Effect of combining multi-jet component with axial swirl blade on evaporation in a spouted bed

Abstract

To improve the fluidization behavior and the heat and mass transfer process in a spouted bed, a multi-jet–axial-swirl-blade spouted bed (MJ-ASB SB) was developed. The water evaporation process of the MJ-ASB SB was simulated and compared with those of the conventional spouted bed (CSB) and an integral multi-jet spout-fluidized bed (IMJSFB). The simulation results showed that the MJ-ASB SB combined the staged spouting action of multi-jet with the swirling action of the axial swirl blade, which promoted particle turbulence in the annulus region and ensured effective particle mixing. The swirl number of the MJ-ASB SB ranged from 0.0816 to 2.7239 with enhanced vortex intensity, thus promoting momentum and heat transfer of gas and particles in the spouted bed. The MJ-ASB SB had a higher slip velocity than the other two bed types, which indicates that the combined internal structure could improve the fluidization state of the bed and intensify the movement and mixing of phases in the spouted bed. The three-phase temperature, water evaporation rate, and gas humidity of the MJ-ASB SB were higher than those of the CSB and IMJSFB, and water evaporation occurred in an enlarged region in the MJ-ASB SB. The mass transfer intensification factors I of the MJ-ASB SB (2.62) and IMJSFB (1.92) were 91% and 161% higher than that of the CSB (1), respectively, indicating that the combined internal structure of the MJ-ASB SB significantly contributed to the water evaporation process.