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Lignite drying in a bench-scale pulsation-assisted fluidized bed dryer

Abstract A bench-scale indirect pulsation-assisted fluidized bed dryer with a 0.24 m2 cross-section area has been built to confirm the drying performance of lignite. The fluidized bed dryer with tube bundles was utilized to investigate the scale-up effect on the drying rate of the pulsed flow using superheated steam as the drying medium. Particles agglomeration was found a serious problem when to increase the scale of the fluidized bed dryer. Agglomeration reduction could be achieved through increasing horizontal diffusion rate using the pulsation-assisted flow and then drying rate was enhanced. Drying rate enhancement effect increased with the increase of the pulsation-assisted flow velocity. The pulsation-assisted flow could enhance the drying rate by nearly 40% compared to that of the steady flow at the gas velocity of 0.29 m/s, and 20% at the gas velocity of 0.19 m/s. Frequency of pulsed flow also affected the drying rate, which 3 and 5 Hz-pulsed flow has a higher drying rate than that of 1 Hz. Highlights Drying characteristics of lignite in pulsation-assisted fluidized bed was studied. Pulsation-assisted flow enhanced the lignite drying rate. Particle horizontal dispersion rate increased by pulsation-assisted flow. 3 and 5 Hz pulsed flow increased the drying rate than 1 Hz.