Research On Control Method Based On Boiler Flame Image Signal Of Power Station

For large coal-fired boilers,it is very important to monitor the working state of suspension combustion for reliability,security and economic barometer of boilers. The burning process of pulverized coal boiler is a kind of very complex suspension combustion that its working condition is very unstable.And the security of boilers is mainly decided by the stability of flame.To prevent the explosive event of boilers, coal powder must be completely burnt.If the burning process is unstable or the temperature image is asymmetrical in boilers,it is very easy to get terrible results, and the efficiency of boilers will be synchronously reduced greatly.Therefore,the temperature image in furnace is the key to judge the burning state of a furnace,and regulate working parameters of boilers.Enhancing the capacity of judgment, prediction and fault diagnosis in burning process,and making operators to get clearer image,we research on the technology of image processing for furnaces flame emphatically.Although two-dimension temperature image cannot nicely reflect temperature changes in the furnace space along the altitude direction,it can reflect the distributive characteristics of the flame in two-dimension space.If CCD camera is installed appropriately,it can provide important information such as the flame burning state. Acquired temperature fields from the image provide temperature references to operators,and then they can supervise for further combustion operation,which has very important meaning for safety operation and combustion diagnosis in the plant. This paper proposed the principle of the colorimetric algorithm for temperature measure and error analysis,and also provides realization methods.In this paper,the noise source of image is analyzed according to the characteristic of system.There is a great deal of dynamic and stochastic noise in the burning process of the furnace flame.These noise signals must be eliminated.Fast median filtration method based on the characteristics of furnace flame is designed. The new median filtration method can directly calculate the median value without sort. In order to obtain clear flame,Temperature-Hue and Pseudo-color are discussed by the technology of image processing.Basing on the analyses of existing diagnosing techniques of combustion,this paper presents an evaluation technique of the flame combustion state Kohonen self-adaptive neural network.The input variables of neural network are the combustion parameters that symbolize flame image.And this method classifies the output into three grades:fire close to Furnace wall,combustion unnatural,combustion natural.This paper also introduces the application of the developed flame image processing system in boiler in detail.At last,a two-step fuel control system,which takes the radiation temperature as an intermediate controlled parameter is designed to improve the control character of boiler.Control model and respective control strategy is introduced and simulation calculation result is demonstrated in this article.