Evaluation of FGD (Flue Gas Desulfurization) Dry Injection Sorbents and Additives. Volume 2. Pilot Plant Evaluation of High Reactivity Sorbents

摘要

The report describes a mini-pilot test program to investigate potential new sorbents and processes for dry SO2 removal. Initial tests showed that the 85 cu m/h pilot plant could be used successfully to evaluate both spray dryer and dry injection processes using traditional calcium or sodium based sorbents. The major part of the test program investigated the use of flyash or diatomaceous earth for enhancement of lime with respect to SO2 removal in a dry injection process. This part of the test program verified the silica enhancement of Ca(OH)2 which previously had been extensively studied on a bench-scale reactor. The pilot program showed that 50-90% SO2 removal can be achieved for a stoichiometric ratio of 1 to 2 by dry injection of the silica enhanced lime when using a duct + baghouse configuration, or when using a duct + cyclone configuration including recycle. The sorbent preparation procedure was developed throughout the test program, and an important result was that the silica enhanced lime can be prepared as a semidry sorbent containing 20-30% moisture, suitable for duct injection. Evaporative cooling of the flue gas is allowed as a result of the sorbent injection, thereby lowering the approach to saturation and increasing the SO2 removal.