Study Of Flame Combustion Temperature Field Reconstruction Based On Radiation Imaging

In the 21st century, energy has become the important material foundation for survival and development. At the same time it relates to the development of the national economy and the sustainable development of the globalization. Coal-fired thermal power generating units play an important role in energy supply in China and this trend would not be changed in a long time. For a large-scale coal-fired boiler, the combustion condition of the flame must be stable and uniform. And the pulverized coal combustion in large boiler is a very complex physical chemical process of heat exchanges. So, monitor the furnace flame temperature is very important to the reliability, safety and economy of boiler operation. The main point of this paper is to explore how to reconstruct the boiler furnace flame two-dimensional temperature field in numerical and experimental simulation.For the numerical simulation part, different models had been built for different radiation inverse problem solving algorithm. Two different temperature field forms, unimodal symmetric and bimodal bias, had been studied. The first method was the Monte Carlo method combined with Tikhonov regularization algorithm. The Monte Carlo method had been used to get READ number and the Tkhonov regularization algorithm had been used to get two-dimensional temperature field. The second method was SVD algorithm, which had been widely used in acoustic method. In this paper, common points of model had been found and then parameters had been reasonable processed, at last a more accurate two-dimensional temperature field was obtained. The third method was particle swarm algorithms. A modified particle swarm algorithms called TSRPSO had been presented. The new method can speed up the rate of convergence, avoid trapping in local optimal solution and improve the reconstruction precision. After simulation, the relative error was putted as the evaluation criterion of discrete elements and root-mean-square error for the whole reconstruction region to analyze and compare the three methods. The results showed, on the basis of reasonable reconstruction model was built, every algorithm can good rebuild temperature field and the unimodal symmetric form was better.For the experimental part, how to use blackbody furnace to calibration CCD camera was studied. In order to obtain the relationship between the grey value of image and the spectral radiant energy, method of getting fitting function by finite points was presented. Polynomial fitting method was used to get third derivative curve-fitting of finite points in three different wave lengths which can lay a foundation for reconstruction of temperature field in the future.