Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilizaton

Hassett, D.J.; Heebink, Loreal V.; Pflughoeft-Hassett, Debra F.; Buckley, Tera D.; Zacher, Erick J.; Xin, Mei; Gustin, Mae Sexauer; Jung, Rob

doi:10.2172/981821

Cited by 2 publications

(6 citation statements)

References 9 publications

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“…The average Hg release peak temperatures for the samples are presented in Table 7-5. Hg release profiles similar to those presented in have been reported for other coal fly ashes (28). The Hg evolved from the sieved baseline fly ash at a lower temperature relative to the corresponding as-received sample, apparently because the Hg associated with the larger ash particles is more volatile.…”

Section: Thermal Stabilitysupporting

confidence: 82%

Large-Scale Mercury Control Technology Testing for Lignite-Fired Utilities - Oxidation Systems for Wet FGD

Benson¹,

Holmes²,

McCollor³

et al. 2007

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Mercury (Hg) control technologies were evaluated at Minnkota Power Cooperative's Milton R. Young (MRY) Station Unit 2, a 450-MW lignite-fired cyclone unit near Center, North Dakota, and TXU Energy's Monticello Steam Electric Station (MoSES) Unit 3, a 793-MW lignite-Powder River Basin (PRB) subbituminous coal-fired unit near Mt. Pleasant, Texas. A cold-side electrostatic precipitator (ESP) and wet flue gas desulfurization (FGD) scrubber are used at MRY and MoSES for controlling particulate and sulfur dioxide (SO 2) emissions, respectively. Several approaches for significantly and cost-effectively oxidizing elemental mercury (Hg 0) in lignite combustion flue gases, followed by capture in an ESP and/or FGD scrubber were evaluated. The project team involved in performing the technical aspects of the project included Babcock & Wilcox, the Energy & Environmental Research Center (EERC), the Electric Power Research Institute, and URS Corporation. Calcium bromide (CaBr 2), calcium chloride (CaCl 2), magnesium chloride (MgCl 2), and a proprietary sorbent enhancement additive (SEA), hereafter referred to as SEA2, were added to the lignite feeds to enhance Hg capture in the ESP and/or wet FGD. In addition, powdered activated carbon (PAC) was injected upstream of the ESP at MRY Unit 2. The work involved establishing Hg concentrations and removal rates across existing ESP and FGD units, determining costs associated with a given Hg removal efficiency, quantifying the balance-of-plant impacts of the control technologies, and facilitating technology commercialization. The primary project goal was to achieve ESP-FGD Hg removal efficiencies of >55% at MRY and MoSES for about a month. Hg in the lignite coal fired in MRY Unit 2 varied from 0.05 to 0.25 ppm and averaged 0.112 ±0.014 ppm (dry coal basis). Most of the Hg was associated with Hg-rich (2.28 ppm) pyrite grains that ranged in concentration from about 1 to 6 wt% (on a dry coal basis). During routine power plant operations, total Hg concentrations at the ESP and FGD inlets varied from about 12 to 16 µg/dNm 3 , whereas at the stack, concentrations were consistently at approximately 13 µg/dNm 3 , indicating that the ESP and FGD were very inefficient at removing Hg primarily because Hg 0 was dominant. MgCl 2 and CaCl 2 injections were relatively ineffective in promoting Hg 0 oxidation and capture in an ESP-FGD. Relatively low additions of SEA2, however, significantly improved the Hg removal efficiency of the ESP-FGD, although the goal of 55% Hg removal was not achieved using as much as 75 ppm SEA2 (dry coal basis). Most of the Hg removal occurred in the ESP, suggesting that SEA2 addition promoted the conversion of Hg 0 to particulate-bound Hg. SEA2 addition (50-100 ppm, dry coal basis) combined with 0.15-lb/Macf PAC injection was performed for a month during which Hg removal efficiencies generally ranged from 50% to 65%. The mobility of Hg in MRY fly ashes sampled before and after PAC and SEA2 injections was evaluated using a synthetic groundwater leaching procedure augmented wit...

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Section: Thermal Stabilitysupporting

confidence: 82%

Large-Scale Mercury Control Technology Testing for Lignite-Fired Utilities - Oxidation Systems for Wet FGD

Benson¹,

Holmes²,

McCollor³

et al. 2007

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“…4 Decreasing Se leachate concentrations using SGLP and LTL were noted in earlier work at the EERC. 5 ADA-ES, Inc., reported TCLP Se leachate concentrations greater in the evaluated MCT test CCPs than the standard CCPs but similar Se leachate concentrations between the samples when SGLP and LTL were performed. 2 The mineral ettringite is the primary hydration phase that is seen during the reaction of alkaline CCPs with water.…”

Section: Environmental Impactmentioning

confidence: 83%

“…pH increases of up to 4.3 pH units over a 24 h period were noted in standard and MCT test (with AC) samples in a previous EERC project. 5 The pH values of the CCPs and of the leachate samples are shown in Table 2.…”

Section: Resultsmentioning

confidence: 99%

“…The standard CCP Hg concentrations fall within those found in the reviewed literature except sample F1. 1,2,[4][5][6]13,14 The authors believe sample F1 may have been collected as a contaminated baseline sample since it was collected just 2-3 days following a different long-term MCT testing program.…”

Section: Resultsmentioning

confidence: 99%

“…2,3 Although the concentration of Hg increased in MCT test CCP samples, leaching tests indicated that mercury was not readily leached from the samples. 2,[4][5][6] Mercury leachate concentrations did not correlate with total mercury concentrations. Generally, the total concentrations of As and Cr were similar between the standard and MCT test samples (where tested), while total Se concentrations increased more often.…”

Section: Introductionmentioning

confidence: 99%

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Effects of mercury emission control technologies using halogens on coal combustion product chemical properties

2010

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Fly ash and spray dryer absorber (SDA) material samples collected during mercury emission control technology tests that incorporated the use of halogens were evaluated for select chemical composition and leachability. Corresponding samples were also collected under standard operating conditions and examined using the same protocols. Included in these evaluations were pH and total and leachable concentrations of the mercury control technology (MCT) halogen of interest (Br, Cl, or I) and Hg, As, Cr, and Se. The use of a MCT using halogens decreased the pH values of coal combustion products (CCPs) collected in fabric filters compared with that of the corresponding standard CCPs. In many cases, the total As, Cr, and Se concentrations were similar between the standard and MCT test CCPs. However, at least a slight increase in total Se was noted in each sample set from the standard to the MCT test CCPs. Short-term leaching was performed on all samples, and long-term leaching was performed on most highly alkaline samples. On the basis of percentage of maximum leachability, the MCT additive halogens were more mobile than the other elements evaluated. The Hg in fly ash and SDA material samples was stable. Generally, more As and Se leached from the MCT test CCPs than the standard CCPs. Cr leachate results were more variable. The data indicate a need to further examine the effects of MCT using halogens applications on CCPs.

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Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilizaton

Cited by 2 publications

References 9 publications

Large-Scale Mercury Control Technology Testing for Lignite-Fired Utilities - Oxidation Systems for Wet FGD

Large-Scale Mercury Control Technology Testing for Lignite-Fired Utilities - Oxidation Systems for Wet FGD

Effects of mercury emission control technologies using halogens on coal combustion product chemical properties

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