Simulation Research On Acoustic Propagation Of Acoustic Thermometry In Furnace

Furnace temperature field in the plant boiler is an important factor for safe and economical operation of the boiler and energy saving and emission reduction. Acoustic thermometry, as an advanced non-contact temperature measurement, has advantages of real-time online monitoring and full-field measurement, and has good prospect of application in temperature field measurement of boiler furnace. On the one hand, the exact reconstruction of the furnace temperature field needs the exact acoustic transit time, on the other hand, acoustic wave bending caused by furnace temperature field and flow field should be considered when using temperature field reconstruction algorithm. This paper studies the bending effects by furnace temperature field and flow field, and the effect on the acoustic wave propagation by installing acoustic pipes to protect acoustic transmitters and receivers, which provides references for furnace acoustic thermometry.According to the characteristics of furnace temperature field and flow field, temperature filed and flow field model is set up. The paper embarks from the theory of sound wave propagation, based on finite element multi-physical field analyzing software Comsol Mutiphysics, and uses the ray model to simulate the bending effects on the acoustic wave propagation path by temperature field and flow field, respectively and collectively. Quantitative analysis of temperature field and flow field are derived respectively. Acoustic pipes of different types are modeled and their effects on wave propagation of source signals at different frequencies in frequency-domain. And the results are verified by experiment on the acoustic experimental platform.By simulation, visualization results are obtained of the bending effects on the acoustic wave propagation path by furnace temperature field and flow field. Results show temperature field has a greater impact on the bending of the acoustic wave propagation path than flow field, but in the fields near the furnace wall where temperature is much lower, the effect of flow filed cannot be ignored. By further research, an algorithm which is easy to implement has been provided to calculate the acoustic wave propagation path of the acoustic wave in temperature field and flow field, which also improves temperature reconstruction accuracy. By simulation research on acoustic pipes, the appropriate type of acoustic pipe is determined and experimental platform of acoustic thermometry is set up. Hot experiment is carried out in the power plant and experiment results verify the correctness of the simulation results. Above research provides reference and advice for furnace acoustic thermometry.