Master of Engineering Science
Chemical and Biochemical Engineering
Gas-solid bubbling fluidized bed with binary particles is a potential candidate for performing the dry coal beneficiation process due to its advantages such as the ability to adjust separation density and the elimination of process water. A two-dimensional (2D) fluidized bed was used to study bubble dynamics and dense phase composition distribution in order to gain some fundamental understanding of this system. Digital image analysis (DIA) was employed to measure bubble diameter, bubble rise velocity, bed expansion and particle composition distribution. Magnetite and sand particles as pure and binary mixtures were used in the fluidized bed. Bubble diameter and bubble rise velocity both increased with the distance above the gas distributor and excess gas velocity. Bubble diameter of the binary mixtures is smaller than that of pure particles. Unlike the binary particles of the same size, bubble diameter was at its smallest when the amounts of sand and magnetite were almost identical in the system of binary particles having the same aerodynamic diameter, however the effect was not appreciable at a higher magnetite particles concentration. Bubble rise velocity was found to be proportional to the bubble diameter and did not change with axial position for the same bubble size. Bubble rise velocity increased while ascending in the bed due to an increase in bubble size. In addition, a preliminary experiment of tracing dense phase composition using DIA was carried out and a correlation for estimating the bed density based on the dense phase composition and bed expansion was developed.
Bai, Tianzi, "Bubble Dynamics and Dense Phase Composition in 2-D Binary Gas-Solid Fluidized Bed" (2018). Electronic Thesis and Dissertation Repository. 5514.