Dual SO 2 -NO x Concentration Reduction by Calcium Salts of Carboxylic Acids
Publication: Journal of Environmental Engineering
Volume 121, Issue 8
Abstract
The simultaneous removal of SO 2 and NO x by calcium salts of carboxylic acids was evaluated in a laboratory-scale furnace in atmospheres containing 2,000 ppm SO 2, 1,000 ppm NO, 3% O 2, and 12% CO 2 at gas temperatures between 550 and 1,250°C (825 and 1,425 K) with a residence times of 4 s in an isothermal zone. The salts studied included calcium formate (CF, Ca(COOH) 2 ), calcium acetate (CA, Ca(CH 2 COOH) 2 ), calcium propionate CP, (Ca(CH 2 CH 2 COOH) 2 ) and calcium benzoate (CB, Ca(C 6 H 4 COOH) 2 ). Maximum reductions in SO 2 concentration due to the formation of CaSO 4 were recorded as follows: 60% for CP, 55% for CF, 35% for CA, and 18% for CB at gas temperatures in the neighborhood of 950°C and at a Ca/S molar ratio near 2.8. With the organic portion of the injected salts acting as secondary fuel for NO x control, maximum NO x concentration reductions were 88% for CP, 65% for CB, 22% for CA and less than 10% for CF at gas temperatures near 950°C at bulk equivalence ratios (actual to stoichiometric organic fuel-to-air ratio) that varied between 0.5 for CF and 2.1 for CB. A recently constructed, narrower furnace increased the gas flow velocities and the particle dispersion in the gas. Therein, at residence times as low as 1 s, CP achieved simultaneous SO 2 and NO x removal of over 80% at gas temperatures ≥950°C. The addition of an oxidizing zone following the carboxylic acid sorbent injection zone affected the overall SO 2 -NO x removal according to the stoichiometry of the sorbent injection zone. When this zone was: (1) fuel-lean, the overall SO 2 removal improved; (2) stoichiometric, the overall SO 2 removal was not affected; and (3) significantly fuel-rich, the overall SO 2 removal worsened. Under most conditions, the overall reduction of NO x was not affected by the oxidizing zone. At temperatures below 800°C, Ca either was retained as CaCO 3 or remained bound to the organic compounds in the sorbents. At temperatures between 950 and 1,150°C, increasing amounts of CaO were found. The composition of the calcined sorbent and the availability of Ca was used to interpret the results of a cenosphere sulfation model. The sorbent sulfation kinetics were found to be bounded by those of pure CaO and pure CaCO 3 .
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Barin, I. (1989). Thermochemical data of pure substances . VCH Publishers, New York, N.Y.
2.
Barnett, E. P., Joyner, L. S., and Halenda, P. P. (1981). J. Am. Chem. Soc., Vol. 73, 0–373.
3.
Bhatia, S. K., and Perlmutter, D. D. (1981). “The effect of pore structure on fluid-solid reactions: application to the SO 2 -lime reaction.”AIChE J., 27(2), 226.
4.
Cassidy, F. J. (1974). “Evaluation of the Permapure dryer for drying stack gases.”AID.8BA.74, Exxon Res. and Engrg., Linden, N.J.
5.
CRC handbook of chemistry and physics. (1990). CRC Press, Boca Raton, Fla.
6.
Gavalas, G. R. (1980). “A random capillary model with application to char gasification at chemically controlled rates.”AIChE J., Vol. 26, 577.
7.
Gavalas, G. R. (1981). “An analysis of char combustion including the effect of pore enlargement.”Comb. Sci. Tech., Vol. 24, 197.
8.
Kothandaraman, G., and Simons, G. A. (1984). “Evolution of the pore structure in PSOC 140 lignite during pyrolysis.”Proc., 20th Symp. (Int.) on Combustion, Combustion Inst., Ann Arbor, Mich.
9.
Levendis, Y. A., Zhu, W., Wise, D. L., and Simons, G. A. (1993). “The effectiveness of calcium magnesium acetate (CMA) as an SO x sorbent in coal combustion.”AIChE J., 39(5), 761.
10.
Palasantzas, I. A., and Wise, D. L. (1994). “Preliminary economic analysis for production of calcium magnesium acetate from organic residues.”Resour., Conservation and Recycling, Vol. 11, 225–243.
11.
“Reburning for NO x reduction.” (1993). PETC Rev., 9(fall), 27–29.
12.
Simons, G. A., and Finson, M. L. (1979). “The structure of coal char: Part I. Pore branching.”Comb. Sci. Tech., 19(5 and 6), 217–226.
13.
Simons, G. A. (1979a). “The structure of coal char: Part II. Pore combination.”Comb. Sci. Tech., 19(5 and 6), 227–235.
14.
Simons, G. A. (1982). “The pore tree structure of porous char.”Proc., 19th Symp. (Int.) on Combustion, Combustion Inst., Pittsburgh, Pa.
15.
Simons, G. A., and Garman, A. R. (1986). “Small pore closure and the deactivation of the limestone sulfation reaction.”AIChE J., Vol. 32, 1491.
16.
Simons, G. A., Garman, A. R., and Boni, A. A. (1987). “The kinetic rate of SO 2 sorption by CaO.”AIChE J., Vol. 33, 211.
17.
Simons, G. A. (1991). “Predictions of CMA utilization for in-situ SO 2 removal in utility boilers.”Resour., Conservation and Recycling, Vol. 7, 161–170.
18.
Simons, G. A., Parker, T. E., Moore, T. E., Senior, C. L., and Levendis, Y. A. (1992). “Combined NO x /SO x control using a single liquid injection system.”PSI-2186/TR-1169; Prepared for the Department of Energy, Contract No. DE-FG02-91ER81189, Physical Sci., Andover, Mass.
19.
Snow, M. J. H., Longwell, J. P., and Sarofim, A. F. (1988). “Direct sulfation of calcium carbonate.”Industrial and Engrg. Chemical Res., Vol. 27, 268.
20.
Stacy, W. O., and Walker, P. L. Jr. (1972). Structure and properties of various coal chars . Coal Res. Section, Coll. of Earth and Mineral Sci., Pennsylvania State Univ., University Park, Pa.
21.
Steciak, J., Zhu, W. G., Levendis, Y. A., and Wise, D. L. (1994a). “The effectiveness of calcium (magnesium) acetate and calcium benzoate as NO x reduction agents in coal combustion.”Combustion Sci. and Technol., 102(1).
22.
Steciak, J., Levendis, Y. A., Wise, D. L., and Simons, G. A. (1994b). “Dual SO 2 -NO x concentration reduction by fine mists of CMA.”Proc., 19th Int. Conf. on Coal Utilization and Fuel Systems, Clearwater, Fla.
23.
Steciak, J., Levendis, Y. A., and Wise, D. L. (1995). “The effectiveness of calcium magnesium acetate as a dual SO 2 -NO x emission control agent.”AIChE J., 41(3), 712.
24.
Su, F. (1990). “Process for manufacturing crystalline calcium magnesium acetate.”Int. Patent, WO 90/15112, PCT/US90/02766.
25.
Tullin, C., and Ljungström, E. (1989). “Reaction between calcium carbonate and sulfur dioxide.”Energy and Fuels, Vol. 3, 284.
Information & Authors
Information
Published In
Journal of Environmental Engineering
Volume 121 • Issue 8 • August 1995
Pages: 595 - 604
Copyright
Copyright © 1995 American Society of Civil Engineers.
History
Published online: Aug 1, 1995
Published in print: Aug 1995
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.