Experimental study on three-stage microwave-assisted fluidized bed drying of Shengli lump lignite

ABSTRACT The drying characteristics of Shengli lump lignite in a three-stage microwave-assisted fluidized bed dryer (MFBD) are investigated in this study. The fluidized bed was operated with a continuous feed in the modes with one to three stages. The effects of microwave power and microwave time on the drying rate and fragmentation rate are studied. The drying rate of Shengli lump lignite increased with increasing microwave power. The fragmentation rate depended on microwave power, microwave time, and final moisture content. The fragmentation rate of dried lignite was in the range of 3–15%. Furthermore, an increase in fragmentation rate at a high microwave power correlates with an increase of the drying time. Pore size distribution in the lignite was determined by mercury intrusion porosimetry (MIP method). With increasing microwave power, total pore volume significantly decreased and average pore diameter was nearly unchanged.

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