The effect of ash and filter media characteristics on particle filtration efficiency in fluidized bed

• Published in: Journal of hazardous materials 2005-05, Vol.121 (1), p.175-181
• Main Authors: Wey, Ming-Yen, Chen, Ke-Hao, Liu, Kuang-Yu
• Format: Article
• Language: English
• Subjects: Applied sciences; Atmospheric pollution; Carbon - chemistry; Chemical engineering; Coal Ash; Exact sciences and technology; Filter; Filtration; Filtration - instrumentation; Filtration - methods; Fluidization; Fluidized bed; General processes of purification and dust removal; Incineration; Incinerator ash; Kinetics; Liquid-liquid and fluid-solid mechanical separations; Particle; Particle Size; Particulate Matter; Pollution; Prevention and purification methods; Silicon Dioxide - chemistry; Temperature; Water Pollutants - isolation & purification; Water Pollution - prevention & control
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2005.02.005

The phenomenon of filtering particles by a fluidized bed is complex and the parameters that affect the control efficiency of filtration have not yet been clarified. The major objective of the study focuses on the effect of characteristics of ash and filter media on filtration efficiency in a fluidized bed. The performance of the fluidized bed for removal of particles in flue gas at various fluidized operating conditions, and then the mechanisms of collecting particles were studied. The evaluated parameters included (1) various ashes (coal ash and incinerator ash); (2) bed material size; (3) operating gas velocity; and (4) bed temperature. The results indicate that the removal efficiency of coal ash increases initially with gas velocity, then decreases gradually as velocity exceeds some specific value. Furthermore, the removal of coal ash enhance with silica sand size decreasing. When the fluidized bed is operated at high temperature, diffusion is a more important mechanism than at room temperature especially for small particles. Although the inertial impaction is the main collection mechanism, the “bounce off” effect when the particles collide with the bed material could reduce the removal efficiency significantly. Because of layer inversion in fluidized bed, the removal efficiency of incinerator ash is decreased with increasing of gas velocity.