【作者】 王富强；

【导师】 李争起；

【作者基本信息】 哈尔滨工业大学 ， 热能工程， 2007， 硕士

【摘要】 本文对中心给粉旋流煤粉燃烧器的不同一次风扩口位置和一次风扩口角度下的气固两相流动特性进行了试验研究。采用相似模化的原理,设计并建立了气固两相试验台系统,采用三维相位多普勒颗粒分析仪对燃烧器出口区域的气固两相流场进行了测量。中心给粉燃烧器在两种扩口位置下,从燃烧器出口至x/d=0.5的截面,颗粒体积流量呈双峰分布,在燃烧器中心形成较高的颗粒浓度分布。与径向浓淡燃烧器和蜗壳燃烧器相比,中心给粉燃烧器靠近中心线的颗粒体积流量的峰值位置更加靠近燃烧器的中心线,靠近边壁颗粒体积流量的峰值要低。实际扩口位置的燃烧器在中心线处的气固两相轴向速度衰减速度快;从x/d=1.5的截面开始,出现了颗粒穿越了部分回流区。扩口外伸的燃烧器中心回流区的尺寸大,回流区的起点距离喷口较近,更适合于燃用贫煤等较差煤质。实际扩口位置燃烧器中心回流区的尺寸相对小一些,中心回流区的起点距离喷口稍远,因此实际扩口位置的中心给粉燃烧器适合燃烧烟煤等含有较高挥发分的较好煤质。在两种扩口角度下,在燃烧器中心线附近存在着较大的颗粒体积流量和颗粒相对数密度,此区域烟气温度高,轴向RMS脉动速度大,与回流区的对流换热强烈,有利于颗粒的加热、着火和稳定燃烧。一次风扩口角度为0°时,燃烧器的中心回流区的尺寸大,中心回流区的起点距离喷口近,适合于燃用贫煤等较差煤质。一次风扩口角度为25°时,燃烧器的中心回流区的尺寸相对小一些,含有多个内部回流区,回流区的起点距离喷口稍远,适合燃烧烟煤等含有较高挥发份的较好煤质。两种扩口位置和两种扩口角度下的中心给粉燃烧器的气固两相轴向RMS脉动速度分布、径向RMS脉动速度分布和切向RMS脉动速度以及粒径分布规律基本相同。更多还原

【Abstract】 The experimental study of the characteristics of gas-particle two phase flows with the centrally-fuel-rich swirl coal combustion (CSCC) burner at two different positions and two different angles of primary air outlet are carried out.The gas-solid two phase testing system is designed according to similarity-simulation principle, and the gas-particle two phase flow field is measured by Phase Doppler Anemometry system.With the two different positions of CSSS burner, we find, from the burner jet to x/d=0.5 cross section, particle relative volume fraction profiles for air and particles have two crest zones. In the centerline, there is a large volume fraction distribution. Compared to Radial Bias Combustion burner and Volute burner, the position of the near burner relative volume fraction crest zone is much nearer to the burner center, and the peak of the relative volume fraction near the wall is much smaller.Axial mean velocities for air and particles with the actual position reduce faster and particles penetrate some central recirculation zone (CRZ) beginning from x/d=1.5 cross section. The size of CRZ is bigger and the begging of CRZ is closer to the burner jet with the stretched primary outlet, so the CSCC burner with stretched primary outlet fits combust low grade coal like lean-coal. The size of CRZ is smaller and the beginning of CRZ is far to the burner jet with the actual primary outlet, so the CSCC burner with actual primary outlet fits combust high grade coal with high volatile like lean-coal.The two different angles of CSSS burner form a high particle volume flux in the near centerline region. In this region, there is a high gas temperature and the axial RMS velocities are large.We find that from the burner jet to x/d=0.5 cross section, particle relative volume fraction profiles for air and particles have two crest zones; in the centerline, there is a large volume fraction distribution. Compared to Radial Bias Combustion burner and Volute burner, the position of the near burner relative volume fraction crest zone is much nearer to the burner center ,and the peak of the relative volume fraction near the wall is much slower ,the heat convection with CRZ is intensive, these factors are advantageous to heating particles ,combustion and flame stability.The size of CRZ is bigger and the begging of CRZ is closer to the burner jet with 0°primary outlet, so the CSCC burner with 0°primary outlet fits combust low grade coal like lean-coal; The size of CRZ is smaller and the beginning of CRZ is far to the burner jet with 25°primary outlet, so the CSCC burner with 25°primary outlet fits combust high grade coal with high volatile like lean-coal.The CSCC burners with two different positions and two different angles of primary air outlet have the similar distributions of axial RMS velocities, tangential RMS velocities, radial RMS velocities and particle mean diameter.更多还原