Promotion effect of activated carbon, coal char and graphite on lignite microwave dehydration process

Abstract

Activated carbon, graphite, fast pyrolysis char and slow pyrolysis char produced by pyrolysis of the same lignite were selected as additives to promote the microwave dehydration process of lignite. The influences of those four additives on the lignite dehydration process of microwave heating and physical and chemical properties of products after microwave drying were studied in detail and compared. Based on the performance of different additives, this paper aimed to find the optimal carbon material additives to promote the microwave dehydration process of lignite. Moreover, lignite chars were tested to promote the microwave dehydration process to avoid the adverse effects of impurities caused by additives on the subsequent utilization of upgraded coal. Additives accelerated the microwave dehydration process of lignite and achieved higher moisture removal; the surface hydrophobicity of solid products was enhanced, and its combustion characteristics were improved; the concentration of organic and inorganic matter in liquid products increased. The effect of additives on the lignite microwave heating dehydration process is in the following order: active carbon <fast pyrolysis char <slow pyrolysis char <graphite. With the increased promotion effect of additives, these above changes became more significant.