The Effect Of Ultrasonic Atomization On Behavior Of Fine Dust In Air-Filtration Process

In the research of air pollution controlling, the removal of Inhalable particulate matter from air stream was a very important topic. Bag filter is one of several popular unit operations used for gas-particulate separation processes. Filters are performing with high collection efficiency, particularly for using PTFE membrane filter media as the filter material.its collection efficiency can reach to 99.999%. However, the pressure drop across these filters increase rapidly with time, particularly for feeds with high concentrations and/or fine (inhalable particulate) particle. The results show that the pressure comes from the filter cake layer. Therefore, effective way to reduce the use of the filter cake resistance and cake structure of the energy consumption for the bag filter is significant.In this work, in order to find how reasonably the filter to reduce the filtration resistance, ultrasonic atomization Humidification technology were combined with Bag Filter technology under various operation conditions.Meanwhile, in order to investigative the cake layer structure, we used new methods of cake layer structure visualization. In the study, we adding fixative to the dust powder, and then pass into the ultrasonic micro-droplet to a fixed filter cake structure and make it reach a certain intensity, and then using a scanning electron microscope photographs of cake microstructure.The results of ultrasonic atomization experiment show that:(1) there is an optimal ratio range of fog and dust (0.8-1.3). In this context, the same dust load conditions, after ultrasonic humidification, the cake pressure drop is reduced to 50%. (2) The backwash frequency is decreased. (3) Filter cake was wet. The cake is easy separate from filter material. And in the process it does not produce the phenomenon of secondary dust. Therefore, the technique can effectively reduce the resistance.The study of cake structure visualization results show that:(1) When the radio of fog and dust is fit, the cake structure is more loose than. The same time, the cake porosity is larger and thicker cake layer. Once, The fog is too large, the cake structure formed is more compact; (2) The results show that the cake layer structure which close to the membrane side of is more compact, but the other side is loose.The method is time-consuming short, the process is simple, and can directly reflect the real microstructure of the cake. Therefore, this study provides a characterization of cake structure visualization methods, Also shown that the ultrasonic atomization technology can effectively reduce the cake filtration resistance.