1. Fasten Group, Wuxi 214433, China
2. Post-Doctoral Research Station of Materials and Engineering, Nanjing University, Nanjing 210008, China
3. Jiangyin Excen Broaden Polymer Co., Ltd., Wuxi 214446, China
摘要： 分布式光纤温度传感系统(distributed temperature sensing，DTS)是基于拉曼光谱对温度敏感的效应，可以实现长距离分布式温度监测，特别适用于火灾报警、高温液体泄漏和低温气体泄漏等应用场景。但对于常温介质，如化工管道中输送的强腐蚀性溶液，因管道腐蚀发生渗漏时，渗漏介质温度与周围环境温度没有太大差别，此时采用DTS测温技术很难识别渗漏事件的发生。为解决常温下强酸溶液管道或储罐渗漏检测的问题，提出了一种基于光纤传感的酸溶液介质渗漏监测技术。设计了一种新颖的酸溶液自感知特种光缆结构，与泄漏电缆相比，不需要消耗电能，不容易发生误报，精准定位、敷设简单，可实现管道全线多点泄漏检测。光缆外护套材质采用耐碱不耐酸的特殊材料，由尼龙、氢氧化镁、氢氧化铝和少量色母粒组成，能够被一定质量分数的酸溶液迅速溶解，与泄漏点处的酸溶液发生化学中和反应并放热，从而引发感测光纤中后向散射的拉曼光谱发生变化，使感测光缆的温度能够升高5 ℃以上。传感光缆连接DTS系统，系统采用基于反斯托克斯光和斯托克斯光双路解调方法，能够精确计算出传感光纤中各个位置处的温度值。因此，当特种光缆与管道同沟敷设后，某一位置若发生酸溶液渗漏，引起该位置上的光缆温度升高，根据色散补偿和温度校准后的反斯托克斯光和斯托克斯光的比值变化就可以判断出是否发生酸液渗漏事件。该技术不仅能解决酸溶液运输和存储过程中渗漏监测报警的工程化应用问题，而且不受弱酸或碱溶液的误报干扰，节能环保，能够精准检测出强腐蚀性酸溶液渗漏事件，提升危化品的数字智能化安全监测水平。
关键词：渗漏检测；光纤传感；危化品；应急管理
Abstract：Distributed Temperature Sensing System (DTS) is based on the effect of Raman spectrum on temperature sensitivity. It can realize long-distance distributed temperature monitoring, especially suitable for fire alarm, high-temperature liquid leakage, low-temperature gas leakage and other application scenarios. However, for normal temperature media, such as highly corrosive solutions transported in chemical pipelines, when corrosion occurs in the pipeline infiltration, there is basically no temperature change between the leakage location and the surrounding environment. At this time, DTS temperature measurement technology is difficult to identify the occurrence of leakage events. In order to solve the problem of leakage detection of strong acid solution pipelines or tanks under normal temperature, in this paper, a technology based on optical fiber sensing to detect the leakage of acid solution medium was proposed. A novel self-sensing structure of acid solution was designed. Compared with leaking cable, it does not need to consume electricity and is not easy to cause a false alarm. Precise positioning and simple laying. Multi-point leakage detection can be realized across the pipeline. Fiber optic cable outer sheath material is alkali resistant and acid-resistant material, composed of nylon, magnesium hydroxide, aluminum hydroxide and a small number of colors masterbatch. It can be dissolved quickly by hydrochloric acid with the certain mass fraction. Exothermic chemical neutralization reaction occurs. Then the Raman spectrum of backscattering in the sensor fiber is changed, and the temperature of the sensor fiber can be increased by more than 5℃. The sensing fiber optic cable is connected to the DTS system, and the system adopts the dual demodulation method based on anti-stokes light and stokes light to calculate the temperature value of each position in the sensing fiber. Therefore, when the special optical cable and pipeline are laid in the same ditch, if acid solution leakage occurs in a certain position, resulting in the temperature rise of the point. After the dispersion compensation and the temperature calibration, the acid leakage event can be determined, according to the ratio change between the anti-stokes light and the stokes light. This technology not only solves the problem of engineering application of leakage detection and alarm in the transportation and storage of acid solution but also avoids the interference of false alarm of weak acid or alkali solution, saving energy and protecting the environment. It can accurately detect the leakage of the highly corrosive acid solution and improve the digital intelligent safety monitoring level of hazardous chemicals.
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