The Experts below are selected from a list of 16338 Experts worldwide ranked by ideXlab platform
John H Pavlish - One of the best experts on this subject based on the ideXlab platform.
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Mercury Control technologies for coal combustion and gasification systems
Fuel, 2010Co-Authors: John H Pavlish, Lucinda L Hamre, Ye ZhuangAbstract:Development and testing of Mercury Control technologies have largely focused on coal-fired combustion systems, with less emphasis on advanced power systems. Mercury Control is influenced by coal properties and chemistry, plant configuration, pollution Control devices, flue gas conditions, and plant operations, which differ between combustion and gasification systems. Sorbents such as treated activated carbons have shown promising results in low-temperature environments; however, elevated temperature and reducing environments of many advanced systems remain challenging, requiring research and development to obtain acceptable Mercury Control levels. Concurrent pollutant/multipollutant Control strategies that include CO2 Control are critically needed for both conventional and advanced power systems.
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sorbent injection into a slipstream baghouse for Mercury Control project summary
Fuel Processing Technology, 2009Co-Authors: Jeffrey S Thompson, John H Pavlish, Lucinda L Hamre, Melanie D Jensen, David W Smith, Steve Podwin, Lynn A BrickettAbstract:Abstract A project led by the Energy and Environmental Research Center to test and demonstrate sorbent injection as a cost-effective Mercury Control technology for utilities burning lignites has shown effective Mercury capture under a range of operating conditions. Screening, parametric, and long-term tests were carried out at a slipstream facility representing an electrostatic precipitator–activated carbon injection–fabric filter configuration (called a TOXECON™ in the United States). Screening tests of sorbent injection evaluated nine different sorbents, including both treated and standard activated carbon, to compare Mercury capture as a function of sorbent injection rate. Parametric tests evaluated several variables including air-to-cloth (A/C) ratio, flue gas temperature, cleaning frequency, and dust loading to determine the effect on Mercury Control and systems operation. Long-term tests (approximately 2 months in duration) evaluated the sustainability of systems operation. The screening tests identified four sorbents that achieved greater than 90% Mercury capture. Longer-term tests demonstrated Mercury capture of 82% at sorbent injection rates of about 2–2.5 lb/Macf. Ash loading and A/C ratio affected the operation of the fabric filter. At lower ash loadings, A/C ratios as high as 6 ft/min could be sustained while operating with conventional bags, but higher ash loadings required the use of high-permeability bags to overcome pressure drop issues.
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investigations on bromine corrosion associated with Mercury Control technologies in coal flue gas
Fuel, 2009Co-Authors: Ye Zhuang, Chuanmin Chen, Ron Timpe, John H PavlishAbstract:Abstract Mercury Control technologies are often associated with adding halogens to the flue gas to enhance oxidation of elemental Mercury. The present research was to evaluate the corrosion characteristics of iron in a flue gas containing bromine to simulate Mercury Control applications in coal-fired utility plants. An AISI 1008 cold rolled steel was exposed to a synthetic flue gas (7.1 vol% O 2 , 14.3 vol% CO 2 , 2.0 vol% H 2 O, 51 ppmv HBr, 510 ppmv SO 2 , 51 ppmv NO x , and the balance N 2 ). Exposure times ranged from 30 days to 6 months. Metal coupons were exposed with simulated flue gases at 300°, 150°, and 80 F (149°, 66°, and 27 °C), respectively. The corroded coupons were analyzed using scanning electron microscope and micrometer measurements to determine the deposit chemistry and corrosion loss. The corrosion products consisted mainly of iron oxides and iron bromide. A mechanism for HBr corrosion is suggested. Bromine dew point corrosion took place on metal surfaces at temperatures below or close to the dew point of HBr, while active oxidation occurred at higher temperatures.
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impact of calcium chloride addition on Mercury transformations and Control in coal flue gas
Fuel, 2007Co-Authors: Ye Zhuang, Jeffrey S Thompson, Chris Zygarlicke, John H PavlishAbstract:Abstract Pilot-scale experiments were conducted to investigate Mercury transformations in coal flue gas when firing subbituminous coal with a CaCl 2 additive. Cofiring the CaCl 2 additive with the subbituminous coal resulted in approximately 50% oxidized Mercury, as a result of reactive chlorine species formed in coal flue gas, compared to the dominance of elemental Mercury in the baseline flue gas. The Mercury data indicate that Mercury-flue gas chemistry reactions may occur at fairly high temperatures (>400 °C) in chlorine-enriched flue gas. Field tests were conducted to further demonstrate the impact of cofiring CaCl 2 on the eventual fate of Mercury. These tests were completed on a 650-MW subbituminous coal-fired power plant equipped with selective catalytic reduction (SCR), a fabric filter (FF), and a wet scrubber. Overall Mercury removals across the SCR-FF-wet scrubber system ranged from 75% to 96% with 200–800 ppm (coal basis) chlorine addition compared to 18–32% during baseline operations. Field data indicate that the SCR enhanced Mercury oxidation, possibly as a result of the supplemental formation of reactive chlorine species and the aid of the SCR catalyst. As a result, most of the Mercury in the flue gas was in an oxidized state and was removed in the downstream wet scrubber, indicating that cofiring CaCl 2 is an effective Mercury Control approach for a subbituminous coal-fired plant equipped with an SCR and wet scrubber.
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application of sorbents for Mercury Control for utilities burning lignite coal
Fuel Processing Technology, 2004Co-Authors: John H Pavlish, Michael J Holmes, Steven A Benson, Charlene R Crocker, Kevin C GalbreathAbstract:Abstract The Energy and Environmental Research Center (EERC) is conducting the first phase of a 3-year, two-phase U.S.–Canadian consortium project to develop and demonstrate Mercury Control technologies for utilities burning lignite coal. Control of Mercury from lignite-fired plants is much more difficult in comparison to plants burning other ranks of coal. The overall project goal is to provide utilities that burn lignite coal with low-cost technology options for meeting future Mercury emission 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 removal of elemental Mercury from flue gases, and demonstrate the effectiveness of the most promising technologies at the pilot scale. The Phase II objective is to demonstrate and quantify technology, performance, and cost at a sponsor-owned/operated power plant. Preliminary results are presented for Phase I bench- and pilot-scale tests, and results are encouraging for continuation of Phase II activities.
Ye Zhuang - One of the best experts on this subject based on the ideXlab platform.
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Mercury Control technologies for coal combustion and gasification systems
Fuel, 2010Co-Authors: John H Pavlish, Lucinda L Hamre, Ye ZhuangAbstract:Development and testing of Mercury Control technologies have largely focused on coal-fired combustion systems, with less emphasis on advanced power systems. Mercury Control is influenced by coal properties and chemistry, plant configuration, pollution Control devices, flue gas conditions, and plant operations, which differ between combustion and gasification systems. Sorbents such as treated activated carbons have shown promising results in low-temperature environments; however, elevated temperature and reducing environments of many advanced systems remain challenging, requiring research and development to obtain acceptable Mercury Control levels. Concurrent pollutant/multipollutant Control strategies that include CO2 Control are critically needed for both conventional and advanced power systems.
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investigations on bromine corrosion associated with Mercury Control technologies in coal flue gas
Fuel, 2009Co-Authors: Ye Zhuang, Chuanmin Chen, Ron Timpe, John H PavlishAbstract:Abstract Mercury Control technologies are often associated with adding halogens to the flue gas to enhance oxidation of elemental Mercury. The present research was to evaluate the corrosion characteristics of iron in a flue gas containing bromine to simulate Mercury Control applications in coal-fired utility plants. An AISI 1008 cold rolled steel was exposed to a synthetic flue gas (7.1 vol% O 2 , 14.3 vol% CO 2 , 2.0 vol% H 2 O, 51 ppmv HBr, 510 ppmv SO 2 , 51 ppmv NO x , and the balance N 2 ). Exposure times ranged from 30 days to 6 months. Metal coupons were exposed with simulated flue gases at 300°, 150°, and 80 F (149°, 66°, and 27 °C), respectively. The corroded coupons were analyzed using scanning electron microscope and micrometer measurements to determine the deposit chemistry and corrosion loss. The corrosion products consisted mainly of iron oxides and iron bromide. A mechanism for HBr corrosion is suggested. Bromine dew point corrosion took place on metal surfaces at temperatures below or close to the dew point of HBr, while active oxidation occurred at higher temperatures.
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impact of calcium chloride addition on Mercury transformations and Control in coal flue gas
Fuel, 2007Co-Authors: Ye Zhuang, Jeffrey S Thompson, Chris Zygarlicke, John H PavlishAbstract:Abstract Pilot-scale experiments were conducted to investigate Mercury transformations in coal flue gas when firing subbituminous coal with a CaCl 2 additive. Cofiring the CaCl 2 additive with the subbituminous coal resulted in approximately 50% oxidized Mercury, as a result of reactive chlorine species formed in coal flue gas, compared to the dominance of elemental Mercury in the baseline flue gas. The Mercury data indicate that Mercury-flue gas chemistry reactions may occur at fairly high temperatures (>400 °C) in chlorine-enriched flue gas. Field tests were conducted to further demonstrate the impact of cofiring CaCl 2 on the eventual fate of Mercury. These tests were completed on a 650-MW subbituminous coal-fired power plant equipped with selective catalytic reduction (SCR), a fabric filter (FF), and a wet scrubber. Overall Mercury removals across the SCR-FF-wet scrubber system ranged from 75% to 96% with 200–800 ppm (coal basis) chlorine addition compared to 18–32% during baseline operations. Field data indicate that the SCR enhanced Mercury oxidation, possibly as a result of the supplemental formation of reactive chlorine species and the aid of the SCR catalyst. As a result, most of the Mercury in the flue gas was in an oxidized state and was removed in the downstream wet scrubber, indicating that cofiring CaCl 2 is an effective Mercury Control approach for a subbituminous coal-fired plant equipped with an SCR and wet scrubber.
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JV TASK 45-Mercury Control TECHNOLOGIES FOR ELECTRIC UTILITIES BURNING LIGNITE COAL, PHASE I BENCH-AND PILOT-SCALE TESTING
University of North Dakota (United States), 2003Co-Authors: Pavlish, John H., Holmes, Michael J., Benson, Steven A., Crocker, Charlene R., Olson, Edwin S., Galbreath, Kevin C., Ye Zhuang, Pavlish, Brandon M.Abstract: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. The 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
Kevin C Galbreath - One of the best experts on this subject based on the ideXlab platform.
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application of sorbents for Mercury Control for utilities burning lignite coal
Fuel Processing Technology, 2004Co-Authors: John H Pavlish, Michael J Holmes, Steven A Benson, Charlene R Crocker, Kevin C GalbreathAbstract:Abstract The Energy and Environmental Research Center (EERC) is conducting the first phase of a 3-year, two-phase U.S.–Canadian consortium project to develop and demonstrate Mercury Control technologies for utilities burning lignite coal. Control of Mercury from lignite-fired plants is much more difficult in comparison to plants burning other ranks of coal. The overall project goal is to provide utilities that burn lignite coal with low-cost technology options for meeting future Mercury emission 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 removal of elemental Mercury from flue gases, and demonstrate the effectiveness of the most promising technologies at the pilot scale. The Phase II objective is to demonstrate and quantify technology, performance, and cost at a sponsor-owned/operated power plant. Preliminary results are presented for Phase I bench- and pilot-scale tests, and results are encouraging for continuation of Phase II activities.
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status review of Mercury Control options for coal fired power plants
Fuel Processing Technology, 2003Co-Authors: John H Pavlish, Kevin C Galbreath, Everett A Sondreal, Michael D Mann, Edwin S Olson, Dennis L Laudal, Steven A BensonAbstract:This paper presents an overview of research related to Mercury Control technology for coal-fired power plants and identifies areas requiring additional research and development. It critically reviews measured Mercury emissions; the chemistry of Mercury transformation and Control; progress in the development of promising Control technologies: sorbent injection, Control in wet scrubbers, and coal cleaning; and projects costs for Mercury Control. Currently, there is no single best technology that can be broadly applied. Combinations of available Control methods may be able to provide up to 90% Control for some plants but not others. In August 2000, the National Research Council completed a study that determined that the U.S. Environmental Protection Agency's (EPA) conservative exposure reference dose of 0.1 μg Mercury/kg body weight/day was scientifically justified to protect against harmful neurological effects during fetal development and early childhood. Subsequently, in December 2000, EPA made its regulatory decision that Mercury emissions from coal-fired electric generating plants will need to be Controlled on a schedule that calls for a proposed rule by December 2003, a final rule by December 2004, and full compliance by the end of 2007. Coal-fired utility boilers are currently the largest single-known source of Mercury emissions in the United States. EPA's Information Collection Request (ICR) to coal-burning utilities indicated that there were 75 tons of Mercury in the 900 million tons of coal used in U.S. power plants during 1999. Estimates of total Mercury emissions from coal-fired plants based on ICR data range from 40 to 52 tons. On average, about 40% of the Mercury entering a coal-fired power plant is captured and 60% emitted. Percentage emissions of Mercury for individual plants tested under the ICR varied widely depending on coal type and emission Control equipment. Western subbituminous coals on average contain only about half as much Mercury as Appalachian bituminous coals, but the higher chlorine content of the latter promotes Mercury oxidation and results in a higher percentage of Mercury capture. Some iron minerals found in coal also catalyze Mercury oxidation, whereas calcium and sulfur tend to impede oxidation. Review of ICR data on Mercury capture in boilers and existing Control devices indicates very little Mercury removal within a pulverized coal-fired boiler, and the level of Mercury oxidation at the exit of the boiler was increased for higher coal chlorine contents and lower exit temperatures. Mercury removals across cold-side electrostatic precipitators (ESPs) averaged 27%, compared to 4% for hot-side ESPs. Removals for fabric filters (FFs) were higher, averaging 58%, owing to additional gas–solid contact time for oxidation. Both wet and dry flue gas desulfurization (FGD) systems removed 80% to 90% of the gaseous Mercury(II), but elemental Mercury (Hg0) was not affected. High Mercury removals, averaging 86%, in fluidized-bed combustors with FFs were attributed to Mercury capture on high-carbon fly ash. Tests on the two coal-fired integrated gasification combined-cycle plants in the United States suggest that about half of the coal Mercury was emitted predominantly in elemental form. ICR tests on selective catalytic reduction and selective noncatalytic reduction used for NOx Control were inconclusive, and additional full-scale tests are in progress. The mechanisms responsible for varied levels of Mercury oxidation and capture are beginning to be understood. Mercury in coal occurs in association with pyrite and other sulfide minerals and may also be organically bound. Coal Mercury is converted to gaseous Hg0 in the combustion flame and is subsequently partially oxidized (35% to 95%) as the combustion gases cool. Mercury oxidation in boiler systems is kinetically Controlled; homogeneous oxidation reactions are promoted by chlorine and atomic chlorine, and heterogeneous oxidation is promoted by fly ash and sorbents. Acid gases critically influence the heterogeneous oxidation of Mercury, particularly as it affects capture on sorbents. HCl, NO, and NO2 all promote oxidation and capture both individually and in combination. However, the combination of SO2 with NO2 greatly reduces capture of Hg0 on activated carbon, whereas oxidation continues on the solid surface. Mass transfer of gaseous Mercury by diffusion from the bulk gas to the solid surface can also limit heterogeneous oxidation and capture of Mercury, but diffusion within a porous sorbent is not believed to be rate-limiting. Reducing the size of the sorbent particles and increasing their dispersion can greatly enhance Control where mass transfer is limiting. To achieve 90% Control of a Mercury concentration of 10 μg/scm in 2-s residence time by activated carbon injection requires a minimum carbon-to-Mercury (C/Hg) mass ratio of about 3000:1 for 4-μm particles compared to 18,000:1 for 10-μm particles. Mercury removals in some tests performed to characterize sorbents have been mass transfer-limited by the large particle size of the sorbents used. Mercury sorption capacities between about 200 and 5000 μg Hg/g C have been reported for conditions applying to coal combustion. However, higher measured capacities do not always correlate with higher removal levels in practice because of the effect of other variables. What is important is that several of the activated carbons tested have sufficient capacity to capture Mercury at carbon injection rates below a C/Hg mass ratio of 10,000, based on both laboratory and field sorption tests. Since capacity is defined in reference to an assumed sorption equilibrium, the equilibrium capacity of a sorbent determined over a period of hours in the laboratory may have limited relevance to the amount of Mercury captured in a few seconds' time of flight or in minutes of contact time on an FF. Laboratory tests that are more representative of the conditions in an actual Control device are needed to determine more useful capacity factors. Injection of activated carbon upstream of either an ESP or an FF baghouse is a retrofit Control technology that has potential application to 75% of all coal-fired power plants in the United States that are not equipped with FGD scrubbers. Field and pilot-scale tests on activated carbon injection for Mercury Control have resulted in Mercury removals between about 25% and 95% over the range of 2000–15,000 C/Hg mass ratio. The Mercury removal data from some tests could be correlated with carbon injection rates by assuming that the removal was mass transfer-limited, whereas in tests on other coals, removals appeared to be Controlled by catalytic oxidation and capture on fly ash. Mercury capture on sorbents, therefore, depends on the properties of the coal being burned, and pilot-scale tests on particular coals should be performed before a full-scale sorbent injection system is designed. Development of low-cost, ultrafine sorbents with high effective sorption capacities and rapid reaction kinetics would revolutionize injection technology. Engineering development is also needed to improve sorbent dispersion and to optimize gas–solid contact time. Wet FGD units currently installed on about 25% of the U.S. coal-fired utility boilers remove nearly 90% of the Mercury(II) entering but essentially none of the Hg0. Research to enhance Mercury removal in scrubbers focuses on converting Hg0 to an oxidized form in or ahead of the scrubber using proprietary reagents. Palladium and carbon-based catalysts have shown the most promise for oxidizing Hg0. Mercury removals from near 0% to about 60% are reported for the physical washing methods of the type that are widely used to remove pyritic sulfur and ash from 77% of all bituminous coal used in the United States. Advanced cleaning methods and hydrothermal treatment offer higher removals, but no coal-cleaning method is likely to reliably meet a 70% or greater removal requirement. Coal cleaning could, however, contribute to overall Mercury Control under a cap-and-trade form of Mercury regulation. Concerns over the release of Mercury from coal combustion by-products by leaching or atmospheric reemission will be heightened with the installation of Mercury Control technologies. Concentrations of Mercury in leachates from fly ashes, FGD materials, and activated carbon saturated with Mercury are very low and usually below detection limits. Essentially, no Mercury emission from these materials into air has been measured at ambient temperature. However, Mercury is released from saturated sorbents upon heating above 135 °C. Preliminary results on the stability of Mercury on fly ash, FGD materials, and saturated carbons are encouraging, but more testing is needed before the concerns are fully resolved.
Jiming Hao - One of the best experts on this subject based on the ideXlab platform.
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Mercury mass flow in iron and steel production process and its implications for Mercury emission Control
Journal of Environmental Sciences-china, 2016Co-Authors: Fengyang Wang, Shuxiao Wang, Lei Zhang, Hai Yang, Wei Gao, Jiming HaoAbstract:The iron and steel production process is one of the predominant anthropogenic sources of atmospheric Mercury emissions worldwide. In this study, field tests were conducted to study Mercury emission characteristics and mass flows at two iron and steel plants in China. It was found that low-sulfur flue gas from sintering machines could contribute up to 41% of the total atmospheric Mercury emissions, and desulfurization devices could remarkably help reduce the emissions. Coal gas burning accounted for 17%-49% of the total Mercury emissions, and therefore the Mercury Control of coal gas burning, specifically for the power plant burning coal gas to generate electricity, was significantly important. The emissions from limestone and dolomite production and electric furnaces can contribute 29.3% and 4.2% of the total Mercury emissions from iron and steel production. More attention should be paid to Mercury emissions from these two processes. Blast furnace dust accounted for 27%-36% of the total Mercury output for the whole iron and steel production process. The recycling of blast furnace dust could greatly increase the atmospheric Mercury emissions and should not be conducted. The Mercury emission factors for the coke oven, sintering machine and blast furnace were 0.039-0.047gHg/ton steel, and for the electric furnace it was 0.021gHg/ton steel. The predominant emission species was oxidized Mercury, accounting for 59%-73% of total Mercury emissions to air.
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meeting minamata cost effective compliance options for atmospheric Mercury Control in chinese coal fired power plants
Energy Policy, 2016Co-Authors: Maria Pia Ancora, Shuxiao Wang, Lei Zhang, Jeremy Schreifels, Jiming HaoAbstract:Abstract A new international treaty, Minamata Convention, identifies Mercury (Hg) as a global threat to human health and seeks to Control its releases and emissions. Coal-fired power plants are a major source of Mercury pollution worldwide and are expected to be the first key sector to be addressed in China under Minamata Convention. A best available technique (BAT) adoption model was developed in the form of a decision tree and cost-effectiveness for each technological option. Co-benefit Control technologies and their enhancement with coal blending/switching and halogen injection (HI) can provide early measures to help China meet the Minamata Convention obligations. We project future energy and policy scenarios to simulate potential national Mercury reduction goals for China and estimate costs of the Control measures for each scenario. The “Minamata Medium” scenario, equivalent to the goal of the US Mercury and Air Toxics Standards (MATS) rule, requires the application of activated carbon injection (ACI) and HI on 30% and 20% of power plants, respectively. The corresponding total costs would be $2.5 billion, approximately one-fourth the costs in the US. An emission limit of 3 µg/m3 in 2030 was identified as a feasible policy option for China to comply with Minamata Convention.
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economic analysis of atmospheric Mercury emission Control for coal fired power plants in china
Journal of Environmental Sciences-china, 2015Co-Authors: Maria Pia Ancora, Shuxiao Wang, Lei Zhang, Jeremy Schreifels, Jiming HaoAbstract:Coal combustion and Mercury pollution are closely linked, and this relationship is particularly relevant in China, the world's largest coal consumer. This paper begins with a summary of recent China-specific studies on Mercury removal by air pollution Control technologies and then provides an economic analysis of Mercury abatement from these emission Control technologies at coal-fired power plants in China. This includes a cost-effectiveness analysis at the enterprise and sector level in China using 2010 as a baseline and projecting out to 2020 and 2030. Of the Control technologies evaluated, the most cost-effective is a fabric filter installed upstream of the wet flue gas desulfurization system (FF+WFGD). Halogen injection (HI) is also a cost-effective Mercury-specific Control strategy, although it has not yet reached commercial maturity. The sector-level analysis shows that 193 tons of Mercury was removed in 2010 in China's coal-fired power sector, with annualized Mercury emission Control costs of 2.7 billion Chinese Yuan. Under a projected 2030 Emission Control (EC) scenario with stringent Mercury limits compared to Business As Usual (BAU) scenario, the increase of selective catalytic reduction systems (SCR) and the use of HI could contribute to 39 tons of Mercury removal at a cost of 3.8 billion CNY. The economic analysis presented in this paper offers insights on air pollution Control technologies and practices for enhancing atmospheric Mercury Control that can aid decision-making in policy design and private-sector investments.
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a review of atmospheric Mercury emissions pollution and Control in china
Frontiers of Environmental Science & Engineering in China, 2014Co-Authors: Shuxiao Wang, Lei Zhang, Long Wang, Fengyang Wang, Jiming HaoAbstract:Mercury, as a global pollutant, has significant impacts on the environment and human health. The current state of atmospheric Mercury emissions, pollution and Control in China is comprehensively reviewed in this paper. With about 500–800 t of anthropogenic Mercury emissions, China contributes 25%–40% to the global Mercury emissions. The dominant Mercury emission sources in China are coal combustion, non-ferrous metal smelting, cement production and iron and steel production. The Mercury emissions from natural sources in China are equivalent to the anthropogenic Mercury emissions. The atmospheric Mercury concentration in China is about 2–10 times the background level of North Hemisphere. The Mercury deposition fluxes in remote areas in China are usually in the range of 10–50 μg·m−2·yr−1. To reduce Mercury emissions, legislations have been enacted for power plants, non-ferrous metal smelters and waste incinerators. Currently Mercury contented in the flue gas is mainly removed through existing air pollution Control devices for sulfur dioxide, nitrogen oxides, and particles. Dedicated Mercury Control technologies are required in the future to further mitigate the Mercury emissions in China.
Steven A Benson - One of the best experts on this subject based on the ideXlab platform.
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application of sorbents for Mercury Control for utilities burning lignite coal
Fuel Processing Technology, 2004Co-Authors: John H Pavlish, Michael J Holmes, Steven A Benson, Charlene R Crocker, Kevin C GalbreathAbstract:Abstract The Energy and Environmental Research Center (EERC) is conducting the first phase of a 3-year, two-phase U.S.–Canadian consortium project to develop and demonstrate Mercury Control technologies for utilities burning lignite coal. Control of Mercury from lignite-fired plants is much more difficult in comparison to plants burning other ranks of coal. The overall project goal is to provide utilities that burn lignite coal with low-cost technology options for meeting future Mercury emission 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 removal of elemental Mercury from flue gases, and demonstrate the effectiveness of the most promising technologies at the pilot scale. The Phase II objective is to demonstrate and quantify technology, performance, and cost at a sponsor-owned/operated power plant. Preliminary results are presented for Phase I bench- and pilot-scale tests, and results are encouraging for continuation of Phase II activities.
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status review of Mercury Control options for coal fired power plants
Fuel Processing Technology, 2003Co-Authors: John H Pavlish, Kevin C Galbreath, Everett A Sondreal, Michael D Mann, Edwin S Olson, Dennis L Laudal, Steven A BensonAbstract:This paper presents an overview of research related to Mercury Control technology for coal-fired power plants and identifies areas requiring additional research and development. It critically reviews measured Mercury emissions; the chemistry of Mercury transformation and Control; progress in the development of promising Control technologies: sorbent injection, Control in wet scrubbers, and coal cleaning; and projects costs for Mercury Control. Currently, there is no single best technology that can be broadly applied. Combinations of available Control methods may be able to provide up to 90% Control for some plants but not others. In August 2000, the National Research Council completed a study that determined that the U.S. Environmental Protection Agency's (EPA) conservative exposure reference dose of 0.1 μg Mercury/kg body weight/day was scientifically justified to protect against harmful neurological effects during fetal development and early childhood. Subsequently, in December 2000, EPA made its regulatory decision that Mercury emissions from coal-fired electric generating plants will need to be Controlled on a schedule that calls for a proposed rule by December 2003, a final rule by December 2004, and full compliance by the end of 2007. Coal-fired utility boilers are currently the largest single-known source of Mercury emissions in the United States. EPA's Information Collection Request (ICR) to coal-burning utilities indicated that there were 75 tons of Mercury in the 900 million tons of coal used in U.S. power plants during 1999. Estimates of total Mercury emissions from coal-fired plants based on ICR data range from 40 to 52 tons. On average, about 40% of the Mercury entering a coal-fired power plant is captured and 60% emitted. Percentage emissions of Mercury for individual plants tested under the ICR varied widely depending on coal type and emission Control equipment. Western subbituminous coals on average contain only about half as much Mercury as Appalachian bituminous coals, but the higher chlorine content of the latter promotes Mercury oxidation and results in a higher percentage of Mercury capture. Some iron minerals found in coal also catalyze Mercury oxidation, whereas calcium and sulfur tend to impede oxidation. Review of ICR data on Mercury capture in boilers and existing Control devices indicates very little Mercury removal within a pulverized coal-fired boiler, and the level of Mercury oxidation at the exit of the boiler was increased for higher coal chlorine contents and lower exit temperatures. Mercury removals across cold-side electrostatic precipitators (ESPs) averaged 27%, compared to 4% for hot-side ESPs. Removals for fabric filters (FFs) were higher, averaging 58%, owing to additional gas–solid contact time for oxidation. Both wet and dry flue gas desulfurization (FGD) systems removed 80% to 90% of the gaseous Mercury(II), but elemental Mercury (Hg0) was not affected. High Mercury removals, averaging 86%, in fluidized-bed combustors with FFs were attributed to Mercury capture on high-carbon fly ash. Tests on the two coal-fired integrated gasification combined-cycle plants in the United States suggest that about half of the coal Mercury was emitted predominantly in elemental form. ICR tests on selective catalytic reduction and selective noncatalytic reduction used for NOx Control were inconclusive, and additional full-scale tests are in progress. The mechanisms responsible for varied levels of Mercury oxidation and capture are beginning to be understood. Mercury in coal occurs in association with pyrite and other sulfide minerals and may also be organically bound. Coal Mercury is converted to gaseous Hg0 in the combustion flame and is subsequently partially oxidized (35% to 95%) as the combustion gases cool. Mercury oxidation in boiler systems is kinetically Controlled; homogeneous oxidation reactions are promoted by chlorine and atomic chlorine, and heterogeneous oxidation is promoted by fly ash and sorbents. Acid gases critically influence the heterogeneous oxidation of Mercury, particularly as it affects capture on sorbents. HCl, NO, and NO2 all promote oxidation and capture both individually and in combination. However, the combination of SO2 with NO2 greatly reduces capture of Hg0 on activated carbon, whereas oxidation continues on the solid surface. Mass transfer of gaseous Mercury by diffusion from the bulk gas to the solid surface can also limit heterogeneous oxidation and capture of Mercury, but diffusion within a porous sorbent is not believed to be rate-limiting. Reducing the size of the sorbent particles and increasing their dispersion can greatly enhance Control where mass transfer is limiting. To achieve 90% Control of a Mercury concentration of 10 μg/scm in 2-s residence time by activated carbon injection requires a minimum carbon-to-Mercury (C/Hg) mass ratio of about 3000:1 for 4-μm particles compared to 18,000:1 for 10-μm particles. Mercury removals in some tests performed to characterize sorbents have been mass transfer-limited by the large particle size of the sorbents used. Mercury sorption capacities between about 200 and 5000 μg Hg/g C have been reported for conditions applying to coal combustion. However, higher measured capacities do not always correlate with higher removal levels in practice because of the effect of other variables. What is important is that several of the activated carbons tested have sufficient capacity to capture Mercury at carbon injection rates below a C/Hg mass ratio of 10,000, based on both laboratory and field sorption tests. Since capacity is defined in reference to an assumed sorption equilibrium, the equilibrium capacity of a sorbent determined over a period of hours in the laboratory may have limited relevance to the amount of Mercury captured in a few seconds' time of flight or in minutes of contact time on an FF. Laboratory tests that are more representative of the conditions in an actual Control device are needed to determine more useful capacity factors. Injection of activated carbon upstream of either an ESP or an FF baghouse is a retrofit Control technology that has potential application to 75% of all coal-fired power plants in the United States that are not equipped with FGD scrubbers. Field and pilot-scale tests on activated carbon injection for Mercury Control have resulted in Mercury removals between about 25% and 95% over the range of 2000–15,000 C/Hg mass ratio. The Mercury removal data from some tests could be correlated with carbon injection rates by assuming that the removal was mass transfer-limited, whereas in tests on other coals, removals appeared to be Controlled by catalytic oxidation and capture on fly ash. Mercury capture on sorbents, therefore, depends on the properties of the coal being burned, and pilot-scale tests on particular coals should be performed before a full-scale sorbent injection system is designed. Development of low-cost, ultrafine sorbents with high effective sorption capacities and rapid reaction kinetics would revolutionize injection technology. Engineering development is also needed to improve sorbent dispersion and to optimize gas–solid contact time. Wet FGD units currently installed on about 25% of the U.S. coal-fired utility boilers remove nearly 90% of the Mercury(II) entering but essentially none of the Hg0. Research to enhance Mercury removal in scrubbers focuses on converting Hg0 to an oxidized form in or ahead of the scrubber using proprietary reagents. Palladium and carbon-based catalysts have shown the most promise for oxidizing Hg0. Mercury removals from near 0% to about 60% are reported for the physical washing methods of the type that are widely used to remove pyritic sulfur and ash from 77% of all bituminous coal used in the United States. Advanced cleaning methods and hydrothermal treatment offer higher removals, but no coal-cleaning method is likely to reliably meet a 70% or greater removal requirement. Coal cleaning could, however, contribute to overall Mercury Control under a cap-and-trade form of Mercury regulation. Concerns over the release of Mercury from coal combustion by-products by leaching or atmospheric reemission will be heightened with the installation of Mercury Control technologies. Concentrations of Mercury in leachates from fly ashes, FGD materials, and activated carbon saturated with Mercury are very low and usually below detection limits. Essentially, no Mercury emission from these materials into air has been measured at ambient temperature. However, Mercury is released from saturated sorbents upon heating above 135 °C. Preliminary results on the stability of Mercury on fly ash, FGD materials, and saturated carbons are encouraging, but more testing is needed before the concerns are fully resolved.
