同轴四通道喷嘴气流式雾化特性影响因素研究

Study on air-blast atomization characteristics influencing factors of a proposed coaxial four-channel nozzle

提出一种新型同轴四通道喷嘴——由内到外采用气-液-气-液设置,最外环液体可以将合成气和氧气隔离,大幅降低喷嘴出口温度,可望延长气化炉中喷嘴使用寿命。为研究喷嘴雾化效果的影响因素,以水和空气为介质,利用马尔文激光粒度分析仪对同轴四通道喷嘴的气流式雾化液滴索特平均直径进行实验研究。发现对雾化效果影响程度从大到小依次为通道三、通道四、通道二和通道一;增大通道二、四液量分配比可以降低雾化粒径;增大外环液膜厚度会增大雾化粒径;通道一、三气量分配比对雾化颗粒的影响是非单调性的,雾化粒径先增大后减小。基于实验结果进行数值分析,拟合获得了同轴四通道喷嘴雾化液滴粒径关系式。

A new proposed coaxial four-channel nozzle with a gas-liquid-gas-liquid arrangement from the center towards the wall is investigated.The liquid stream in the outer channel can isolates the syngas and oxygen in operation;the outlet temperature of the nozzle is consequentially lowered,and then its service life in gasifier is increased.Water-air system is used as the experimental medium,and the influencing factors of the nozzle on the air-blast atomization are studied by analyzing the Sauter mean diameter D_(32) with the Malvern laser particle size analyzer.The sequence of the influences on atomization from high to low is channel 3,channel 4,channel 2 and channel 1.The atomized droplet size reduces with an increasing liquid volume distribution ratio of channel 2 to channel 4 while increases with the increasing of the outermost liquid film thickness.The effect of the gas distribution ratio of channel 1 to channel 3 on the atomized droplets is non-monotonic,i.e.the droplet size increases first and then decreases.In addition,an empirical formula for estimating the droplet size of the coaxial four-channel nozzle was obtained based on the numerical analysis of experimental results.