Measurement and correction integrated fiber grating array temperature measuring device and use method thereof

Abstract

The invention relates to the technical field of optical fiber temperature measurement, and discloses a measurement and correction integrated fiber grating array temperature measuring device, which comprises an optical fiber temperature sensor and an optical fiber demodulator, and further comprises a thermocouple and a thermocouple temperature acquisition device which are connected with each other and are used for calibrating temperature, the optical fiber temperature sensor comprises an optical fiber grating array used for measuring temperature and a quartz optical fiber used for transmission. The optical fiber grating array comprises at least one temperature measuring grating arranged at the front end and a reference grating arranged behind the temperature measuring grating. An output temperature signal of the thermocouple temperature acquisition device and a wavelength signal of the optical fiber demodulator are processed and compared through the upper computer, temperature calibration is carried out on the reference grating, and the temperature calibration is used as a calibration reference of the temperature measurement grating, so that real-time calibration is realized. According to the optical fiber temperature sensor, the reference grating and the thermocouple probe are integrated, measurement errors caused by light source fluctuation, optical fiber stress changes or environmental interference are effectively eliminated, measurement and calibration can be synchronously carried out, and external calibration equipment is omitted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical fiber temperature measurement, and particularly relates to a measurement and calibration integrated fiber grating array temperature measurement device and a use method thereof. BACKGROUND

[0002] As a kind of optical fiber device based on wavelength reflection change sensing, Fiber Bragg Grating (FBG) has the advantages of anti-electromagnetic interference, high sensitivity, fast response speed, small size and distributed measurement, and is widely used in temperature monitoring in the fields of power, oil, aerospace and high-temperature industry. In multi-point temperature monitoring occasions, fiber grating array realizes synchronous temperature measurement of multiple monitoring points by connecting multiple gratings in series or distributing them in the same optical fiber, which is one of the current mainstream high-precision fiber temperature measurement technologies.

[0003] The fiber grating array temperature measurement system shows good stability and sensitivity in actual application, but its measurement accuracy still depends on the accurate calibration of the relationship between the wavelength of each grating and temperature. In the long-term operation process, the performance of the fiber grating may drift due to factors such as stress relaxation and material aging, and needs to be recalibrated regularly. The traditional calibration method usually relies on constant temperature ovens, high-precision temperature control platforms or reference sensors, and needs to rely on independent calibration equipment or manual operation, and often does not have feasibility in the field environment, especially in closed, harsh or high-continuity measurement industrial environments such as the inside of power equipment, oil and gas pipelines, transformer windings, etc. At the same time, frequent disassembly may introduce mechanical damage and affect the long-term monitoring stability.

[0004] The existing Chinese patent with publication number CN 201666828 U provides a distributed fiber temperature sensor system temperature field calibration device, which compares the temperature measured by the distributed fiber temperature sensor system with the temperature measured by the infrared thermal imager to realize the calibration process. However, it can only be calibrated on the surface that can be detected by the infrared thermal imager, and cannot be calibrated in a closed application scenario, and the accuracy of the infrared thermal imager is not high enough, with large measurement deviation.

[0005] The existing Chinese patent with publication number CN 206990129 U provides a fiber grating temperature sensor calibration device, which uses a sensor fixing bracket to stably fix the fiber grating temperature sensor to be calibrated in a constant temperature field plug-in block, and the standard platinum resistance thermometer is in the same temperature field, which can realize accurate calibration. However, since the calibration process relies on additional instruments or manual operation, the efficiency of field implementation is low, and mechanical stress may accumulate in the repeated disassembly process of the equipment, thereby affecting the structural integrity and temperature measurement consistency.

[0006] The existing Chinese patent with the publication number CN119533715A provides a calibration method for a multi-measurement-point fiber grating temperature sensor. First, a test environment for calibrating the multi-measurement-point fiber grating temperature sensor is laid out, and multiple calibration temperature points are set. This can reduce errors introduced during calibration due to the non-uniformity and instability of the temperature in the calibration oven. However, the grating array is easily affected by environmental stress, material aging, and other factors after long-term operation, leading to wavelength drift. The existing device lacks real-time online calibration and correction functions, making it difficult to dynamically correct errors.

[0007] These existing technologies have improvements and innovations in sensor fixation, temperature field consistency control, portable calibration, and multi-point calibration methods, but they all have the following technical problems:

[0008] 1. Relying on independent calibration equipment or manual operation, real-time online calibration cannot be achieved, and field adaptability is poor;

[0009] 2. Fiber sensors are easily affected by stress relaxation, material aging, and other factors during long-term operation, causing wavelength drift, and lack of dynamic correction means, resulting in insufficient measurement stability and reliability;

[0010] 3. Some calibration devices need to be frequently disassembled, which can easily cause mechanical damage, affecting the integrity of the fiber structure and long-term temperature measurement consistency;

[0011] 4. It is difficult to implement effective calibration in a closed or complex working condition, limiting the application and promotion in high-temperature, high-pressure, and continuous operation industrial equipment. SUMMARY

[0012] To overcome or alleviate one or more of the above technical problems, the purpose of the present application is to provide a measurement and calibration integrated fiber grating array temperature measurement device and its use method. The device sets a reference grating and integrates a thermocouple as a wavelength drift compensation reference to achieve synchronous and accurate measurement and calibration of multi-point grating temperature measurement. The structure is compact, easy to operate, and can realize the integration of measurement and calibration of the fiber grating temperature measurement device, thereby improving the flexibility of field application.

[0013] The present application provides the following technical solutions:

[0014] A measurement and calibration integrated fiber grating array temperature measurement device, comprising a fiber temperature sensor and a fiber demodulator connected to each other, and further comprising a thermocouple for calibrating temperature and a thermocouple temperature acquisition device connected to each other; the fiber temperature sensor comprises a fiber grating array for temperature measurement and a quartz optical fiber for transmission, the fiber grating array comprises at least one temperature measurement grating placed at the front end and a reference grating placed behind it, the temperature measurement grating is used for measuring the temperature of the target area, and the reference grating is used as a compensation reference for wavelength drift for synchronous calibration of multi-point temperature measurement grating.

[0015] The thermocouple and the fiber temperature sensor are fixed in a fixed sleeve, the reference grating is aligned with a thermocouple probe of the thermocouple;

[0016] The thermocouple temperature acquisition device and the fiber demodulator are connected to the host computer, the output temperature signal of the thermocouple temperature acquisition device and the wavelength signal of the fiber demodulator are processed and compared by the host computer, the reference grating is temperature calibrated, and serves as a calibration reference of the temperature measurement grating, so that real-time calibration of the temperature measurement process is realized.

[0017] According to some embodiments, the fixed sleeve is provided with through channels for respectively placing the fiber temperature sensor and the thermocouple, and the diameters of the through channels are the same as the packaging diameters of the fiber temperature sensor and the thermocouple.

[0018] According to some embodiments, the thermocouple probe is located at the packaging top end of the thermocouple.

[0019] According to some embodiments, the thermocouple has an accuracy of 0.4% or above.

[0020] According to some embodiments, the fiber demodulator comprises a photodetector and a signal processing unit, the photodetector collects wavelength signals emitted by the temperature measurement grating and the reference grating, and the signal processing unit processes the wavelength signals and transmits them to the host computer.

[0021] According to some embodiments, the host computer is a server and / or a cloud.

[0022] According to some embodiments, the number of fiber temperature sensors is multiple, and the number of thermocouples corresponds to the number of fiber temperature sensors.

[0023] According to some embodiments, the packaging form of the fiber temperature sensor is stainless steel armor.

[0024] In another aspect, the application also provides a use method of the above-mentioned measurement and calibration integrated fiber grating array temperature measurement device, which comprises the following steps:

[0025] S1: placing the fiber temperature sensor and the thermocouple in the fixed sleeve, and aligning the reference grating of the fiber temperature sensor with the thermocouple probe of the thermocouple;

[0026] S2: connecting the thermocouple to the thermocouple temperature acquisition device, connecting the fiber temperature sensor to the fiber demodulator, and controlling the fiber demodulator through the host computer;

[0027] S3: the fiber temperature sensor and the thermocouple are integrated through the fixed sleeve, are placed in a target temperature measurement area, a plurality of temperature measurement gratings transmit wavelength signals to the upper computer through the fiber demodulator, and convert the wavelength signals into temperature signals, so that multi-point temperature measurement of the target area is realized;

[0028] S4: the temperature signal obtained by the reference grating of the fiber temperature sensor is compared with the temperature signal obtained by the thermocouple probe of the thermocouple, temperature calibration of the reference grating is performed, the reference grating is used as a calibration reference of the temperature measurement grating, and real-time calibration of the temperature measurement process is realized.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] (1) The measurement and calibration integrated fiber grating array temperature measurement device provided by the present application integrates the reference grating of the fiber temperature sensor with the thermocouple probe, effectively eliminates measurement errors caused by light source fluctuations, fiber stress changes or environmental interference, can realize simultaneous measurement and calibration, and saves external calibration equipment.

[0031] (2) The measurement and calibration integrated fiber grating array temperature measurement device provided by the present application supports fiber grating array layout for the fiber temperature sensor, and is divided into temperature measurement gratings and reference gratings. The temperature measurement gratings can simultaneously monitor multiple temperature points, improve the spatial resolution of the temperature measurement system, and simultaneously realize overall calibration in combination with the reference gratings, thereby ensuring the temperature measurement accuracy of the fiber temperature sensor under long-term operation.

[0032] (3) The measurement and calibration integrated fiber grating array temperature measurement device provided by the present application adopts a modular design, the reference grating of the fiber temperature sensor is coaxially arranged with the temperature measurement grating, and is integrated and packaged with the thermocouple, so that the structure is compact, suitable for narrow or complex application environments, and calibration of the temperature measurement device does not need to be frequently disassembled on site, thereby effectively reducing the risk of fiber damage or grating falling caused by mechanical stress or external force impact, and prolonging the service life. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The structure schematic diagram of the measurement and calibration integrated fiber grating array temperature measurement device provided by the embodiment of the present application.

[0034] Figure 2 The integrated schematic diagram of the fiber temperature sensor and the thermocouple provided by the embodiment of the present application.

[0035] Figure 3 The connection use and calibration principle block diagram of the fiber temperature sensor and the fiber demodulator of the temperature measurement device provided by the embodiment of the present application.

[0036] In the drawings:

[0037] 1-Fiber optic temperature sensor; 2-Temperature measuring grating; 3-Reference grating; 4-Thermocouple probe; 5-Thermocouple; 6-Fixed sleeve; 7-Thermocouple temperature acquisition device; 8-Fiber optic demodulator; 9-Host computer; 10-Photodetector; 11-Signal processing unit. Detailed Implementation

[0038] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention.

[0039] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "front," and "rear," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0040] The invention will now be further described with reference to the accompanying drawings.

[0041] like Figure 1 As shown, the integrated fiber optic grating array temperature measurement device of this embodiment includes a fiber optic temperature sensor 1, a thermocouple 5, a fixing sleeve 6, a thermocouple temperature acquisition device 7, a fiber optic demodulator 8, and a host computer 9. The fiber optic temperature sensor 1 includes a quartz optical fiber for transmitting optical signals and a fiber optic grating array for temperature measurement, and is encapsulated in stainless steel armor. The fiber optic grating array is divided into a temperature-sensing grating 2 placed at the front end and a reference grating 3 placed behind the temperature-sensing grating 2. The temperature-sensing grating 2 is used to measure the temperature of the target area, while the reference grating 3 serves as a compensation reference for wavelength drift, realizing synchronous calibration of the multi-point temperature-sensing gratings.

[0042] The fixed sleeve 6 is provided with a through channel for placing the fiber temperature sensor 1 and the thermocouple 5 respectively, and the channel diameter is the same as the packaging diameter of the fiber temperature sensor 1 and the thermocouple 5. The fixed sleeve 6 fixes the fiber temperature sensor 1 and the thermocouple 5, and the reference grating 3 of the fiber temperature sensor 1 is aligned with the thermocouple probe 4 of the thermocouple 5, wherein the thermocouple probe 4 is located at the packaging top end of the thermocouple 5, and the specific integration diagram is shown in Figure 2 The positions of the temperature measuring grating 2 and the reference grating 3 and the armored diameter of the fiber temperature sensor 1 can be adjusted according to actual application.

[0043] The thermocouple temperature acquisition device 7 receives the temperature signal of the thermocouple 5, the fiber demodulator 8 includes a photodetector 10 and a signal processing unit 11, the photodetector 9 collects the wavelength signals emitted by the temperature measuring grating 2 and the reference grating 3, and the signal processing unit 11 processes the wavelength signals and uploads them to the host computer 9. The fiber demodulator 8 has several demodulation channels, which can simultaneously demodulate the wavelength signals of multiple fiber temperature sensors 1, and the thermocouple temperature acquisition device 7 can simultaneously acquire the temperature signals of multiple thermocouples 5.

[0044] In this embodiment, the precision of the thermocouple reaches 0.4% and above, the resolution of the thermocouple temperature acquisition device is 0.1℃, and the wavelength of the fiber sensor is prone to drift, resulting in a temperature drift greater than the thermocouple, so the thermocouple technology is a relatively mature and stable calibration method.

[0045] In this embodiment, the use method of the integrated fiber grating array temperature measuring device is shown in the principle as Figure 3 The steps are as follows:

[0046] S1: Place the fiber temperature sensor 1 and the thermocouple 5 in the fixed sleeve 6, and align the reference grating 3 of the fiber temperature sensor 1 with the thermocouple probe 4 of the thermocouple 5;

[0047] S2: Connect the thermocouple 5 to the thermocouple temperature acquisition device 7, and connect the fiber temperature sensor 1 to the fiber demodulator 8, and control the fiber demodulator 8 through the host computer 9;

[0048] S3: After the fiber temperature sensor 1 and the thermocouple 5 are integrated through the fixed sleeve 6, they are placed in the target temperature measuring area, and the wavelength signals of the several temperature measuring gratings 2 are transmitted to the host computer 9 through the fiber demodulator 8 and converted into temperature signals, realizing multi-point temperature measurement of the target area;

[0049] S4: Compare the temperature signals obtained by the reference grating 3 of the fiber temperature sensor 1 with the temperature signals obtained by the thermocouple probe 4 of the thermocouple 5, calibrate the temperature of the reference grating 3, and use it as a calibration reference for the temperature measuring grating 2, realizing real-time calibration of the temperature measuring process.

[0050] The above embodiments are only preferred embodiments of the present application, and the protection scope of the present application is not limited to the above embodiments. Any technical scheme falling within the concept of the present application belongs to the protection scope of the present application. It should be pointed out that improvements and refinements made by those of ordinary skill in the art without departing from the principles of the present application should also be considered as falling within the protection scope of the present application.

Claims

1. A temperature measurement device integrating measurement and calibration of fiber optic grating array, comprising fiber optic temperature sensors and fiber optic demodulators connected to each other, characterized in that: It also includes thermocouples and thermocouple temperature acquisition devices connected to each other for temperature calibration; the fiber optic temperature sensor includes a fiber optic grating array for temperature measurement and a quartz fiber for transmission, the fiber optic grating array includes at least one temperature-sensing grating placed at the front end and a reference grating placed thereafter, the temperature-sensing grating is used to measure the temperature of the target area, and the reference grating serves as a compensation reference for wavelength drift and synchronously calibrates the multi-point temperature-sensing gratings. The thermocouple and the fiber optic temperature sensor are fixed inside a fixed sleeve, and the reference grating is aligned with the thermocouple probe of the thermocouple. Both the thermocouple temperature acquisition device and the fiber optic demodulator are connected to a host computer. The host computer processes and compares the output temperature signal of the thermocouple temperature acquisition device and the wavelength signal of the fiber optic demodulator, performs temperature calibration on the reference grating, and uses it as a calibration reference for the temperature measuring grating, thereby realizing real-time calibration of the temperature measurement process.

2. The integrated fiber optic grating array temperature measuring device according to claim 1, characterized in that: The fixed sleeve has through channels for placing the fiber optic temperature sensor and the thermocouple, respectively, and the diameter of the through channels is the same as the encapsulation diameter of the fiber optic temperature sensor and the thermocouple.

3. The integrated fiber optic grating array temperature measuring device according to claim 2, characterized in that: The thermocouple probe is located at the top of the thermocouple's encapsulation.

4. The integrated fiber optic grating array temperature measuring device according to claim 3, characterized in that: The thermocouple accuracy is 0.4% or higher.

5. The integrated fiber optic grating array temperature measuring device according to claim 1, characterized in that: The fiber optic demodulator includes a photodetector and a signal processing unit. The photodetector collects the wavelength signals emitted by the temperature measuring grating and the reference grating, and the signal processing unit processes the wavelength signals and transmits them to the host computer.

6. The integrated fiber optic grating array temperature measuring device according to claim 1, characterized in that: The host computer is a server and / or the cloud.

7. The integrated fiber optic grating array temperature measuring device according to claim 1, characterized in that: The number of fiber optic temperature sensors is multiple, and the number of thermocouples corresponds to the number of fiber optic temperature sensors.

8. The integrated fiber optic grating array temperature measuring device according to claim 7, characterized in that: The fiber optic temperature sensor is packaged in stainless steel armor.

9. A method of using the integrated fiber optic grating array temperature measuring device according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1: Place the fiber optic temperature sensor and the thermocouple inside the fixed sleeve, and align the reference grating of the fiber optic temperature sensor with the thermocouple probe of the thermocouple. S2: Connect the thermocouple to the thermocouple temperature acquisition device, connect the fiber optic temperature sensor to the fiber optic demodulator, and control the fiber optic demodulator through the host computer. S3: The fiber optic temperature sensor and the thermocouple are integrated through the fixed sleeve and placed in the target temperature measurement area. Several temperature measuring gratings transmit wavelength signals to the host computer through the fiber optic demodulator and convert them into temperature signals to realize multi-point temperature measurement of the target area. S4: The temperature signal obtained through the reference grating of the fiber optic temperature sensor is compared with the temperature signal obtained through the thermocouple probe of the thermocouple to perform temperature calibration of the reference grating, and it is used as a calibration reference for the temperature measuring grating to realize real-time calibration of the temperature measurement process.

Images