As, Hg, and Se Flue Gas Sampling in a Coal-Fired Power Plant and Their Fate during Coal Combustion

Abstract

As, Hg, and Se are the most volatile elements in the flue gas from a coal-fired power plant. Significant amounts of these elements cause an undesired direct gaseous emission, which leads to a serious environmental health risk. The main focus of this study is to evaluate the possibility of simultaneous sampling of these volatile elements using an accurate official method for Hg (the most volatile element). A study of As, Hg, and Se emissions from a 1400 MW coal-fired power plant equipped with electrostatic precipitators (ESPs) was carried out for the combustion of a mixture of two types of coal. Simultaneous sampling of coal, bottom ash, fly ash, flue gas, and particles associated with the gas phase has been performed. Flue gas has been sampled by the Ontario Hydro Method Sampling Train, an ASTM method for Hg speciation. This sampling method was tested for As and Se sampling. As and Se determinations have been performed by HG-AAS, and Hg has been determined by CV-AAS. The results were used to examine the following: overall mass balances, relative distribution of these elements in the coal-fired power plant; As, Hg, and Se concentrations in coal and combustion residues; and predominant oxidation state for Hg in flue gas. The mass balances obtained for As, Hg, and Se were satisfactory in all cases; nevertheless, relative enrichment values in fly ash for As and Se were low; therefore, we concluded that As sampling in flue gas can be conducted by application of the Ontario Hydro Method; nevertheless Se released in the gas phase is not completely collected by this sampling train. Application of this sampling method allowed for performance of Hg speciation. The results indicated that Hg(II) was the predominant species in flue gas. It has also been proved that 24%, more than 99.8%, and 90% for As, Hg, and Se in the stack emissions, respectively, were in the gaseous phase.

Reconstructing historical Pb and Hg pollution in NW Spain using multiple cores from the Chao de Lamoso bog (Xistral Mountains)

“…Elevated Hg concentrations were also found by Carballeira and Fernández (2002) in mosses collected in the surroundings of this power plant. More than 99.8% of Hg stack emissions of the power plant are in the gaseous phase, mostly as Hg(II) (Otero-Rey et al, 2003).…”

Concentration Of Trace Elements in Airborne PM10 from Jobos Bay National Estuary, Puerto Rico

“…During coal combustion, elements bound to coal particles are distributed into bottom ash, fly ash and flue gas while Hg remains essentially in the gas phase. Recent reports have demonstrated that particles bind less than 0.02% of the total atmospheric Hg released by coal combustion (Otero-Rey et al, 2003). This behavior can explain the relatively low concentration of Hg found absorbed to particulate matter in air when compared to other elements.…”

“…Mn and Fe are enriched in slag. Some elements (As, Cd, Hg, Pb, V, Ni and Zn) are fractioned between fly and slag (Querol et al, 1995;Otero-Rey et al, 2003).…”

Mercury Air Emission from Coal-Fired Public Power Sector: Uncertainty and Its Monthly Distribution. Case Study from Poland

“…The technological structure of APC devices applied before 2010 [47] based on data derived from the ENVIRO database is comparable with data included in this paper. Basing on uncertainty range: A, average estimation; B, low estimation; C high estimation; , no estimation made for 1990 Based on available elaborations [4,17,32,37], also papers and guidelines on uncertainty assessment [10, 13,40,46], the mercury removal efficiencies are assigned with a 30% uncertainty range. Results are presented in Table 13.…”