新型旋流-颗粒床耦合分离设备的三维气相流场分布

采用五孔球探针测量了无尘负荷条件下新型旋流-颗粒床耦合分离设备内复杂的三维气相流场，分析了内部流场特点。结果表明:在不同入口气速条件下，无量纲切向速度与无量纲轴向速度的分布形态基本类似；切向速度分布轴对称性较好，旋流中心与几何中心基本重合；切向速度沿轴向呈减小趋势，沿径向的分布则与常规旋风分离器不同；在入口环形空间内，切向速度在0°~180°方位区间内增大，而在180°~270°方位区间内减小；旋流空间内轴向速度整体方向向下，局部螺旋上升气流集中在筒-锥连接段270°方位；径向速度分布的规律不明显，在直筒段径向速度数值与轴向速度在同一数量级，且对气流方向有重要影响；在排气管入口截面处，外旋流方向与入口气速密切相关。各截面平均静压沿轴向呈增大趋势，结合动压场分布可判断出筒-锥连接段气体流量显著减小，部分气体螺旋向上进入颗粒床，在实际操作过程中可能会导致粉尘堆积。由于内置颗粒床的影响，设备内部的气相整体呈螺旋向下的旋流运动，内外旋流边界不太明显。排气管口处短路流、顶灰环与返混现象消失。

THREE-DIMENSIONAL GAS-PHASE FLOW FIELD IN A COUPLED CYCLONE WITH BUILT-IN GRANULAR BED FILTER

The five-hole probe was used to investigate three-dimensional gas flow field in a new cyclone-granular bed coupling separation equipment. The results show that the distribution of dimensionless tangential velocity is similar to that of configurations axial velocity under different inlet gas velocities; the axial symmetry of tangential velocity distribution is good, and the center of swirl is coincident with the center of geometry; the tangential velocity is decreased along the axial direction, but the radial distribution is different from that of the conventional cyclone; in the entrance annular space, the tangential velocity is increased in the range of 0°- 180°, but is decreased in the range of 180°- 270°; in the swirl space, the local spiraling air is concentrated at the 270° direction of the cylinder-cone connection; the law of radial velocity distribution is not obvious, and the radial velocity is the same order as the axial velocity in the straight tube section and has an important influence on the direction of the air flow; at the inlet section of exhaust pipe, the direction of external swirl flow is closely related to the inlet gas velocity. Combined with the distribution of the dynamic pressure field, it can be concluded that the gas flow in the cylinder-cone connection section is obviously decreased, and some gas is spiraled up into the granular bed, which may lead to the accumulation of dust in the actual operation. Due to the influence of the built-in particle bed, the whole gas phase inside the device moves in a spiral downward swirl flow, and the inner and outer boundary of the swirl flow is not very obvious. Because of the phenomena of short-circuit flow, the top ash ring and the back mixing are disappeared at the outlet of exhaust pipe.