Experimental Study on Combustion Behaviors and Carbon Monoxide Emission Characteristics of Single Coal Pellets

Abstract

Combustion behaviors and carbon monoxide emission characteristics of four kinds of coals and their blends, which were shaped into pellets, were investigated in a drop-tube furnace with various gas flow temperature (65–85°C) and oxygen concentration (1–7%). Pellets of 6 mm were hung by a wire basket and the combustion process was recorded at 6 frames/s using a high-performance camera. The ignition of the bituminous pellet was found to be homogeneous but it was heterogeneous for anthracite. When the oxygen concentration was more than 5%, an obvious fragment was found for the anthracite pellet, which caused higher surface temperature compared with the predicted temperature. The instantaneous CO emission of the bituminous coal had two peaks, whereas there was only one peak for that of anthracite. The total CO emission decreased exponentially when the temperature and oxygen concentration increased, and the oxygen concentration had more influence on the reduction of CO emission. CO generation was also affected by coal type; the higher the carbon and ash component of the coal, the more CO was generated with the same conditions.