Journal of Zhejiang University SCIENCE A
(Monthly)

2006   Vol. 7   Suppl. II   p. 335-339

Kinetic modelling of homogeneous low temperature multi-pollutant oxidation by ozone: The importance of SO and HCl in predicting oxidation

Wei Lin-Sheng^†, Zhou Jun-Hu, Wang Zhi-Hua, Cen Ke-Fa

(State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China)
^†E-mail: lswei1981@zju.edu.cn
Received Nov. 12, 2005 revision accepted May 10, 2006

Abstract: A detailed kinetic model consisting of 126 reactions and 37 species modelled homogeneous low temperature multi-pollutant oxidation in flue gases by ozone. The kinetic model includes the oxidation and chlorination of key flue-gas components, as well as reactions involving SO. An important and previously unrecognized pathway of homogeneous Hg oxidation mechanism includes Hg reactions involving oxygen-containing compounds and chlorine-containing compounds. Analyses by sensitivity simulations revealed that the pathway Hg+Cl=HgCl and HgCl+Cl₂=HgCl₂+Cl is more significant than some of the key reactions in the kinetic mechanism proposed in the literature except Hg+NO₃=HgO+NO₂, which indicates the possibility to promote the Hg removal by adding HCl in the inlet stream. Studies on the effects of SO show that SO violently prevents NO consumption through the pathway SO+NO₂=NO+SO₂, even the net NO produced under the condition of low O₃ concentration and high SO concentration.

Key words: Low temperature oxidation, Multi-pollutant removal, Kinetic modelling, Reaction mechanism
doi:10.1631/jzus.2006.AS0335             CLC number: TK01; X5

References:

[1] Bowman, C.T., 1991. Chemistry of Gaseous Pollutant Formation and Destruction. In: Bartok, W., Sarofim, A.F. (Eds.), Fossil Fuel Combustion. Wiley, New York, p.215.

[2] Edwards, J.R., Srivastave, R.K., Kilgroe, J.D., 2001. A study of gas-phase mercury speciation using detailed chemical kinetics. Air & Waste Manage. Assoc., 51:869-877.

[3] Fu, Y., Diwekar, U.M., 2004. Cost effective environmental control technology for utilities. Advances in Environmental Research, 8(2):173-196.

[4] Hall, B., Lindqvist, O., Ljungstrom, E., 1990. Mercury chemistry in simulated flue gases related to waste incineration conditions. Environ. Sci. Technol., 24(1):108-111.

[5] Jarvis, J.B., Day, A.T., Suchak, N.J., 2003. LoTOx^TM Process Flexibility and Multi-Pollutant Control Capability. Power Plant Air Pollutant Control Mega Symposium, Washington, D.C.

[6] Kee, R.L., Rupley, F.M., Meeks, E., Miller, J.A., 1996. CHEMKIN—III: A Fortran Chemical Kinetics Package for the Analysis of Gas Phase Chemical Kinetics. SAND96-8216.

[7] Kilgroe, J., Senior, C., 2003. Fundamental Science and Engineering of Mercury Control in Coal-Fired Power Plants. The Air Quality IV Conference, Arlington, VA.

[8] Mallard, W.G., Westley, F., Herron, J.T., Hampson, R.F., Frizzell, D.H., 1998. NIST Chemical Kinetic Database. National Institute of Standards and Technology, USA.

[9] Mamani-Paco, R., Helble, J.J., 2000. Bench Scale Examination of Mercury Oxidation under Non-Isothermal Conditions. 93rd Annual Conference of the Air and Waste Management Association, Salt Lake City, UT.

[10] Niksa, S., Helble, J.J., Fujiwara, N., 2001. Kinetic modeling of homogeneous mercury oxidation: the importance of NO and H₂O in predicting oxidation in coal-derived systems. Environ. Sci. Technol., 35(18):3701-3706.

[11] Senior, C.L., Sarofim, A.F., Zeng, T., Helble, J., Mamani-Paco, R., 2000. Gas-phase transformations of mercury in coal-fired power plants. Fuel Process. Technol., 63(2-3): 197-213.

[12] Sliger, R.N., Kramlich, J.C., Marinov, N.M., 2000. Towards the development of a chemical kinetic model for the homogeneous oxidation of mercury by chlorine species. Fuel Proc. Tech., 65-66(1):423-438.

[13] Widmer, N.C., Cole, J.A., Seeker, W.R., Gaspar, J.A., 1998. Practical limitation of mercury speciation in simulated municipal waste incinerator flue gas. Combust. Sci. Technol., 134:315-326.