声波团聚脱后烟气细颗粒物的数值模拟.docxVIP

声波团聚脱硫后烟气细颗粒物的数值模拟摘要：对传统分组法进行改进，可以根据质量浓度的大小自动调整分组的大小，在质量浓度较大处，划分精细，可保证计算精度；质量浓度较小处，划分粗略，可减少计算耗时。研究了声波团聚作用对细颗粒物粒径分布的影响，并在团聚过程中考虑了布朗团聚的效果。引入质量守恒率的概念，方便判断计算结果是否能代表实际质量浓度分布。结果表明，声波作用2秒钟后，可以使细颗粒物的总数目浓度降低40 %以上；提高声强级比提高声波频率更具有增加团聚的效果；存在最优的声波频率，且大粒径的颗粒比小粒径的颗粒更容易受声波频率的影响。关键字：脱硫烟气；细颗粒物；声波团聚；分组法；数值模拟DOI：中图分类号：TK16文献标志码：A文章编号：Numerical Simulation of Acoustic Agglomeration on Fine Particles from Coal-fired Flue after the Wet Flue Gas Desulfurization SystemAbstract：Fly-ash particles from the outlet of the wet flue gas desulphurization system are finer than that before thecyclone.It is of vital importance to deal with those finer particles when cleaning the flue gas.The effect of acoustic agglomeration on fine particles was investigated with sectional arithmetic, which was widely used. Brown agglomeration was also taken into account for accuracy of the calculation. Improvements, such as sectional size could adjust automaticallyaccording to the mass density of the particles,was put forward in this paper. Besides, Mass conservation rate was introduced to estimate the calculationerror in the compute of mass density, which turned out over to 95% when frequency was below 2500Hz and sound intensity was level (SIL) below 160DB. The results show thatthe total number density decreased more than 40% within 2 second. Improving SIL is more effective than improving frequency in strengthening agglomeration effect.Optimized wave frequency is proved to be existing. Coarse particles were more sensitive to wave frequency than fine particles.Key words：wet flue gas desulfurization；fine particles；acoustic agglomeration；sectional arithmetic；numericalsimulation；引 言空气污染源中，细颗粒物是最主要的污染源之一，危害极大[1]。细颗粒物不但降低空气的能见度，而且对人体的呼吸系统及心血管系统形成较大威胁[2]。粒径小于10μm的颗粒称为可吸入颗粒物。2013年2月，全国科学技术名词审定委员会将粒径小于2.5μm的颗粒定义为细颗粒物，粒径小于1μm的颗粒物为超细颗粒物[3]。我国对于细颗粒物的治理相对落后，相关的法律法规也在完善之中，所以我国细颗粒物的污染问题较世界各发达国家更加严重[4]。据相关部门统计，我国细颗粒物主要来源于燃煤烟气和汽车尾气的排放，大约各占30%[5]。对于燃煤烟气，传统的烟气净化装置(如电除尘器、布袋除尘器、旋风除尘器等)，对粒径大于10μm的颗粒物脱除效率较高，但对小于10μm的颗粒脱除效率很低[6]。湿法脱硫系统中，脱