回转干馏炉内颗粒运动及停留时间分析

Analysis of Particles' Motion and Residence Time in Rotary Retorting

为了研究颗粒在倾斜的回转干馏炉内的运动及停留时间,采用离散单元法(Discrete Element Method,DEM)进行数值模拟.回转炉模型的倾角为3.24°,选取17 r/min、13.3 r/min、10 r/min、6.8r/min、3.4 r/min五种转速进行对比.结果表明:可以将示踪颗粒在干馏炉中的运动过程分成两个阶段.第一阶段为颗粒集中阶段,第二阶段为颗粒分散阶段.干馏炉的转动和干馏炉存在倾角分别造成了示踪颗粒的径向分离和轴向分离.随着转速的提高,平均停留时间减小,其减小的程度逐渐变小,经拟合后得出转速与平均停留时间的函数关系近似于指数函数;转速越高,示踪颗粒在干馏炉内的停留时间数据与正态分布拟合得越好,概率密度函数最大值随着转速的增大而逐渐降低.

To investigate the motion and residence time of particles in rotary retorting,a numerical analysis using the discrete element method （DEM） was adopted in this paper.The slant angle of retorting is 3.24°.For investigating the effect of rotational speed,five rotational speeds were adopted：17 r/min、13.3 r/min、10 r/min、6.8 r/min、3.4 r/min.The results showed that the motion process of tracing particles in rotary retorting can be divided into two stages：the concentrated stage and the dispersive stage.The rotation of rotary retorting results in the separation of tracing particles in the direction of radius,the existence of slant angle of retorting leads to the separation of tracing particles in the direction of axis.The mean residence time of tracing particles decreased with the increase of rotational speed,and the degree of decrease decreased gradually.The functional relationship of rotational speed and mean residence time of tracing particles is exponential function approximately,after fitting the data.The higher the rotational speed was,the more the data of tracing particles’ residence time approached to normal distribution.The maximum value of probability density function gradually decreased with the increase of rotational speed.