An experimental investigation on the drying kinetics of a single coarse particle of Belchatow lignite in an atmospheric superheated steam condition

The efficiency of lignite-fired power plants is sacrificed by the high moisture content of this energy carrier. The most adequate effort for upgrading the potential of lignite is the drying process, influenced by both the drying conditions and the physicochemical features of lignite. This paper presents studies on the drying kinetic of the Belchatow lignite originating from the biggest Polish lignite mine. Experimental attempts were conducted for spherical lignite samples dried in a superheated steam atmosphere at the temperature range of 110-170 °C. Each experiment includes the simultaneous measurements of changes in weight and temperature profiles for a single sample. Additionally, the drying process was recorded to observe the cracking on the surface of the sample and its shrinkage. The kinetics were described in the form of moisture content, drying rate and temperature profiles over the drying process. The time and rate of the superheated steam drying process depending on the sample size and steam temperature were estimated. Those parameters are essential for the design of an effective industrial coal drying system, which allows for the latent heat recovery of water evaporation from the lignite, which in turn will improve the thermal efficiency of the lignite-fired power generation.