Fluidization characteristics and fine coal dry beneficiation using a pronation-grille baffle dense phase medium fluidized bed

Abstract

The fluidization of Geldart B particles commonly falls under the bubbling fluidization category, where the coalescence of bubbles is the dominant phenomenon. If the diameter of bubbles becomes too large, the fluidization quality will deteriorate and lead to significant maldistribution of bed density. In this study, a pronation-grille baffle was introduced into a gas-solid dense phase fluidized bed (GDPFB) in order to improve fluidization quality. This was termed as a pronation-grille baffle dense phase medium fluidized bed (PGBFB). The inhibitory effect of the pronation-grille baffle on the coalescence of bubbles and the large-scale particles back mixing, as well as the collaborative optimization of the baffle placing height and operating gas velocity were investigated. The density standard deviation (Sδ) and density skewness (SKδ) were employed to evaluate the uniformity and stability of the bed density distribution. According to the experimental results, the Sδ of a PGBFB was substantially reduced by 83.7%, compared to a GDPFB, and the lowest SKδ value was decreased to −0.0106, significantly improving the uniformity and stability of the bed density. Additionally, the beneficiation experiments were performed on a 1–6mm raw coal in a PGBFB. The beneficiation results showed that the probable error, E, was 0.091g/cm3 and the ash content of clean coal was 16.63%, being reduced by 21.76%, compared to the ash content of the raw coal. This indicates that fine coal beneficiation using a PGBFB can provide a simple and efficient way for coal cleaning in arid and cold regions.