Experimental Investigations of a Pilot Scale Coal Impinging Stream Dryer

Abstract

ABSTRACT A method for drying hard coals using an impinging stream dryer has been proposed in the article. A series of screening tests were conducted, seeking optimum process parameters of an innovative coal impinging stream dryer using flue gas as the drying medium. The article addresses measurement results obtained for the flue gas and feedstock flow rate, feedstock sort, and initial moisture content on the specific energy consumption, volumetric water evaporation rate, and moisture reduction. The maximum volumetric water evaporation rate was found to be around 230 kgwater/m3·h and the maximum volumetric heat transfer coefficient came to ca. 2.5 kW/m3·°C. In terms of specific energy consumption, the lowest specific energy consumption was found to be around 1.79 kWh/kgwater. It was established that the relation between specific energy consumption and a product of the flue gas flow rate and the initial water (in the feedstock) flow rate is a power function. The best performance of the impinging stream dryer was achieved for high-moisture coal and high flue gas flow rates. The impinging stream dryer proved to be suitable for surface moisture removal from particulate materials that contain very high moisture. The initial tests conducted at the pilot plant successfully demonstrated reliable operation and promising results.