Preparation and Characterization of Porous Composite Filter Medium by Polytetrafluoroethylene Foam Coating
Abstract The high costs of ceramic and Teflon filter media for hot gas cleaning has limited their industrial applications. This paper presents a foam coating technology that can be used to produce an inexpensive and highly efficient filter for industrial applications. A new apparatus was designed and built that coats porous glass mats with liquid-phase polytetrafluoroethylene (PTFE). The machine generates bubbles, enables the formation of uniform micropores less than 45 μm in diameter, and produces a product with air permeability greater than 5.5 cm3/cm2/sec. The resulting filter was found to be thermally stable up to 270 °C without any visible distortion and was comparable in dust collection efficiency to other commercial filter media. In addition, its de-dusting efficiency was greater than 85%, which is similar to that of other test filter media.
Effective filtration area of a pleated filter bag in a pulse-jet bag house
Abstract Pleated filter bags have received a considerable amount of attention due to their higher filtration area compared to that of cylindrical filter bags. They can be used to increase both the filtration efficiency and dust holding capacity, as it is possible to decrease the filtration velocity when using the same amount of exhaust gas. However, the effective filtration area of pleated filter bags remains uncertain, despite the fact that it is an important design parameter in pulse-jet bag house systems. The effective filtration area of a pleated filter bag is determined in this study by assuming the effective filtration area (50%, 60%, 70% and 100% of the theoretical filtration area) and comparing its filter cleaning characteristics with those of a cylindrical filter bag. The filtration characteristics of a pleated filter bag with optimal geometry were investigated under the conditions of a filtration velocity of 1.2 m/min and a dust concentration of 10 g/m3. As a result, we found that the pleated filter bag assessed here had an effective filtration area of approximately 50 to 60%, in contrast to the theoretical filtration area, due to the dead space caused by filter pleating. In addition, particle clogging in the outer pleating section of the pleated filter bag significantly affected the decrease in the effective filtration area.
SR topography of plastically deformed Fe-Si bicrystals - observation in situ and post mortem
SR reflection topography was applied to study the interaction of slip dislocations with the grain boundaries in Fe-4at%Si bicrystals deformed by compression. Three experimental settings with either a white or monochromatic beam were used and the corresponding orientation contrast analysed. Dislocation transmission through the grain boundary was observed in bicrystals with favourable geometry of the slip systems.