Experimental Study on Recirculation Zone and Ignition Standoff Distance of HBS-LNSB Ⅲ Swirl Burner
The experimental investigation of recirculation zone and ignition characteristics on a swirl burner were studied.The effects of central air quantity,external secondary air quanti-ty,internal secondary air quantity and swirl intensity of internal secondary air on the size of recirculation zone were investigated.It was found that the change of internal secondary air quantity had the greatest influence on the width of recirculation zone while the change of cen-tral air quantity had the greatest influence on the distance between the recirculation zone and burner.The experimentation results provided a basis for the selection of air distribution for coal combustion with different combustion characteristics.The ignition standoff distance of pulverized coal under various influencing factors was studied.It was found that the ignition standoff distance of free-burning coal is short.In order to avoid burner port burning,the most effective measures are increasing the central air quantity and primary air velocity.Due to the low temperature of furnace,the ignition standoff distance of pulverized coal become longer and the blending ratio of free-burning coal can be increased at low load.For the coal with high ignition temperature,the changes of central air quantity,external secondary air quantity and internal secondary air quantity have obvious regular effects on ignition standoff distance.The influence of swirl intensity of internal secondary air must comprehensively con-sider the influence of air quantity change caused by swirl intensity.The industrial tests of dif-ferent coal ignition standoff distance provide guidance for the selection of burner air distribu-tion.Industrial test on ignition distance and recirculation zone should be carried out when the coal types change greatly in order to find the best choice for burner air distribution.
swirl burnerrecirculation zoneignition standoff distanceswirl intensitycentral air
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