扰流件排列对亚微米颗粒湍流团聚效率影响研究

Study on the effect of disturbing structure arrangement on the turbulentagglomeration efficiency of the submicron particulate

燃煤工业亚微米颗粒物的排放会危害环境和人体健康,而团聚方法是脱除亚微米颗粒的主要手段之一。通过搭建亚微米颗粒湍流团聚试验台,利用扫描电迁移率粒径谱仪(SMPS)测量湍流段前后进出口亚微米不同粒径数量浓度,研究不同扰流柱排列对亚微米颗粒团聚效率的影响,并结合Fluent软件分析了流场对颗粒团聚效率的影响。结果表明,亚微米颗粒湍流团聚效率与颗粒粒径大小有关,粒径较小的亚微米颗粒团聚效果较好,小粒径颗粒(粒径<30 nm)团聚效率在10%~90%,但对于大粒径颗粒(粒径>30 nm)团聚效率均在10%以下,颗粒直径大于502 nm时,不同流速下颗粒的团聚效率变为负值;对流速分析,发现亚微米颗粒团聚效率随流速增大出现先增大后减小的趋势,是由扰流区湍流强度及颗粒停留时间造成;探究扰流柱布置及排列对团聚效率的影响时,发现亚微米颗粒的团聚效率随扰流件的增大而减小,随扰流件横向间距的增大而逐渐减小,随纵向间距的增大先变大后减小,随排数的增大而变大,主要是扰流件尾迹区域内涡街强度与涡街长度的综合作用,涡街强度大会促进颗粒的碰撞几率,而涡街长度能提高颗粒在湍流区的停留时间,进而提高团聚效率。

The emission of submicron particles in coal-fired industry will harm the environment and human health,and the agglomeration method is one of the main means for removing sub-micron particles.In this work,an experimental platform for the turbulent agglomeration of submicron particulates was built.The Scanning Mobility Particle Sizer(SMPS)was used to measure the concentration of the inlet and outlet particulates.The effects of different disturbing structure arrangement on the submicron particulates turbulent agglomeration efficiency were studied.Moreover,the effects of flow field on particulate agglomeration efficiency were further analyzed by Fluent software.The results show that the turbulent agglomeration efficiency of micron particles is related to the particle size.The agglomeration efficiency of submicron particles with smaller particle size is better than that of submicron particles.the agglomeration efficiency of small particulates(particulates size<30 nm)is from 10%to 90%,but it is less than 10%for large particulates(particulates size>30 nm),and when the particle diameter is greater than 502 nm,the agglomeration efficiency becomes negative at different flow rates;according to the analysis of flow velocity,it is found that the agglomeration efficiency of sub-micron particles increases first and then decreases with the flow velocity,which is caused by the intensity of turbulence in the turbulence zone and the residence time of particles.What′s more,when exploring the influence of the arrangement and arrangement of the spoiler on the agglomeration efficiency,the agglomeration efficiency of sub-micron particles decreases with the increase of the spoiler,and gradually decreases with the increase of the lateral spacing of the spoiler,first becomes larger and then decreases with the increase of the longitudinal spacing,and increase with the increase of the number of rows.The effects of the disturbing structure on the agglomeration efficiency are mainly influenced by the strength and length of the vortex.The strength of the vortex street promotes the collision probability of particles,and the length of the vortex street can increase the residence time of the particles in the turbulent zone,thereby increasing the agglomeration efficiency.