燃烧场内多路径温度与H_2O浓度的在线检测

Multipath Real-Time Measurement of Temperature and H_2O Concentration for Combustion Diagnosis

可调谐二极管激光吸收光谱(TDLAS)技术以其响应速度快、灵敏度高、非接触等优点得到了广泛应用。基于该技术以燃烧参数诊断为目标,使用一台窄线宽、波长可调谐的分布反馈式(DFB)激光器产生扫描1395.51 nm和1395.69 nm两条H2O吸收谱线的激光,经1×4光纤分束器实现燃烧场内4条平行路径中温度和H2O浓度的同时在线检测,采用分段温度梯度测量方法补偿低温段对高温区域测量的影响,使中心燃烧区域温度的测量精度由原来的10%提高到3%以内。通过控制空气流量,测量三种不同燃烧状态下中心燃烧区域的温度与H2O浓度变化,结果表明,三种燃烧状态的中心燃烧区域温度差约为80 K,H2O浓度与温度变化情况一致,验证了实验系统和数据处理方法的稳定性和可行性,为下一步燃烧层析诊断及燃煤锅炉燃烧效率优化提供了支持。

Tunable diode laser absorption spectroscopy（TDLAS） has been widely used in combustion diagnosis because of its excellent characteristics such as fast response, high sensitivity and non-intrusive feature. The system uses a pair of H2 O absorption lines（1395.51 nm and 1395.69 nm） by a narrow linewidth and tunable wavelength distributed feedback（DFB） laser. The laser is divided into four beams by a 1×4 optical fiber splitter to measure the temperature and H2 O concentration simultaneously. Sectional measurement is proposed to improve the temperature accuracy from 10% to 3% compared with K-type thermocouple. What′s more, the temperature and H2 O concentration at combustion center position are measured while the ratio of air and fuel changes. The results show that combustion temperature of central area at the three kinds of combustion state has difference of about 80 K, and the H2 O concentration change is well consistent with temperature change, demonstrating the stability and feasibility of the experimental setup and the data processing method. This provides strong support for tomographic diagnosis and optimization of combustion efficiency of coal-fired boiler in the future.