Research Of Three-Dimensional Temperature Fields Construction In Furnace Based On Feature Matching

Power plant boilers'temperature fields directly affect combustion stability and pollutant emissions so the study of temperature fields in furnace has significance for boiler control and combustion optimization. Numerical simulation and acoustic method are widely used to rebuild the temperature fields. The former can reconstruct a three-dimensional temperature field with a longer time, and the latter algorithm is simple, but three-dimensional temperature field reconstruction just started. Jn order to reconstruct the three-dimensional temperature field in a rapid way, feature matching method will be applied to combine two temperature reconstruction ways. Thus, the study includes three parts:1. CFD simulation method is introduced at first with flow, combustion and radiation heat transfer models during the combustion process. A tangentially boiler is selected to be the simulation object. Then, the simulation results reliability is verified from the qualitative and quantitative aspects.2. The feature matching method to reconstruct the furnace temperature field is introduced. Based on the actual operation of boilers, the load, excess air ratio, secondary air distribution, coal distribution and coal quality (calorific value) are chosen as one-level features.30 simulations of the boiler in different operation conditions are used to study the relationship between one-level features and temperature fields which is the basis of interpolation method to get an initial three-dimensional temperature field. Meanwhile, flying time as a two-level feature, is applied in two temperature correction methods which are location translation method and location compression method, to raise the adaptability when temperature center moves. The location compression method is obvious scientifically for correcting the initial three-dimensional temperature fields based on the simulation results.3. In order to improve the accuracy of the temperature field obtained offset information using the acoustic method, acoustic path tracking method in temperature and velocity fields that based on the forward deploying triangles and Snell law for moving mediums is introduced. The bending effects in tangentially temperature fields and velocity fields that from CFD simulation are discussed where the two-level feature are involved. The simulation results show that bending effects in tangentially temperature field is more obvious than in velocity fields which is the foundation of improving the accuracy of temperature field reconstruction.