Ontario Hydro Research Articles

Investigation of Mercury Transformation by HBr Addition in a Slipstream Facility with Real Flue Gas Atmospheres of Bituminous Coal and Powder River Basin Coal

An investigation of speciated mercury transformation with the addition of hydrogen bromide (HBr) at elevated temperatures was conducted in a slipstream reactor with real flue gas atmospheres. A real flue gas atmosphere is composed of bituminous coal (with high sulfur and high chlorine contents) and Powder River Basin (PRB) coal (with lower sulfur and chlorine contents). The average sulfur, chlorine, and mercury contents in the tested bituminous coal were 1.31% and 1328 and 0.11 ppm and 0.61% and 170 and 0.08 ppm, respectively, for tested PRB coal. The average CaO, Fe2O3, and loss on ignition in collected fly ash contents of tested bituminous coal were 1.71, 17.51, and 7.13% and 22.95, 4.91, and 0.64%, respectively, for tested PRB coal. The different contents of coal chlorine, CaO, and Fe2O3 in fly ash can be attributed to the different mercury speciations at baseline tests for these two coals in this study. The addition of HBr concentrations into the flue gas was controlled in the 3−15 ppm range. Semi-continuous mercury emission monitors were used to check the variation of mercury speciation at sampling locations. The Ontario Hydro Method (ASTM D6784-02) was used for data validation or comparison. For both methods, a high temperature inertial sampling probe was used to minimize the interference between vapor phase mercury and fly ash. Its temperatures were controlled consistently with flue gas temperatures at their installation locations in the slipstream reactor. Test results indicated that adding HBr into the flue gas at several parts per million strongly impacted the mercury oxidation and adsorption, which were dependent upon temperature ranges. Higher temperatures (in the range of 300−350 °C) promoted mercury oxidation by HBr addition but did not promote mercury adsorption. Lower temperatures (in a range of 150−200 °C) enhanced mercury adsorption on the fly ash by adding HBr. Test results also verified effects of flue gas atmospheres on the mercury oxidation by the addition of HBr, which included concentrations of chlorine and sulfur in the flue gas. Chlorine species seemed to be involved in the competition with bromine species in the mercury oxidation process. With the addition of HBr at 3 ppm at a temperature of about 330 °C, the additional mercury oxidation could be reached by about 55% in a flue gas atmosphere by burning PRB coal in the flue gas and by about 20% in a flue gas by burning bituminous coal. These are both greater than the maximum gaseous HgBr2 percentage in the flue gas (35% for PRB coal and 5% for bituminous coal) by thermodynamic equilibrium analysis predictions under the same conditions. This disagreement may indicate a greater complexity of mercury oxidation mechanisms by the addition of HBr. It is possible that bromine species promote activated chlorine species generation in the flue gas, where the kinetics of elemental mercury oxidation were enhanced. However, SO2 in the flue gas may involve the consumption of the available activated chlorine species. Thus, the higher mercury oxidation rate by adding bromine under the flue gas by burning PRB coal may be associated with its lower SO2 concentration in the flue gas.

COMPARISON AND VALIDATION OF OHM AND SCEM MEASUREMENTS FOR A FULL-SCALE COAL-FIRED POWER PLANT

Mercury emission measurements were performed at a 250 MW coal-fired power plant using the Ontario Hydro method (OHM) and semi-continuous emission monitors (SCEM). Flue gas sampling was performed at the inlet of the air preheater and at the outlet of the electrostatic precipitator. The results indicated that there is some agreement between the OHM and SCEM measurements on the total mercury species. However, the SCEM results were not always in good agreement with the OHM measurements on the elemental mercury species. These discrepancies in elemental mercury concentrations are probably the result of the differences in the location of the SCEM and OHM probes, the temperature difference between the SCEM sampling probe and the flue gas, and the nonuniformities in mercury concentration over the flue gas duct cross section. The other factor that contributed to the deviation between the SCEM and OHM measurement results is the sampling method: the SCEM measurements were performed at a single point while the OHM probe was traversed over multiple points over the duct cross section and the results were averaged. The effect of the SCEM sampling probe temperature was investigated by designing a sampling probe that could be heated to the sampled flue gas temperatures. This resulted in improvements in the accuracy of the elemental mercury measurements by the SCEM system.

Mercury speciation and its emissions from a 220 MW pulverized coal-fired boiler power plant in flue gas

Distributions of mercury speciation of Hg0, Hg2+ and Hg P in flue gas and fly ash were sampled by using the Ontario Hydro Method in a 220 MW pulverized coal-fired boiler power plant in China. The mercury speciation was varied greatly when flue gas going through the electrostatic precipitator (ESP). The mercury adsorbed on fly ashes was found strongly dependent on unburnt carbon content in fly ash and slightly on the particle sizes, which implies that the physical and chemical features of some elemental substances enriched to fly ash surface also have a non-ignored effect on the mercury adsorption. The concentration of chlorine in coal, oxyge nand NO x in flue gas has a positive correlation with the formation of the oxidized mercury, but the sulfur in coal has a positive influence on the formation of elemental mercury.

Mercury removal from coal combustion by Fenton reactions. Paper B: Pilot-scale tests

This second paper in a series describes results of pilot-scale testing for mercury (Hg) removal from coal combustion flue gas using a scrubbing solution based on the Fenton reactions. The selected reagents contain hydrogen peroxide and iron salts. The mercury scrubbing was performed in a condensing heat exchanger (CHX) with flue gas generated by coal combustion in CANMET’s vertical combustor research facility (VCRF). Both the Ontario Hydro method and a Hg CEM were used for Hg sampling and speciation. The results, obtained with the combustion of three different pulverized coals – bituminous, sub-bituminous and lignite – showed that the CHX was very effective in removing oxidized mercury (Hg(II)). Concerning the performance of the scrubbing solutions, 30–40% of elemental mercury (Hg(0)) oxidation was achieved for the lignite coal, with the solution being preferably composed of FeCl 3 and H 2O 2 and with pH value between 1 and 3. Results also showed that better Hg removal results were achieved by combining sulphur removal and Hg removal in the same stage of the CHX. An additional test done on the pilot-scale research boiler with a conventional wet scrubber showed that the Hg removal capability using the Fenton reactions was not dependent on the configuration of the wet scrubber. Although the Hg(0) oxidation ratio was not particularly high compared to the achievements from bench-scale tests, considering the economic and non-toxic nature of the scrubbing solution and the readily available equipment, the current results are encouraging and deserve further work to develop a better understanding of the chemistry in order to determine if the method can be further optimized.

Emission and speciation of mercury from various combustion sources

Characterization of mercury emission and behavior from various stationary combustion processes were carried out for the major sources including coal-fired power plants and incinerators. Emission sampling and analysis of mercury at inlet and outlet of air pollution control devices (APCDs) for various sources have been made as the first attempt in Korea and now several institutions in governmental sectors are preparing the inventory on mercury. Speciation whether mercury forms are elemental or oxidized, was also studied by employing two different types of sampling method: Ontario Hydro(OH) method and US EPA 101A. Mercury emission and speciation depended on the Hg concentration in the fuels, type of APCDs, and flue gas temperature and composition. Measurement results showed that elemental mercury (Hg 0) was dominant at stack of coal power plants, while oxidized mercury was dominant at stack of incinerators, which could be due to the formation of mercury compounds in furnaces and APCDs configuration differences between them. The data for other sources were also obtained to understand the mercury emission. More intensive investigations were performed for a power plant and a municipal waste incinerator for observing the distribution of mercury at all the effluents. Mass balance of mercury in the process was figured out from the emission data and analysis results of mercury at all the in- and out-streams such as fuel (coals or wastes) fed, lime/lime stone, fly ash, bottom ash, gypsum and effluent water from wet flue-gas desulfurization(FGD). Approximate Hg mass balance could be obtained from sampled and analyzed data for those processes. However, a series of long-term and comprehensive studies are required to evaluate the reliable Hg distribution at coal-fired power plants and municipal waste incinerators. There were no significant differences between two sampling methods, but OH method seemed to have more advantage for Hg sampling from plants because mercury speciation was a very important factor for estimating the mercury emission and control efficiency from combustion flue gas.

Thermodynamic Comprehension of the Effect of Basic Ash Compositions on Gaseous Mercury Transformation

The gaseous mercury conversion between elemental mercury and oxidized mercury in the flue gas cooling process is a key problem in the mercury emission study. This paper focused on the effect of basic fly ash compositions, such as CaO, which may react with chlorine to produce CaCl2 in the same temperature range as mercury oxidation, hence decrease the chlorine concentration in flue gas and inhibit the oxidation of mercury. The thermodynamic equilibrium simulation shows that, in CaO-bearing flue gas, the stable Cl species shift from HCl to CaCl2 below 900 K and the conversion temperature between Hg and HgCl2 decreases as the CaO concentration increases. On-site experimental results in power plants by applying the Ontario Hydro method also supported this conclusion.

Characterization of Mercury Emissions from a Coal-Fired Power Plant

An emissions study for mercury was conducted at a 300 MW coal-fired plant equipped with an electrostatic precipitator (ESP). The input and output streams such as coal, slag, ESP ash, and flue gas were collected. Gaseous mercury was sampled using the Ontario Hydro method. The experimental data indicate that the majority of mercury goes into flue gas. The mercury quantity in flue gas to total combustion products is about 83%. The distribution of mercury in slag and fly ash is about 1 and 13%, respectively. The result also shows that, among the stack emissions after ESP, the gaseous mercury concentration in the flue gas is about 13−21 μg N-1 m-3. The proportion in particulate form was extremely low; the content of Hg2+ in flue gas is about 55−69%; and the content of Hg0 is about 31−45%. In addition, the absorption mechanism of mercury in fly ash was studied. It was found that the mercury concentration in fly ash is independent of the particle size and has a positive correlation with the loss of ignition of fly ash.

Factors Impacting Gaseous Mercury Speciation in Postcombustion

In the bench scale, gaseous mercury oxidization was investigated in postcombustion conditions with the experimental flue gas. The baseline experimental flue gas consisted of CO2 and N2. Other flue-gas constituents varied with O2, SO2, HCl, and NO. The measurement of mercury speciation was carried out at the downstream of the reaction tube using the Ontario Hydro method. Results showed that the possible intermediates Cl and Cl2 from HCl are the most important factors in mercury oxidization in the experimental flue gases. More mercury oxidization occurs with a higher reaction temperature and higher HCl concentration in most of experimental flue gases with HCl addition. O2 and NO also enhance mercury oxidization in the experimental flue gases with or without HCl and SO2. However, the effect of SO2 on mercury oxidization depends upon the presence of HCl.

Study of Mercury Oxidation by a Selective Catalytic Reduction Catalyst in a Pilot-Scale Slipstream Reactor at a Utility Boiler Burning Bituminous Coal

One of the cost-effective mercury control technologies in coal-fired power plants is the enhanced oxidation of elemental mercury in selective catalytic reduction (SCR) followed by the capture of the oxidized mercury in the wet scrubber. To better understand Hg oxidation chemistry within a SCR, the Institute for Combustion Science and Environmental Technology at Western Kentucky University set up a pilot-scale SCR slipstream facility at a selected utility boiler burning bituminous coal. The greatest benefit of this scaled-down SCR slipstream test is the ability to investigate the effects of Hg oxidation in a SCR using actual flue gas with fly ash included and to isolate and control specific flue-gas compositions with spike gas additions. The average sulfur, chlorine, and mercury contents in the burned coal were 1.67% and 731 and 0.13 ppm, respectively. CaO and Fe2O3 and loss on ignition of the fly ash, which are reported to possibly affect Hg speciation, are approximately 1.65, 14.6, and 2.6% on average, respectively. The maximum concentrations of spike gases were 500, 25, 2000, 50, and 15 ppm for HCl, Cl2, SO2, SO3, and HBr, respectively. Semicontinuous mercury emission monitors were used to monitor the variation of mercury speciation at the inlet and outlet of the SCR slipstream reactor, and the American Society for Testing and Materials certified Ontario hydro method was used for data comparison and validation. This paper is the first in a series of two in which the validation of the SCR slipstream test and Hg speciation variation in runs with or without SCR catalysts inside the SCR slipstream reactor under special gas additions (HCl, Cl2, SO2, and SO3) are presented. Effects of HBr additions on mercury speciation within the SCR will be presented in the second part of the series. Tests indicate that the use of a catalyst in a SCR slipstream reactor can achieve greater than 90% NO reduction efficiency with a NH3/NO ratio of about 1. There is no evidence to show that the reactor material affects mercury speciation. Both SCR catalysts used in this study exhibited a catalytic effect on the elemental mercury oxidation but had no apparent adsorption effect. SCR catalyst 2 seemed more sensitive to the operational temperature. The spike gas tests indicated that HCl can promote Hg0 oxidation but not Cl2. The effect of Cl2 on mercury oxidation may be inhibited by higher concentrations of SO2, NO, or H2O in real flue-gas atmospheres within the typical SCR temperature range (300−350 °C). SO2 seemed to inhibit mercury oxidation; however, SO3 may have some effect on the promotion of mercury oxidation in runs with or without SCR catalysts.

Sustainable development in an industrial enterprise: the case of Ontario Hydro

PurposeThis paper seeks to present a longitudinal case study of Ontario Hydro – an industrial organization that used sustainable development as the basis for a strategy of social and organizational transformation.Design/methodology/approachThe paper describes the complex factors that influenced the formulation and implementation of this strategy.FindingsThe findings indicate the advanced ambition and authenticity of Ontario Hydro's strategy, even though it was formulated some ten years ago. The study suggests that the strategy was abandoned for reasons that include the gap between the processes identified in the strategy and the processes followed in practice, the absence of platforms to discuss and agree the meaning and practice of sustainable development within the company and its wider system, and the scarcity of skills to facilitate sustainable development as a process of multi‐actor innovation. Consequently, the concept of sustainable development was not translated into practices that had shared meaning for the many actors involved in the energy system of Ontario. While based on a case study of one organization, the findings appear to speak to more general issues of sustainable development as the management of organizational and contextual change.Practical implicationsThe paper indicates much about the process of organizational change to effect more sustainable practices within a company and its social context.Originality/valueNo other organization has pursued a strategy for sustainable development with the same claim to authenticity as that of Ontario Hydro, where the strategy was cross‐referenced to Agenda 21 and developed with input from some of the main architects of Agenda 21. Moreover, few studies of sustainable development in the literature span a period as long as this case.

Mercury transformation across particulate control devices in six power plants of China: The co-effect of chlorine and ash composition

This paper presents the results of field measurements on mercury speciation in six power plants of China by applying the Ontario hydro method. During the tests, flue gas was sampled simultaneously before and after particulate control devices (electrostatic precipitator and fabric filter baghouse) along with the pulverized coal, bottom ash and fly ash sampling. The amount of oxidized mercury in gas phase before and after ESP/FF suggests that mercury oxidation after combustion is a kinetically controlled process. The comparison of mercury speciation in different power plant indicates a clear relationship with coal type, especially the chlorine concentration and the basic ash compositions in coal. Both of the factors are analyzed quantitatively in this study. A new parameter C (ratio of chlorine in coal to base/acid ratio) has been introduced to evaluate the co-effect of the two factors above on mercury speciation.

Relative Accuracy Testing of an X-Ray Fluorescence-Based Mercury Monitor at Coal-Fired Boilers

The relative accuracy (RA) of a newly developed mercury continuous emissions monitor, based on X-ray fluorescence, was determined by comparing analysis results at coal-fired plants with two certified reference methods (American Society for Testing and Materials [ASTM] Method D6784-02 and U.S. Environment Protection Agency [EPA] Method 29). During the first determination, the monitor had an RA of 25% compared with ASTM Method D6784-02 (Ontario Hydro Method). However, the Ontario Hydro Method performed poorly, because the mercury concentrations were near the detection limit of the reference method. The mercury in this exhaust stream was primarily elemental. The second test was performed at a U.S. Army boiler against EPA Reference Method 29. Mercury and arsenic were spiked because of expected low mercury concentrations. The monitor had an RA of 16% for arsenic and 17% for mercury, meeting RA requirements of EPA Performance Specification 12a. The results suggest that the sampling stream contained significant percentages of both elemental and oxidized mercury. The monitor was successful at measuring total mercury in particulate and vapor forms.

Nature’s Power and Native Persistence: The Influence of First Nations and the Environment is the Development of the Mattagami Hydro-Electric System During the Twentieth Century

To date, most analyses of hydro-electric development portray the environment and Aboriginal Peoples as victims unable to alter or resist its intrusion on to the landscape. However, an examination of the Mattagami river developments in northeastern Ontario illustrates that environmental conditions constantly influence the shape and development of the hydro-electric system. Also, while the ability of the northeastern Aboriginal Peoples to affect hydro-electric development is limited for much of this century, by the 1990s, their persistence and perseverance coalesces with changing court decisions and legislation, empowering them to negotiate with Ontario Hydro a moratorium on further development on the Mattagami River.

Speciation and mass distribution of mercury in a bituminous coal-fired power plant

Characterization and mass balance of mercury in a coal-fired power plant were carried out in a 500 MW, bituminous coal consuming electric utility boiler. This facility is equipped with a cold-side electrostatic precipitator (ESP) and a wet flue gas desulfurization (FGD) in series as air pollution control devices (APCDs). Mercury sampling points were selected at both the up and down streams of the ESP and outlet of the FGD, which is at stack. Two different types of sampling methods were employed, one is the Ontario Hydro (OH) method (ASTM D6784) and the other is US EPA101A. Various samples were collected from the coal-fired power plant such as fuel coals, fly ash in hopper, lime/lime stone, gypsum, and effluent water from FGD. These samples were analyzed by US EPA 7470A and 7471A to understand the behavior and mass balance of mercury in the process of a coal-fired power plant. There are no significant differences between the two sampling methods, but the OH method seems to have more advantages for Hg sampling from a coal-fired power plant because mercury speciation is quite an important factor to estimate the mercury emission and control efficiency from combustion flue gas. Approximate Hg mass balance could be obtained from various samples in the study; however, a series of long-term and comprehensive study is required to evaluate the reliable Hg mass distribution and behavior in a coal-fired power plant.

Impact of Coal Chlorine on Mercury Speciation and Emission from a 100-MW Utility Boiler with Cold-Side Electrostatic Precipitators and Low-NOx Burners

Field tests on mercury speciation and emission while burning Kentucky and Illinois coals with different chlorine contents were performed in a 100-MWe pulverized-coal boiler with low-NOx burners. Seven coals were used during the tests and were grouped into two sets for comparison, with the baseline coal being shared between the two sets. The first set of four coals was used to investigate the effect of chlorine in coal on mercury emission and its speciation by selecting coals with similar mercury contents and different chlorine contents. The four coals in the second set were selected to investigate the effect of mercury contents in coal on mercury emission and its speciation by choosing coals with similar chlorine contents and different mercury contents. The mercury concentration and speciation in the flue gas were determined using the American Society for Testing and Materials (ASTM) standard Ontario Hydro Method (OHM) and a PS Analytical Semi-continuous Emissions Monitoring (SCEM) system. Flue gas sampli...

Public Power: The Fight for Publicly Owned Electricity (review)

Reviewed by: Public Power: The Fight for Publicly Owned Electricity Kenneth C. Dewar (bio) Howard Hampton, with Bill Reno. Public Power: The Fight for Publicly Owned Electricity Insomniac. 298. $21.95 In the mid-1960s, around the time when Arizona senator Barry Goldwater was the Republican party candidate for president of the United States, a cartoon appeared in which Goldwater was depicted - in a photograph, dialogue cloud above his head - proposing that the US Postal Service be turned into a private corporation. The humour lay in the absurdity of the idea, which also exposed the lunatic-fringe extremism of Goldwater's conservative views. Today, few would see the joke. By the 1990s, what had been laughable thirty years earlier in both Canada and the US had become mainstream public policy in the form of deregulation and privatization. This book by Howard Hampton, leader of the New Democratic party of Ontario, traces a part of this paradigm shift and critically analyses its results. The book was written in anticipation of the Ontario provincial election of 2003, in which the NDP made the privatization of Ontario Hydro its leading issue, and it bears some of the marks of an election pamphlet. Claims are made hyperbolically; for example, in the opening paragraph, public power is described as an issue fundamental, among other things, 'to any semblance of social order in our daily lives,' and shortly afterward as the 'most essential' of public services. Hampton denies that his approach to the issue is 'ideological' - distinguishing himself from the Conservative government of then premier Ernie Eves - yet he also claims that the people of Ontario, in establishing a public power system in the early twentieth century, decided that 'public need must trump private greed.' The picture he draws of the origins of the system is highly idealized: they lay in a movement, he says, that 'transcended all social, economic and class differences,' a view not many serious historians today would endorse. In fact, the text relies heavily on older popular histories - notably W.R. Plewman's biography of Adam Beck and Merrill Denison's general history of Hydro - for its account of the origins and development of the public utility. Still, idealization - or myth - is not necessarily a bad thing. Here, it is put to effective use, as Hampton evokes a pantheon of founding heroes - Francis Spence, E.W.B. Snider, D.B. Detweiler, and, above all, Adam Beck, the London businessman who came to personify 'the Hydro' - who had the courage and imagination to create Ontario's (and one of Canada's) most important public enterprises. He describes the opposition they had to overcome from private power interests in Canada and the US, yet how Hydro also inspired imitation, especially in New York under Franklin Roosevelt's governorship and in the New Deal of Roosevelt's presidency during the 1930s. The echoes of medicare in modern times are impossible to miss. [End Page 526] The partisan purpose of this book takes nothing away from the substance of its argument. Hampton follows the progress of deregulation and privatization from it first trials in Augusto Pinochet's Chile, through Margaret Thatcher's Britain, to Ronald Reagan and George Bush Senior's US. In all cases, consumers and taxpayers were stuck with huge unanticipated (if predictable) costs, partly because governments assumed the debts of publicly owned facilities to make them more attractive to private investors, and partly because the price of deregulated electricity went up instead of down. In Ontario, the Conservative governments of Mike Harris and Ernie Eves nevertheless persisted in their determination to privatize Ontario Hydro because, Hampton argues, unlike their early twentieth-century predecessors, they were blinded by their faith in free enterprise. Along the way, he also argues vigorously against nuclear power ('madness,' he calls it) and in favour of small-scale, diversified production and more efficient consumption, both of which are more environmentally friendly, as well as economically manageable, than the mega-projects of the old central station model of production and the encouragement of profligate consumption that often accompanied it. In doing so, he holds Ontario Hydro itself responsible for the policies and spending that undermined its legitimacy, though it might...

04/02474 Mercury emissions from a 100-MW wall-firedboiler as measured by semicontinuous mercury monitor and Ontario Hydro Method: Kellie, S. et al. Fuel Processing Technology, 2004, 85, (6–7), 487–499

04/02474 Mercury emissions from a 100-MW wall-firedboiler as measured by semicontinuous mercury monitor and Ontario Hydro Method: Kellie, S. et al. Fuel Processing Technology, 2004, 85, (6–7), 487–499

Effects of NO x, α-Fe 2O 3, γ-Fe 2O 3, and HCl on mercury transformations in a 7-kW coal combustion system

Bench-scale investigations indicate that NO, NO 2, hematite (α-Fe 2O 3), maghemite (γ-Fe 2O 3), and HCl promote the conversion of gaseous elemental mercury (Hg 0) to gaseous oxidized mercury (Hg 2+) and/or particle-associated mercury (Hg[p]) in simulated coal combustion flue gases. In this investigation, the effects of NO x , α-Fe 2O 3, γ-Fe 2O 3, and HCl on Hg transformations were evaluated by injecting them into actual coal combustion flue gases produced from burning subbituminous Absaloka and lignitic Falkirk coals in a 7-kW down-fired cylindrical furnace. A bituminous Blacksville coal known to produce an Hg 2+-rich combustion flue gas was also burned in the system. The American Society for Testing and Materials Method D6784-02 (Ontario Hydro method) or an online Hg analyzer equipped to measure Hg 0 and total gaseous mercury (Hg[tot]) was used to monitor Hg speciation at the baghouse inlet (160–195 °C) and outlet (110–140 °C) locations of the system. As expected, the baseline Blacksville flue gas was composed predominantly of Hg 2+ (Hg 2+/Hg[tot]=0.77), whereas Absaloka and Falkirk flue gases contained primarily Hg 0 (Hg 0/Hg[tot]=0.84 and 0.78, respectively). Injections of NO 2 (80–190 ppmv) at 440–880 °C and α-Fe 2O 3 (15 and 6 wt.%) at 450 °C into Absaloka and Falkirk coal combustion flue gases did not significantly affect Hg speciation. The lack of Hg 0 to Hg 2+ conversion suggests that components of Absaloka and Falkirk combustion flue gases and/or fly ashes inhibit heterogeneous Hg 0–NO x –α-Fe 2O 3 reactions or that the flue gas quench rate in the 7-kW system is much different in relation to bench-scale flue gas simulators. An abundance of Hg 2+, HCl, and γ-Fe 2O 3 in Blacksville flue gas and the inertness of injected α-Fe 2O 3 with respect to heterogeneous Hg 0 oxidation in Absaloka and Falkirk flue gases suggested that γ-Fe 2O 3 catalyzes Hg 2+ formation and that HCl is an important Hg 0 reactant. The filtration of Absaloka and Falkirk combustion flue gases at 150 °C through fabric filters with ≈60 g/m 2 γ-Fe 2O 3 indicated that about 30% of the Hg 0 in Absaloka and Falkirk flue gases was converted to Hg 2+ and/or Hg(p). HCl injection (100 ppmv) into the Absaloka combustion flue gas converted most of the Hg 0 to Hg 2+, whereas HCl injection into the Falkirk flue gas converted most of the Hg 0 and Hg 2+ to Hg(p). Additions of γ-Fe 2O 3 and HCl did not have a synergistic effect on Hg 0 oxidation. The filtration of Absaloka and Falkirk flue gases through much greater fabric filter loadings of 475 g/m 2 γ-Fe 2O 3 essentially doubled the baghouse Hg[tot] removal efficiency to about 50%. Results from this investigation demonstrate the importance of evaluating potential Hg 0 reactants and oxidation catalysts in actual coal combustion flue gases.

Mercury emissions from a 100-MW wall-fired boiler as measured by semicontinuous mercury monitor and Ontario Hydro Method

Western Kentucky University (WKU) recently established a mobile laboratory for monitoring mercury emissions (MMEML). The lab contains facilities to perform both continuous emissions monitoring and the Ontario Hydro Method for mercury analysis. Among the instruments available in the lab are a semicontinuous mercury emissions monitor (SCEM), pretreatment and speciation unit for the SCEM, and an atomic absorption spectrometer with automated sampler. The MMEML was recently utilized at a power plant site that had a 100-MW, wall-fired combustor with low-NO x burners. At this site, a comparison between OHM and SCEM data was possible for testing locations before and after the ESP. OHM and SCEM produced analogous results for the measurement of total mercury, but differ in their measurement of mercury speciation. Testing by OHM also showed that vapor-phase mercury decreases as temperature decreases and as fly ash is removed. Our results suggest that the removal of vapor-phase mercury by fly ash is mostly the removal of oxidized mercury.

Mercury emissions from selected stationary combustion sources in Korea

Mercury emissions from various stationary combustion sources such as coal-fired power plants, oil-fired power plants, industrial utility oil boilers, iron manufacturing plants, and industrial waste incinerators, were measured. The US EPA (Environmental protection agency) method 101A and the Ontario hydro method were used to sample the mercury containing combustion flue gases, at the inlet of the air pollution control devices (APCDs) and at the stack. Collected samples of both gaseous and particulate forms were then analyzed using CVAA (cold vapor atomic absorption) type analyzer. Measurement results from the coal-fired power plant showed percentages of elemental mercury (Hg 0) as high as 31.4% and as low as 9.5%. However, the content of Hg 0 was in the range of 1.3–3.7% from the industrial waste incinerator. Differences in mercury speciation from various stationary combustion sources are believed to be coming from: (1) difference in the fuel types; (2) difference in the major flue gas compositions (ex. HCl and SO x ); and (3) difference in the types of air pollution control devices (APCDs). When the measurement results obtained using different sampling methods were compared, the Ontario Hydro Method gave a slightly higher mercury concentration measurement than that of the US EPA Method 101A.