摘要
目前钢铁行业已成为大气污染防治的重点,为解决现有钢铁行业对于PM2.5细颗粒难以捕集的难题,实现粉尘的超低排放.基于CFD-DPM(computational fluid dynamics-discrete phase model)方法对磁性纤维产生的磁场以及高梯度磁场等不同磁场形式下单纤维对钢铁行业捕集PM2.5性能的影响进行研究,通过X射线衍射图谱分析可知钢铁行业生产过程产生的粉尘因含有Fe3O4以及单质Fe而具有磁特性,进而提出了利用磁场来增强单纤维捕集PM2.5性能的方法.计算结果表明,在运动轨迹方面,磁性纤维产生的磁场会在纤维周围形成引力区,高梯度磁场会在纤维周围形成2个引力区和2个斥力区;在捕集性能方面,当粉尘粒径dp为0.5~1.0μm,入口风速v≤0.2 m·s-1时,高梯度磁场下磁性纤维的捕集能力要强于单一磁性纤维的捕集能力,若磁场强度H=0.5 T,磁感应强度B=0.01 T,v=0.1 m·s-1,高梯度磁场可以使单纤维的捕集效率提高为传统单纤维捕集的28.32倍,若B=0.01 T,v=0.1 m·s-1,磁性纤维产生的磁场可以使捕集效率提高为传统单纤维捕集的4.037倍;在磁性纤维产生的磁场中,当磁感应强度B≥0.03 T时,磁性单纤维对PM2.5的捕集效率随着入口风速的增加而减小,后趋于稳定,当B<0.03 T时,捕集效率随入口风速逐渐减小;捕集效率随粉尘粒径的增加而增大.而对于高梯度磁场,单纤维对PM2.5捕集效率同样随着入口风速的增加而减小,当v>0.4 m·s-1时,捕集效率为0,B越大,捕集效率下降越快;捕集效率随着粉尘粒径增大呈现先增加后减小的趋势.
At present,the steel industry has become the focus of air pollution prevention and control.To solve the difficulty in collecting PM2.5 fine particles and achieving ultra-low emission of dust,based on the method of computational fluid dynamics-discrete phase model(CFD-DPM),the influence of different magnetic field forms,such as magnetic field generated by magnetic fiber and highgradient magnetic field,on the performance of PM2.5 collection in the iron and steel industry was studied.Through X-ray diffraction(XRD)analysis,it was found out that the dust produced in the iron and steel industry production process has magnetic characteristics due to the presence of Fe3O4 and elemental Fe,furthermore,the method of using magnetic field to enhance the PM2.5 collection performance of single fiber was proposed.The results show that the magnetic field generated by the magnetic fiber will form a gravitational region around the fiber,and the high-gradient magnetic field will form two gravitational regions and two repulsive regions around the fiber.In terms of the collection ability,when particle diameter dp between 0.5 and 1.0μm,inlet velocity v≤0.2 m·s-1,the collection ability of magnetic fiber under the high-gradient magnetic field is stronger than that of the single magnetic fiber.If magnetic field intensity H=0.5 T,magnetic induction intensity B=0.01 T,and v=0.1 m·s-1,the high-gradient magnetic field can improve the single fiber collection efficiency by 28.32 times as much as the original;if B=0.01 T,v=0.1 ms-1,the magnetic field generated by the magnetic fiber can improve the single fiber collection efficiency by 4.037 times as much as the original.In terms of the collection law,in the magnetic field generated by the magnetic fiber,when the magnetic flux density B≥0.03 T,the collection efficiency of magnetic single fiber on PM2.5 decreases with the increase of inlet velocity speed and then tends to be stable.When B<0.03 T,the collection efficiency decreases with the inlet velocity speed.The collection efficiency increases with the increase of dust particle size.For the high-gradient magnetic field,the single fiber collection efficiency of PM2.5 particles also decreases with the increase of inlet velocity speed.When v>0.4 ms-1,the collection efficiency is 0.The larger B is,the faster the collection efficiency decreases.The collection efficiency increases first and then decreases with a increase in dust particle size.
作者
张俪安
刁永发
庄加玮
周发山
沈恒根
ZHANG Li-an;DIAO Yong-fa;ZHUANG Jia-wei;ZHOU Fa-shan;SHEN Heng-gen(School of Environmental Science and Engineering College,Dong Hua University,Shanghai 201620,China)
出处
《工程科学学报》
EI
CSCD
北大核心
2020年第2期154-162,共9页
Chinese Journal of Engineering
基金
国家重点研发计划资助项目(2018YFC0705300)
中央高校基本科研业务费重点资助项目(2232017A-09).
关键词
磁性纤维
高梯度磁场
PM2.5
铁磁性
捕集性能
magnetic fiber
high-gradient magnetic field
PM2.5
ferromagnetism
collection performance
