Mercury transformations in coal combustion flue gas

Abstract Mercury chlorination [i.e., formation of HgCl 2 (g)] is generally assumed to be the dominant mercury-transformation mechanism in coal combustion flue gas. Other potential mechanisms involve mercury interactions with ash particle surfaces where reactive chemical species, oxidation catalysts, and active sorption sites are available to transform Hg 0 (g) to Hg 2+ X(g) (e.g., where X is Cl 2 or O) as well as Hg 0 (g) and HgCl 2 (g) to particulate mercury, Hg(p). Results from an investigation of Hg 0 (g)–O 2 (g)–HCl(g) and Hg 0,2+ (g)–HCl(g)–CaO(s)-fly ash interactions in a 42-MJ/h combustion system are consistent with the following mechanisms: mercury chlorination, catalysis of mercury oxidation by Al 2 O 3 (s) and/or TiO 2 (s), and mercury sorption on a calcium-rich (25.0 wt.% CaO) subbituminous coal fly ash. Additions of 50 and 100 ppmv of HCl(g) and ≈12.6 wt.% of CaO(s) to the subbituminous coal combustion environment inhibited Hg(p) formation, primarily via a change in ash surface chemistry and a decrease in particle surface area, respectively.

[1]  R. Finkelman.  Modes of occurrence of potentially hazardous elements in coal: levels of confidence , 1994 .

[2]  B. Hall,et al.  An experimental study on the rate of reaction between mercury vapour and gaseous nitrogen dioxide , 1995 .

[3]  R. Lauf.  Characterization of the mineralogy and microchemistry of fly ash , 1985 .

[4]  John Munthe,et al.  Atmospheric mercury—An overview , 1998 .

[5]  J. Hower,et al.  Mercury capture by fly ash : Study of the combustion of a high-mercury coal at a utility boiler , 2000 .

[6]  J. Hayashi,et al.  Characteristics of Vaporization of Coal Ash Minerals Chlorinated by Gaseous Hydrogen Chloride , 1998 .

[7]  B. J. Aylett.  The chemistry of zinc, cadmium and mercury , 1975 .

[8]  ScienceDirect.  Fuel processing technology , 1977 .

[9]  T. R. Carey,et al.  CLEAR LIQUOR SCRUBBING WITH ANHYDRITE PRODUCTION , 1997 .

[10]  Wojciech Jozewicz,et al.  Mercury control in municipal waste combustors and coal‐fired utilities , 1997 .

[11]  Michigan.,et al.  Unburned Carbon from Fly Ash for Mercury Adsorption: I. Separation and Characterization of Unburned Carbon , 2002 .

[12]  T. Zeng,et al.  A fundamental study of mercury partitioning in coal fired power plant flue gas , 1997 .

[13]  B. Gullett,et al.  Reaction Mechanisms of Dry Ca-Based Sorbents with Gaseous HCl , 1995 .

[14]  T. D. Brown,et al.  Mercury speciation methods for utility flue gas , 1997 .

[15]  Brian K. Gullett,et al.  Role of Sulfur in Reducing PCDD and PCDF Formation , 1996 .

[16]  S. Mendioroz,et al.  Effect of morphology of sulfurized materials in the retention of mercury from gas streams , 1998 .

[17]  R. Meij.  The fate of mercury in coal-fired power plants and the influence of wet flue-gas desulphurization , 1991 .

[18]  J. Morency,et al.  Interactions between vapor-phase mercury and coal fly ash under simulated utility power plant flue gas conditions , 1998 .

[19]  J. Hower,et al.  Intra- and inter-unit variation in fly ash petrography and mercury adsorption: Examples from a western Kentucky power station , 2000 .

[20]  Dalway J. Swaine,et al.  Trace Elements in Coal , 1990 .

[21]  B. Hall.  The Gas Phase Oxidation of Elemental Mercury by Ozone , 1995 .

[22]  J. A. Cole,et al.  Practical Limitation of Mercury Speciation in Simulated Municipal Waste Incinerator Flue Gas , 1998 .

[23]  T. D. Brown,et al.  Optimization of Sulfur Impregnation Protocol for Fixed-Bed Application of Activated Carbon-Based Sorbents for Gas-Phase Mercury Removal , 1998 .

[24]  T. Tsotsis,et al.  Process for Converting Hydrogen Chloride to Chlorine , 1994 .

[25]  R. L. Lindbauer,et al.  Combustion dioxin supression in municipal solid waste incineration with sulphur additives , 1992 .

[26]  D. Musmarra,et al.  Adsorption of Mercuric Chloride Vapours from Incinerator Flue Gases on Calcium Hydroxide Particles , 1993 .

[27]  Oliver Lindqvist,et al.  Atmospheric mercury—a review* , 1985 .

[28]  R. Vidic,et al.  Effect of Sulfur Impregnation Method on Activated Carbon Uptake of Gas-Phase Mercury , 1997 .

[29]  Oliver Lindqvist,et al.  Chemical reactions of mercury in combustion flue gases , 1991 .

[30]  D. J. Hassett,et al.  Mercury capture on coal combustion fly ash , 1999 .

[31]  O. Lindqvist,et al.  Mercury chemistry in simulated flue gases related to waste incineration conditions , 1990 .

[32]  J. Craig,et al.  The inorganic geochemistry of coal, petroleum, and their gasification/combustion products , 1994 .

[33]  Y. Otani,et al.  Adsorption of mercury vapor on particles. , 1986, Environmental science & technology.

[34]  G. Rochelle,et al.  Mercury Absorption in Aqueous Oxidants Catalyzed by Mercury(II) , 1998 .

[35]  T. Zacharewski,et al.  FTIR investigation of the heterogeneous reaction of HgO(S) with SO2(G) at ambient temperature , 1987 .

[36]  L. Friberg,et al.  Mercury In The Environment , 1971 .

[37]  A. Sarofim,et al.  Inorganic aerosols and their role in catalyzing sulfuric acid production in furnaces. , 1998, Journal of the Air & Waste Management Association.

[38]  W. Seiler,et al.  Distribution, speciation, and budget of atmospheric mercury , 1985 .

[39]  Christopher J. Zygarlicke,et al.  Mercury Speciation in Coal Combustion and Gasification Flue Gases , 1996 .

[40]  Lars Håkanson,et al.  Mercury in the Swedish environment — Recent research on causes, consequences and corrective methods , 1991 .

[41]  Toman,et al.  Evaluating mercury transformation mechanisms in a laboratory--scale combustion system , 2000, The Science of the total environment.

[42]  M. Maroto-Valer,et al.  Mercury capture by distinct fly ash carbon forms , 2000 .

[43]  P. Schager,et al.  The homogeneous gas phase reaction of mercury with oxygen, and the corresponding heterogeneous reactions in the presence of activated carbon and fly ash , 1995 .

[44]  H. Niki,et al.  Transformation processes involving mercury species in the atmosphere — results from a literature survey , 1991 .