荷电液滴润湿无烟煤微观机制研究

    Study on microscopic mechanism of wetting anthracite by charged droplets

    • 摘要: 水雾荷电增效降尘技术作为1种新型高效除尘方法,较传统湿式喷雾降尘技术在煤尘治理效率上有显著提升,但其对煤尘捕集与润湿的微观作用机制尚不明确。首先采用多尺度研究方法研究了荷电液滴润湿无烟煤微观机制,通过试验探究了荷电液滴的润湿性能及对无烟煤尘的静电团聚作用;其次,采用分子模拟方法,从量子力学层面的电子结构计算及分子动力学层面的构象演化2个维度,深入探究了荷电液滴与无烟煤之间的相互作用机制。结果表明:荷电溶液对煤尘的润湿性能更佳,且随着荷电电压的增加,带电液滴对煤尘的接触角总体呈下降趋势,当荷电电压为−24 kV时接触角最小,润湿性能最佳;荷电喷雾沉降后的煤尘粒径显著增大,粒径集中分布趋势则向100 μm方向迁移,表明荷电液滴对煤尘存在静电团聚作用;相较于普通水分子,荷电水分子的极性更强,整体静电势均呈现为负值,且与无烟煤分子之间的静电势差值更大,表明二者的静电相互作用更强;荷电水分子在无烟煤分子表面吸附程度更高,聚集的水分子层更为致密,且体系中氢键数量更多;从能量组成角度来看,在荷电水分子与无烟煤分子之间的相互作用中,静电效应占据主导因素。

       

      Abstract: As a new type of high-efficiency dust removal method, water-mist charge-enhanced dust reduction technology has been shown to significantly improve the efficiency of coal dust management in comparison with traditional wet spray dust reduction technology. However, the microscopic mechanism of the technology on coal dust capture and wetting has not yet been thoroughly explained. In this study, a multi-scale approach was adopted to experimentally investigate the wetting performance of charged droplets and the electrostatic agglomeration of anthracite dust. Secondly, the molecular simulation method was employed to investigate the interaction mechanism between the charged droplets and anthracite from the dimensions of electronic structure calculation at the quantum mechanical level and conformational evolution at the molecular dynamics level. The findings indicate that the charged solutions exhibited superior wetting performance on coal dust, with the contact angle between charged droplets and coal dust showing an overall downward trend as the charging voltage increased, and the minimum contact angle and optimal wetting performance were achieved at −24 kV charging voltage. The particle size distribution of coal dust after charged spray sedimentation showed significant enlargement, with distribution trends shifting towards 100 μm, indicating the existence of electrostatic agglomeration of coal dust by charged droplets. Compared to ordinary water molecules, charged water molecules demonstrated enhanced polarity, presented uniformly negative electrostatic potential distributions, and exhibited greater electrostatic potential differences with anthracite molecules, suggesting stronger electrostatic interactions. Charged water molecules displayed higher adsorption density on anthracite surfaces, formed more compact molecular layers, and generated increased hydrogen bond quantities within the system. Furthermore, the energy composition analysis confirmed that electrostatic effect is the dominant factor in the interaction between charged water molecules and anthracite molecules.

       

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