Effect of moisture distribution in pore structure on fragmentation characteristics of lignite

ABSTRACT

The experiments were performed to explore the effect of moisture on fragmentation properties of Mengdong (MD) lignite, Xiao Longtan (XLT) lignite, and Zhaotong (ZT) lignite with temperature of 200°C and particle size of 13–10 mm using the fixed bed reactor. It showed fragmentation ratio and pulverization ratio increased, and particle size variation ratio decreased with an increase in initial moisture of lignite. The distribution of moisture in pores under different initial moisture contents was analyzed by nuclear magnetic resonance. The distribution of moisture in pores between raw and dried lignite was different. The water content in macropores rapidly decreased, but water content in mesopores remained constant in prior period and then slightly decreased with the residence time increasing. There was a good connectivity between macropores and mesopores. The water in micropores, which hardly influenced fragmentation, was generally closed and not favored for the mobility of water. The water in macropores had a significant effect on fragmentation of lignite. However, when the moisture content in macropores was less than 0.10 g/g coal, the degree of fragmentation became little.

KEYWORDS:

• Drying
• fragmentation characteristics
• lignite
• moisture content
• pore structure

Additional information

Funding

This research was supported by the National Nature Science Foundation of China (Grant No. 51774285, 51574239 and 51704291), Research and Practice on Teaching Reform of Graduate Education (Grant No. YJSJG2017042).