Alumina intermittent drying using new draft tubes for scaling up conical spouted beds

Novel draft tubes have been assessed to scale up the spouted bed technology. Accordingly, alumina drying runs have been conducted using different configurations (without tube and with open-sided and nonporous tubes) under intermittent strategies consisting in alternating periods of drying and periods of reduction or interruption of the air flow rate, and they have been compared with continuous drying. Furthermore, the influence the draft tubes have on the drying performance and energy requirements in the drying process has been evaluated. The results allow inferring that intermittent drying considerably decreases both drying time and energy requirements. Moreover, the new draft tubes improved the drying of alumina, as a similar energy efficiency than without draft tube was attained with lower specific energy consumption, which is essential to reduce the high-energy demand in the drying process and mitigate climate change. These findings, along with the stability the new tubes provided to the process, involve a further step in the scale up of spouted beds for industrial operations. • Novel draft tubes have been assessed to scale up the spouted bed technology. • Intermittent drying considerably decreases both drying time and energy requirements. • New open-sided draft tube enhances spouting and drying operation.