The report gives results of an extensive study of dry flue gas desulfurization (FGD) systems, involving dry injection of absorbents or spray drying. (The study was undertaken because they appear to have both process and economic advantages over wet FGD.) Design concepts (e.g., type of absorbent and atomizer, approach to flue gas saturation temperature, and particulate collection method) remain to be demonstrated at full scale. Most vendors prefer a lime slurry system with rotary atomizers and fabric filter particulate collection, while all systems now under contract to utilities apply to low-sulfur coal. SO2 removal efficiencies sufficient for high-sulfur coal applications at stable operating conditions and economically feasible absorbent utilization rates have not yet been demonstrated. In conceptual design cost comparisons based on a new 500-MW utility power generation unit, a lime spray dryer/fabric filter combination had lower capital investments and annual revenue requirements for 0.7% sulfur western coal and both 0.7 and 3.5% sulfur eastern coal than a wet limestone scrubbing process. With lignite fuel, similar cost advantages were evident for dry (relative to wet) FGD. The capital investment advantage of dry over wet FGD increased with increasing coal sulfur content.

"February 1981." Includes bibliographical references. "TVA EDT-127." "EDT-127"--Cover. "EPA interagency agreement no. D9-E712-BI, program element no. INE827."