Drying characteristics of fine powders in an inert medium circulating fluidized bed with binary inert media

The effects of two types of inert particles (binary: 180 and 500 μm or mono: 500 μm), inlet gas temperature (40–100 °C), and mass ratio of fine to inert particles (F/I) (0.05–0.2) on the batch type fluidized bed drying characteristics of fine powders were investigated in an inert media circulating fluidized bed (0.087 m-ID × 1.0 m-height). Copper dendrimer powder (X₀ = 25.0% wet basis, d_p = 2.7 μm, ρ_p = 5980 kg/m³) and aluminum flux (Al flux) (X₀ = 30.2% wet basis, d_p = 8.6 μm, ρ_p = 2730 kg/m³) were used as the fine humid materials, and glass beads (180 and 500 μm) were used as the inert media particles. The moisture contents of the dried powders were sufficiently low, from 0.2% to 0.7% (wet basis). The result shows that the aggregation phenomenon rarely occurs. Compared with using the mono type inert media fluidized bed dryer, the amount of dried product using an inert media circulating fluidized bed with binary inert media increased by two to three times. The maximum drying rate of the inert media circulating fluidized beds with binary inert media is higher than that of the agitated pan dryer and inert media bubbling fluidized bed dryer (mono type inert). Additionally, the optimum condition (T_g = 60 °C, F/I ratio = 0.1, binary inert media) was derived from the energy efficiency.