective.

[0023] Specifically, the braided sheath layer 1 is made of polymer synthetic fiber. Polymer synthetic fiber has good wear resistance, corrosion resistance, tensile strength, high and low temperature stability, and extremely low hygroscopicity, and has very good adaptability to burial; reasonable design of the braiding density can ensure the permeability of oil products. The braided sheath layer 1 provides sheath protection for the entire sensor optical cable. Its tensile strength depends on the material strength, wire diameter and weaving method of the synthetic fiber. It can be designed according to different installation environments. Generally, for occasions with higher tensile requirements, it is necessary to select synthetic fibers with higher strength and thicker wire diameter, and adopt a tighter weaving method, and vice versa.

[0024] The spiral armor layer 2 is made of stainless steel to ensure the buried anti-corrosion ability of the sensor cable itself. The metal spiral armor structure has good lateral pressure resistance and can resist the squeezing force of the soil layer during buried installation; the spiral armor is an open structure, which makes the oil have good permeability to it. The mechanical properties of the spiral armor layer 2 can be adjusted by changing the outer diameter D2, cross-sectional width b, cross-sectional thickness t and pitch P of the spiral armor layer 2: Generally, the larger the outer diameter D2, the weaker the compressive resistance; the larger the cross-sectional width b, the stronger the compressive resistance, and the bending performance will decrease; the larger the cross-sectional thickness t, the stronger the compressive resistance; the larger the pitch P, the weaker the compressive resistance, and the bending performance will also decrease.

[0025] There are two main sensing principles for the distributed optical fiber oil sensing cable core 3: distributed optical fiber sensing based on the Brillouin signal demodulation principle and grating array optical fiber sensing based on the grating wavelength demodulation principle. The present invention combines the above two demodulation principles to provide two distributed optical fiber oil sensing cable core structures, as shown in the attached figure. Figure 2 , Attachment Figure 3 shown.

[0026] Attached Figure 2 In the embodiment, the distributed optical fiber oil sensing cable core 3 comprises an oil sensing sheath 31, a spiral armor elastic layer 32, an optical fiber tight sleeve layer 33, and a sensing optical fiber 34. The optical fiber tight sleeve layer 33 is sleeved on the sensing optical fiber 34, the spiral armor elastic layer 32 is sleeved on the optical fiber tight sleeve layer 33, the oil sensing sheath 31 is sleeved on the spiral armor elastic layer 32, and is tightly fitted with the outer surface of the spiral armor elastic layer 32, and 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 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 element.

[0027] Furthermore, the oil-sensitive sheath 31 is made of oil-absorbing and swelling polymer materials, such as TPE, TPV, SBS, etc. When the oil-sensitive sheath 31 contacts petrochemical oil, it will rapidly expand in volume. For different petrochemical oils, the volume expansion ratio will vary, and 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.

[0028] Furthermore, the spiral armor elastic layer 32 is made of stainless steel or high modulus polymer and has a certain elastic rigidity.

[0029] Furthermore, the material of the optical fiber tight cladding 33 is a polymer material, such as Hytrel, PE, PVC, PA, etc.; the optical fiber tight cladding 33 is used to protect the sensing optical fiber 34, improve its mechanical strength, and further inhibit the growth of internal cracks of the sensing optical fiber 34 to ensure its service life.

[0030] Furthermore, the interval between the spiral armor elastic layer 32 and the optical fiber tight jacket layer 33 is filled with fixed glue dots 35. The function of the fixed glue dots 35 is to fix the sensing optical fiber 34 to the center of the spiral armor elastic layer 32 and put the sensing optical fiber 34 in a pre-tensioned state.

[0031] Furthermore, for the grating array sensing fiber, the spacing of the fixed glue 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 in any segment between the adjacent fixed glue dots 35 can be monitored by the grating between the fixed glue dots 35, that is, the distributed continuous sensing function of the grating array sensing fiber is realized; and for the ordinary communication fiber based on the Brillouin signal demodulation principle, the signal of a single point of the sensing fiber can be expanded to the range of the optical fiber fixed by the fixed glue dots 35, so that the spatial signal accumulation intensity is amplified and the sensing sensitivity is improved.

[0032] Attached Figure 3Provided is a distributed optical fiber oil-sensing cable core 3 specially designed based on the Brillouin signal demodulation principle, the distributed optical fiber oil-sensing cable core 3 comprises an oil-sensing jacket 36, a coupling agent 37a, an optical fiber tight sheath 38 and a distributed sensing optical fiber 39, the optical fiber tight sheath 38 is sleeved on the distributed sensing optical fiber 39, the oil-sensing jacket 36 is sleeved on the optical fiber tight sheath 38, and the coupling agent 37a is filled in the gap between the oil-sensing jacket 36 and the optical fiber tight sheath 38.

[0033] The coupling agent 37a is an anaerobic single-component glue, and its function is to enhance the bonding strength between the oil-sensitive jacket 36 and the optical fiber tight sheath 38, so that when the oil-sensitive jacket 36 absorbs oil and expands, its strain energy can be effectively transmitted to the distributed sensing optical fiber 39 inside the optical fiber tight sheath 38, thereby improving the sensing sensitivity.

[0034] Beneficial effects of the present invention: The distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation provided by the present invention includes a braided sheath layer, a spiral armor layer and a distributed optical fiber oil sensing cable core, wherein the spiral armor layer is sleeved on the distributed optical fiber oil sensing cable core, and the braided sheath layer is sleeved on the spiral armor layer, wherein there is a gap between the spiral armor layer and the distributed optical fiber oil sensing cable core, and the spiral armor layer is sleeved on the distributed optical fiber oil sensing cable core, and the braided sheath layer is sleeved on the spiral armor layer, wherein there is a gap between the spiral armor layer and the distributed optical fiber oil sensing cable core. The gap ensures that even if the oil sensing optical cable is in a buried state, the distributed optical fiber oil sensing cable core inside it always has space to absorb oil and swell, and even if the oil sensing optical cable is completely wrapped, it can still produce swelling strain when it contacts leaked oil, ensuring that optical fiber sensing is always effective.

[0035] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation, characterized in that: It includes: A braided sheath layer, a spiral armor layer and a distributed optical fiber oil sensing cable core, wherein the spiral armor layer is sleeved on the distributed optical fiber oil sensing cable core, and the braided sheath layer is sleeved on the spiral armor layer, wherein a gap is provided between the spiral armor layer and the distributed optical fiber oil sensing cable core.

2. The distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation according to claim 1 is characterized in that: The distributed optical fiber oil-sensing cable core comprises an oil-sensing sheath, a spiral armor elastic layer, an optical fiber tight sheath, and a sensing optical fiber. The optical fiber tight sheath is sleeved on the sensing optical fiber, the spiral armor elastic layer is sleeved on the optical fiber tight sheath, the oil-sensing sheath is sleeved on the spiral armor elastic layer and fits tightly with 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.

3. The distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation according to claim 2 is characterized in that: The interval between the spiral armor elastic layer and the optical fiber tight sleeve is filled with fixed glue points, which are used to fix the sensing optical fiber to the center of the spiral armor elastic layer and put the sensing optical fiber in a pre-tensioned state.

4. The distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation according to claim 3 is characterized in that: The spacing between the fixed glue dots is equal to the grating spacing of the sensing optical fiber.

5. The distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation according to claim 2 is characterized in that: The spiral armor elastic layer is made of stainless steel or high modulus polymer.

6. The distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation according to claim 2 is characterized in that: The oil-sensitive sheath is made of oil-absorbing and swelling polymer material.

7. The distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation according to claim 1 is characterized in that: The distributed optical fiber oil-sensing cable core comprises an oil-sensing jacket, a coupling agent, an optical fiber tight sheath and a distributed sensing optical fiber. The optical fiber tight sheath is sleeved on the distributed sensing optical fiber, the oil-sensing jacket is sleeved on the optical fiber tight sheath, and the coupling agent is filled in the gap between the oil-sensing jacket and the optical fiber tight sheath.

8. The distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation according to claim 7 is characterized in that: The coupling agent is an anaerobic single-component glue.

9. The distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation according to claim 1 is characterized in that: The braided sheath layer is made of high molecular synthetic fiber.

10. The distributed oil leakage monitoring optical cable structure suitable for direct burial and net-hanging installation according to claim 1 is characterized in that: The spiral armor layer is made of stainless steel.

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