Combustion of Pulverized, Solvent-Refined Coal

Abstract

The handling, pulverizing, combustion, and fouling characteristics of solvent-refined coal (SRC) were studied in a multiburner, water-wall furnace designed to burn pulverized, bituminous coal at a rate of 500 lb/hr. The products from two SRC plants, Southern Services, Inc., at Wilsonville, Alabama, and ERDA’s plant at Fort Lewis, Washington, were included in the study. SRC obtained from the Southern Services, Inc. plant had a fluid temperature less than 300°F while the product obtained from Fort Lewis had a fluid temperature of about 430°F. When operating at secondary air temperatures of 500–600°F it was necessary to water-cool the primary air-coal passages and burner nozzle to prevent melting and subsequent fouling. In addition, secondary air swirl adjustments were made to optimize recirculation and flame shape to overcome burner fouling. Flame temperatures obtained with SRC were several hundred degrees (°F) higher than those measured with bituminous coal, however, NOx emissions were considerably lower than those obtained with coal fired through the more conventional burners originally used in the combustion system. Sulfur oxides emissions of 0.8–1.0 lb SO2 /106 Btu would meet emissions regulations in most air regions in the U. S. Carbon conversion values were similar to those obtained when firing bituminous coal. To provide a basis for comparison, combustion tests were also conducted on a Pittsburgh seam coal, and an Illinois No. 6 coal, the parent coal for the SRC produced at the Wilsonville plant.