Intensification Of Acoustic Agglomeration And Ultrasonic Atomization On Behavior Of Fine Dust In Air Filtration Process

In recent years, the particulate matter(PM10), especially fine particulate matter(PM2.5) whose aerodynamic diameter is less than 2.5 microns has become a very prominent atmospheric environmental problems. Fine particulate pollution has become a very prominent atmospheric environmental problems, which has drawn attention from the countries all over the world. Power plant discharge and industrial fine dust resulting from all kinds of furnaces are important source of atmospheric fine particulate matter, therefore, continue to develop industrial dust removal technology is still the important direction of the atmospheric pollution control. One of methods is that the aerosol particles are preprocessed before entering into the dust removal device. After pretreatment, the average particle size in the aerosols increase, and fly ash is effectively removed in the traditional dust control unit. The combination action of sound field and ultrasonic atomization is beneficial to strengthen the effect of agglomeration and removal, which is an effective pretreatment method. In this paper, fly ash from power plant was studied. Middle intensity acoustic field was employed to study the agglomeration characteristics of inhalable particles. Under the condition of sound waves and atomization, the removal efficiency of coal fly ash was studied under different sound pressure levels and different quantities of humidification, filtering characteristics of filter and pulse jet cleaning performance were also studied.The research results show that moderate intensity acoustic field(110~140dB) changed particle size distributions and made fine particles become larger ones, within the scope of the PM10, quality percentage of the smaller particles significantly reduced, quality percentage of large particles increased obviously. With the increase of the sound field sound pressure level, the effect of agglomeration improves. There existed an optimum frequency for a particular particle size, in this experiment the best frequency is about 1400 Hz. Residence time of fly ash in the acoustic field is about 4 ~ 7s. With the increase of Residence time, the effect of the particle agglomeration enhanced.Results indicate that the combination of acoustic waves and atomization humidifying is an effective technology to remove fine particles. Under the fixed intensity of sound field, within the range of proper humidification(saturation S=1~2), increasing the atomization humidifying quantity improves the removal rate of fly ash and in a fixed amount of atomization humidifying, increasing the intensity of acoustic field can also achieve the same effect. The combination of acoustic field and ultrasonic atomization can be used as a pretreatment method, which improves the agglomeration and sedimentation of fly ash and effectively reduces the loading of subsequent dust removal facilities, improving the dust removal efficiency.With the combined effect of the sound field and the atomization as a pretreatment of filtration, deposition behavior of fly ash on the surface of the filter material is studied, as well as the analysis of forces on particles. After the pretreatment particle layer structure is changed, resulting in the increase of porosity, deposition of particles are not prone to slip. Results show that the combined effect of sound and atomization humidifying can effectively remove coal-fired PM10, PM2.5, transform the inter-force and motion track of particles, thereby improve the pore structure of fly ash particles layer, increase layer porosity, extend the cleaning cycle, reduce the pulse jet cleaning frequency, delay filter blocking, reduce the residual resistance after cleaning, extend the service life of filter media.