OCR Text |
Show natural gas or LPG, the catalyst lifetime may reach five years; whereas for flue gases from the burning of high sulfur fuel oil or coal, the catalyst lifetime may be less than a year. For applications with such dirty gases, particulates and/or sulfur oxides removal systems may be incorporated. Such flue gas conditioning complicates the overall system; and where substantial reheat is required after a wet scrubber removal of sulfur oxides, there is considerable loss in unit efficiency. 2.3.2 Development Status In general, SCR performance for clean flue gas has been quite good (90+% NOx removal with catalyst lifetime of several years). Recent applications to coal burning facilities, sintering plants, and oil burning facilities are expanding the experience base at a rapid rate. It appears that application to units burning coal or producing dry particulate material is feasible. Application to units which produce soot and sticky particulates is undesirable. Applicability to low-sulfer residual oil fueled units is not clear at this time based on published information. Demonstration projects are in progress as follows: SCR pilot plant scale demonstration of Hitachi-Zosen NOx reduction process on a 0.6 MW equivalent side stream from a coal fired utility boiler (funded by EPA). Pilot scale demonstration of UOP-shell simultaneous NOx/SOx removal on a 0.6 MW equivalent side stream from a coal fired utility boiler (funded by EPA). SCR demonstration of Kawasaki Heavy Industries process on a 2.5 MW equivalent side stream from a coal fired utility boiler (funded by Electric Power Research Institute). SCR demonstration of Kawasaki Heavy Industries process on a 100 MW equivalent side stream from a gas/oil fired utility boiler by Southern California Edison. 4-23 P-233 |