Flame characteristics in a novel petal swirl burner

A three-dimensional (360°) body-fitted coordinate mathematical model to simulate pulverized coal particle combustion in a petal swirl burner (PSB) is first set up to analyze the flame stability and its characteristics. The studies on the flow pattern, the temperature distribution, and the flue gas composition of the flame, the ignition location, and the combustion efficiency of the pulverized coal particle are conducted. The results show that owing to the special geometric design of the PSB, some of the pulverized coal particles leaving the burner can directly enter the radial recirculation zone (RRZ) behind the petal flame stabilizer (PFS) and are immediately ignited and burned in the RRZ, producing a sort of flame that is always on duty behind each petal, which is called the permanent flame. The flame pattern, which is a combination of the main flame and several permanent flames, provides a sufficient heat source for reliable ignition and steady combustion even for the low-volatile coal-firing and turndown capacity operation, and is advantageous to lower NOxNOx emission. Moreover, the mechanisms by which the special flame pattern of PSB can be existed are analyzed. A PSB test was undertaken in a 210-MW power plant boiler to investigate the performance of the PSB with firing of low-volatile pulverized coal. The temperature measurement value along the burner axis is given, in which the temperature distribution and the ignition location are clearly shown.