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Title: Characterization of mercury-enriched coal combustion residues from electric utilities using enhanced sorbents for mercury control

Abstract

This report evaluates changes that may occur to coal-fired power plant air pollution control residues from the use of activated carbon and other enhanced sorbents for reducing air emissions of mercury and evaluates the potential for captured pollutants leaching during the disposal or use of these residues. Leaching of mercury, arsenic, and selenium during land disposal or beneficial use of coal combustion residues (CCRs) is the environmental impact pathway evaluated in this report. Coal combustion residues refer collectively to fly ash and other air pollution control solid residues generated during the combustion of coal collected through the associated air pollution control system. This research is part of an on-going effort by US Environmental protection Agency (EPA) to use a holistic approach to account for the fate of mercury and other metals in coal throughout the life-cycle stages of CCR management. This report focuses on facilities that use injected sorbents for mercury control. It includes four facilities with activated carbon injection (ACI) and two facilities using brominated ACI. Fly ash has been obtained from each facility with and without operation of the sorbent injection technology for mercury control. Each fly ash sampled was evaluated in the laboratory for leaching as amore » function of pH and liquid-to-solid ratio. Mercury, arsenic and selenium were the primary constituent of interest; results for these elements are presented here. 30 refs., 30 figs., 14 tabs., 10 apps.« less

Authors:
; ; ;  [1]
  1. Vanderbilt University, Nashville, TN (United States). Dept. of Civil and Environmental Engineering
Publication Date:
Research Org.:
Environmental Protection Agency (EPA), Washington, DC (United States)
OSTI Identifier:
20885797
Report Number(s):
EPA-600-R-06-008
ep-c-04-023; TRN: 070500475
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; USA; MERCURY; COAL; FLY ASH; FOSSIL-FUEL POWER PLANTS; RESIDUES; ADSORBENTS; COMBUSTION; AIR POLLUTION CONTROL; INJECTION; LEACHING; ARSENIC; SELENIUM; ENVIRONMENTAL IMPACTS; SORBENT INJECTION PROCESSES

Citation Formats

Sanchez, F., Keeney, R., Kosson, D., and Delapp, R. Characterization of mercury-enriched coal combustion residues from electric utilities using enhanced sorbents for mercury control. United States: N. p., 2006. Web.
Sanchez, F., Keeney, R., Kosson, D., & Delapp, R. Characterization of mercury-enriched coal combustion residues from electric utilities using enhanced sorbents for mercury control. United States.
Sanchez, F., Keeney, R., Kosson, D., and Delapp, R. Wed . "Characterization of mercury-enriched coal combustion residues from electric utilities using enhanced sorbents for mercury control". United States. doi:.
@article{osti_20885797,
title = {Characterization of mercury-enriched coal combustion residues from electric utilities using enhanced sorbents for mercury control},
author = {Sanchez, F. and Keeney, R. and Kosson, D. and Delapp, R.},
abstractNote = {This report evaluates changes that may occur to coal-fired power plant air pollution control residues from the use of activated carbon and other enhanced sorbents for reducing air emissions of mercury and evaluates the potential for captured pollutants leaching during the disposal or use of these residues. Leaching of mercury, arsenic, and selenium during land disposal or beneficial use of coal combustion residues (CCRs) is the environmental impact pathway evaluated in this report. Coal combustion residues refer collectively to fly ash and other air pollution control solid residues generated during the combustion of coal collected through the associated air pollution control system. This research is part of an on-going effort by US Environmental protection Agency (EPA) to use a holistic approach to account for the fate of mercury and other metals in coal throughout the life-cycle stages of CCR management. This report focuses on facilities that use injected sorbents for mercury control. It includes four facilities with activated carbon injection (ACI) and two facilities using brominated ACI. Fly ash has been obtained from each facility with and without operation of the sorbent injection technology for mercury control. Each fly ash sampled was evaluated in the laboratory for leaching as a function of pH and liquid-to-solid ratio. Mercury, arsenic and selenium were the primary constituent of interest; results for these elements are presented here. 30 refs., 30 figs., 14 tabs., 10 apps.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2006},
month = {Wed Feb 15 00:00:00 EST 2006}
}

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  • The Energy & Environmental Research Center has completed the first phase of a 3-year, two-phase consortium project to develop and demonstrate mercury control technologies for utilities that burn lignite coal. The overall project goal is to maintain the viability of lignite-based energy production by providing utilities with low-cost options for meeting future mercury regulations. Phase I objectives are to develop a better understanding of mercury interactions with flue gas constituents, test a range of sorbent-based technologies targeted at removing elemental mercury (Hg{sup o}) from flue gases, and demonstrate the effectiveness of the most promising technologies at the pilot scale. Themore » Phase II objectives are to demonstrate and quantify sorbent technology effectiveness, performance, and cost at a sponsor-owned and operated power plant. Phase I results are presented in this report along with a brief overview of the Phase II plans. Bench-scale testing provided information on mercury interactions with flue gas constituents and relative performances of the various sorbents. Activated carbons were prepared from relatively high-sodium lignites by carbonization at 400 C (752 F), followed by steam activation at 750 C (1382 F) and 800 C (1472 F). Luscar char was also steam-activated at these conditions. These lignite-based activated carbons, along with commercially available DARCO FGD and an oxidized calcium silicate, were tested in a thin-film, fixed-bed, bench-scale reactor using a simulated lignitic flue gas consisting of 10 {micro}g/Nm{sup 3} Hg{sup 0}, 6% O{sub 2}, 12% CO{sub 2}, 15% H{sub 2}O, 580 ppm SO{sub 2}, 120 ppm NO, 6 ppm NO{sub 2}, and 1 ppm HCl in N{sub 2}. All of the lignite-based activated (750 C, 1382 F) carbons required a 30-45-minute conditioning period in the simulated lignite flue gas before they exhibited good mercury sorption capacities. The unactivated Luscar char and oxidized calcium silicate were ineffective in capturing mercury. Lignite-based activated (800 C, 1472 F) carbons required a shorter (15-minute) conditioning period in the simulated lignite flue gas and captured gaseous mercury more effectively than those activated at 750 C (1382 F). Subsequent tests with higher acid gas concentrations including 50 ppm HCl showed no early mercury breakthrough for either the activated (750 C, 1382 F) Bienfait carbon or the DARCO FGD. Although these high acid gas tests yielded better mercury capture initially, significant breakthrough of mercury ultimately occurred sooner than during the simulated lignite flue gas tests. The steam-activated char, provided by Luscar Ltd., and DARCO FGD, provided by NORIT Americas, were evaluated for mercury removal potential in a 580 MJ/hr (550,000-Btu/hr) pilot-scale coal combustion system equipped with four particulate control devices: (1) an electrostatic precipitator (ESP), (2) a fabric filter (FF), (3) the Advanced Hybrid{trademark} filter, and (4) an ESP and FF in series, an EPRI-patented TOXECON{trademark} technology. The Ontario Hydro method and continuous mercury monitors were used to measure mercury species concentrations at the inlet and outlet of the control technology devices with and without sorbent injection. Primarily Hg{sup o} was measured when lignite coals from the Poplar River Plant and Freedom Mine were combusted. The effects of activated Luscar char, DARCO FGD, injection rates, particle size, and gas temperature on mercury removal were evaluated for each of the four particulate control device options. Increasing injection rates and decreasing gas temperatures generally promoted mercury capture in all four control devices. Relative to data reported for bituminous and subbituminous coal combustion flue gases, higher sorbent injection rates were generally required for the lignite coal to effectively remove mercury. Documented results in this report provide the impacts of these and other parameters and provide the inputs needed to direct Phase II of the project.« less
  • An NOx control technology assessment study was conducted to examine the effectiveness of low-excess-air firing, staged combustion, flue gas recirculation, and current burner/boiler designs as applied to coal-fired utility boilers. Significant variations in NOx emissions exist with boiler type, firing method, and coal type, but a relative comparison of emissions control performance, cost, and operational considerations is presented for each method. The study emphasized the numerous operational factors that are of major importance to the user in selecting and implementing a combustion modification technique. Staged combustion and low-excess-air operation were identified as the most cost-effective methods for existing units. Closemore » control of local air/fuel ratios and rigorous combustion equipment maintenance are essential to the success of both methods. Flue gas recirculation is relatively ineffective and has the added concern of tube erosion. More research is needed to resolve potential corrosion concerns with low-NOx operating modes. Low-NOx burners in conjunction with a compartmentalized windbox are capable of meeting a 0.6-lb/million Btu emission level on new units. Advanced burner designs are being developed to meet research emission goals of approximately 0.25 lb/MBtu.« less
  • This report presents some of the results of two studies pertaining to low sulfur coal and nuclear power as energy sources. It is shown that there is considerably less low sulfur coal than the amount indicated in the conventional data supplied by the Bureau of Mines and others. It is indicated that the amount of nuclear power available by 1985 will be considerably less than estimates made by the Atomic Energy Commission and will cost significantly more. The results presented are important in terms of utility decision making with respect to future fuel use and the type of power generatingmore » facility. A significant part of the decision to adopt a particular type of generating plant depends upon expected relative fuel costs at the time the plant is due to begin operation. Much tabular data are presented on the estimates of resources and recoverable reserves of coal. Factors affecting these estimates are reviewed. Air quality standards are discussed and the costs of nuclear power are considered at length.« less
  • This is a Technical Report under a program funded by the Department of Energy's National Energy Technology Laboratory (NETL) to obtain the necessary information to assess the viability of lower cost alternatives to commercially available activated carbon for mercury control in coal-fired utilities. During this reporting period, ongoing tests and analysis on samples from Powerton and Valley to yield waste characterization results for the COHPAC long-term tests were conducted. A draft final report for the sorbent evaluations at Powerton was submitted. Sorbent evaluations at Valley Power Plant were completed on April 24, 2003. Data analysis and reporting for the Valleymore » evaluations are continuing. A statement of work for sorbent evaluations at We Energies' Pleasant Prairie Power Plant was submitted and approved. Work will begin late August 2003. A no cost time extension was granted by DOE/NETL.« less