Application of Distributed Fiber Optic Temperature System in Tunnel Fire Alarms-INNO

Sistem Suhu Serat Optik Terdistribusi Prinsip

Sistem penginderaan suhu serat optik terdistribusi menggunakan dua prinsip pengukuran suhu utama; Efek hamburan Raman dan teknologi refleksi domain waktu optik. Menurut prinsip pengukuran suhu sistem penginderaan suhu serat optik, sistem deteksi terdiri dari modul optik yang terhubung ke kabel serat optik penginderaan, melalui konversi fotolistrik ke dalam perangkat lunak aplikasi, sehingga dapat mewujudkan deteksi suhu.

Prinsip penentuan posisi pengukuran suhu

(1) Efek hamburan Raman dengan prinsip pengukuran suhu serat optik. Saat cahaya merambat di serat, pulsa laser dan molekul serat serta kotoran saling bertabrakan, menghasilkan berbagai jenis cahaya yang dipantulkan, seperti; Hamburan brillouin, hamburan Rayleigh, Mie berhamburan dan Raman berhamburan. Prinsip pengukuran suhu pada a serat optik terdistribusi sistem penginderaan (DTS) adalah efek hamburan Raman. Ketika foton merambat dalam serat optik, foton berinteraksi dengan molekul dalam serat, menghasilkan dua jenis cahaya; Menyalakan cahaya (stokes) dan lampu Anti-Stokes (Anti-Stokes). Intensitas cahaya Stokes tidak bergantung pada perubahan suhu, intensitas cahaya anti-Stokes berhubungan dengan perubahan suhu. Suhu titik mana pun dalam pandu gelombang optik dapat diperoleh dari rasio intensitas sinyal cahaya non-Stokes dengan sinyal cahaya Stokes..

According to the Raman scattering temperature measurement technology and optical time-domain reflection spatial positioning technology, the distributed fiber optic sensing system structure is divided into four modules; optical circuit module, sensing cable, circuit module and application software. The optical module is the core structure of the system, in which the semiconductor laser generates effective laser pulses, which are coupled through the spectral path, reach the temperature sensing fiber, and propagate along the temperature sensing fiber to the measured area. During the propagation of the laser in the fiber optic cable, Raman scattering phenomenon occurs, resulting in Stokes and non-Stokes light, which continues to propagate backward along the temperature-sensitive fiber, and then enters the optical filter through the beam splitter again. The optical filter filters out the other interfering light, removes the Stokes and non-Stokes light, and extracts the two types of light separately. The detector absorbs the extracted Stokes and non-Stokes light, and a photoelectric converter converts the optical signal into an electrical signal. Circuit module will receive the electrical signal processing, through the dual high-speed amplifier, the signal is collected by the high-speed data acquisition system, converted to digital signals, the temperature and positioning information into the host computer, and then the fire and faults to the fire alarm controller, to achieve the alarm function.

(1) Distribute continuous temperature measurement along the line. Sensor sistem penginderaan suhu serat optik terdistribusi didistribusikan di sepanjang kabel serat optik, yang menentukan bahwa teknologi penginderaan suhu serat optik terdistribusi cocok untuk memberikan peringatan pada titik suhu mana pun di terowongan panjang, dengan data pengukuran yang besar, akurasi posisi yang tinggi, pemantauan real-time perubahan suhu sensor di setiap sirkuit di 1 interval m, dan pembagian terowongan menjadi zona proteksi kebakaran sesuai dengan kebutuhan terowongan.

(2) Pengukuran yang stabil dan akurat. Berdasarkan prinsip pengukuran suhu optik, sistem penginderaan suhu serat optik terdistribusi bebas dari interferensi elektromagnetik dan bahaya kebakaran terbuka, dan memiliki keunggulan yang jelas dibandingkan teknologi lainnya. Teknologi penginderaan suhu serat optik terdistribusi mampu mempertahankan kinerja yang stabil di lingkungan pengukuran terowongan jalan raya yang mudah terbakar dan meledak. Laser memancarkan puluhan ribu pulsa laser efektif per detik dan mengeluarkan nilai rata-rata suhu yang diukur ke sistem, yang sebagian besar mengurangi kesalahan, dan kemudian secara manual menentukan dan memverifikasi alarm setelah pra-alarm, yang secara efektif mengurangi alarm palsu dan membuat sistem mengukur secara akurat.

(3) Teknologi canggih. Dalam beberapa tahun terakhir, banyak negara maju (wilayah) di luar sistem penginderaan suhu serat optik terdistribusi telah menggantikan detektor titik api dan detektor kebakaran suhu tetap linier tradisional, dan perkembangan teknologi sudah matang. The application of distributed fiber-optic temperature sensing system to the monitoring system of road tunnels not only does not affect the stability of the data emergency plan of the tunnel comprehensive monitoring system, but also realizes the linkage between the distributed fiber-optic temperature sensing system and other electromechanical systems.

Comparison between fiber optic temperature sensing system and traditional temperature sensing system The detectors applied to tunnel fire are divided into point detectors and wire distributed fiber optic temperature sensing system.

Main features

Distributed fiber-optic relative to the traditional point-type temperature sensors have significant advantages, more adapted to the harsh monitoring environment of the tunnel fire, more and more widely used in the current tunnel fire monitoring detector of two types.

(1) Point-type detector mainly has dual-wavelength or three-wavelength flame automatic detector, the principle is to detect the specific wavelength and spectral range of the open flame, the system set up two or three sensors for receiving different wavelengths, to identify the spectrum and frequency of the flame combustion, to achieve the detection of the fire. Point detectors have fast response time, but they are susceptible to interference from smoke and open flames, as well as omission or false alarms caused by objects blocking the fire source. Point detectors do not provide a continuous measurement of the temperature inside the tunnel and cannot monitor the complete temperature distribution inside the tunnel. Sensornya mudah kotor, mengakibatkan akurasi deteksi yang lebih rendah dan mempengaruhi pengoperasian normal sistem.

(2) Detektor kebakaran linier terutama mencakup: detektor perbedaan suhu pipa udara, kabel penginderaan suhu, detektor perbedaan suhu kawat paduan termal, dan sensor suhu serat optik. Detektor perbedaan suhu pipa udara dan kabel penginderaan suhu adalah pendeteksi awal, yang telah tersingkir dari pasar karena keandalan deteksinya yang rendah, sistem yang tidak stabil, dan ketidakmampuan untuk memenuhi kebutuhan deteksi terowongan saat ini. Detektor suhu kabel paduan termal rentan terhadap interferensi gelombang elektromagnetik dan memiliki frekuensi alarm palsu yang tinggi, dan tidak mampu memantau terowongan berukuran sedang dan ekstra panjang di jalan raya.

Distributed fiber optic temperature sensing system is one kind of wire-type fire detector. Compared with point-type detector and traditional wire-type detector, sistem penginderaan suhu serat optik terdistribusi can accurately determine the location of fire and fire temperature, dengan sensitivitas tinggi, kinerja yang stabil, kemampuan anti-interferensi yang kuat, and realize long-distance monitoring.

Comparison between sistem penginderaan suhu serat optik terdistribusi and traditional temperature sensing system

Design of Tunnel Fire Monitoring System

Due to the difficulties in fighting tunnel fires and serious losses, it is of great significance to set up tunnel fire monitoring and early warning fire fighting system.

The company has independently developed a complete tunnel fire monitoring and early warning system with video fire detectors assisted by distributed fiber-optic fire detectors and fire control linkage.

Video surveillance system The video surveillance system is used to review and confirm the event and provide additional information in case of fire in the tunnel. The video surveillance system consists of a front-end system, a transmission system, a control system and a display system. It distributes, stores and restores the monitored image signals. When detecting the alarm signal from the fiber optic sensor, the monitor can obtain the specific situation of the fire scene (the location of the fire point, the direction and speed of the fire and smoke spreading, and the situation of the people in the tunnel) more clearly and quickly, which is conducive to the rapid judgment of the video monitoring personnel, effective control of the development of the fire, and facilitates the fire fighting and rescue of the fire.

Fire fighting system The fire fighting system is an emergency response to tunnel fires and consists of 4 major systems: ventilation control system, lighting control system, broadcasting system and emergency telephone system. The ventilation control system can effectively control the wind speed, wind direction, carbon monoxide concentration and smoke concentration inside the tunnel, while the lighting control system is used to minimize the visual problems caused by the large brightness difference between the tunnel and the outside world. The broadcasting system is used to disseminate information to the tunnel personnel and to facilitate the evacuation of vehicles and people outside the tunnel in the event of a fire. The emergency telephone system is used in the event of a fire to enable the drivers of vehicles in the tunnel to call for help directly from the outside world.