工业炉旋风预燃器煤粉颗粒运动轨迹

Kinematic Trajectory of Pulverized Coal Particles in the Cyclone Precombustor of Industrial Furnace

在预燃器冷态模型流场内 ,考虑气流曳引力、重力和 Magnus旋转升力 ,建立颗粒的运动微分方程 ,并考察颗粒与壁面相互碰撞过程 .采用龙格库塔法进行数值求解 ,得到了不同粒径的颗粒在 4种流场工况中的运动和停留时间 .经计算 ,还可得出以下结论 .(1)颗粒的运动轨迹主要受气相流场分布、颗粒粒径和颗粒初始速度等因素的影响 .(2 )颗粒粒径较小时 ,可以忽略升力和重力的影响 .但大颗粒与壁面碰撞后 ,必须连同考虑颗粒旋转及 Magnus升力的作用 .(3)选择合适的入口一二次风量比 (Q2 /Q1)和颗粒的初始速度 ,可延长颗粒在预燃器内的停留时间 ,能分离大于 30μm的颗粒 .

For reflecting kinematics of pulverized coal particles in the flow field of the cold state model of cyclone precombuster, a differential equation is formulated and solved numerically by adopting Runge Kutta method. In the equation, draw force of gas flow and gravity and Megnus lift force are taken into account. By investigating the effect from collision of partlcles with wall surface, kinematic trajectory and retention time of particles of different sizes in four operating modes are obtained. The following conclusions can also be obtained through computation:(a) Kinematic trajectory of particles is mainly influenced by such factors as distribution of gas phase flow field, particle size and initial speed of particles. (b) For the smaller particles, the effect of lift force and gravity can be ignored; but for the larger particles and those collided with wall surface in particular, particle rotation and action of Magnus lift force must be considered altogether. (c) The retention time of particle in cyclone precombustor can be prolonged and particles larger than 30 μm can be separated by choosing appropriate ratio of primary air quantity and secondary ones at the inlet ( Q 2/Q 1 ) and appropriate initial speed of particles, These results will provide the optimized design of cyclone precombustor for pulverized coal with theoretical basis.