Research On Flame Characteristic And Its Detection Technology

There are two kind of flame in industry internally fired boiler. One is boiler-body flame the other is flame from burner nozzles. In order to judge the operation status of boiler, workers need to know whether the burner nozzle is burning or not under the background flame of boiler-body. In industry we define "peek" as phenomenon that the detector take the boiler-body flame as burner-nozzle's flame .We define "leak" as phenomenon that the detector can not probe the burner-nozzle's flame though boiler-body flame. These two phenomena will damage boiler if they happen too frequently. The essential of the phenomena is the detector cannot judge the overlapping status of flame. So how to judge the overlapping status of flame is the focus of the problem.This thesis introduces the foundation and development of flame detection technology and summarizes the application of photoelectric technology in flame detection. Through comparing and analyzing of photoelectric detecting circuit, an efficient signal detecting circuit is established based on the data obtained from experimentation. A precision voltage programmable filter is used to deal with the signal. Using TMS320LF2407A DSP as controller, a hardware system for photoelectric transforming, signal dealing and sampling is designed. As for software design, it realizes the function of system controlling, frequency analyzing and communication with PC using assembly language. At the same time graph of real time data is displayed on PC using VC++ as programming tool. Based on the detection method of flame flicking frequency, a new method for judge the overlap status of two flames is proposed. The method use FFT (Fast Fourier transform) to analyze frequency spectrum of flame flicking frequency and build the flame overlapping criterion then compare the field data with the criterion to know whether the two flames overlap or not. This method is a new solution for "peek" and "leak" phenomena.Furthermore advice for deep research and optimizing design is also presented.