燃煤飞灰低频下声波团聚的实验研究  

Acoustic agglomeration of coal-fired fly ash particles in low frequency sound fields

作　　者：张光学[1] 刘建忠[1] 周俊虎[1] 岑可法[1] 

机构地区：[1]浙江大学能源清洁利用国家重点实验室,浙江杭州310027

出　　处：《化工学报》2009年第4期1001-1006,共6页CIESC Journal

基　　金：国家自然科学基金项目(50576083);新世纪优秀人才支持计划项目(NCET-04-0533)~~

摘　　要：通过实验研究了低频下燃煤飞灰的声波团聚。燃煤飞灰气溶胶在声波作用下粒径分布发生明显变化,大量细颗粒团聚产生粗颗粒,气溶胶浓度降低。在147dB、1400Hz时,气溶胶总浓度和PM2.5浓度分别减少了68.4%和75.6%,达到很好的团聚效果。从扫描电镜照片中可以观察到声波团聚过程中产生了粒径大于10μm的链状团聚体。在声波作用下,气溶胶总浓度随团聚时间呈指数衰减规律降低。实验证明了声波团聚中存在最佳频率,在此频率下团聚效果最好,偏离该值团聚效果急剧降低。另外,实验发现最佳频率随声压级的增大而轻微降低。同时,研究了声压级、停留时间和气溶胶初始浓度等参数对声波团聚的影响。Acoustic agglomeration is a potential aerosol preconditioning process, which shifts the particle size distribution towards a larger size and reduces the number of fine particles to enhance the performance of conventional filtering devices. This paper presents an experimental study on acoustic agglomeration of coal-fired fly ash at low frequencies. The particle size distribution of fly ash changed towards a larger size with sound application because lots of fine particles agglomerated. At a frequency of 1400 Hz and a sound pressure level of 147 dB, the total number concentration and PM2.5 number concentration were reduced by 68. 4% and 75.6%, respectively. Aggregates larger than 10μm were observed in scanning electron microscopy photographs. The total number concentration of aerosol decreased exponentially with time in the acoustic agglomeration process. The results showed that the effect of sound waves was very sensitive to the frequency change, which meant that orthokinetic interaction governed the process. There existed an optimum frequency for a given particle size distribution, which decreased slightly as sound pressure level increased. Besides, the influences of sound pressure level, residence time and initial total number concentration on agglomeration were investigated.

关 键 词：声波团聚 低频 燃煤飞灰 同向团聚 PM2.5 

分 类 号：X513[环境科学与工程—环境工程]