高梯度磁场提升单纤维捕集PM2.5性能的机理

以钢铁厂和有色金属行业排放的PM_2.5为研究对象，基于离散相模型DPM（Discrete Phase Model），并加入UDF自定义编程，研究高梯度磁场下不同入口风速、颗粒粒径、外磁场强度、磁性纤维磁感应强度以及磁化率对捕集效率的影响，并结合颗粒运动轨迹和受力情况对其进行分析.结果表明：当0.5μm≤d_p≤2.5μm，v=0.1m/s时，利用高梯度磁场（H=0.1T，B=0.06T）可以使单纤维捕集PM_2.5的效率提高为原来的4.23倍，得出磁性纤维周围存在2个引力区和2个斥力区.同时，在高梯度磁场中磁性纤维对PM_2.5的捕集效率随入口风速呈先减小后趋于平稳的规律；而捕集效率随粉尘粒径呈先增大后减小的规律.当d_p=1.0μm时的捕集效率提升最大，无论是外磁场强度还是磁性纤维磁感应强度，磁性纤维对颗粒的捕集效率与场强都呈一次函数关系，效率增长率K_B>K_H；随着颗粒磁化率的增加，磁性纤维对颗粒的捕集呈现两段线性增长规律，前后两段效率增长率K₁>K₂.当颗粒经过高梯度磁场区域时，入口风速、粉尘粒径、场强对运动轨迹影响较大，而磁化率对运动轨迹影响较小.

The mechanism of high gradient magnetic field improving the performance of single fiber capture PM2.5

PM_2.5 emissions from iron and steel and nonferrous industries as object, based on the discrete particle model DPM and UDF custom programming, The effects of inlet velocity, particle diameter, external magnetic field strength, magnetic fiber magnetic flux density and magnetic susceptibility on the capture efficiency were studied and analyzed by combination between the particle motion trajectory and force. The results showed that when 0.5μm£d_p£2.5μm, v=0.1m/s, the efficiency of single fiber to capture PM_2.5 could be improved by using high gradient magnetic field(H=0.1T, B=0.06T)4.23times. It was also found that there were two gravitational zones and two repulsive zones around the magnetic fibers. At the same time, in the high gradient magnetic field, the capture efficiency of the magnetic fiber to PM_2.5 decreased first and then stabilized with the inlet velocity; while the capture efficiency increased first and then decreased with the particle diameter of the dust. When d_p=1.0μm, the increasing of capture efficiency was maximized at this time; whether it was the external magnetic field strength or the magnetic fiber magnetic flux density, the capturing efficiency of magnetic fiber to particles was a linear function of the field intensity, with the efficiency growth rate of K_B>K_H; with the increase of the magnetic susceptibility of the particles, the capturing of particles by magnetic fibers presented a two-stage linear growth law, and the growth rate K₁>K₂. When the particles passed through the high gradient magnetic field, the inlet velocity, dust particle diameter and field strength had a great influence on the motion trajectory, while the magnetic susceptibility had little effect on the motion trajectory.