Development of Criteria for Extension of Applicability of Low Emission, High Efficiency Coal Burners

摘要

The report gives results of the first year's effort on this contract. Experimental studies were conducted at three scales to determine the influence of coal properties on NOx emissions. In addition, the use of sorbents to reduce SOx emissions from coal flames was investigated. Bench-scale (0.1 million Btu/hr) investigation concentrated on studies to define the effect of coal characteristics on fuel nitrogen conversion. Based on these investigations, the total coal nitrogen content does not appear to be the primary variable controlling fuel NO production in pulverized-coal flames. Experiments were conducted with research-design low-NOx burners at two scales (12.5 and 100 million Btu/hr) using three coal types. Under optimum conditions, the NOx emissions, typically below 200 ppm (dry at 0% O2), were only slightly dependent on coal characteristics. Preliminary investigations assessed the use of the low-NOx burner design to reduce NOx and SOx emissions by adding sorbents to the coal before the pulverizer. Limestone added this way gave 50, 70, and 80% reductions in SO2 emissions at calcium/sulfur molar ratios of 1, 2, and 3, respectively.