顶置七喷嘴气化炉冷态速度场研究

摘要

In order to investigate the flow field of the top-setting seven-nozzle gasifier,a model gasifier was designed based on the similarity principle with the height of 4 000 mm and the diameter 800 mm based on industrial dry-coal fed gasifiers.The velocity fields were measured using PDA for the top-setting seven-nozzle scheme and top-setting single-nozzle scheme,respectively.The results indicate that the top-setting single-nozzle scheme has a center-jet flow field,but the top-setting seven-nozzle scheme is of a plug-flow like field with much less axial velocity degradation along the radial direction.In addition,the center velocity of the top seven-nozzle scheme reduces more dramatically than that of the top-setting single-nozzle scheme resulting in fewer short-way particles.The top-setting seven-nozzle scheme has much smaller reflux zone and better gas-solid mixing effects that the top-setting single-nozzle scheme.The calculated reflux ratio of particles near the nozzle exit positions of the top-setting seven-nozzle scheme is higher than that of the top-setting single-nozzle scheme,which indicates that the top-setting seven-nozzle scheme can effectively enhance the gas-solid mixing and improve the carbon conversion efficiency.%为研究顶置七喷嘴气化炉流场情况,基于相似准则设计并模拟工业规模干粉气化炉条件,采用激光多普勒动态分析仪(PDA)在高4 000 mm、直径800 mm的模型炉中测定了顶置七喷嘴的速度场分布,并与单喷嘴速度场进行对比.结果表明:单喷嘴偏向于中心射流,而顶置七喷嘴轴向速度沿径向分布速度剪切小,更倾向于平推流,且顶置七喷嘴中心轴向速度衰减快,颗粒不易“短路”.此外,相比单喷嘴而言,顶置七喷嘴回流区域更小且中心气固混合效果更好.而通过计算出的回流比结果表明,项置七喷嘴在喷嘴出口附近的回流比较高,能有效促进气化剂与燃料的混合,提高气化碳转化率.