Quantitative measurement of the stability of a pulverized coal fired flame through digital image processing and statistical analysis

The stability of pulverized coal flames is a well-known problem in the power industry. Unstable flames often lead to lower combustion efficiency, higher pollutant emissions, and other operational problems. Many methods are available for flame monitoring and characterization, but very few are suitable for flame stability monitoring. This paper presents a method for assessing flame stability continuously and quantitatively by introducing a term named numerical indicator of flame stability based on digital image processing. This numerical indicator combines the statistical characteristics of four flame parameters which are derived from the flame images. To evaluate the effectiveness of the proposed method, the numerical indicator of a pulverized coal flame during a routine unit "turning off" process was determined on a 600 MWth coal-fired supercritical unit. Experimental results suggest that the flame stability at different stages of the turning off process is correctly quantified with the numerical indicator.