磁化荷电液滴碰撞浸润微细煤尘的影响因素研究

    Research on the influencing factors of collision and infiltration of fine coal dust by magnetized charged droplets

    • 摘要: 磁化荷电技术作为一种新型耦合增效降尘技术,可有效改善传统湿式水雾捕集微细、难浸润煤尘效率不佳的问题。采用理论分析与试验相结合的方法,对磁化荷电液滴碰撞疏水性无烟煤尘颗粒的润湿效果及动力学行为开展研究,并确定了最佳碰撞粒径比与初始速度。结果表明:普通液滴因其表面张力和黏度较大,在与强疏水性煤尘颗粒碰撞过程中,铺展范围小、速度慢,呈现完全反弹的现象;磁化荷电作用通过降低表面张力和黏性有效抑制了液滴撞击煤尘的反弹现象,低速下在煤尘颗粒表面形成薄前驱体薄膜,从而使润湿面积增大,液滴粒径减半更易破碎,加快了液滴铺展速度和包覆范围;相较于纯水,磁化荷电液滴浸润捕捉煤尘颗粒具备显著的优越性,利于喷雾降尘凝并呼吸性粉尘;低速下磁化荷电液滴与煤尘易发生偏心碰撞,部分液滴不参与撞击使流场强度峰值交错,液滴进入松弛态时间长、有效包覆面积小、瞬时润湿速率和效果变差,因此液−尘粒径比不宜小于0.8;当碰撞速度达到4.31 m/s,液膜中心高度系数迅速下降至稳定,同一无量纲时间下,液膜中心高度系数最小值与碰撞速度成反比;当磁化荷电液滴粒径比为0.8、速度为4.31 m/s时,对总粉尘、呼吸性粉尘沉降效果显著,降尘效率可达95%以上。

       

      Abstract: Magnetized charging technology, as a new type of coupling enhanced dust reduction technology, can effectively improve the poor efficiency of traditional wet water mist in capturing fine and difficult to infiltrate coal dust. This study adopts theoretical analysis and experimental methods to study the wetting effect and dynamic behavior of magnetized charged droplets colliding with hydrophobic anthracite coal dust particles. It determines the optimal collision particle size ratio and initial velocity. The results show that due to their high surface tension and viscosity, ordinary droplets have a small spreading range and slow velocity during collision with strongly hydrophobic coal dust particles, exhibiting a complete rebound phenomenon. The magnetization charging effect effectively suppresses the rebound phenomenon of droplets hitting coal dust by reducing surface tension and viscosity. At low speeds, a thin precursor film is formed on the surface of coal dust particles, thereby increasing the wetting area, halving the particle size of the droplet, making it easier to break, and accelerating the droplet spreading speed and coverage range. Compared with pure water, magnetized charged droplets have obvious advantages in soaking and capturing coal dust particles, which is conducive to spray dust reduction, condensation and respiratory dust; at low speeds, magnetized charged droplets are prone to eccentric collisions with coal dust, and some droplets do not participate in the collision, resulting in staggered flow field intensity peaks. The droplets enter a relaxed state for a long time, have a small effective coverage area, and their instantaneous wetting rate and effect deteriorate. Therefore, the droplet dust particle size ratio should not be less than 0.8; when the collision speed reaches 4.31 m/s, the center height coefficient of the liquid film rapidly decreases to stability. At the same dimensionless time, the minimum value of the center height coefficient of the liquid film is inversely proportional to the collision speed; when the particle size ratio of magnetized charged droplets is 0.8 and the velocity is 4.31 m/s, the settling effect on total dust and respiratory dust is significant, and the dust removal efficiency can reach over 95%.

       

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