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The flue gas leaves the boiler at a temperature of 400°F (204°C) and the SCR needs to operate at a minimum temperature of 425°F (218°C). Thus, only minor reheating of flue gas is required.
Generally sodium bicarbonate works when the flue gas temperature is a minimum of 320°F (160°C). However, a higher temperature improves its reactivity and thus, the selected combination of low temperature tail-end SCR with sodium bicarbonate feed to the reactor is an effective solution.
Conclusions
The construction of many coal-fired power plants has been suspended or cancelled, and receiving permits for new units is proving to be very difficult. By contrast, the future of biomass combustion looks very promising; the country continues to need power, and renewable power is in high demand because of public opinion. Many states also have renewable portfolio standards requiring more renewable generation.
Because of the low emissions, fuel flexibility and high combustion efficiency, fluidized bed technologies are an attractive option
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Editor’s note: This paper, PWR2009-81052, was printed with permission from ASME and was edited from its original format. To purchase this paper in its original format or find more information, visit the ASME Digital Store at www.asme.org.
Rainio has more than 20 years of experience in the boiler industry, and fluidized bed technologies have always been close to his heart. He has held various positions, ranging from R&D to consulting engineering, and from designing fluidized bed boilers to project engineering and management. Rainio has a master’s degree in mechanical engineering from Lappeenranta University of Technology, Finland. He has lived in the U.S. since 1997. He recently worked for AE&E – Von Roll in Norcross, Ga., as group leader in Process Engineering department, and was recently invited to join ASME’s Steam Generators and Auxiliaries Committee. He now works for Andritz Inc.
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