Efficient use of low rank coal: Current status of low rank coal utilization

Abstract

Despite vast reserves, low rank coals are not used as a main fuel in industry because their high moisture content, potential spontaneous combustion in transportation and storage, and the low thermal efficiency during the combustion in conventional power plants. With a view to secure and strengthen low rank coal's position as high available energy source, in recent years many attempts have been made to develop technologies for an energy-efficient upgrading process. This paper reviews these technologies mainly categorized as drying for reducing moisture, stabilization for decrease self-heating characteristics and cleaning the coal for reducing mineral content of coal. Drying technologies consist of both evaporate and non-evaporative types. There are also highly advanced coal cleaning technologies that produce ash-free coal. The paper discusses some of the promising upgrading technologies aimed at improving these coals in terms of their moisture, ash and other pollutants. Korea's activity for the drying and stabilization technologies will be introduced in this paper and the utilization of dried low rank coal also introduced. © Tsinghua University Press, Beijing and Springer-Verlag Berlin Heidelberg 2012.