CaO interaction in the staged combustion of coal. Seventh quarterly technical progress report, April 1, 1982-June 30, 1982

Efforts were directed to the coal combustion studies. Two modifications were made to the methane-coal (M-C) combustor, one, to allow introduction of the pulverized coal into the early postflame zone of the methane flame (in contrast to preflame injection used in previous runs), and the second to provide better control of the postflame temperature zone. The early postflame injection procedure is being used to reduce the effects of methane chemistry, if any, on the coal combustion process. Control of the postflame temperature is important in studying temperature and residence time effects on sulfur retention chemistry. Five runs were made using the postflame injection method. Pulverized coal treated with lime (Ca/S = 3.8) was burned in the modified methane-coal (M-C) burner to examine the sulfur capture potential of the coal at various temperature and equivalence ratios. Data obtained from the fuel-rich M-C firings continue to show a strong correlation between sulfur retention and carbon burnout of the coal as expressed by the equation, Sulfur retention = -0.827 x Carbon burnout +93.7, where sulfur and carbon burnout are expressed as percent. Lowering the temperature of the postflame reaction zone produced the same sulfur retention-carbon burnout relationship shown above. Analysis of the ashesmore » showed that the sulfur was retained as sulfate with little or no sulfides present. Thus, results from the postflame firings this quarter are in agreement with those from the preflame firings last quarter. Progress has been made in obtaining more reliable analyses of the gaseous sulfur-bearing products (e.g., H/sub 2/S, COS and SO/sub 2/) formed in fuel-rich firings. However, it appears that the sulfur retention values from the ash data are more reliable.« less