基于LCFM的分布式光纤热风管温度检测

Temperature detection of hot air tubes with distributed optical fiber based on light center frequency matching method

为了解决分布式光纤温度传感器在高炉热风管现场出现的温度漂移问题,采用光源中心频率匹配法对其进行了理论推导和实验验证。通过对入射光电流与参考光电流的差值进行检测来实时调整F-P光滤波器的带宽,使滤波器允许通过的频率范围始终包含光源的中心频率,实现滤波器带宽与光源中心频率的匹配。采用频率匹配法使光纤传感器输出的Raman比与距离的曲线在不同环境温度下基本重合,传感器的线性度约为0.52%。结果表明,采用光源中心频率匹配法可减小光纤传感器的温漂,且不影响传感器的线性度。将中心频率匹配法与分布式光纤温度传感技术相结合对于实现热风管表面温度的有效测量具有一定的意义。

In order to solve drift problem of distributed optical fiber temperature sensorfor detection of blast of hot air tubes, a new solution of light center frequency matching ( LCFM ) method was proposed after theoretical derivation and experimental verification. By measuring the difference between the incident optical current and the reference photo current to adjust F-P light filter bandwidth, filter center frequency can always be kept in pass-band range of the filter. The match of filter bandwidth and light center frequency was achieved. The curves between Raman ratio and distance substantially coincided at different ambient temperatures when using frequency matching method. The linearity of the distributed optical fiber temperature sensor was about 0. 52%. The experimental results show that LCFM method can reduce temperature drift of a fiber optical sensor and does not affect the linearity of the sensor. It is of great significance for achieving effective temperature measurement on hot air tube surface to combined center frequency matching mothod with distributed optical fiber temperature sensing technology.