Experimental Study on Solar Drying of Lignite

In this study, a thin-layer solar drying experiment was conducted outdoors to investigate characteristics of solar drying of lignite. The maximum temperature of lignite in the solar dryer reached 87 in 140 minutes when the hourly average of solar radiation intensity was about 950 W/m2. Meanwhile the moisture content of lignite was reduced to 1.38 % from 23.08%. To examine the feasibility of using a solar drier for drying lignite, another drying experiment has been conducted under two different modes (a) solar drying of lignite (b) open sun drying of lignite. The useful temperature rise of about 25 was achieved in the solar dryer, which increased the drying potential of lignite by 6.21%. Moreover, influencing factors in solar drying of lignite, including the effect of solar radiation intensity, the particle size of lignite and the thickness of lignite layer, were investigated. The results indicated that strong solar radiation, small lignite particles and thin lignite layer are good for the increase of the performance of solar drying of lignite.