SO{sub 3}'s impacts on plant O & M: part II

Part 1 of this three-part series (Power, October 2006, Coal Abstracts entry Jan 2007 00224) explored the negative impacts of sulfur trioxide (SO{sub 3}) on the operation and maintenance of back-end plant equipment. This article lists and quantifies the likely and potential benefits of limiting the concentration of SO{sub 3} in flue gas to 3 ppm at the entrance to the air heater. Benefits include: reduced acid dew point and back-end corrosion; reduced heat rate and fuel costs; reduced or eliminated ABS fouling of air heaters; reduced fireside corrosion; enabling the use of lower-oxidation catalysts; higher mercury removal efficiency; and lower temperature SCR operation. Part III, to appear in April 2007, will describe the characteristics of an optimal SO{sub 3} removal technology and present the technical details and operating experience of one patented process that has worked successfully at a half-dozen plants for up to three years. 1 ref., 5 figs.