Bubble behaviour investigation in a wet fluidized bed using digital image analysis. (24th August 2021)

• Record Type: Journal Article
• Authors: Dai, Li; Yuan, Zhulin; Guan, Lei; Wu, Kai; Gu, Conghui
• Is Part Of: Canadian journal of chemical engineering. Volume 100:Number 8(2022)
• Page Start: 1965
• Page End: 1976
• Publication Date: 2021-08-24
• Subjects: bubble fraction -- bubble shape -- bubble size -- image analysis -- liquid saturation; Chemical engineering -- Periodicals; Technology -- Periodicals; 660.05
• DOI: 10.1002/cjce.24279
• Languages: English
• ISSNs: 0008-4034

Abstract

Abstract: Due to the presence of liquid bridge forces, wet particles reveal totally different fluidization behaviours than dry fluidized beds. This paper studies the bubble dynamics of wet Geldart‐D particles in a wet 2D fluidized bed. A digital image analysis method is adopted to identify bubbles and extract bubble properties based on MATLAB software. During fluidization, the bubble feature analysis of optimized binary images captures the bubble size variation, bubble fraction, and bubble shape. The results show that the increasing liquid saturation promotes the gas holding capacity of the emulsion phase, leading to the decreasing bubble fraction. When the particle size grows, the stability of the emulsion phase is promoted and hence the average bubble diameter increases. As the liquid saturation increases, the enhancing liquid bridge forces limit the bubble growth and promote the bubble breakage, which contributes to the small bubbles. With respect to the wet particles, of which the diameter is 1 mm and the liquid saturation is over 15%, slugging is likely to be observed, resulting in the increasing equivalent bubble diameter. The growing liquid saturation increases the wide aspect ratio, decreases the shape factor, and disperses the dependence between the two parameters. This indicates that small and irregular bubbles are likely to be seen in wet fluidized beds.