Cabling rack capable of monitoring cable temperature and methane gas concentration and automatically extinguishing fire

Abstract

The invention provides a cabling rack capable of monitoring cable temperature and automatically extinguishing fire, and relates to the field of cabling racks used in closed areas. The gas guide pipe is arranged above the mounting frame and is connected with the flame-retardant gas bottle through an electric control valve; the air inlet is formed in the top of the mounting frame and corresponds to the air outlet in position; the wiring holes are formed in the two sides of the mounting frame and the side wall between the warehouse channels respectively; the monitoring optical fiber is in communication connection with the distributed optical fiber temperature measurement system and the methane gas monitoring system, obtains the temperature in the cabling rack and the methane gas concentration in the surrounding environment, is connected with the master control center and is used for controlling the flame-retardant gas bottle to be opened or closed. The temperature and the methane gas concentration in the mounting rack are monitored through the monitoring optical fiber, the space coordinate L of an abnormal point is determined according to the time when the master control system receives the feedback signal of the monitoring optical fiber, the cabling rack where the abnormal point is located is accurately judged, rapid alarming and accurate fire extinguishing are achieved, and the cable safety level is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable tray used in enclosed areas, in particular to a cable tray capable of monitoring cable temperature and methane gas concentration and automatically extinguishing fire and a cable routing device. BACKGROUND

[0002] Cable tray, also known as cable bridge, is a special equipment used for supporting and managing optical cables and electrical cables in communication machine rooms, base stations and data centers. Its core function is to standardize cable laying path, support horizontal, vertical and multi-layer separated wiring, and facilitate subsequent expansion and maintenance. In the process of daily maintenance and management of optical cables and electrical cables, cable safety is of great importance. Once overload, short circuit, aging or high temperature working environment occurs, fire may occur, which will cause irreparable economic loss and casualties. Therefore, how to effectively monitor cable safety and respond quickly at the first time after discovering fire is an important issue in the field of cable safety.

[0003] With the rapid development of information technology, data centers have increasingly high requirements for cable management. Indoor cable tray, as an important part of cable management system, is gradually developing towards intelligence and automation. Traditional cable tray mainly provides physical support, while modern cable tray needs to have functions such as classified routing, real-time monitoring, fault alarm and automatic fire extinguishing to cope with potential fire risks and other special needs.

[0004] In addition, in environments with high methane (CH4) gas concentration such as coal mine underground, natural gas / methane facilities, petroleum and chemical facilities, and enclosed industrial spaces, special attention should be paid to the explosion-proof of electrical equipment and the fireproof design of cables, because methane is a flammable and explosive gas (explosion limit is 5%-15% by volume). It has been reported that in these scenarios, cable overheating has led to explosions. In the face of such scene requirements, current solutions mainly focus on improving cable explosion-proof level, using a large amount of flame-retardant materials, and using metal pipes to isolate cables. However, none of these can fundamentally improve the ability to discover and quickly handle accidents on site.

[0005] In summary, modern indoor environments such as data centers and dangerous working condition environments such as coal mine underground have provided new functional positioning and strong new technology development needs for cable trays. This not only reflects the importance of safety in related industries, but also is the trend of the application of intelligent technology in disaster prevention and disaster resistance. However, current common cable trays lack clear functional positioning and necessary functional design in cable safety monitoring and environmental methane gas detection. People focus more on the functional design of cable installation and the development of simple support functions of cable trays. The existing technology cannot meet the functional positioning needs of cable trays in current application scenarios. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a cable tray capable of monitoring cable temperature and methane gas concentration and automatically extinguishing fires. It utilizes optical fibers and a distributed optical fiber temperature measurement system to monitor the temperature within the cable tray in real time, and to rapidly and accurately extinguish fires in areas where fires occur. Simultaneously, it uses optical fibers and a methane gas monitoring system to monitor and provide early warnings of methane gas concentration in the environment. When the concentration reaches a set threshold, an alarm device is activated to notify relevant personnel for timely action. This solves the problems of traditional cable trays having limited functionality and insufficient methane gas monitoring capabilities in relatively enclosed spaces, hindering cable safety.

[0007] Specifically, on the one hand, the present invention provides a cable tray that can monitor cable temperature and methane gas concentration and automatically extinguish fires. The system includes a mounting frame with several parallel channels for cable passage, and further includes: Flame-retardant cylinder: located outside the mounting bracket; Gas delivery pipe: Located above the mounting frame, the gas delivery pipe is connected to the flame-retardant cylinder through an electrically controlled valve, and the bottom of the gas delivery pipe has several gas outlet holes; Air inlet: The air inlet is located on the top of the mounting bracket and its position corresponds to the plurality of air outlets, so that the flame-retardant gas in the air guide tube can flow out through the plurality of air outlets and enter the mounting bracket through the plurality of air inlets; Cable routing holes: These are respectively opened on both sides of the mounting frame and on the side walls between each of the compartments, for the passage of monitoring optical fibers. The monitoring optical fibers enter through the cable routing holes on one side of the mounting frame, pass through each compartment, and exit through the cable routing holes on the other side of the mounting frame. The monitoring optical fiber is communicatively connected to the distributed optical fiber temperature measurement system and the methane gas monitoring system, respectively, to obtain the temperature in each compartment of the mounting frame and the concentration of methane gas in the surrounding environment. The distributed optical fiber temperature measurement system and the methane gas monitoring system are electrically connected to the central control center, and the central control center is electrically connected to the electrically controlled valve to control the opening or closing of the flame-retardant cylinder.

[0008] The method for determining abnormal temperature rise points in the distributed optical fiber temperature measurement system is as follows: periodically injecting probe light pulses into the detection optical fiber through an optical time-domain reflectometry device and capturing backscattered light signals in real time; The distributed optical fiber temperature measurement system synchronously demodulates the temperature gradient distribution along the transmission path of the monitoring optical fiber. When a temperature abrupt change signal exceeding a preset threshold is detected, the propagation speed of the optical signal in the medium, c / n, can be obtained based on the propagation speed c of the optical signal in vacuum and the refractive index n of the optical fiber. Simultaneously, combined with the time delay Δt of the Raman scattering signal, the system further... The defined time-domain analytical algorithm calculates the spatial coordinates L of the abnormal temperature rise point.

[0009] Furthermore: the method for measuring temperature in the distributed optical fiber temperature measurement system is as follows: transmitting wavelengths of λ into the monitoring optical fiber. AS , λ S The anti-Stokes beam and the Stokes beam exhibit a frequency shift Δν under the influence of temperature; let Planck's constant be h and Boltzmann's constant be k. B Using the Stokes component I in Raman scattering spectrum S (T) and anti-Stokes component I AS The difference in light intensity (T) can be used to establish a physical relationship: ; By establishing a quantitative model for the intensity ratio of two wavelengths, and based on the exponential relationship: ; Temperature calculations are performed to achieve the measurement of the distributed temperature field T.

[0010] Further: The method for determining methane concentration by the methane gas monitoring system is as follows: the methane gas monitoring system drives the signal source to output a modulation signal with frequency f, which drives the wavelength of the light source of the methane monitoring system to periodically scan the characteristic absorption peak of methane in the near-infrared band, and the light source of the methane monitoring system simultaneously outputs reference light and probe light; The reference light enters a reference gas chamber containing a known concentration of methane gas. After being absorbed by the methane, it is converted into an electrical signal by a photodetector PIN and sent to a lock-in amplifier. The lock-in amplifier detects the first harmonic signal. The reference gas chamber and the tail end of the optical fiber inside the gas chamber are connected to a collimating lens to form an optical coupling system. The reference light passes through the detection fiber and is collimated by the lens at the entrance of the reference gas chamber before being uniformly incident into the reference gas chamber. It then propagates along a preset path within the reference gas chamber, making full contact with methane molecules, and is finally output from the collimating lens and fiber optic pigtail at the exit of the reference gas chamber. The probe light enters the gas chamber through a monitoring fiber and is collimated by a lens at the gas chamber inlet before being uniformly incident inside the gas chamber. It then propagates along a preset path within the gas chamber, making full contact with methane molecules, and is output from the collimating lens and fiber optic pigtail at the gas chamber outlet. After passing through the methane gas inside the gas chamber, the probe light carries concentration information and is then converged to the return fiber via an optical coupling system composed of the fiber optic pigtail and collimating lens. The return fiber transmits the probe light back to the photodetector PIN and converts it into an electrical signal, which is then input into a lock-in amplifier to detect the second harmonic signal. The output signal of the reference gas cell is divided with the output signal of the gas cell in a divider to eliminate common-mode interference. The ratio of the second harmonic signal to the first harmonic signal is used as the transmitted light intensity I to eliminate laser intensity fluctuation errors. Let the incident light power be I, the optical path length through the wiring frame be S, the absorption coefficient of the light signal in methane gas with concentration C be α, and the transmitted light intensity I exhibit an exponential decay relationship with the gas concentration. ; This allows us to determine the concentration C of methane gas.

[0011] Furthermore: Both the distributed fiber optic temperature measurement system and the methane gas monitoring system are connected to the monitoring fiber optic cable through optical couplers and circulators, and are controlled by a time-sharing control unit to achieve time-sharing operation and real-time monitoring of temperature and gas concentration; The pulsed light emitted by the temperature control monitoring system of the distributed optical fiber temperature measurement system and the detection light emitted by the methane monitoring system of the methane gas monitoring system are controlled by a time-division control unit to achieve time-division entry control of the coupler, so as to ensure that the two signals emitted and received by the distributed optical fiber temperature measurement system and the methane gas monitoring system do not interfere with each other. The pulsed light of the distributed optical fiber temperature measurement system is controlled by the time-division control unit to enter the coupler, and then enters the monitoring optical fiber through the circulator. The monitoring optical fiber transmits the back Raman scattering signal excited by the pulsed light back to the circulator in real time, and then enters the temperature monitoring signal processing unit for signal analysis through the optical switch. The optical switch and the temperature monitoring signal processing unit are synchronously controlled by the time-division control unit. The detection light of the methane gas monitoring system is controlled by the time-division control unit to enter the coupler, then enters the monitoring optical fiber through the circulator and is incident on the methane gas in the gas chamber. The light is then focused by the optical coupling system to the return optical fiber and enters the methane monitoring signal processing unit for signal analysis and processing. The methane monitoring system light source and the methane monitoring signal processing unit are synchronously controlled by the time-division control unit.

[0012] Furthermore, the mounting bracket is provided with gas cylinder supports on both sides, and the gas cylinder supports include at least two parallel arc-shaped claws for mounting the gas-retardant cylinders.

[0013] Furthermore, the cross-section of the air outlet is cross-shaped.

[0014] Furthermore: the mounting bracket includes an outer frame for the cable tray and an inner frame for the cable tray that is inserted into the outer frame from the side, and the outer frame for the cable tray and the inner frame for the cable tray are fixedly connected by positioning screws.

[0015] Furthermore, the gas chamber in the methane gas monitoring system is placed in the environment to be tested, and the gas chamber is provided with an inlet and an outlet to ensure that the methane gas concentration in the gas chamber is consistent with the methane gas concentration in the environment to be tested.

[0016] The present invention also discloses a cable routing device that can monitor cable temperature and methane gas concentration and automatically extinguish fire, comprising several cable routing racks, each of the compartments of each mounting rack being provided with a shield; the several mounting racks are arranged in a row to form a cable routing rack group, adjacent mounting racks are connected to each other by connectors, and each compartment is interconnected to form a complete cable channel; The monitoring optical fiber enters the mounting frame through the wiring hole on the first side of the wiring frame assembly, passes through the wiring hole on the other side of the mounting frame to the second side of the wiring frame assembly, and then passes through the wiring hole of the adjacent mounting frame on the second side of the wiring frame assembly, and so on. The monitoring optical fiber is arranged in an S-shape in the wiring frame assembly.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention monitors the temperature inside and outside the cable tray by using an optical fiber. A detection light pulse is periodically injected into the detection optical fiber using an optical time-domain reflectometry device, and backscattered light signals are captured in real time. When the distributed optical fiber temperature measurement system detects a temperature surge exceeding a preset threshold, it indicates that the cables in the cable tray are overheating and pose a fire risk. After receiving the signal from the distributed optical fiber temperature measurement system, the central control system opens the control valve, allowing gas from the fire-retardant cylinder to enter the mounting bracket through the air inlet, thus extinguishing or controlling the fire immediately and buying valuable time for subsequent firefighting measures. On the other hand, for cable routing devices composed of several cable trays, the spatial coordinates L of the temperature anomaly point can be determined by combining the time delay Δt of the Raman scattering signal and the time when the central control system receives the feedback signal from the monitoring fiber. Since the length of the monitoring fiber in each mounting bracket is fixed, the cable tray where the fire is located can be accurately determined by the spatial coordinate point L, thereby achieving precise fire extinguishing and fast response speed, which greatly improves the cable safety level.

[0018] 2. This invention employs a methane gas monitoring system that simultaneously outputs a reference light and a probe light from its light source. The reference light enters a reference gas chamber, where a lock-in amplifier detects the first harmonic signal at frequency f. Simultaneously, the probe light emitted from the light source is injected into the measurement gas chamber via a circulator to measure the methane concentration. The lock-in amplifier detects the first and second harmonic components at two modulation frequencies. The first harmonic component is primarily caused by light intensity modulation, and its amplitude is proportional to the average power of the light source. The second harmonic component contains gas concentration information.

[0019] The amplitude of the first harmonic is primarily determined by the periodic variation in light intensity accompanying wavelength scanning: the light intensity of the methane monitoring system's light source fluctuates synchronously with the periodic modulation of the driving current / temperature, and this fluctuation is independent of the methane concentration. However, the value of the first harmonic lies in the fact that it, like the second harmonic, is affected by the same light intensity fluctuations. Therefore, the output signal of the reference gas cell is divided with the output signal of the measurement gas cell in a divider to eliminate common-mode interference such as light source power fluctuations and optical transmission losses. The second harmonic carries gas concentration information. When the light source wavelength scans past the 1.665 μm characteristic absorption peak of methane, the amount of light absorbed by methane changes non-linearly with wavelength. According to the Fourier transform principle, this non-linear response generates a second harmonic, and the amplitude of the second harmonic is proportional to the methane concentration. By using the ratio of the second harmonic to the first harmonic as the light transmission intensity I, the error of laser light intensity fluctuation is further eliminated, thereby more accurately calculating the methane concentration information in each cable tray. When the methane concentration exceeds the set threshold, the main control system opens the electronically controlled valve, allowing the flame-retardant gas in the flame-retardant cylinder to enter the cable tray, diluting the methane gas and effectively preventing explosions or fires.

[0020] 3. The path setting of the S-shaped monitoring fiber optic cable ensures that the monitoring fiber optic cable can measure the temperature inside the cable tray and also detect the ambient temperature. If a fire breaks out outside the cable tray in the environment, the release of flame-retardant gas can also protect the cables inside the cable tray, providing a reliable guarantee for subsequent rescue.

[0021] 4. The distributed fiber optic temperature measurement system and the methane gas monitoring system in this invention, through innovative design of optical and electrical paths and time-sharing control system, enable simultaneous measurement of temperature inside and outside the cable tray and ambient methane gas concentration by sharing the same monitoring fiber. This not only greatly expands the function of traditional cable trays, but also controls system and deployment costs. This is a more efficient and safer cable management solution.

[0022] By integrating a distributed fiber optic sensing system, the cable tray can monitor the temperature and other indicators of the cables within in real time, and also promptly detect abnormal changes in the concentration of gases such as methane in the air. Furthermore, each compartment within the cable tray has an inner wall shielding cover; the application of electromagnetic shielding technology effectively prevents electromagnetic interference and ensures signal stability. The introduction of fire extinguishing technology is also extremely important. The cable tray is equipped with compressed gas cylinders and electrically controlled valves that can automatically release flame-retardant gas to quickly extinguish flames when abnormal conditions are detected within the cable tray. This intelligent design significantly improves safety and enables rapid response to fires, reducing the risk level.

[0023] 5. By periodically injecting probe light pulses into the optical fiber sensing medium using an optical time-domain reflectometry (OTDR) module, when identifying temperature anomalies and methane gas concentration anomalies, the propagation speed of the light signal in the medium can be obtained as c / n based on the propagation speed c of the light signal in vacuum and the refractive index n of the optical fiber. Combined with the time delay Δt of the Raman scattering signal, the coordinates of the anomaly point can be accurately calculated, and it can be determined which cable tray is experiencing the anomaly. This provides an effective guarantee for accurately locating the source of a fire and shortening the troubleshooting time. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the cable tray disclosed in this invention; Figure 2 This is a schematic diagram of the overall structure of the cable tray disclosed in this invention from another direction; Figure 3 This is a bottom view of the cable tray outer frame disclosed in this invention; Figure 4 This is a schematic diagram of the inner frame structure of the cable tray disclosed in this invention; Figure 5 This is a fire extinguishing flowchart for the cable tray disclosed in this invention; Figure 6 This is a schematic diagram of the working principle of the external optical path component—circulator—of the distributed temperature monitoring system disclosed in this invention; Figure 7 This is a time-sharing working principle diagram of the temperature monitoring system and methane gas monitoring system for the cable tray disclosed in this invention; Figure 8 This is a schematic diagram of the working principle of the methane gas monitoring system for cable trays disclosed in this invention; Figure 9 This is a schematic diagram of the wiring device and S-shaped monitoring fiber optic cabling disclosed in this invention.

[0025] The markings in the attached diagram are: 1. Flame-retardant cylinder; 2. Cylinder bracket; 3. Electrically controlled valve; 4. Cable routing hole; 5. Air inlet; 6. Outer frame of the cable tray; 7. Inner frame of the cable tray; 8. Shielding cover; 9. Gas duct; 10. Cable tray fixing hole; 11. Battery compartment and local control center; 12. Gas outlet; 14. Inner frame fixing holes; 15. Distributed temperature monitoring system; 151. Temperature monitoring system light source; 152. Temperature monitoring signal processing unit; 153. Circulator; 154. Fiber optic sensor array; 16. Methane gas monitoring system; 161. Signal source; 162. Frequency multiplier; 163. Photodetector PIN; 164. Reference gas chamber; 165. Methane monitoring system light source; 166. Gas chamber; 167. Divider; 168. A / D converter; 169. Computer; 170. Methane monitoring signal processing unit; 171. Beam splitter; 172. Optical coupler; 180. Lock-in amplifier; 28. Central control center; 29. ​​Monitoring fiber optic cable; 30. Communication fiber optic cable; 200. Time-division control unit; 300. Optical switch; 400. Optical coupling system; 500. Return fiber optic cable. Detailed Implementation

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0027] like Figures 1 to 4 As shown, a cable tray capable of monitoring cable temperature and automatically extinguishing fire includes a mounting frame. The mounting frame includes an outer frame 6 and an inner frame 7. The inner frame 7 is inserted into the outer frame 6 from the side, and screws are inserted into the fixing holes 14 of the inner frame to fix the outer frame 6 and the inner frame 7 together. The inner frame 7 has several parallel channels for cables to pass through. The side of the mounting bracket is provided with a gas cylinder support 2. The gas cylinder support 2 includes at least two parallel arc-shaped claws for placing the flame-retardant cylinder 1. The gas outlet of the flame-retardant cylinder 1 is connected to an electrically controlled valve 3, which can control the outflow of the flame-retardant gas in the flame-retardant cylinder. The flame-retardant gas is preferably carbon dioxide or nitrogen. The opening size of the electrically controlled valve 3 can be controlled by the central control center 28 according to the received temperature and gas concentration information.

[0028] The electrically controlled valve 3 is connected to a gas guide pipe 9, which is mounted on the top of the mounting frame. The bottom of the gas guide pipe 9 has several cross-shaped air outlets 12. Each compartment on the top of the mounting frame has an air inlet 5, the number and position of which correspond to the number of air outlets 12. This allows the gas ejected from the gas guide pipe 9 to enter each compartment of the mounting frame through the air inlets 5 for fire extinguishing, methane gas dilution, and other operations. The cross-shaped air outlets 12 ensure a sufficient gas output rate and facilitate entry into each compartment through the air inlets 5. Combined with… Figure 9As shown, the present invention also discloses a cable routing device that can monitor cable temperature and automatically extinguish fires. It consists of several cable routing frames arranged in a row to form a cable routing frame group, with the compartments of adjacent mounting frames aligned with each other. The side of the outer frame 6 of the cable routing frame is provided with cable routing frame fixing holes 10. Adjacent mounting frames can be fixed to each other by inserting U-shaped connectors into the cable routing frame fixing holes 10. Each mounting frame has wiring holes 4 on both sides for the monitoring optical fiber 29 to pass through. After entering the mounting frame from the first side, the monitoring optical fiber 29 passes over each compartment. Wiring holes 4 are also provided on the side walls of adjacent compartments (not shown in the figure), so that the monitoring optical fiber 29 can pass through each compartment and exit from the second side of the mounting frame. Then, the monitoring optical fiber 29 enters through the wiring hole 4 on the second side of the adjacent mounting frame and exits from the first side of the wiring frame, and so on. Finally, the monitoring optical fiber 29 is arranged in an S-shape in the horizontal direction, so that a single monitoring optical fiber 29 can pass through all wiring frames and the length of the monitoring optical fiber 29 in each wiring frame is equal. This makes it convenient to calculate the corresponding coordinates of the detection optical fiber 29 corresponding to the anomaly point by the response time difference of the monitoring optical fiber 29, thereby accurately determining the wiring frame where the anomaly point is located.

[0029] The central control center 28 and each battery compartment and local control center are electrically connected via cables. In some embodiments, the central control center 28 is also connected to each battery compartment and local control center 11 sequentially via a communication optical fiber 30 outside the mounting frame. Each battery compartment and local control center 11 controls one or more electrically controlled valves 3 around it. Figure 5 As shown, the central control center 28 simultaneously connects to two monitoring systems: the distributed fiber optic temperature measurement system 15 and the methane gas monitoring system 16, using a time-sharing control method. The two monitoring systems share a single monitoring fiber optic cable 29 for signal acquisition. The monitoring fiber optic cable 29 is controlled by the central control center 28 using a time-sharing principle, intermittently providing control signal transmission and environmental parameter sensing feedback to both systems.

[0030] A fire early warning system based on distributed optical fiber temperature measurement technology is embedded in the cable tray architecture. Temperature sensing is achieved by detecting the intensity ratio of Stokes light waves to anti-Stokes light waves in the Raman scattering effect. The specific implementation includes: acquiring the cable tray temperature through the distributed optical fiber temperature measurement system, which includes an optical fiber sensor array 154 as a distributed sensing carrier, deployed along the cable tray extension path in a continuous spatial sampling manner. The distributed optical fiber temperature measurement system uses optical time-domain reflectometry (OTDR) to determine the ignition point location L, and periodically injects probe light pulses into the optical fiber sensing medium through an ODR analysis module, such as... Figure 6As shown, specifically, the temperature monitoring system emits a probe light pulse from the light source 151, which is input to port 1 of the circulator 153 and output from port 2 of the circulator 153, entering the fiber optic sensing array 154. Based on the Raman scattering effect, the Raman backscattered light signal carrying temperature information returns to port 2 of the circulator 153, and then is output from port 3 of the circulator 153, entering the signal processing unit 152 for processing. Based on the temperature-sensitive characteristics of the Stokes and anti-Stokes light intensity ratio, a fully distributed temperature field measurement is achieved. According to the propagation speed of the light signal in vacuum c and the refractive index n of the fiber, the propagation speed of the light signal in the medium can be obtained as c / n. Simultaneously, combined with the time delay Δt of the Raman scattering signal, through... The defined time-domain analytical algorithm accurately calculates the spatial coordinates L of the abnormal temperature rise point. Since the distance of the monitoring fiber optic cable 29 in each cable tray is constant, the location of the abnormal temperature rise point can be determined based on this spatial coordinate L. The distributed fiber optic temperature measurement system is equipped with an analysis unit that can synchronously demodulate the temperature gradient distribution along the fiber optic transmission path. When a temperature jump signal exceeding a preset threshold accompanied by a characteristic gas spectral absorption peak is detected, the electronically controlled valve 3 is activated to open the fire-retardant cylinder 1 for fire extinguishing.

[0031] The specific method for measuring temperature is as follows: Wavelengths λ are emitted into the optical fiber. AS , λ S The anti-Stokes beam and the Stokes beam exhibit a frequency shift Δν under the influence of temperature. Let Planck's constant be h and Boltzmann's constant be k. B Using the Stokes component I in Raman scattering spectrum S (T) and anti-Stokes component I AS The difference in light intensity (T) satisfies the following physical relationship: Among them, I AS (T) / I S (T) and (λ) S / λ AS ) 4 It exhibits a linear correlation and is related to exp(-hΔν / (k B T)) constitutes an exponential function relationship. The core innovation of this invention lies in establishing a quantitative model of the dual-wavelength light intensity ratio, based on the aforementioned exponential relationship: Temperature calculations are performed to achieve high-precision distributed temperature field T reconstruction.

[0032] This invention also utilizes a methane gas monitoring system 16 for real-time monitoring of methane gas concentration. This system can monitor the methane gas concentration in each cable tray in real time, thereby preventing fires or even explosions caused by excessive methane gas concentration in the cable trays. The methane gas monitoring system involved in this invention employs the principle of spectral absorption, based on Beer-Lambert's law. Methane absorbs light of specific wavelengths, and methane gas has a characteristic absorption peak in the near-infrared band; in this embodiment, 1.665 μm is used. Let the power of the incident light be I0, the optical path length through the cable tray be S, the absorption coefficient of the light signal in methane gas of concentration C be α, and the transmitted light intensity exhibit an exponential decay relationship with the gas concentration. The methane gas monitoring system of this invention modulates the methane monitoring system light source 165 via a signal source 161, causing its output wavelength to periodically scan the methane absorption peak. The methane monitoring system light source 165 outputs reference light and probe light. The reference light enters a reference gas chamber 164 containing methane gas of known concentration. The methane gas absorbs the reference light, and the light signal output from the reference gas chamber is converted into an electrical signal by a photodetector PIN 163, which is then input to a lock-in amplifier 180 for detection. The temperature of the methane monitoring system light source 165 is controlled by detecting the first harmonic as a feedback signal, ensuring that its wavelength is precisely locked to the gas absorption peak. The modulated probe light is transmitted via optical fiber to a gas chamber 166, where it interacts with the methane gas. The light signal carrying gas concentration information is then transmitted to the photodetector 163, which converts it into an electrical signal, which is then sent to the lock-in amplifier 180. The reference signal output from the reference gas chamber 164 and the probe signal output from the gas chamber 166 are divided in a divider 165 to eliminate the influence of power fluctuations during light source or light transmission on the measurement results. After passing through the last cable tray, the monitoring fiber optic cable 29 continues to extend forward to the gas chamber 166, which is located in the environment to be tested. The gas chamber 166 has an air inlet and an air outlet, which are located at asymmetrical positions in the gas chamber 166 to ensure that the methane gas concentration in the gas chamber 166 is consistent with the methane gas concentration in the environment to be tested.

[0033] The first and second harmonic components of the two modulation frequencies were detected. The first harmonic component is mainly caused by light intensity modulation, and its amplitude is proportional to the average power of the light source. The second harmonic component contains gas concentration information. Using the ratio of the second harmonic to the first harmonic as the system output can effectively eliminate the error caused by common-mode noise such as laser intensity fluctuations. After the above processing, the signal containing gas concentration is sent to the A / D converter 166, converted into a digital quantity, and sent to the computer 167 for processing, display, and printing.

[0034] When the methane gas monitoring system 16 detects that the methane gas level is too high or about to reach the explosion threshold, the central control center 28 will activate the emergency mechanism, promptly issue an early warning in the control room, and coordinate the release of early warning information to the work scenario and the slow release of flame-retardant gas from the flame-retardant cylinder 1 throughout the area, thus gaining time for the safe handling of the crisis. Simultaneously, the central control center 28 is electrically connected to the alarm device, immediately alerting staff to promptly initiate maintenance.

[0035] like Figure 8 As shown, signal source 161 outputs a modulation signal with frequency f, driving the wavelength of light source 165 in the methane monitoring system to periodically scan the characteristic absorption peak of methane in the near-infrared band. Light source 165 simultaneously outputs reference light and probe light: the reference light enters a reference gas chamber 164 with a known methane concentration, is absorbed by methane, and is converted into an electrical signal by photodetector PIN163, which is then sent to lock-in amplifier 180 to detect the first harmonic signal with frequency f. Meanwhile, the probe light passes through circulator 153 and is injected into gas chamber 166 to measure the methane concentration. The probe light returning from the gas chamber is converted into an electrical signal by photodetector PIN163 and then input to lock-in amplifier 180 to detect the second harmonic signal. Lock-in amplifier 180 detects the first and second harmonic components at the two modulation frequencies. The first harmonic component is mainly caused by light intensity modulation, and its amplitude is proportional to the average power of the light source. The second harmonic component contains gas concentration information.

[0036] The amplitude of the first harmonic is mainly determined by the periodic change in light intensity accompanying wavelength scanning: the light intensity of the methane monitoring system's light source fluctuates synchronously with a frequency f due to the periodic modulation of the driving current / temperature, and this fluctuation is independent of the methane concentration. The value of the first harmonic lies in the fact that it and the second harmonic are affected by the same light intensity fluctuations; for example, when the light source power suddenly increases, their amplitudes will increase synchronously. Therefore, the output signal of reference cell 164 is divided with the output signal of cell 166 in divider 167 to eliminate common-mode interference such as light source power fluctuations and optical transmission losses. Lock-in amplifier 180 detects the first and second harmonics of the signal. The ratio of the second harmonic to the first harmonic is used as the transmitted light intensity I to further eliminate the error of laser light intensity fluctuations. The second harmonic carries concentration information; when the light source wavelength scans past the 1.665μm characteristic absorption peak of methane, the amount of light absorbed by methane changes non-linearly with wavelength (the slope change rate is larger near the absorption peak). According to the Fourier transform principle, this nonlinear response will generate a second harmonic, and the amplitude of the second harmonic is proportional to the methane concentration.

[0037] Let the power of the incident light be I0, the optical path length through the wiring frame be S, the absorption coefficient of the light signal in methane gas with concentration C be α, and the transmitted light intensity I decrease exponentially with the gas concentration: This allows us to determine the concentration C of methane gas.

[0038] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A cable tray capable of monitoring cable temperature and methane gas concentration and automatically extinguishing fires, comprising a mounting frame, wherein the mounting frame has a plurality of parallel channels for cable passage, characterized in that, Also includes: Flame-retardant cylinder (1): disposed outside the mounting bracket; Gas pipe (9): It is set above the mounting frame. The gas pipe (9) is connected to the gas-resistant cylinder (1) through an electric control valve (3). Several gas outlet holes (12) are opened at the bottom of the gas pipe (9). Air inlet (5): The air inlet (5) is located on the top of the mounting frame. The position of the air inlet (5) corresponds to the plurality of air outlets (12), so that the flame-retardant gas in the air guide pipe (9) can flow out through the plurality of air outlets (12) and enter the mounting frame through the plurality of air inlets (5). Wiring holes (4): are respectively opened on both sides of the mounting frame and on the side wall between each of the compartments, for the monitoring optical fiber (29) to pass through. The monitoring optical fiber (29) enters through the wiring hole (4) on one side of the mounting frame, passes through each compartment, and exits through the wiring hole (4) on the other side of the mounting frame. The monitoring optical fiber (29) is connected to the distributed optical fiber temperature measurement system (15) and the methane gas monitoring system (16) respectively, and is used to obtain the temperature in each compartment of the mounting frame and the concentration of methane gas in the surrounding environment. The distributed optical fiber temperature measurement system (15) and the methane gas monitoring system (16) are electrically connected to the central control center (28) respectively. The central control center (28) is electrically connected to the electric control valve (3) to control the opening or closing of the gas-resistant cylinder (1).

2. The cable tray as described in claim 1, capable of monitoring cable temperature and methane gas concentration and automatically extinguishing fire, characterized in that: The method for determining the abnormal temperature rise point by the distributed optical fiber temperature measurement system (15) is as follows: periodically injecting detection light pulses into the detection optical fiber through an optical time domain reflection device and capturing backscattered light signals in real time; The distributed optical fiber temperature measurement system (15) synchronously demodulates the temperature gradient distribution along the transmission path of the monitoring optical fiber (29). When a temperature jump signal exceeding a preset threshold is detected, the propagation speed of the optical signal in the medium is obtained as c / n based on the propagation speed c of the optical signal in vacuum and the refractive index n of the optical fiber. Simultaneously, the time delay Δt of the Raman scattering signal is combined with... The defined time-domain analytical algorithm calculates the spatial coordinates L of the abnormal temperature rise point.

3. The cable tray as described in claim 2, capable of monitoring cable temperature and methane gas concentration and automatically extinguishing fire, characterized in that: The distributed optical fiber temperature measurement system (15) measures temperature by transmitting wavelengths λ into the monitoring optical fiber. AS , λ S The anti-Stokes beam and the Stokes beam exhibit a frequency shift Δν under the influence of temperature; let Planck's constant be h and Boltzmann's constant be k. B Using the Stokes component I in Raman scattering spectrum S (T) and anti-Stokes component I AS The difference in light intensity (T) can be used to establish a physical relationship: ； By establishing a quantitative model for the intensity ratio of two wavelengths, and based on the exponential relationship: ； Temperature calculations are performed to achieve the measurement of the distributed temperature field T.

4. The cable tray as described in claim 1, capable of monitoring cable temperature and methane gas concentration and automatically extinguishing fire, characterized in that: The method for determining the methane concentration by the methane gas monitoring system (16) is as follows: the methane gas monitoring system (16) drives the signal source (161) to output a modulation signal with a frequency of f, which drives the wavelength of the methane monitoring system light source (165) to periodically scan the characteristic absorption peak of methane in the near-infrared band. The methane monitoring system light source (165) simultaneously outputs reference light and probe light. The reference light enters a reference gas chamber (164) containing a known concentration of methane gas. After being absorbed by the methane, it is converted into an electrical signal by a photodetector PIN (163) and sent to a lock-in amplifier (180). The lock-in amplifier (180) detects the first harmonic signal. The ends of the optical fibers inside the reference gas chamber (164) and the gas chamber (166) are connected to collimating lenses to form an optical coupling system (400). The reference light passes through the detection fiber (29), and after being collimated by the lens at the entrance of the reference gas chamber (164), it is uniformly injected into the reference gas chamber (164), and propagates along a preset path in the reference gas chamber (164), making full contact with methane molecules, and then is output from the collimating lens and fiber optic pigtail at the exit of the reference gas chamber (164). The probe light enters the gas chamber (166) through the monitoring fiber (29), and after being collimated by the lens at the entrance of the gas chamber (166), it is uniformly injected into the interior of the gas chamber (166) and propagates along a preset path in the gas chamber (166), making full contact with methane molecules. Then it is output from the collimating lens and fiber optic pigtail at the outlet of the gas chamber (166). After passing through the methane gas in the gas chamber, the probe light carries the concentration information and is then converged to the return fiber (500) by the optical coupling system (400) composed of the fiber optic pigtail and the collimating lens. The return fiber transmits the probe light back to the photodetector PIN (163) and converts it into an electrical signal, which is then input into the lock-in amplifier (180) to detect the second harmonic signal. The output signal of the reference gas cell (164) is divided with the output signal of the gas cell (166) in the divider (167) to eliminate common-mode interference. The ratio of the second harmonic signal to the first harmonic signal is used as the transmitted light intensity I to eliminate the error of laser light intensity fluctuation. Let the power of the incident light be I0, the optical path length of the light through the wiring frame be S, the absorption coefficient of the light signal in methane gas with a concentration of C be α, and the transmitted light intensity I have an exponential decay relationship with the gas concentration. ； This allows us to determine the concentration C of methane gas.

5. The cable tray as described in claim 1, capable of monitoring cable temperature and methane gas concentration and automatically extinguishing fire, characterized in that: The distributed fiber optic temperature measurement system (15) and the methane gas monitoring system (16) are both connected to the monitoring fiber optic cable (29) through an optical coupler (172) and a circulator (153), and are controlled by a time-sharing control unit (200) to achieve time-sharing operation and real-time monitoring of temperature and gas concentration. The pulsed light emitted by the temperature control monitoring system light source (151) of the distributed optical fiber temperature measurement system (15) and the detection light emitted by the methane monitoring system light source (165) of the methane gas monitoring system (16) are controlled by the time-division control unit (200) to achieve time-division entry control of the coupler (172), so as to ensure that the two signals emitted and received by the distributed optical fiber temperature measurement system (15) and the methane gas monitoring system (16) do not interfere with each other; The pulsed light of the distributed optical fiber temperature measurement system (15) is controlled by the time-division control unit (200) to enter the coupler (172), and then enters the monitoring optical fiber (29) through the circulator (153). The monitoring optical fiber (29) transmits the back Raman scattering signal excited by the pulsed light back to the circulator (153) in real time, and enters the temperature monitoring signal processing unit (152) through the optical switch (300) for signal analysis. The optical switch (300) and the temperature monitoring signal processing unit (152) are synchronously controlled by the time-division control unit (200). The detection light of the methane gas monitoring system (16) is controlled by the time-division control unit (200) to enter the coupler (172), then enters the monitoring optical fiber (29) through the circulator (153) and is incident on the methane gas in the gas chamber (166). It is then focused by the optical coupling system (400) to the return optical fiber (500) and enters the methane monitoring signal processing unit (170) for signal analysis and processing. The methane monitoring system light source (165) and the methane monitoring signal processing unit (170) are synchronously controlled by the time-division control unit (200).

6. The cable tray as described in claim 1, capable of monitoring cable temperature and methane gas concentration and automatically extinguishing fire, characterized in that: Both sides of the mounting frame are provided with gas cylinder brackets (2), and the gas cylinder brackets (2) include at least two parallel arc-shaped claws for mounting the gas-retardant cylinders (1).

7. The cable tray as described in claim 1, capable of monitoring cable temperature and methane gas concentration and automatically extinguishing fire, characterized in that: The cross-section of the air outlet (12) is cross-shaped.

8. The cable tray as described in claim 1, capable of monitoring cable temperature and methane gas concentration and automatically extinguishing fire, characterized in that: The mounting bracket includes an outer frame (6) of the cable tray and an inner frame (7) of the cable tray that is inserted into the outer frame (6) from the side. The outer frame (6) and the inner frame (7) of the cable tray are fixedly connected by positioning screws.

9. The cable tray as described in claim 4, capable of monitoring cable temperature and methane gas concentration and automatically extinguishing fire, characterized in that: The gas chamber (166) in the methane gas monitoring system (16) is placed in the environment to be tested. The gas chamber (166) has an inlet and an outlet to ensure that the methane gas concentration in the gas chamber (166) is consistent with the methane gas concentration in the environment to be tested.

10. A cable routing device capable of monitoring cable temperature and methane gas concentration and automatically extinguishing fires, characterized in that: The system includes several cable trays as described in any one of claims 1-9, each of the trays having a shield (8) in each compartment; the trays are arranged in a row to form a cable tray group, adjacent trays are connected to each other by connectors, and each compartment is interconnected to form a complete cable channel; The monitoring optical fiber (29) enters the mounting frame through the wiring hole (4) on the first side of the wiring frame group, passes through the wiring hole (4) on the other side of the mounting frame to the second side of the wiring frame group, and then passes through the wiring hole (4) of the adjacent mounting frame on the second side of the wiring frame group. In this way, the monitoring optical fiber (29) is arranged in an S-shape in the wiring frame group.

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