Design and operational considerations for selective catalytic reduction technologies at coal-fired boilers

Abstract

By the end of 2010, China had approximately 650 GW of coal-fired electric generating capacity producing almost 75% of the country’s total electricity generation. As a result of the heavy reliance on coal for electricity generation, emissions of air pollutants, such as nitrogen oxides (NO_x), are increasing. To address these growing emissions, the Ministry of Environmental Protection (MEP) has introduced new NO_x emission control policies to encourage the installation of selective catalytic reduction (SCR) technologies on a large number of coal-fired electric power plants. There is, however, limited experience with SCR in China. It is therefore useful to explore the lessons from the use of SCR technologies in other countries. This paper provides an overview of SCR technology performance at coal-fired electric power plants demonstrating emission removal rates between 65% and 92%. It also reviews the design and operational challenges that, if not addressed, can reduce the reliability, performance, and cost-effectiveness of SCR technologies. These challenges include heterogeneous flue gas conditions, catalyst degradation, ammonia slip, sulfur trioxide (SO₃) formation, and fouling and corrosion of plant equipment. As China and the rest of the world work to reduce greenhouse gas emissions, carbon dioxide (CO₂) emissions from parasitic load and urea-to-ammonia conversion may also become more important. If these challenges are properly addressed, SCR can reliably and effectively remove up to 90% of NO_x emissions at coal-fired power plants.

Keywords

nitrogen oxides (NO_x) / coal / selective catalytic reduction (SCR) / air pollution control

References

[1] China Electricity Council (CEC). 2011 Annual Development Report of China’s Power Industry. Beijing: CEC, 2011 (in Chinese)

[2] Zhao Y, Wang S, Duan L, Lei Y, Cao P, Hao J. Primary air pollutant emissions of coal-fired power plants in China: current status and future prediction. Atmospheric Environment, 2008, 42(36): 8442-8452

[3] Ministry of Environmental Protection (MEP). Report on the State of the Environment in China. Beijing: MEP, 2009.

[4] US Environmental Protection Agency (EPA). Nitrogen: Multiple and Regional Impacts. Washington, DC: EPA, 2002

[5] US Environmental Protection Agency (EPA). NO_x Budget Trading Program 2008 Emission, Compliance, and Market Analyses. Washington, DC: EPA, 2009

[6] US Environmental Protection Agency (EPA). Review of the National Ambient Air Quality Standards for Ozone: Policy Assessment of Scientific and Technical Information. Research Triangle Park, NC: EPA, 2007

[7] US Environmental Protection Agency (EPA). Policy Assessment for the Review of the Particulate Matter National Ambient Air Quality Standards. Research Triangle Park, NC: EPA, 2011

[8] Pope C A 3rd, Ezzati M, Dockery D W. Fine-particulate air pollution and life expectancy in the United States. New England Journal of Medicine, 2009, 360(4): 376-386

[9] Butler T J, Likens G E, Vermeylen F M, Stunder B J B. The relation between NO_x emissions and precipitation NO3- in the eastern USA. Atmospheric Environment, 2003, 37(15): 2093-2104

[10] Streets D G, Fu J S, Jang C J, Hao J, He K, Tang X, Zhang Y, Wang Z, Li Z, Zhang Q, Wang L, Wang B, Yu C. Air quality during the 2008 Beijing Olympic games. Atmospheric Environment, 2007, 41(3): 480-492

[11] Wang X, Manning W, Feng Z, Zhu Y. Ground-level ozone in China: distribution and effects on crop yields. Environmental Pollution, 2007, 147(2): 394-400

[12] Chan C K, Yao X. Air pollution in mega cities in China. Atmospheric Environment, 2008, 42(1): 1-42

[13] Xu J, Zhang Y, Fu J S, Zheng S, Wang W. Process analysis of typical summertime ozone episodes over the Beijing area. The Science of the Total Environment, 2008, 399(1-3): 147-157

[14] Zhang J, Mauzerall D L, Zhu T, Liang S, Ezzati M, Remais J V. Environmental health in China: progress towards clean air and safe water. Lancet, 2010, 375(9720): 1110-1119

[15] Tan J H, Duan J C, Chen D H, Wang X H, Guo S J, Bi X H, Sheng G Y, He K B, Fu J M. Chemical characteristics of haze during summer and winter in Guangzhou. Atmospheric Research, 2009, 94(2): 238-245

[16] Tan J, Duan J, He K, Ma Y, Duan F, Chen Y, Fu J. Chemical characteristics of PM_2.5 during a typical haze episode in Guangzhou. Journal of Environmental Sciences (China), 2009, 21(6): 774-781

[17] Hu M, Wu Z, Slanina J, Lin P, Liu S, Zeng L. Acidic gases, ammonia and water-soluble ions in PM_2.5 at a coastal site in the Pearl River Delta, China. Atmospheric Environment, 2008, 42(25): 6310-6320

[18] Zhao X, Zhang X, Xu X, Xu J, Meng W, Pu W. Seasonal and diurnal variations of ambient PM_2.5 concentration in urban and rural environments in Beijing. Atmospheric Environment, 2009, 43(18): 2893-2900

[19] Ye B, Ji X, Yang H, Yao X, Chan C K, Cadle S H, Chan T, Mulawa P A. Concentration and chemical composition of PM_2.5 in Shanghai for a 1-year period. Atmospheric Environment, 2003, 37(4): 499-510

[20] Song Y, Tang X, Xie S, Zhang Y, Wei Y, Zhang M, Zeng L, Lu S.Source apportionment of PM_2.5 in Beijing in 2004. Journal of Hazardous Materials, 2007, 146(1,2): 124-130

[21] Zhao Y, Duan L, Xing J, Larssen T, Nielsen C P, Hao J. Soil acidification in China: is controlling SO₂ emissions enough? Environmental Science & Technology, 2009, 43(21): 8021-8026

[22] Meng Z Y, Xu X B, Wang T, Zhang X Y, Yu X L, Wang S F, Lin W L, Chen Y Z, Jiang Y A, An X Q. Ambient sulfur dioxide, nitrogen dioxide, and ammonia at ten background and rural sites in China during 2007-2008. Atmospheric Environment, 2010, 44(21-22): 2625-2631

[23] Zhang Y, Liu X J, Fangmeier A, Goulding K T W, Zhang F S. Nitrogen inputs and isotopes in precipitation in the north China plain. Atmospheric Environment, 2008, 42(7): 1436-1448

[24] Shen J L, Tang A H, Liu X J, Fangmeier A, Goulding K T W, Zhang F S. High concentrations and dry deposition of reactive nitrogen species at two sites in the North China Plain. Environmental Pollution, 2009, 157(11): 3106-3113

[25] Ministry of Environmental Protection (MEP). Emission Standard for Air Pollutants from Thermal Power Plants. GB 13223-1996, Beijing: MEP, 1996, (in Chinese)

[26] Ministry of Environmental Protection (MEP). Emission Standard for Air Pollutants from Thermal Power Plants. GB 13223-2003, Beijing: MEP, 2003 (in Chinese)

[27] Ministry of Environmental Protection (MEP). Emission Standard for Air Pollutants from Thermal Power Plants. GB 13223-2011, Beijing: MEP, 2011 (in Chinese)

[28] Wen J B. Report on the Work of the Government 2011. Beijing: National People’s Congress, 2011 (in Chinese)

[29] Ministry of Environmental Protection (MEP). Notice of Issuance of Fossil-Fired Power Plant’s NO_x Emission Prevention and Control Policy. Beijing: MEP, 2010 (in Chinese)

[30] Srivastava R K, Hall R E, Khan S, Culligan K, Lani B W. Nitrogen oxides emission control options for coal-fired electric utility boilers. Journal of the Air & Waste Management Association, 2005, 55(9): 1367-1388

[31] Radojevic M. Reduction of nitrogen oxides in flue gases. Environmental Pollution, 1998, 102( Suppl 1): 685-689

[32] Wu Z. NO_x Control for Pulverized Coal Fired Power Stations. London: IEA Clean Coal Centre, 2002

[33] Kitto J B, Stultz S C. Steam: Its Generation and Use. Barberton, Ohio: Babcock & Wilcox Company, 2005

[34] Nalbandian H. NO_xControl for Coal-fired Plant. London: IEA Clean Coal Centre, 2009

[35] Sloss L. Nitrogen Oxides Control Technology Factbook. Norwich, NY: William Andrew Publishing, 1992

[36] Chu P, Downs B, Holmes B. Sorbent and ammonia injection at economizer temperatures upstream of a economizer temperatures upstream of a high—temperature baghouse. Environment and Progress, 1990, 9(3): 149-155

[37] Nalbandian H. Economics of Retrofit Air Pollution Control Technologies. London: IEA Clean Coal Centre, 2006

[38] Erickson C A, Staudt J E. Selective catalytic reduction system performance and reliability review. In: Proceedings of the power plant air pollutant control “MEGA” symposium 2006. Baltimore, MD: Air and Waste Management Association, 2006

[39] Institute of Clean Air Companies (ICAC). Selective Catalytic Reduction (SCR) for Controlling NO_x Emissions from Fossil Fuel Fired Electric Power Plants. Washington, DC: ICAC, 2009

[40] Pritchard S, DiFrancesco C, Kaneko S, Kobayashi N, Suyama K, Lida K. Optimizing SCR catalyst design and performance for coal-fired boilers. In: EPA/EPRI Joint Symposium on Stationary Combustion NO_x Control. Kansas City, Kansas: EPRI, 1995

[41] Cichanowicz J E, Muzio L J. Twenty-five years of SCR evolution: implications for US application and operation. In: Proceedings of the Power Plant Air Pollutant Control “MEGA” Symposium 2001. Baltimore, Maryland: Air and Waste Management Association, 2001

[42] Rogers K J. Mixing performance characterization for optimization and development on SCR applications. In: DOE 2003 Conference on SCR/SNCR for NO_x Control. Pittsburgh, Pennsylvania: DOE, 2003

[43] Strege J R, Zygarlicke C J, Folkedahl B C, McCollor D P. SCR deactivation in a full-scale cofired utility boiler. Fuel, 2008, 87(7): 1341-1347

[44] Wang J. Selective catalytic reduction (SCR). In: 2nd U.S.-China NO_x and SO₂ Control Workshop. Dalian: MOST, 2005

[45] Bartholomew C H. Mechanisms of catalyst deactivation. Applied Catalysis A: General, 2001, 212(1,2): 17-60

[46] Srivastava R K, Miller C A, Erickson C, Jambhekar R. Emissions of sulfur trioxide from coal-fired power plants. Journal of the Air & Waste Management Association, 2004, 54(6): 750-762

[47] Menasha J, Dunn-Rankin D, Muzio L, Stallings J. Ammonium bisulfate formation temperature in a bench-scale single-channel air preheater. Fuel, 2011, 90(7): 2445-2453

[48] Sobolewski H, Jancauskas J, Harrell M, Hartenstein H, Martin M. Large particle ash (LPA) screen retrofits at coal-fired units in Indiana and Ohio. In: 2006 US DOE Environmental Controls Conference. Pittsburgh, PA. Washington: DOE, 2006

[49] Connell D P, Locke J E, Abrams R F, Beittel R. The Greenridge multi-pollutant control project: performance and cost results from the first year of operation. In: Proceedings of the Power Plant Air Pollutant Control “MEGA” Symposium 2008. Baltimore, Maryland: Air and Waste Management Association, 2008

[50] Senior C L, Lignell D O, Sarofim A F, Mehta A. Modeling arsenic partitioning in coal-fired power plants. Combustion and Flame, 2006, 147(3): 209-221

[51] Staudt J E, Engelmeyer T, Weston W H, Sigling R. The impact of arsenic on coal fired power plants equipped with SCR. In: ICAC Forum. Houston, Texas: Institute for Clean Air Companies, 2002

[52] Wang M, Zheng B, Wang B, Li S, Wu D, Hu J. Arsenic concentrations in Chinese coals. Science of the Total Environment, 2006, 357(1-3): 96-102

[53] Zhao Y, Zhang J, Huang W, Wang Z, Li Y, Song D, Zhao F, Zheng C. Arsenic emission during combustion of high arsenic coals from southwestern Guizhou, China. Energy Conversion and Management, 2008, 49(4): 615-624

[54] He B, Liang L, Jiang G. Distributions of arsenic and selenium in selected Chinese coal mines. Science of the Total Environment, 2002, 296(1-3): 19-26

[55] Staudt J E, Engelmeyer A J. SCR catalyst management strategies-modeling and experience. In: Proceedings of COAL-GEN 2003. Columbus, Ohio: PennWell, 2003

[56] taudt J E. Minimizing the impact of SCR catalyst on total generating cost through effective catalyst management. In: Proceedings of the ASME Power Conference. Baltimore, Maryland: ASME, 2004

[57] Chothani C, Morey R. Ammonium bisulfate (ABS) measurement for NO_x control and air heater protection. In: Proceedings of the Power Plant Air Pollutant Control “MEGA” Symposium 2008. Baltimore, Maryland: Air and Waste Management Association, 2008

[58] Wright T, DeLallo M. Increased SO₃ and ammonia slip from SCR: balancing air heater deposits, ammonia in effluent discharge, and SO₃ plume. In: Proceedings of 2002 Conference on Selective Catalytic Reduction (SCR) and Selective Non-catalytic Reduction (SNCR) for NO_x Control. Pittsburgh, Pennsylvania: National Energy Technology Laboratory (NETL), 2002

[59] Schmidtchen P A, Hatern M J, Lombardi D E, Wajer M. High activity magnesia use for SCR related SO₃ problems. In: Proceedings of 2002 Conference on Selective Catalytic Reduction (SCR) and Selective Non-catalytic Reduction (SNCR) for NO_x Control. Pittsburgh, Pennsylvania: National Energy Technology Laboratory (NETL), 2002

[60] Sutton M A, Erisman J W, Dentener F, Möller D. Ammonia in the environment: from ancient times to the present. Environmental Pollution, 2008, 156(3): 583-604

[61] Apsimon H, Kruse M, Bell J, 0. Kruse M, Bell J N B. Ammonia emissions and their role in acid deposition. Atmospheric Environment, 1987, 21(9): 1939-1946

[62] Zhao P, Zhu T, Liang B, Hu M, Kang L, Gong J. Characteristics of mass distributions of aerosol particle and its inorganic water-soluble ions in summer over a suburb farmland in Beijing. Frontiers of Environmental Science & Engineering in China, 2007, 1(2): 159-165

[63] Louie P K K, Chow J C, Chen L W A, Watson J G, Leung G, Sin D W M. PM_2.5 chemical composition in Hong Kong: urban and regional variations. The Science of the Total Environment, 2005, 338(3): 267-281

[64] Louie P K K, Watson J G, Chow J C, Chen A, Sin D W M, Lau A K H. Seasonal characteristics and regional transport of PM_2.5 in Hong Kong. Atmospheric Environment, 2005, 39(9): 1695-1710

[65] Lai S C, Zou S C, Cao J J, Lee S C, Ho K F. Characterizing ionic species in PM_2.5 and PM₁₀ in four Pearl River Delta cities, south China. Journal of Environmental Sciences (China), 2007, 19(8): 939-947

[66] Hu M, Wu Z, Slanina J, Lin P, Liu S, Zeng L. Acidic gases, ammonia and water-soluble ions in PM_2.5 at a coastal site in the Pearl River Delta, China. Atmospheric Environment, 2008, 42(25): 6310-6320

[67] He K, Yang F, Ma Y, Zhang Q, Yao X, Chan C K, Cadle S, Chan T, Mulawa P. The characteristics of PM_2.5 in Beijing, China. Atmospheric Environment, 2001, 35(29): 4959-4970

[68] Ye B, Ji X, Yang H, Yao X, Chan C K, Cadle S H, Chan T, Mulawa P A. Concentration and chemical composition of PM_2.5 in Shanghai for a 1-year period. Atmospheric Environment, 2003, 37(4): 499-510

[69] Kai Z, Yuesi W, Tianxue W, Yousef M, Frank M. Properties of nitrate, sulfate and ammonium in typical polluted atmospheric aerosols (PM₁₀) in Beijing. Atmospheric Research, 2007, 84(1): 67-77

[70] Zhao D W, Wang A P. Estimation of anthropogenic ammonia emissions in Asia. Atmospheric Environment, 1994, 28(4): 689-694

[71] Zhang Y, Dore A J, Ma L, Liu X J, Ma W Q, Cape J N, Zhang F S. Agricultural ammonia emissions inventory and spatial distribution in the North China Plain. Environmental Pollution, 2010, 158(2): 490-501

[72] Forzatti P, Nova I, Beretta A. Catalytic properties in deNO_x and SO₂-SO₃ reactions. Catalysis Today, 2000, 56(4): 431-441

[73] Ritzenthaler D P. SO₃ control: AEP pioneers and refines trona injection process for SO₃ mitigation. 2007-<month>03</month>-<day>01</day>, http://www.coalpowermag.com/plant_design/SO3-Control-AEP-Pioneers-and-Refines-Trona-Injection-Process-for-SO3-Mitigation_29.html

[74] Drbal L, Westra K, Boston P. Power Plant Engineering. New York: Springer-Verlag, 1995

[75] Graus W H J, Worrell E. Effects of SO₂ and NO_x control on energy-efficiency power generation. Energy Policy, 2007, 35(7): 3898-3908

[76] Bhattacharya S, Peters H J, Fisher J, Spencer H W III. Urea to ammonia (U2A) systems: operation and process chemistry. In: Proceedings of the power plant air pollutant control “MEGA” symposium 2003. Washington, DC: Air and Waste Management Association, 2003

[77] Spencer H W III, Peters H J, Hankins W. Design considerations for generating ammonia from urea for NO_x control with SCRs. In: 2007 (100th) A&WMA Annual Conference. Pittsburgh, Pennsylvania: Air and Waste Management Association, 2007

[78] Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt K B, Tignor M, Miller H L, eds. Climate Change 2007: the Physical Science Basis. Cambridge, UK: Cambridge University Press, 2007

[79] Heck R M. Catalytic abatement of nitrogen oxides-stationary applications. Catalysis Today, 1999, 53(4): 519-523

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg