The Design And Implementation Of Temperature Field Reconstruction Of The Furnace In Power Plant Coal-Fired Boiler Based On Acoustic Method

The temperature of the furnace in power plant coal-fired boiler is an important operating parameter for inspection and control of the furnace flame. Because of the complexity of the boiler combustion process, the traditional temperature measurement technology is difficult to realize the entire temperature field measurement. The acoustic thermometry as a new temperature measurement technology with non-intrusive, wide range of temperature measurement, simple temperature measurement principle, available online measurement, plays an increasingly important role in furnace temperature measurement. In this paper, the design of the temperature field reconstruction system on acoustic method has been studied based on former research.In this paper, the acoustic sensor is put in front of the acoustic waveguide to ensure it can work under the high-temperature environment; therefore it need make a study of acoustic wave propagation in acoustic waveguide. Combining power plant boiler background noise and results of previous studies, it is determined to choose the linear sweep signal as the acoustic signal, and describe the conduit structure and lining materials. Based on the research, experimental study of acoustic waveguide system has been established. The experiment of acoustic waveguide propagation shows that the introduction of the acoustic waveguide makes the cross-correlation envelope of the transmitted and received signal generate a plurality of peaks, and the use of acoustic waveguide with sound-absorbing material laying pipe wall will eliminate the multipath effects, but there will be a lot of attenuation for the received signal, it is related to waveguide's length and inner diameter and the signal frequency, reasonable choice for acoustic waveguide is important.In order to obtain more accurate the time of flight (TOF), combine the cross-correlation time delay estimation method with correlation peak interpolation algorithms is proposed in this paper, based on MATLAB platform, it is verified with its reduction for the quantization error which is brought by the sampling frequency, assurance of the accuracy of time delay estimation, and it does not affect the real-time performance of time delay estimation.For the sake of verifying the validity of acoustic temperature field reconstruction method, the acoustic temperature measurement system has been established. And experiments for the measurement of TOF and the temperature field reconstruction under the condition of laboratory have been carried out. The experiments for the area to be measured at room temperature without high-temperature region and the presence of high-temperature region have been carried out respectively. The experimental results show that the acoustic temperature measurement system can reflect the temperature distribution of the area to be measured, and sensitive to the position of the high temperature region. And it is pointed out that the use of industrial electric heater for the simulation of the boiler temperature field has some discrepancies with a parabolic function model. Therefore, in the experiment, using the reconstruction algorithm of least square method to reconstruct temperature field gets better results. The establishment of acoustic temperature measurement system and experimental study play an important role on the temperature field reconstruction of the furnace in power plant coal-fired boiler.