EVALUATION OF THE PERFORMANCE OF A TWO-STAGE, WARM AIR DRYER FOR FINE COAL PARTICLES

摘要

De-watering of coal fines is an important concern in the processing, transportation, handling and combustion ofcoal. The weight of the moisture in coal leads to higher transportation costs, and the adhesive nature of wet coalleads to numerous materials handling issues. Among these issues is clogging in silos, bunkers andcrushing/grinding equipment. In addition, many pulverized coal power plants operate with coal feed stocks that cancontain upwards of 40% moisture, which is a major contributing factor to power plant inefficiencies. In manyinstances, the economic costs of drying the coal prior to combustion are prohibitive.In an effort to address the difficulties associated with wet coal, a two-stage fluidized bed system has been designedand constructed at t West Virginia University. This Warm Air Dryer for Fine Particles (WADFP) consists of asteam-jacketed, two-stage fluidized bed with secondary air injection.Preliminary tests have been carried out using a low-rank lignite coal from Texas. These initial tests resulted inreductions of moisture content ranging from 31% to 74%, and an overall increase in the higher heating value(HHV) of the coal ranging from 9% to 23%.