Activity and characteristics of “Oxygen-enriched” highly reactive absorbent for simultaneous flue gas desulfurization and denitrification

Abstract

An “Oxygen-enriched” highly reactive absorbent was prepared by mixing fly ash, lime and a small quantity of KMnO₄ for simultaneous desulfurization and denitrification. Removal of SO₂ and NO simultaneously was carried out using this absorbent in a flue gas circulating fluidized bed (CFB). The highest simultaneous removal efficiency, 94.5% of SO₂ and 64.2% of NO, was achieved under the optimal experiment conditions. Scanning Electron Microscope (SEM) and Accessory X-ray Energy Spectrometer (EDX) were used to observe the surface characteristics of fly ash, lime, “Oxygen-enriched” highly reactive absorbent and the spent absorbent. An ion chromatograph (IC) and chemical analysis methods were used to determine the contents of sulfate, sulfite, nitrate and nitrite in the spent absorbents, the results showed that sulfate and nitrite were the main products for desulfurization and denitrification respectively. The mechanism of removing SO₂ and NO simultaneously was proposed based on the analysis results of SEM, EDX, IC and the chemical analysis methods.

Keywords

“Oxygen-enriched” highly reactive absorbent / Surface characteristics / Flue gas circulating fluidized bed / Simultaneous desulfurization and denitrification

References

[1] Tsai C K. Removal of SO₂ from industrial waste gases. Dissertation for the Doctoral Degree. Lubbock: Texas Tech University, 1996

[2] Reed G D, R, Davis W T, Pudelek R E. Analysis of coal fly ash properties of importance to sulfur dioxide reactivity potential. Environmental Science and Technology, 1984, 18(7): 548–552

[3] Petersen Tom, Karlsson H T. Significance of fly ash in wet-dry scrubbing of SO₂. Chemical Engineering and Technology, 1988, 11(5): 298–305

[4] Izquierdo J F, Cunill F, Martinez J C, Tejero J, Garcia A. Fly ash reactivation for the desulfurization of coal-fired utility station’s flue gas. Separation Science and Technology, 1992, 27(1): 61–72

[5] Peterson J R., Rochelle G T. Aqueous reaction of fly ash and Calcium hydroxide to produce calcium silicate absorbent for flue gas desulfurization. Environmental Science and Technology, 1988, 22(11): 1299–1304

[6] Ho C S, Shih S M. Calcium hydroxide/fly ash sorbents for SO₂ removal. Industrial and Engineering Chemistry Research, 1992, 31(4): 1130–1135

[7] Davini P. Investigation of flue gas desulphurization by fly ash and calcium hydroxide mixtures. Resources, Conservation and Recycling, 1995, 15(3–4): 193–201

[8] Davini P. Investigation of the SO₂ adsorption properties of Ca(OH)₂-fly ash systems. Fuel, 1996, 75(6): 713–716

[9] Fernández J, Renedo J, Garea A, Viguri J, Irabien J A. Preparation and characterization of fly ash / hydrated lime sorbents for SO₂ removal. Powder Technology, 1997, 94(2): 133–139

[10] Li Y,Nishioka, Sadakata M. High calcium utilization and gypsum formation for dry desulfurization process. Energy Fuels, 1999, 13(5): 1015–1020

[11] Renedo M J, Fernández J, Garea A, Ayerbe A, Irabien J A. Microstructural changes in the desulfurization reaction at low temperature. Industrial and Engineering Chemistry Research, 1999, 38(4): 1384–1390

[12] Shi L M, Xu X C. Study of the effect of fly ash on desulfurization by lime. Fuel, 2001, 80(13): 1969–1973

[13] Liu C F, Shih S M, Lin R B. Kinetics of the reaction of Ca(OH)₂/fly ash sorbent with SO₂ at low temperatures. Chemical Engineering Science, 2002, 57(1): 93–104

[14] Lin R B, Shih S M, Liu C F.Structural properties and reactivities of Ca(OH)₂/fly ash sorbents for flue gas desulfurization. Industrial and Engineering Chemistry Research, 2003, 42(7): 1350–1356

[15] Liu C F, Shih S M, Lin R B. Kinetic model for the reaction of Ca(OH)₂/fly ash sorbents with SO₂ at Low Temperatures. Industrial and Engineering Chemistry Research, 2004, 43(15): 4112–4117

[16] Liu C F, Shih S M, Lin R B. Effect of Ca(OH)₂/fly ash weight ratio on the kinetics of the reaction of Ca(OH)₂/fly ash sorbents with SO₂ at Low temperatures. Chemical Engineering Science, 2004, 59(21): 4653–4655

[17] Renedo M J, Fernández J. Preparation, characterization, and calcium utilization of fly ash/Ca(OH)₂ sorbents for dry desulfurization at low temperature. Industrial and Engineering Chemistry Research, 2002, 41(10): 2412–2417

[18] Ho C S, Shih S M. Characteristics and SO₂ capture capacities of sorbents prepared from products of spray-drying flue gas desulfurization. Canadian Journal of Chemical Engineering, 1993, 71(6): 934–939

[19] Kind K K, Wasserman P D, Rochelle G T. Effects of salts on preparation and use of calcium silicates for flue gas desulfurization. Environmental Science and Technology, 1994, 28(2): 277–283

[20] Tsuchiai H, Ishizuka T, Ueno T, Hattori H, Kita H. Highly active absorbent for SO₂ removal prepared from coal fly ash. Industrial and Engineering Chemistry Research, 1995, 34(4): 1404–1411

[21] Ishizuka T, Tsuchiai H, Murayama T, Tanaka T, Hattori H. Preparation of active absorbent for dry-type flue gas desulfurization from calcium oxide, coal fly ash, and gypsum. Industrial and Engineering Chemistry Research, 2000, 39(5): 1390–1396

[22] Ishizuka T, Yamamoto T, Murayama T, Tanaka T, Hattori H. Effect of calcium sulfate addition on the activity of the absorbent for dry flue gas desulfurization. Energy Fuels, 2001, 15(2): 438–443

[23] Fernández J, Renedo M J. Study of the influence of calcium sulfate on fly ash/Ca(OH)₂ sorbents for flue gas desulfurization. Energy and Fuels, 2003, 17(5): 1330–1337

[24] Renedo M J, Fernández J. Kinetic modeling of the hydrothermal reaction of fly ash, Ca(OH)₂ and CaSO₄ in the preparation of desulfurant sorbents. Fuel, 2004, 83(4–5): 525–532

[25] Zhao Y, Ma S C, Huang J J, Xu P Y, Wang L D, Hua W. Experimental study on SO₂ and NO_x removal and mechanism by highly reactive sorbent. Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering. 2003, 23(10): 236–240(in Chinese)

[26] Zhao Y, Fu Y C, Ma S C, Huang J J. Experimental study on the simultaneous desulfurization and denitrification by duct injection. Journal of Environmental Sciences (China), 2004, 16(4): 674– 677

[27] Zhao Y, Han Y H, Ma T Z, Guo T X. Simultaneous desulfurization and denitrification from flue gas by Ferrate(VI). Environmental Science and Technology, 2011, 45(9): 4060–4065

[28] Su C Y, Ran X, Hu J L, Shao C L. Photocatalytic process of simultaneous desulfurization and denitrification of flue gas by TiO₂–polyacrylonitrile nanofibers. Environmental Science and Technology, 2013, 47(20): 11562–11568

[29] Zhao Y, Han Y H, Chen C. Simultaneous removal of SO₂ and NO from flue gas using multicomposite active absorbent. Industrial and Engineering Chemistry Research, 2012, 51(1): 480–486

[30] Bai M D, Zhang Z T, Bai M D. Simultaneous desulfurization and denitrification of flue gas by ·OH radicals produced from O₂⁺and water vapor in a duct. Environmental Science and Technology, 2012, 46(18): 10161–10168

[31] Zhao Y, Guo T X, Chen Z Y, Du Y R. Simultaneous removal of SO₂ and NO using M/NaClO₂ complex absorbent. Chemical Engineering Journal, 2010, 160(1): 42–47.

[32] Hao X W, Ma C Y, Dong Y, Yang J G. Composite fluidization in a circulating fluidized bed for flue gas desulfurization. Powder Technology, 2012, 215–216: 46–53

[33] Sakai M, Su C L, Sasaoka E. Simultaneous removal of SO_x and NO_x using slaked lime at low temperature. Industrial and Engineering Chemistry Research, 2002, 41(20): 5029–5033

Acknowledgements

The work was supported by the National High Technology Research and Development Program of China (863 Program, No. 2013AA065403), Program for Changjiang Scholars and Innovative Research Team in University (IRT1127) and Zhejiang Provincial Engineering Research Center of Industrial Boiler & Furnace Flue Gas Pollution Control, Hangzhou, China (311202).

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2014 Higher Education Press and Springer-Verlag Berlin Heidelberg