Abstract
Recently, the use of NOx control retrofits is significantly increasing due to further tightening of regulations caused by worldwide environmental concerns. In order to reduce NOx emissions, most of the generators are equipped with SCR (Selective Catalytic Reduction) or OFA (Over-Fire Air) systems, while some generators being equipped with both systems. Here we present experimental evidence of higher boiler efficiency with efficient NOx control with consideration for influences on unburned carbon, under the condition that it should meet local and federal emissions requirements. The higher boiler efficiency has been achieved for a newly installed SCR system by optimizing OFA and reducing excess air quantity. The test was conducted over 6 months with a 500 MW coal-fired boiler. Stepwise closing of OFA dampers was carried out with and without simultaneous excess air optimization at a 500 MW nominal rating. We confirmed that our new operation leads to the following benefits: a) Reduction of UBC due to higher temperature in the furnace’s main combustion zone, b) Improved fly-ash recycling ratio, c) Reduction of spray water into re-heater due to lower temperatures in the second (upper) combustion zone, and d) Reduction of exhaust gas loss. As a result, the boiler efficiency has increased by up to 0.4% and UBC (unburned carbon) has decreased by 0.8%. In conclusion, we confirmed that our new operation mode yields better boiler efficiency for newly installed SCR systems and mixed coal firing operating conditions.
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This paper was recommended for publication in revised form by Associate Editor Oh Chae Kwon
Wook Kim was born in Pusan, Korea on February 11, 1968. He received B.S., M.S. and Ph.D. degrees in Electrical Engineering from Seoul National University in 1990, 1992 and 1997, respectively. He is a senior manager of overseas business team at Korea Southern Power Co. His research interests include power economics, electricity and carbon trading, smart grid, renewable energy and generation expansion planning.
Dong-Jun Lee Lee was born in Jin-ju, Korea on May 22, 1978. He received B.S degrees in Mechanical Engineering from Chang-won National University in 2005. He was a main supervisor in Boiler section in Ha-dong thermal power plant in 2005 to 2007 and is an assistant manager of wind power development team at Korea Sothern Power Co. His research interests include power plant management, renewable energy and power planning.
Sang-Woon Park was born in Heanam, Korea on June 29, 1967. He received B.S. degree in Mechanical Engineering from Chosun University in 1991. He is a senior manager at Ha-Dong Thermal power plant of Korea Southern Power co. His research interests include power plant operation and emissions control.
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Kim, W., Lee, DJ. & Park, SW. Experimental study on optimization of over-fire air in modified combustion condition with selective catalytic reduction. J Mech Sci Technol 25, 901–909 (2011). https://doi.org/10.1007/s12206-011-0208-3
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DOI: https://doi.org/10.1007/s12206-011-0208-3