Experimental Study Of Acoustic Agglomeration And Fragmentation On Inhalable Particles Of Coal-fired Ash

As themajor constituent of air pollution,inhalable particles,especially the fine particles are inflicting great harmon human health due to their small particle size and absorption of hazardous components on them.However,the current conventional devices used for removing these particles suffer from low removal efficiency.It is urgent to seek a new technique for removing fine particles.Acoustic agglomeration is considered as a very effective pretreatment technique for removing fine particles.High-intensity sound wave promotes the relative motion of particles due to different amplitudes.After colliding and agglomerating,the particle size distributions shift from small to large sizes.Particles wit large sizes could be removed by conventational devices easily.The agglomeration and fragmentation of 3 different kinds of particles with different size distribution are studied experimentally in the sound field.The results show that the agglomeration efficiency of inhalable particles in-creases with SPL increasing for the unimodal particles with particle diameter less than 10μm.For the bimodal particles,the optimal SPLs are 115 and 120 dB with the agglomeration efficiencies of 25%and 55%in this experiment.A considerable effectiveness of agglomeration could only be obtained in a narrow SPL range and it decreases significantly beyond the range for the particles fragmentation.The second peak diameter is more sensitive to high sound pressure level.The greater the second peak diameter is,the lower fragmentation sound pressure is.The particle agglomeration efficiency is improved by the combination of spray.Experiments show that the spray does not change the optimal frequency of acoustic agglomeration.The optimal frequency is 1200Hz still.The addition of a spray enhances agglomeration efficiency while avoiding the agglomeration of particles in the large particle size range at high SPL.