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HIGH REACTIVITY SORBENTS FOR SO2 CONTROL
Citation:
Drehmel, D., D. Kirchgessner, AND S. Rakes. HIGH REACTIVITY SORBENTS FOR SO2 CONTROL. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/D-86/009 (NTIS PB86145794), 1986.
Description:
The paper discusses studies, relating to air pollution control from coal-fired utility boilers, that show that the primary variable affecting sorbent reactivity at high temperature or at low temperature with water droplets is surface area. For the development of high surface area during furnace injection, some limestones appear to be superior to others and can be selected accordingly. Even more striking are the differences in surface area development and sulfur capture between classes of commercially available sorbents. Dolomitic sorbents generally outperform their calcitic counterparts, and hydrates are clearly preferable to carbonates on the basis of SO2 capture. It has been shown further that sorbents can be modified in a number of ways to enhance their performance. Limestones can be precalcined to high surface areas and injected downstream from the burner to preserve their reactivity. Calcitic materials can be pressure hydrated to increase their reactivity over atmospheric hydrates, and hydration parameters can apparently be adjusted to increase reactivity even further. Finally, additives are available that promote SO2 capture in the full range of calcium-based sorbents, and iron has been identified as an effective promoter with minimal adverse effects when added to the water of hydration for pressure hydrated materials.