Study Of Combustion Temperature Field Reconstruction Based On Radiation Energy

Temperature monitoring of boiler furnace has a significant meaning for the safe running, economic efficiency, energy saving and emission reduction of the boiler.In recent years, the non-contact measurement method using radiation energy to detect the temperature filed has become the most widely used method. But conventional detection methods like colorimetry and infrared method can just obtain the cumulative temperature of flame and cannot give the analysis temperature distribution result including the gaseous medium. To obtain accurate analytical temperature distribution including the gas medium, the techniques which utilize border radiant energy from the furnace to rebuild one-dimension and two-dimension were studied and explored in this paper.On the basis of simplified radiation transfer equation and combined with the calculation formula of absorptivity and emissivity of carbon dioxide and water vapor, the forward one-dimensional model of radiation transfer was built. It was then transformed into the inverse model aimed at rebuilding one-dimensional temperature distribution in the detection direction using border multi-wavelengths. The BFGS algorithm was applied to solve the inverse problem model. The results of numerical experiments showed this method can accurately rebuild the one-dimensional temperature distribution in the combustion chamber, and by increasing the number of light channels and choosing suitable flame emissivity, the reconstruction accuracy can be improved.For the reconstruction of two-dimensional temperature distribution in the furnace, two-dimensional radiation transfer model was firstly built. The radiation energy distribution coefficient (READ) was calculated by the Monte Carlo method. In the numerical experiments, the Tikhonov regularization method was used to rebuild the temperature distribution of a two-dimensional rectangular system full of ash emission, absorption, scattering gas. The results showed that the Tikhonov regularization method could solve the pathological problem of this model and can restore the two-dimensional temperature distribution in the furnace well. Temperature field reconstruction error occurred mainly in the low-temperature region.