基于二次–凸扫频声源的声学法烟气速度测量研究

Study on Acoustic Method of Flue Gas Velocity Measurement Based on Quadratic-Convex Frequency Sweeping Sound Source

燃煤电厂中烟气速度测量的准确性是电厂的安全生产和效率提升的基础。本文采用一种新颖的二次–凸扫频声学驱动模式,对燃煤电厂脱硝后烟气流速进行了长周期的测量研究。通过对脱硝烟道内部的背景噪声分析,确定了二次–凸声源频率范围为4 kHz~8 kHz,并通过互相关时延估计算法计算声波飞渡时间。经过理论分析和现场实验,验证了该驱动模式的有效性。通过对测试数据的功率谱密度(PSD)、均方根误差(RMSE)和标准偏差(SD)的分析,对基于三种驱动模式的测速结果的准确性和稳健性进行了定量评估。现场实验结果表明,基于二次–凸扫频驱动模式的RMSE和SD值均小于0.3 m/s。与传统采用的线性扫频方法相比,所提出的声波驱动方案可以显著提高烟气速度测量的准确性和稳健性。

The accuracy of flue gas velocitymeasurements in coal-fired power plants is fundamental to the safe productionand efficiency improvement of the plants. In this paper, a novel quadratic-convexfrequency sweeping driven mode drive mode is used to study the long-periodmeasurement of flue gas flow velocity afterdenitrification in coal-fired power plants. By analyzing the background noiseinside the denitrification flue, the frequency range of the quadratic-convexfrequency sweeping sound source is determined to be 4 kHz~8 kHz, and theacoustic fly-through time is calculated by a mutual-off time delay estimationalgorithm. After theoretical analysis and field experiments, the effectivenessof this driving mode was verified. The accuracy and robustness of thevelocimetry results based on the three driving modes were quantitativelyevaluated by analyzing the power spectral density (PSD), root mean square error(RMSE) and standard deviation (SD) of the test data. The field experimental results show that the RMSE and SD values based on the quadratic-convexfrequency sweeping driven mode are less than0.3 m/s. The proposed acoustic wave driving scheme can significantlyimprove the accuracy and robustness of the flue gas velocity measurementscompared with the traditionally adopted linear sweep method.