Distributed optical fiber temperature sensing system for extreme environment and all-solid-state calibration constant temperature box thereof

Abstract

The utility model discloses an all-solid-state calibration constant-temperature box used in an extreme environment, which comprises a first metal layer and a second metal layer which are the same in size and are oppositely and fixedly arranged. An annular optical fiber groove, a first hole channel and a second hole channel are formed in the surface of the side, facing the second metal layer, of the first metal layer, one end of the first hole channel and one end of the second hole channel are communicated with the annular optical fiber groove, and the other end of the first hole channel and the other end of the second hole channel extend to the periphery of the first metal layer to be exposed. A plurality of temperature measuring holes are formed in the second metal layer and uniformly surround the periphery of the annular optical fiber groove; a calibration optical fiber is arranged in the annular optical fiber groove, and the two ends of the calibration optical fiber extend out of the first metal layer through the first hole channel and the second hole channel respectively; the plurality of temperature measuring sensors are arranged in the corresponding temperature measuring holes; the all-solid-state calibration constant-temperature box adopts an all-solid-state heating structure for the calibration optical fiber, and has the advantages of high integration level, small size and light weight. The utility model further discloses a distributed optical fiber temperature sensing system used in the extreme environment. The distributed optical fiber temperature sensing system comprises the all-solid-state calibration constant-temperature box.

Description

TECHNICAL FIELD

[0001] The utility model relates to distributed optical fiber sensing technology especially relates to a kind of distributed optical fiber temperature sensing system for extreme environment and its full solid calibration constant temperature box. BACKGROUND

[0002] Raman distributed optical fiber sensing system mainly utilizes the spontaneous Raman scattering effect generated when laser propagates in optical fiber, which is generated by the non-elastic collision between incident photons and optical factors in optical fiber. Non-elastic collision leads to energy transfer of incident photons and causes frequency change of incident photons, generating Stokes light lower than incident light frequency and anti-Stokes light greater than incident light frequency. And temperature detection is carried out by using the characteristic that Raman scattering light is only sensitive to temperature. The scattering signal is relatively weak, and scattering intensity is closely related to temperature, but it is not sensitive to stress and other parameter changes. It is this characteristic that makes Raman scattering widely used in distributed optical fiber sensing system.

[0003] In distributed optical fiber temperature sensing system (DTS, Distributed Optical Fiber Temperature Sensing) based on Raman distributed optical fiber sensing, in order to accurately measure the temperature of each point of optical fiber, a section of optical fiber needs to be in constant temperature state to serve as standard reference for optical fiber temperature measurement and calculation, so a calibration constant temperature box is needed to perform constant temperature treatment on optical fiber. At present, calibration constant temperature box is divided into liquid constant temperature box and semi-solid constant temperature box according to the form of heating material in the box.

[0004] Liquid constant temperature box refers to heating optical fiber with liquid in the box, or directly heating optical fiber with water bath furnace in test site, taking the temperature of optical fiber in liquid as reference point to perform temperature calibration and demodulation. It is the most commonly used calibration constant temperature box in current DTS system, but it has the following shortcomings: 1. Liquid is consumable. Although liquid constant temperature box is in sealed state, there is still evaporation phenomenon in the box, and temperature fluctuation will be caused by liquid change; 2. Liquid constant temperature box is difficult to maintain long-term stability in extreme environment in actual production, and there is certain risk of liquid leakage; 3. Liquid constant temperature box has high cost and poor flexibility.

[0005] The semi-solid thermostat box refers to heating the optical fiber by solid + liquid in the box, generally winding the optical fiber on the heating copper column first, then filling the liquid in the box, and heating one side of the optical fiber by the heating copper column and the other side by the liquid. This is the most studied calibration thermostat box in the DTS system in recent years, but it has the following shortcomings: 1. The structure of the semi-solid thermostat box is complex, the internal devices need to be sealed, and the process requirement is high; 2. There is a difference in the thermal conductivity of the optical fiber in the liquid and the solid, and the fluctuation is large in high-precision stable; 3. The semi-solid thermostat box generally adopts a splicing structure, multi-layer design, and large volume. Practical new type content

[0006] In order to solve the above problems of the prior art, the utility model provides a kind of full solid calibration thermostat box for extreme environment, and full solid heating structure is used to calibration optical fiber, with the advantages of high integration, small volume and light weight.

[0007] The utility model also provides a kind of distributed optical fiber temperature sensing system for extreme environment, including above-mentioned full solid calibration thermostat box.

[0008] The technical problem to be solved by the utility model is realized by the following technical scheme:

[0009] A kind of full solid calibration thermostat box for extreme environment, comprising:

[0010] The first metal layer and the second metal layer with the same size are fixedly arranged relative to each other, and the first metal layer is provided with an annular optical fiber groove, a first hole and a second hole on the side surface facing the second metal layer, one end of the first hole and the second hole is communicated with the annular optical fiber groove respectively, and the other end extends to the periphery of the first metal layer and is exposed;Multiple temperature measuring holes are formed in the second metal layer, and each temperature measuring hole is uniformly arranged around the periphery of the annular optical fiber groove;

[0011] The calibration optical fiber is arranged in the annular optical fiber groove, and the two ends of the calibration optical fiber are respectively extended to the outside of the first metal layer through the first hole and the second hole;

[0012] Multiple temperature sensors, each temperature sensor is arranged in the corresponding temperature measuring hole;

[0013] Flexible heating film, the flexible heating film is attached to the peripheral surface of the first metal layer and the second metal layer;

[0014] Temperature controller, the temperature controller is arranged on the side surface of the second metal layer away from the first metal layer, and is connected with the flexible heating film and each temperature sensor.

[0015] Further, the full solid-state calibration thermostat further comprises:

[0016] The heat insulation plate is at least attached to the peripheral surface of the flexible heating film.

[0017] Further, the heat insulation plate is internally provided with a vacuum heat insulation cavity.

[0018] Further, the heat insulation plate is a nanoscale core material with a density of 30-150 kg / m³.

[0019] Further, the calibration optical fiber and the annular optical fiber groove, and the temperature measuring sensor and the temperature measuring hole, are filled with heat-conducting silicone grease.

[0020] Further, the flexible heating film is a PI heating film with a thickness of 0.05-0.3 mm.

[0021] Further, the temperature measuring sensor is a high-precision temperature measuring platinum resistance.

[0022] Further, the first metal layer and the second metal layer are solid copper columns in the shape of a cylinder or a multi-prism.

[0023] Further, the calibration optical fiber is a graded-index multimode optical fiber.

[0024] A distributed optical fiber temperature sensing system for extreme environments comprises a light source device, a Raman wavelength division multiplexer, an optical signal acquisition device, an upper computer, a temperature measuring optical fiber, and the full solid-state calibration thermostat described above. The emission end of the light source device is connected to the first end of the Raman wavelength division multiplexer, one end of the calibration optical fiber in the full solid-state calibration thermostat is connected to the second end of the Raman wavelength division multiplexer, the third end of the Raman wavelength division multiplexer is connected to the input end of the optical signal acquisition device, the other end of the calibration optical fiber in the full solid-state calibration thermostat is connected to one end of the temperature measuring optical fiber, the output end of the optical signal acquisition device is connected to the input end of the upper computer, and the output end of the upper computer is connected to the input end of the light source device and the temperature controller in the full solid-state calibration thermostat, respectively.

[0025] The utility model has the advantages of:

[0026] In the full solid-state calibration thermostat, the first metal layer and the second metal layer form a full solid-state structure, and through the innovative synergy of metal heat conduction, flexible heating, and dynamic temperature control, a high-precision, high-reliability, and maintenance-free constant temperature calibration solution is provided for the distributed optical fiber temperature sensing system. Compared with existing liquid constant temperature boxes and semi-solid constant temperature devices, the utility model has the outstanding advantages of not requiring any chemical medium, meeting environmental protection standards, and having no combustion risk.

[0027] The double-layer metal body formed by the first metal layer and the second metal layer, in combination with the heat insulation plate, can form a vibration isolation structure design, thereby effectively inhibiting the influence of external vibration noise on the calibration optical fiber, ensuring stable operation of the constant-temperature box in a complex extreme environment (such as a sea platform or an industrial site), and finally realizing accurate and stable collection of temperature signals of the optical fiber, thereby achieving lower preparation cost and better universality. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A perspective structural schematic view of the full-solid calibration constant-temperature box is provided.

[0029] Figure 2 An exploded structural schematic view of the full-solid calibration constant-temperature box is provided.

[0030] Figure 3 A principle structural schematic view of the distributed optical fiber temperature sensing system is provided. DETAILED DESCRIPTION

[0031] The utility model will be explained in detail below by combining with the drawings and examples, the example of the example is shown in the drawings, wherein the same or similar signs represent the same or similar elements or elements with the same or similar function throughout. The examples described below by referring to the drawings are exemplary, and are intended to explain the utility model, and cannot be understood as limiting the utility model.

[0032] In the description of the utility model, it is understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as limiting the utility model.

[0033] In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features limited by "first", "second", "third" can explicitly or implicitly include one or more features. In the description of the utility model, the meaning of "a plurality of" is two or more than two, unless otherwise specifically limited.

[0034] In the utility model, unless another definite provision and limitation, the terms "mount", "link", "connect", "fix", "arrange" and so on should do broad sense understanding, for example, can be fixed connection, also can be detachable connection, or be integrated;Can be mechanical connection, also can be electrical connection;Can be direct connection, also can through the intermediate medium indirectly connect, also can be two element internal communication or two element's mutual action relationship.For the ordinary skill in the art, can understand the concrete meaning of the above terms in the utility model according to specific circumstances.

[0035] Example one

[0036] As Figure 1 And 2 A kind of full solid state calibration thermostatic chamber for extreme environment, comprising:

[0037] The first metal layer 1 and the second metal layer 2 of same size, the first metal layer 1 and the second metal layer 2 are relatively fixedly arranged, the first metal layer 1 is provided with annular optical fiber groove 11, first hole 12 and second hole 13 on the side surface towards the second metal layer 2, one end of the first hole 12 and the second hole 13 is communicated with the annular optical fiber groove 11 respectively, and the other end extends to the periphery of the first metal layer 1 and exposes respectively;Multiple temperature measuring holes 21 are formed in the second metal layer 2, and each temperature measuring hole 21 is uniformly arranged on the periphery of the annular optical fiber groove 11;

[0038] Calibration optical fiber, the calibration optical fiber is arranged in the annular optical fiber groove 11, and the two ends thereof extend out of the first metal layer 1 through the first hole 12 and the second hole 13 respectively;

[0039] Multiple temperature measuring sensors, each temperature measuring sensor is arranged in the corresponding temperature measuring hole 21;

[0040] Flexible heating film 6, the flexible heating film 6 is attached to the peripheral surface of the first metal layer 1 and the second metal layer 2;

[0041] Temperature controller 5, the temperature controller 5 is arranged on the side surface of the second metal layer 2 away from the first metal layer 1, and is connected with the flexible heating film 6 and each temperature measuring sensor.

[0042] The first metal layer 1 and the second metal layer 2 constitute a full solid structure, and through innovative cooperation of metal heat conduction, flexible heating and dynamic temperature control, a high-precision, high-reliability and maintenance-free constant temperature calibration solution is provided for a distributed optical fiber temperature sensing system; compared with the existing liquid constant temperature box and semi-solid constant temperature device, the utility model has the outstanding advantages that any chemical medium is not needed, environmental protection standards are met, and there is no combustion risk.

[0043] The first metal layer 1 and the second metal layer 2 can be fixed by screwing and rotating with each other through screw holes, or fixed by mutual adhesion through heat-conducting silica gel, or fixed by mutual buckling through buckle and slot.

[0044] In the embodiment, the calibration optical fiber is a refractive index gradually varied multimode optical fiber, the length of which is about 100 m, and the calibration optical fiber is arranged in a ring structure in the annular optical fiber groove 11; the temperature measuring sensor is a high-precision temperature measuring platinum resistance, and the number of the temperature measuring sensors is four, which are arranged on the periphery of the annular optical fiber groove 11 with a 90-degree offset central angle; the first metal layer 1 and the second metal layer 2 are solid copper columns with good thermal conductivity, and the shapes of the first metal layer 1 and the second metal layer 2 are cylindrical or multi-prism-shaped; the flexible heating film 6 is a PI heating film, the thickness of the PI heating film is only 0.05-0.3 mm, and the PI heating film can be closely attached to the peripheral surface of the first metal layer 1 and the second metal layer 2; meanwhile, the temperature resistance range of the PI base is between-20℃ and 400℃, the PI base has corrosion resistance and bending resistance (bending radius ≥1 mm), is suitable for vibration environments (such as aviation engine monitoring) and extremely complex environments (such as offshore oil and gas well exploitation platforms), the power density of the PI base can reach 5-20 W / cm², the thermal response time of the PI base is less than 1 s, the temperature measuring sensor and the temperature controller 5 are linked, and millisecond-level heating power adjustment can be realized through a PID algorithm.

[0045] Preferably, heat-conducting silicone grease (not shown in the figure) is filled between the calibration optical fiber and the annular optical fiber groove 11, so that the flocculent structure of the heat-conducting silicone grease is fully filled in the winding gap of the calibration optical fiber, and uniform heat conduction of the calibration optical fiber is realized.

[0046] Preferably, heat-conducting silica gel (not shown in the figure) is filled between the temperature measuring sensor and the temperature measuring hole 21, so that the temperature measuring sensor and the temperature measuring hole 21 are adhesively fixed and efficiently heat-conducted.

[0047] When the thickness of the first metal layer 1 is large enough to accommodate the temperature measuring sensor, the second metal layer 2 can not be provided with any temperature measuring hole 21; when the thickness of the first metal layer 1 is small and not enough to accommodate the temperature measuring sensor, the second metal layer 2 can also be provided with a plurality of temperature measuring holes 21, and the temperature measuring holes 21 between the second metal layer 2 and the second metal layer 2 correspond to each other to jointly accommodate each temperature measuring sensor.

[0048] The full solid calibration thermostat further comprises:

[0049] A heat insulation plate 7 is attached to at least the peripheral surface of the flexible heating film 6.

[0050] In the full solid calibration thermostat, the double-layer metal body formed by the first metal layer 1 and the second metal layer 2, in combination with the heat insulation plate 7, can form a vibration isolation structure design, thereby effectively suppressing the influence of external vibration noise on the calibration optical fiber, ensuring stable operation of the thermostat in complex extreme environments (such as offshore platforms and industrial sites), and ultimately realizing accurate and stable temperature signal acquisition of the optical fiber, thereby achieving lower manufacturing cost and better universality.

[0051] Preferably, the heat insulation plate 7 can also cover the side surface of the first metal layer 1 away from the second metal layer 2, and the side surface of the second metal layer 2 away from the first metal layer 1, and is provided with first, second and third slot holes for exposing the two ends of the calibration optical fiber and the temperature controller 5, respectively.

[0052] The heat insulation plate 7 is internally provided with a vacuum insulation cavity to better isolate vibration transmission and simultaneously block the three heat conduction paths of heat conduction, heat convection and heat radiation.

[0053] In this embodiment, the heat insulation plate 7 is a nanoscale core material with a density of 30-150 kg / m³, such as fumed silica and glass fiber, to provide sufficient plate strength to support the vacuum insulation cavity.

[0054] Embodiment two

[0055] As shown in Figure 3 A distributed optical fiber temperature sensing system for extreme environments, comprising: a light source device, a Raman wavelength division multiplexer, an optical signal acquisition device, an upper computer, a temperature measuring optical fiber, and the full solid calibration thermostat of embodiment one, the emission end of the light source device is connected with the first end of the Raman wavelength division multiplexer, the second end of the Raman wavelength division multiplexer is connected with one end of the calibration optical fiber in the full solid calibration thermostat, the third end of the Raman wavelength division multiplexer is connected with the input end of the optical signal acquisition device, one end of the temperature measuring optical fiber is connected with the other end of the calibration optical fiber in the full solid calibration thermostat, the output end of the optical signal acquisition device is connected with the input end of the upper computer, and the output end of the upper computer is connected with the input end of the light source device and the temperature controller 5 in the full solid calibration thermostat, respectively.

[0056] The temperature controller 5 is provided with a USB interface to be connected with the upper computer.

[0057] The light signal acquisition device comprises a first avalanche photodetector, a second avalanche photodetector, a first voltage amplifier, a second voltage amplifier and a data acquisition card, the first avalanche photodetector and the second avalanche photodetector are connected with the third end of the Raman wavelength division multiplexer respectively, the first voltage amplifier is connected between the first avalanche photodetector and the data acquisition card, and the second voltage amplifier is connected between the second avalanche photodetector and the data acquisition card.

[0058] In operation, first, the data acquisition card sends a TTL trigger level, then the light source device emits a same-frequency pulsed light into the optical wavelength division multiplexer, the transmitted light enters the all-solid-state calibration thermostat box and the temperature measuring optical fiber through the internal collimating lens (the calibration optical fiber of the all-solid-state calibration thermostat box needs to be matched with the temperature measuring optical fiber in terms of fiber core diameter), then the back Raman scattered light is transmitted back to the optical wavelength division multiplexer through the temperature measuring optical fiber and the calibration optical fiber, then photoelectric conversion and amplification are performed by the first avalanche photodetector, the second avalanche photodetector, the first voltage amplifier and the second voltage amplifier, the amplified voltage signal is received by the data acquisition card, and then algorithm processing and temperature demodulation are performed by the host computer.

[0059] When the host computer performs algorithm processing and temperature demodulation, according to the sampling rate and the lengths of the calibration optical fiber and the sensing optical fiber, the anti-Stokes light and Stokes light light intensity ratio of the calibration optical fiber and the anti-Stokes light and Stokes light light intensity ratio of the temperature measuring optical fiber are taken from the collected intensity data, the light intensity ratio of the calibration optical fiber is taken as the reference value of the all-solid-state calibration thermostat box at a constant temperature, the light intensity ratio of the temperature measuring optical fiber is corrected, and finally the corresponding ambient temperature is calculated according to the corrected light intensity ratio of the temperature measuring optical fiber.

[0060] The four temperature sensors in the all-solid-state calibration thermostat box upload temperature data in real time to collect T1, T2, T3 and T4 for the whole box body, and then an arithmetic mean value T0 is calculated. Assuming that the system sampling rate is 100M, one temperature collection point is set in the calibration optical fiber about 1m away, and 100 temperature collection points are obtained on the 100m calibration optical fiber. Because the calibration optical fiber is in a constant temperature area, the temperature difference between different points is small, and the arithmetic mean value of the temperature data of the 100 temperature collection points is calculated, and finally the light intensity ratio of the calibration optical fiber is taken as the reference value at the T0 temperature.

[0061] Finally, it needs to be explained that the above examples are only used to illustrate the technical solutions of the embodiments of the present application, but not to limit them. Although the embodiments of the present application have been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the embodiments of the present application can still be modified or replaced equivalently, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A fully solid-state calibration thermostat for extreme environments, characterized in that, include: A first metal layer and a second metal layer of the same size are fixedly disposed relative to each other. The surface of the first metal layer facing the second metal layer is provided with an annular fiber groove, a first channel and a second channel. One end of the first channel and the second channel are respectively connected to the annular fiber groove, and the other end extends to the periphery of the first metal layer and is exposed. A plurality of temperature measuring holes are opened in the second metal layer, and each of the temperature measuring holes is evenly surrounding the periphery of the annular fiber groove. The calibration fiber is disposed in the annular fiber groove, and its two ends extend out of the first metal layer through the first channel and the second channel, respectively. Multiple temperature sensors, each of which is disposed in a corresponding temperature measuring hole; A flexible heating film is attached to the outer surfaces of the first metal layer and the second metal layer. A temperature controller is disposed on the surface of the second metal layer facing away from the first metal layer and is connected to the flexible heating film and various temperature sensors.

2. The all-solid-state calibration constant temperature box according to claim 1, characterized in that, The all-solid-state calibration constant temperature box also includes: A heat insulation plate, wherein the heat insulation plate is at least attached to the outer surface of the flexible heating film.

3. The all-solid-state calibration constant temperature box according to claim 2, characterized in that, The heat insulation board has a vacuum heat insulation cavity inside.

4. The all-solid-state calibration constant temperature box according to claim 2 or 3, characterized in that, The insulation board has a nano-scale core material with a density of 30-150 kg / m³.

5. The all-solid-state calibration constant temperature box according to claim 1, characterized in that, Thermally conductive silicone grease is filled between the calibration optical fiber and the annular optical fiber groove, and between the temperature sensor and the temperature measuring hole.

6. The all-solid-state calibration constant temperature box according to claim 1, characterized in that, The flexible heating film is a PI heating film with a thickness of 0.05-0.3 mm.

7. The all-solid-state calibration constant temperature box according to claim 1, characterized in that, The temperature sensor is a high-precision platinum resistance thermometer.

8. The all-solid-state calibration constant temperature box according to claim 1, characterized in that, The first and second metal layers are solid copper pillars, which are cylindrical or polygonal in shape.

9. The all-solid-state calibration constant temperature box according to claim 1, characterized in that, The calibration fiber is a graded-index multimode fiber.

10. A distributed fiber optic temperature sensing system for extreme environments, characterized in that, include: The device comprises a light source, a Raman wavelength division multiplexer, an optical signal acquisition device, a host computer, a temperature-measuring optical fiber, and the all-solid-state calibration constant temperature box as described in claim 1. The transmitting end of the light source is connected to the first end of the Raman wavelength division multiplexer, the second end of the Raman wavelength division multiplexer is connected to one end of the calibration optical fiber in the all-solid-state calibration constant temperature box, the third end of the Raman wavelength division multiplexer is connected to the input end of the optical signal acquisition device, one end of the temperature-measuring optical fiber is connected to the other end of the calibration optical fiber in the all-solid-state calibration constant temperature box, the output end of the optical signal acquisition device is connected to the input end of the host computer, and the output end of the host computer is connected to the input end of the light source and the temperature controller in the all-solid-state calibration constant temperature box.

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