Boiler small-caliber steel pipe temperature monitoring device based on femtosecond fiber bragg grating

Abstract

The utility model discloses a boiler small-caliber steel pipe temperature monitoring device based on femtosecond fiber bragg grating, which comprises a femtosecond fiber bragg grating sensing network, the femtosecond fiber bragg grating sensing network comprises an optical fiber and a femtosecond fiber bragg grating sensing array, and the optical fiber is connected with the femtosecond fiber bragg grating sensing array. The femtosecond fiber bragg grating sensing array is wound on a plurality of small-caliber steel pipes communicated with a boiler through an encircling piece so as to monitor the temperature of the small-caliber steel pipes in real time and output optical signals; the output end of the femtosecond fiber grating sensing network is sequentially connected with a signal demodulator, a central processing unit and an alarm, after the signal demodulator demodulates optical signals and collects reflection spectrums, the central processing unit processes the reflection spectrums and extracts temperature distribution information, and if the temperature distribution information exceeds a temperature threshold value, the alarm gives an alarm; multi-point on-line temperature monitoring of the small-caliber steel pipe is realized, and temperature abnormity can be found in time.

Description

Technical Field

[0001] This utility model relates to the field of boiler temperature monitoring technology, specifically to a boiler small-diameter steel pipe temperature monitoring device based on femtosecond fiber optic gratings. Background Technology

[0002] The boiler top cover is a large structure on the top of the boiler, usually composed of roof pipes, headers, insulation layers, frame panels, etc. It is used to wrap and protect the pipes, headers and other equipment on the top of the boiler, reduce heat loss, and provide structural support for the equipment on the top.

[0003] The boiler's top ladle contains numerous small-diameter steel pipes used for heat dissipation and convection. Under high temperature and pressure conditions, these pipes are prone to problems due to thermal expansion and structural stress, affecting the boiler's safe operation and efficiency. Conventional periodic shutdown inspection techniques (such as ultrasonic, radiographic, and magnetic particle testing) are traditional point-based random sampling methods, which have a high risk of missed inspections and cannot meet the real-time online monitoring requirements of the high temperature and pressure environment in the production process.

[0004] Using electrical sensing methods such as thermocouples to monitor the temperature of small-diameter steel pipes is a mainstream real-time monitoring device. However, it has problems such as requiring on-site power supply, having a small number of monitoring points, difficulty in reusing sensors, electromagnetic crosstalk, and complex on-site deployment. This makes it difficult to achieve online monitoring of every pipe, which in turn may cause deformation, rupture, or even explosion of unmonitored pipe sections due to abnormal temperature, significantly increasing safety hazards. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of the aforementioned technologies by proposing a boiler small-diameter steel pipe temperature monitoring device based on a femtosecond fiber optic grating, aiming to solve the technical problem that existing technologies cannot perform online monitoring of the temperature of boiler small-diameter steel pipes.

[0006] This utility model provides a temperature monitoring device for small-diameter steel pipes in boilers based on femtosecond fiber Bragg gratings, comprising:

[0007] Femtosecond fiber Bragg grating sensor network, signal demodulator, central processing unit and alarm;

[0008] The femtosecond fiber grating sensor network includes an optical fiber and a femtosecond fiber grating sensor array. The optical fiber is connected to the femtosecond fiber grating sensor array. The femtosecond fiber grating sensor array is wound around multiple small-diameter steel pipes connected to the boiler through a ring-shaped component to monitor the temperature of the small-diameter steel pipes in real time and output optical signals.

[0009] The signal demodulator is connected to the output of the femtosecond fiber grating sensor network. The signal demodulator is used to demodulate the optical signal and collect the reflection spectrum of the femtosecond fiber grating sensor network.

[0010] The central processing unit is connected to the output of the signal demodulator and is used to process the reflection spectrum and extract temperature distribution information.

[0011] The alarm is connected to the output of the central processing unit and is set with a temperature threshold. If the temperature distribution information exceeds the temperature threshold, an alarm is triggered.

[0012] Optionally, the femtosecond fiber Bragg grating sensor array includes multiple femtosecond fiber Bragg grating sensors. Within each femtosecond fiber Bragg grating sensor array, the multiple femtosecond fiber Bragg grating sensors are connected sequentially along the optical path, and each small-diameter steel pipe is connected to one femtosecond fiber Bragg grating sensor.

[0013] Optionally, the number of femtosecond fiber Bragg grating sensors in each of the femtosecond fiber Bragg grating sensor arrays is twenty-eight.

[0014] Optionally, the femtosecond fiber grating sensing network further includes a delay fiber, the input end of which is connected to the output end of the femtosecond fiber grating sensing array.

[0015] Optionally, the circumferential member includes a first connector and a second connector. One end of the first connector is hinged to one end of the second connector, and the other end of the first connector is connected to the other end of the second connector by a fastener. The connection and disassembly of the first connector and the second connector are completed by tightening and loosening the fastener. The top surface of the first connector / second connector is connected to a mounting base. The mounting base has a mounting groove, which is arc-shaped, and the inner wall of the mounting groove abuts against the outer wall of the optical fiber.

[0016] Optionally, the first connector is provided with a hollow groove and the second connector is provided with a through groove. The inner walls of both the hollow groove and the through groove are provided with threads. The fastener is a screw rod, and the screw rod is threadedly connected to the hollow groove and the through groove.

[0017] Optionally, the first connector / second connector is detachably connected to the mounting base by screws.

[0018] Compared with existing technologies, it has the following beneficial effects:

[0019] This invention provides a temperature monitoring device for small-diameter steel pipes in boilers based on femtosecond fiber optic gratings. The device monitors the temperature at different points on the small-diameter steel pipe using a femtosecond fiber optic grating sensor network. The femtosecond fiber optic grating sensor network transmits optical signals to a signal demodulator, which converts the optical signals into electrical signals and performs demodulation processing. The spectral feature information output after demodulation is input to a central processing unit for analysis, extracting temperature distribution information and setting a temperature threshold. If the temperature distribution information exceeds the temperature threshold, an alarm is triggered. This enables online temperature monitoring of the small-diameter steel pipes inside the boiler. Furthermore, by setting multiple temperature detection points on the small-diameter steel pipe, abnormal temperatures can be detected promptly, preventing potential safety hazards. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only preferred embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram of the structure of the boiler small-diameter steel pipe temperature monitoring device based on femtosecond fiber optic grating provided by this utility model;

[0022] Figure 2 A schematic diagram illustrating the connection between the small-diameter steel pipe and the femtosecond fiber optic grating sensor network provided by this utility model;

[0023] Figure 3 The front view of the boiler small-diameter steel pipe temperature monitoring device based on femtosecond fiber optic grating provided by this utility model;

[0024] Figure 4 A schematic diagram of the structure of the circumferential member provided by this utility model;

[0025] Figure 5 A diagram showing the state of the mounting base provided by this utility model when connected by screws;

[0026] Figure 6 A structural diagram of a mounting base with two mounting slots provided by this utility model;

[0027] Figure 7 for Figure 1 Enlarged schematic diagram of the structure at point A in the middle;

[0028] Figure 8 The reflection spectrum of the femtosecond fiber Bragg grating sensor provided by this utility model;

[0029] Figure 9The temperature measurement results of the femtosecond fiber optic grating sensor provided by this utility model are shown in the figure.

[0030] In the diagram, 1. Femtosecond fiber Bragg grating sensor network; 2. Signal demodulator; 3. Central processing unit; 4. Alarm; 5. Femtosecond fiber Bragg grating sensor array; 6. Delay fiber; 7. Boiler; 8. Small-diameter steel pipe; 9. Optical fiber; 10. Femtosecond fiber Bragg grating sensor; 11. Ring component; 111. First connector; 1111. Hollow slot; 112. Second connector; 1121. Through slot; 12. Screw; 13. Mounting base; 131. Mounting slot; 14. Screw. Detailed Implementation

[0031] To better understand the structure, functional features, and advantages of this utility model, the preferred embodiments of this utility model are described in detail below with reference to the accompanying drawings:

[0032] Example 1:

[0033] like Figures 1-3 , Figure 7 As shown, this utility model provides a temperature monitoring device for small-diameter steel pipes in boilers based on femtosecond fiber Bragg gratings, comprising:

[0034] Femtosecond fiber optic grating sensor network 1, signal demodulator 2, central processing unit 3, and alarm 4;

[0035] The femtosecond fiber grating sensor network 1 includes an optical fiber 9 and a femtosecond fiber grating sensor array 5. The optical fiber 9 is connected to the femtosecond fiber grating sensor array 5. The femtosecond fiber grating sensor array 5 is wound around multiple small-diameter steel pipes 8 connected to the boiler 7 through a ring member 11 to monitor the temperature of the small-diameter steel pipes 8 in real time and output optical signals.

[0036] The signal demodulator 2 is connected to the output of the femtosecond fiber grating sensor network 1. The signal demodulator 2 is used to demodulate the optical signal and collect the reflection spectrum of the femtosecond fiber grating sensor network 1.

[0037] The central processing unit 3 is connected to the output of the signal demodulator 2 and is used to process the reflection spectrum and extract temperature distribution information.

[0038] The alarm 4 is connected to the output of the central processing unit 3 and is set with a temperature threshold. If the temperature distribution information exceeds the temperature threshold, an alarm is triggered.

[0039] The femtosecond fiber grating sensor array 5 includes multiple femtosecond fiber grating sensors 10. Within each femtosecond fiber grating sensor array 5, multiple femtosecond fiber grating sensors 10 are connected sequentially along the optical path direction, and each small-diameter steel pipe 8 is connected to one femtosecond fiber grating sensor 10.

[0040] The number of femtosecond fiber grating sensors 10 in each of the femtosecond fiber grating sensor arrays 5 is twenty-eight.

[0041] The femtosecond fiber grating sensing network 1 also includes a delay fiber 6, the input end of which is connected to the output end of the femtosecond fiber grating sensing array 5.

[0042] Specifically, the temperature of the small-diameter steel pipes 8 on the top of the boiler 7 is monitored using a femtosecond fiber grating sensor network 1. Specifically, multiple small-diameter steel pipes 8 are connected to both the front and rear sides of the bottom of the boiler 7, and the small-diameter steel pipes 8 on the front and rear sides are symmetrically arranged and have the same number. Each small-diameter steel pipe 8 is connected to a circumferential member 11, allowing the same optical fiber 9 to pass sequentially through each small-diameter steel pipe 8 via the circumferential member 11. Since the optical fiber 9 is connected to a femtosecond fiber grating sensor array 5, which includes multiple femtosecond fiber grating sensors 10, in this embodiment, fourteen small-diameter steel pipes 8 are arranged on both the front and rear sides of the boiler 7. Therefore, the femtosecond fiber grating sensor array 5 includes twenty-eight femtosecond fiber grating sensors 10, and each small-diameter steel pipe 8 is connected to a femtosecond fiber grating sensor 10.

[0043] When the femtosecond fiber Bragg grating sensor 10 in the femtosecond fiber Bragg grating sensor network 1 detects a temperature change in the small-diameter steel pipe 8 in the top bunker of boiler 7, it converts the temperature information into an optical signal and sends it to the signal demodulator 2. The signal demodulator 2 converts the optical signal output from the femtosecond fiber Bragg grating sensor network 1 into an electrical signal, performs filtering, amplification, and noise reduction on the electrical signal to extract spectral feature information. The spectral feature information includes wavelength offset. The spectral feature information output by the signal demodulator 2 is input to the central processing unit 3. The central processing unit 3 processes the spectral feature information, converts the wavelength offset into a temperature value, and thus extracts the temperature distribution information. The temperature of the small-diameter steel pipe 8 in the top bunker of boiler 7 is monitored in real time. When the temperature distribution information exceeds a set threshold, the alarm 4 issues an alarm signal to remind that the temperature of the small-diameter steel pipe 8 in the top bunker of boiler 7 is too high and needs attention.

[0044] The central processing unit 3 uses a peak extraction algorithm to find the center wavelengths of twenty-eight femtosecond fiber optic sensors 10 from the reflection spectrum demodulated by the signal demodulator 2. Using a pre-calibrated wavelength-temperature relationship, the corresponding temperature value is calculated through the center wavelength, thereby obtaining the temperature distribution information of each boiler 7 small-diameter steel pipe 8. The temperature distribution information is compared with the set temperature threshold. If the temperature exceeds the threshold, an early warning is issued.

[0045] The peak extraction algorithm searches for the location with the highest intensity value (i.e., peak value) in the reflectance spectrum data. The wavelength corresponding to the peak value is the center wavelength of the twenty-eight femtosecond fiber optic grating sensors 10. Using a pre-calibrated wavelength-temperature relationship, each extracted center wavelength is substituted into the relationship to calculate the temperature value corresponding to the location of each femtosecond fiber optic grating sensor 10. Based on the calculated temperature values ​​of each femtosecond fiber optic grating sensor 10, combined with the distribution of the femtosecond fiber optic grating sensors 10 on the small-diameter steel pipes 8 of the boiler 7, the temperature distribution information of each small-diameter steel pipe 8 of the boiler 7 is constructed. The obtained temperature distribution information is compared with a pre-set temperature threshold. If there is a temperature value in the temperature distribution information that exceeds the temperature threshold, an early warning mechanism is triggered to issue an alarm to relevant personnel.

[0046] The delay fiber 6 is used to isolate the reflected signals in each small-diameter steel pipe 8 to prevent crosstalk between signals from different small-diameter steel pipes 8.

[0047] Multiple femtosecond fiber Bragg grating sensor arrays 5 are connected in parallel via optical couplers, allowing them to share the same light source. This connection method enables the femtosecond fiber Bragg grating sensor arrays 10 on the fiber 9 to operate independently without interference, avoiding signal crosstalk between the femtosecond fiber Bragg grating sensors 10 on the fiber 9. The delay fiber 6 introduces a time delay to the femtosecond fiber Bragg grating sensor array 5, avoiding time-domain conflicts when the optical signal output by the femtosecond fiber Bragg grating sensor network 1 is demodulated by the signal demodulator 2. The femtosecond fiber Bragg grating sensors 10 in the same femtosecond fiber Bragg grating sensor array 5 are connected sequentially, sharing the same fiber 9 channel, reducing the number of fibers 9 used.

[0048] Inside the boiler's 7 main chamber, optical fiber 9 passes through each small-diameter steel pipe 8. One end of optical fiber 9 extends out of the boiler's 7 main chamber, and the connector leads to the outdoor ambient temperature environment. It is then connected to a common optical cable relay, and then connected to the delay optical fiber 6, signal demodulator 2, central processing unit 3, and alarm 4 to facilitate subsequent temperature detection.

[0049] The refractive index distribution of the femtosecond fiber Bragg grating sensor 10 remains unchanged at high temperatures over long periods, exhibiting strong temperature resistance and meeting the high-temperature sensing requirements of 1000℃. It possesses excellent high-temperature stability, preventing damage to the femtosecond fiber Bragg grating sensor 10 during real-time monitoring using the femtosecond fiber Bragg grating sensor network 1. The femtosecond fiber Bragg grating sensor 10 has high sensitivity, achieving high-precision temperature measurement of ±0.1℃. It can simultaneously monitor the temperature distribution at multiple locations of small-diameter steel pipes 8, obtaining more comprehensive temperature information. The femtosecond fiber Bragg grating sensor 10 has strong anti-interference capabilities and is unaffected by electromagnetic interference. Furthermore, it is small in size, lightweight, and easy to install and maintain.

[0050] As an optional implementation method, such as Figure 4-5 As shown, the circumferential member 11 includes a first connector 111 and a second connector 112. One end of the first connector 111 is hinged to one end of the second connector 112, and the other end of the first connector 111 is connected to the other end of the second connector 112 by fasteners. The connection and disassembly of the first connector 111 and the second connector 112 are completed by tightening and loosening the fasteners. The first connector 111 and the second connector 112 are detachably connected to the mounting base 13 by screws 14. The mounting base 13 has a mounting groove 131, which is arc-shaped, and the inner wall of the mounting groove 131 abuts against the outer wall of the optical fiber 9.

[0051] The fastener includes a hollow groove 1111 on the first connector 111, a through groove 1121 on the second connector 112, and a screw 12. The inner walls of the hollow groove 1111 and the through groove 1121 are both threaded, and the screw 12 is threaded to the hollow groove 1111 and the through groove 1121.

[0052] Specifically, in actual use, the first connector 111 and the second connector 112 are wrapped around the small-diameter steel pipe 8, and the screw 12 is screwed into the hollow groove 1111 in the first connector 111 and the through groove 1121 in the second connector 112, thereby fixing the first connector 111 and the second connector 112 together and locking the fasteners; since the first connector 111 / second connector 112 are detachably connected to the mounting base 13, and the mounting base 13 has a mounting groove 131, which is arc-shaped, the inner wall of the mounting groove 131 can better fit with the outer surface of the optical fiber 9;

[0053] In this embodiment, each mounting base 13 has one mounting slot 131, and an optical fiber 9 is laid in each mounting base 13;

[0054] Since the retaining member 11 and the fastener need to be in contact with the outer surface of the small-diameter steel pipe 8, all components of the retaining member 11 and the fastener are made of high-temperature resistant materials to ensure that the retaining member 11 and the fastener are not affected by the temperature when the temperature monitoring device monitors the temperature of the small-diameter steel pipe 8.

[0055] Example 2

[0056] like Figure 6 As shown, in another embodiment, when there are two mounting slots 131 on each mounting base 13, two optical fibers 9 are laid in each mounting base 13. The number of mounting slots 131 in the mounting base 13 can be set according to the specific actual situation.

[0057] like Figure 8 As shown, Figure 8 The image shows the reflection spectra of femtosecond fiber grating sensors on fourteen small-diameter steel pipes located on one side of the boiler. The horizontal axis represents wavelength, and the vertical axis represents the intensity of the reflection spectrum. Each small-diameter steel pipe is equipped with a femtosecond fiber grating sensor, and each femtosecond fiber grating sensor corresponds to a reflection spectrum, for a total of fourteen reflection spectra. This allows the fourteen femtosecond fiber grating sensors to simultaneously measure the temperature of the fourteen small-diameter steel pipes. When the temperature changes, the center wavelength of the fourteen reflection spectra will change accordingly. By monitoring the change in the center wavelength, the temperature can be measured.

[0058] like Figure 9 As shown, the horizontal axis represents temperature and the vertical axis represents the center wavelength of the reflection spectrum. In a femtosecond fiber grating sensor array, the wavelength change of each femtosecond fiber grating sensor can be converted into a temperature value through linear fitting curves, thereby realizing temperature measurement.

[0059] The above description is merely a preferred embodiment of this utility model and does not constitute any limitation on this utility model. Any person skilled in the art can make many possible variations and modifications to the technical solution of this utility model, or modify it into equivalent embodiments, without departing from the scope of the technical solution of this utility model. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technology of this utility model without departing from the scope of the technical solution of this utility model shall fall within the protection scope of this technical solution.

Claims

1. A temperature monitoring device for small-diameter steel pipes in boilers based on femtosecond fiber optic gratings, characterized in that... ,include: Femtosecond fiber optic grating sensor network (1), signal demodulator (2), central processing unit (3), and alarm (4); The femtosecond fiber grating sensor network (1) includes an optical fiber (9) and a femtosecond fiber grating sensor array (5). The optical fiber (9) is connected to the femtosecond fiber grating sensor array (5). The femtosecond fiber grating sensor array (5) is wound around multiple small-diameter steel pipes (8) connected to the boiler (7) through a ring (11) to monitor the temperature of the small-diameter steel pipes (8) in real time and output optical signals. The signal demodulator (2) is connected to the output end of the femtosecond fiber grating sensor network (1). The signal demodulator (2) is used to demodulate the optical signal and collect the reflection spectrum of the femtosecond fiber grating sensor network (1). The central processing unit (3) is connected to the output of the signal demodulator (2) and is used to process the reflection spectrum and extract temperature distribution information. The alarm (4) is connected to the output of the central processing unit (3) and a temperature threshold is set. If the temperature distribution information exceeds the temperature threshold, an alarm is triggered.

2. The boiler small-diameter steel pipe temperature monitoring device based on femtosecond fiber optic grating according to claim 1, characterized in that, The femtosecond fiber grating sensor array (5) includes multiple femtosecond fiber grating sensors (10). Within each femtosecond fiber grating sensor array (5), multiple femtosecond fiber grating sensors (10) are connected sequentially along the optical path, and each small-diameter steel pipe is connected to one femtosecond fiber grating sensor (10).

3. The boiler small-diameter steel pipe temperature monitoring device based on femtosecond fiber optic grating according to claim 2, characterized in that, The number of femtosecond fiber grating sensors (10) in each of the femtosecond fiber grating sensor arrays (5) is twenty-eight.

4. The boiler small-diameter steel pipe temperature monitoring device based on femtosecond fiber optic grating according to claim 2, characterized in that, The femtosecond fiber grating sensing network (1) also includes a delay fiber (6), the input end of which is connected to the output end of the femtosecond fiber grating sensing array (5).

5. The boiler small-diameter steel pipe temperature monitoring device based on femtosecond fiber optic grating according to claim 1, characterized in that, The circumferential member (11) includes a first connector (111) and a second connector (112). One end of the first connector (111) is hinged to one end of the second connector (112). The other end of the first connector (111) is connected to the other end of the second connector (112) by fasteners. The connection and disassembly of the first connector (111) and the second connector (112) are completed by locking and unlocking the fasteners. The top surface of the first connector (111) / second connector (112) is connected to a mounting base (13). The mounting base (13) has a mounting groove (131) which is arc-shaped. The inner wall of the mounting groove (131) abuts against the outer wall of the optical fiber (9).

6. The boiler small-diameter steel pipe temperature monitoring device based on femtosecond fiber optic grating according to claim 5, characterized in that, The first connector (111) is provided with a hollow groove (1111) and the second connector (112) is provided with a through groove (1121). The inner walls of the hollow groove (1111) and the through groove (1121) are both provided with threads. The fastener is a screw (12) and the screw (12) is threadedly connected to the hollow groove (1111) and the through groove (1121).

7. The boiler small-diameter steel pipe temperature monitoring device based on femtosecond fiber optic grating according to claim 6, characterized in that, The first connector (111) and the second connector (112) are detachably connected to the mounting base (13) by screws (14).

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