Studies on biomass drying apparatus using swirling fluidization technique

Abstract

Drying of biomass is crucial prior utilizing its high intrinsic and readily available energy. The reduction of moisture content is mandatory to increase overall energy efficiency and reduce emission in systems operating with biomass, especially during combustion or gasification. One of the established methods of drying biomass is through fluidized bed drying. As such, the current work addresses the development of a biomass drying apparatus, designated as the swirling fluidized bed dryer (SFBD). The SFBD features an annular bed with inclined injection of gas through an array of blades which acts as the hot air distributor, which then imparts the swirling motion to the bed. This secondary motion inside the bed promotes the highly desired mixing and solid-fluid contact. The performance of SFBD was studied in terms of its hydrodynamic characteristic using PVC beads before tested with actual biomass from palm frond. The results show that SFBD exhibits excellent hydrodynamic characteristic with distributor to bed pressure drop ratio less then 10%. It is also found that bed pressure drop is proportional with superficial velocity of hot air, but still reasonably low for bed weight up to 2 kg. The findings lead to a conclusion that the SFBD is capable of achieving good fluidization quality for low bed heights and suitable for biomass drying, especially that operates with batch processing.