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Co-effects of sulfur dioxide load and oxidation air on mercury re-emission in forced-oxidation limestone flue gas desulfurization wet scrubber
Abstract
Re-emission of Hg0 refers to the reduction of oxidized mercury (Hg2+) to the elemental mercury (Hg0) in a wet flue gas desulfurization process (WFGD), resulting Hg0 re-emits to the flue gas and increasing mercury emission for a coal combustion power plant. The correlations between re-emission of Hg0 and operation parameters of WFGD process, i.e., sulfur dioxide removal, oxidation air flow, and pH of FGD slurry, were investigated with mercury field data collected from two coal combustion power plants (Plant C and Plant O). At Units 31/32 of Plant C, Coupling mercury results and the plant information (PI) data suggested that an increase of the oxidation air flow in the WFGD effectively inhibited the re-emission of Hg0, and consequently increased the flue gas mercury removal efficiency from 63% to over 92%. But at Plant O, the increase of the oxidation air flow can sometimes increase Hg0 re-emission. It was further found that the re-emission of Hg0 at Plant O was strongly correlated not only to the flow rate of the oxidation air in the forced-oxidation operation conditions, but also to the amount of sulfur dioxide removed from the flue gas by the FGD scrubber (i.e., the sulfur dioxide load in the scrubber). Possible mechanisms were proposed.
... Particulate mercury can be removed by particle collectors such as the electrostatic precipitator (ESP) and fabric filter. Oxidized mercury can be either adsorbed on a fly ash surface and then removed by particle collectors, or dissolved in an absorbent and removed using wet flue gas desulfurization (WFGD) [5]. Hg 0 is highly volatile in ambient air and insoluble in water. ...
Since the signing of the Minamata Convention in 2013, attempts have been primarily focused on reducing the emission of elemental mercury (Hg0) from coal-fired power plants (CFPPs). The most cost-effective measure for controlling the emission of mercury involves oxidizing Hg0 to mercury oxides, which are then removed using wet flue gas desulfurization (WFGD). Thus, novel photocatalysts with the best properties of photocatalytic ability and thermal stability need to be developed urgently. In this study, titanium dioxide (TiO2)-based photocatalysts were synthesized through the modification of three metal oxides: CuO, CeO2, and Bi2O3. All the photocatalysts were further characterized using X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence, and ultraviolet-visible spectrometry. The photocatalytic oxidation efficiencies of Hg0 were evaluated under an atmosphere of N2 + Hg0 at 100–200 °C. The photocatalytic reactions were simulated by kinetic modeling using the Langmuir–Hinshelwood (L–H) mechanism. The results showed that Bi2O3/TiO2 exhibited the best thermal stability, with the best oxidation efficiency at 200 °C and almost the same performance at 100 °C. L–H kinetic modeling indicated that photocatalytic oxidation reactions for the tested photocatalysts were predominantly physical adsorption. Additionally, the activation energy (Ea), taking into account Arrhenius Law, decreased dramatically after modification with metal oxides.
... At the outlet of the WS, the Hg 0 concentration increased slightly (Table 1). The increase in Hg 0 at the WS may be caused by re-emission due to the reduction of Hg 2+ by aqueous S(IV) (sulfite and/or bisulfite) or halides ligands (Cl and ClO -) in the WS (Cheng et al., 2013;Omine et al., 2012;Hsu et al., 2021), which also occurs in the WS of sewage sludge incinerators (Cheng et al., 2020). ...
We evaluated mercury (Hg) behavior in a full-scale sewage sludge torrefaction plant with a capacity of 150 wet ton/day, which operates under a nitrogen atmosphere at a temperature range of 250–350ºC. Thermodynamic calculations and monitoring results show that elemental Hg (Hg⁰) was the dominant species in both the pyrolysis gas during the torrefaction stage and in the flue gas from downstream air pollution control devices. A wet scrubber (WS) effectively removed oxidized Hg from the flue gas and moved Hg to wastewater, and an electrostatic precipitator (ESP) removed significant particulate-bound Hg but showed a limited capacity for overall Hg removal. Hg bound to total suspended solids had a much higher concentration than that of dissolved Hg in wastewater. Total suspended solid removal from wastewater is therefore recommended to reduce Hg discharge. Existing air pollution control devices, which consist of a cyclone, WS, and ESP, are not sufficient for Hg removal due to the poor Hg⁰ removal performance of the WS and ESP; a further Hg⁰ removal unit is necessary. A commercial packed tower with sorbent polymer catalyst composite material was effective in removing Hg (83.3%) during sludge torrefaction.
... HCI and Cl 2 cause oxidation of mercury whereas ammonia which is used for the removal of NOx inhibits oxidation of mercury (Chiu et al., 2015;Hu and Cheng, 2016). As the flue gas temperature decreases, the volatile gaseous elemental mercury is converted into soluble gaseous oxidized mercury, which is removed by FGD wet scrubber (Cheng et al., 2013). The oxidized mercury has a lifetime of a few days due to its high solubility in moisture. ...
Greenhouse gas (GHG) emissions from the textile processes and products are one of the main contributors to air pollution. Some of the main toxic gases and compounds released are carbon dioxide, sulphur oxides (SOx), nitrogen oxides (NOx), mercury, and volatile organic compounds (VOCs). Although various treatment technologies exist to remove these substances, none of them is capable of removing all the substances with high efficiency and as a result, a combination of technologies is used. The activated carbon fibers and biological techniques have shown that they can remove various substances simultaneously. In this chapter, various treatment technologies are presented as the understanding of these technologies is important to reduce textile and fashion GHG emissions.
... Above 8000 m 3 /h, the mercury emissions start decreasing. Such behavior of mercury removal with the effect of oxidation air is reported in the literature [68]. A negligible effect of NO x absorption is observed with the increase in the oxidation airflow rate in Fig. 11(c). ...
The emissions from coal power plants have serious implication on the environment protection and there is an increasing effort around the globe to control these emissions by the flue gas cleaning technologies. This research was carried out on the limestone forced oxidation (LSFO) flue gas desulphurization (FGD) system installed at 2*660 MW super-critical coal fired power plant. Nine input variables of FGD system: pH, inlet SO2, inlet temperature, inlet NOx, inlet O2, oxidation air, absorber slurry density, inlet humidity and inlet dust were used for the development of effective neural network process models for a comprehensive emission analysis constituting outlet SO2, outlet Hg, outlet NOx and outlet dust emissions from LSFO FGD system. Monte-Carlo experiments were conducted on the artificial neural network process models to investigate the relationships between the input control variables and output variables. Accordingly, optimum operating ranges of all input control variables were recommended. Operating the LSFO FGD system under optimum conditions, nearly 35 % and 24 % reduction in SO2 emissions are possible at inlet SO2 values of 1500 mg/m3 and 1800 mg/m3 respectively, as compared to general operating conditions. Similarly, nearly 42 % and 28 % reduction in Hg emissions are possible at inlet SO2 values of 1500 mg/m3 and 1800 mg/m3 respectively as compared to general operating conditions. The findings are useful for minimizing the emissions from coal power plants and development of optimum operating strategies for LSFO FGD system.
... The WFGD system chemistry is very sensitive to the removal of Hg. The removal process is affected by parameters that include coal properties, boiler load, and WFGD process parameters [13,14]. A portion of the oxidized Hg absorbed into the scrubber liquor can be converted back to Hg 0 , in what is called mercury re-emission. ...
Wet flue gas desulfurization Coal-fired power plants Least squares support vector machine A B S T R A C T The oxidation-reduction potential (ORP) is highly related to Hg re-emission in wet flue gas desulfurization (WFGD) systems in coal-fired power plants. Developing an accurate model that describes the ORP characteristics is beneficial to achieve the operation optimization of the WFGD system and Hg re-emission reduction. In this paper, steady and dynamic ORP models were reported based on the least squares support vector machine (LSSVM) technique and using operating data acquired from a coal-fired power plant. For the steady model, input parameters consisted of flue gas flow, flue gas temperature, inlet SO 2 concentration, oxidation air flow, recycle pump currents, and slurry feed flow. For the dynamic model, in addition to the parameters listed above, time delays of these parameters were also considered in the modeling scheme. Both models achieved high accurate predictions. Model sensitivity analysis was conducted to investigate the influence of the input parameters and time delays on ORP. Results show that the parameters are adequate to describe the characteristics of the ORP. In addition, parametric time delays play an important role to represent the dynamic characteristics of the ORP. These models can be extended to design process control strategy and conduct the ORP operation optimization of the WFGD system in power plants to mitigate Hg re-emission from the scrubber.
... During 160-min reaction time, the Hg 2+ residual rate in the Hg 2+ -Cl − systems, Hg 2+ -SO 3 2− systems, and Hg 2+ -Cl − -SO 3 2− systems reached 45.5, 35.3, and 78.1%, respectively. Previous researchers (Cheng et al. 2013;Omine et al. 2012;Wo et al. 2009) speculated that the three systems had different mercuric complexes and gave the formations of mercuric complexes in these systems, which were showed in Eqs. ...
Wet flue gas desulfurization technologies have received much concern for their superior performance on co-controlling the acid gases and mercury. However, high concentrations of mercury-containing desulfurization wastewater, which discharge from wet flue gas desulfurization system regularly, have received researchers' attention since it might generate the risk of secondary pollution. In this paper, the species of mercuric complexes in the desulfurization wastewater was investigated. It speculated that ClHgSO3(-) might determine the residual rate of Hg(2+) in the desulfurization wastewater. Besides, the stability of ClHgSO3(-) on the condition of various wastewater features was also evaluated. The experiment revealed that the high temperature and high pH level promoted the decomposition of ClHgSO3(-). SO3(2-) could restrain the decomposition of ClHgSO3(-) gently; the Hg(2+) residual rate was determined by the new mercury complexes which compounded by Hg(2+) and SO3(2-). The decrease of SO4(2-) and increase of Ca(2+) concentrations could also stimulate the stability of ClHgSO3(-) in wastewater. Cu(2+) and Fe(2+) disturbed the stability of complexes for their catalysis and reduction activities. The study proposed that the ClHgSO3(-) probably decomposes and releases Hg(0) in two pathways. Furthermore, changes of the water's features could disturb the balance of Hg(2+)-Cl(-)-SO3(2-) systems, which might stimulate the decomposition of ClHgSO3.
... fly ash), it canbe captured by current air pollution control devices such as electrostatic precipitator (ESP) and fabric filter (FF). Hg 2+ can be removed efficiently by wet desulfurization device since it is water-soluble [3,4]. Conversely, Hg 0 is most difficult to remove because of its high vapor pressure and low water solubility. ...
... The approaches for enhancing Hg 0 oxidation include the addition of halogens or halides to flue gas [9][10][11][12], using catalysts (e.g., SiO2/TiO2/V2O5 [13], CeO2/TiO2 [14,15], MnOx-CeO2/TiO2 [16], CuCl2/␣-Al2O3 [17], CuO-MnO2-Fe2O3/␥-Al2O3 [18], CuCl2/TiO2 [19] and modified SCR [20]) or membrane delivery with catalytic oxidation system [21,22], and ozone injection [23]. Because of the reduction of dissolved Hg 2+ and re-emission of Hg 0 in wet-FGD [24][25][26][27], the Hg 0 removal efficiency of oxidation/absorption is not usually high. Recently, several absorbents have been developed to oxidation and absorption Hg 0 from flue gas, such as K2S2O8/Ag + /Cu 2+ solution [28], NaClO2 [29], diperiodatocuprate(III) coordination ion and diperiodatonickelate(IV) solutions [30,31]. ...
1-alkyl-3-methylimidazolium chloride ionic liquids ([Cnmim] Cl, n = 4, 6, 8) were prepared. The ionic liquid was then mixed with hydrogen peroxide (H2O2) to form an absorbent. The Hg0 removal performance of the absorbent was investigated in a gas/liquid scrubber using simulated flue gas. It was found that the ionic liquid/H2O2 mixture was an excellent absorbent and could be used to remove Hg0 from flue gas. When the mass ratio of H2O2 to ionic liquid was 0.5, the absorbent showed high Hg0 removal efficiency (up to 98%). The Hg0 removal efficiency usually increased with the absorption temperature, while decreased with the increase of alkyl chain length in ionic liquid molecule. The Hg0 removal mechanism involved with Hg0 oxidation by H2O2 and Hg2+ transfer from aqueous phase to ionic liquid phase.
... The approaches for enhancing Hg 0 oxidation include the addition of halogens or halides to flue gas [9][10][11][12], using catalysts (e.g., SiO 2 /TiO 2 /V 2 O 5 [13], CeO 2 /TiO 2 [14,15], MnO x -CeO 2 /TiO 2 [16], CuCl 2 /a-Al 2 O 3 [17], CuO-MnO 2 -Fe 2 O 3 /c-Al 2 O 3 [18], CuCl 2 /TiO 2 [19] and modified SCR [20]) or membrane delivery with catalytic oxidation system [21,22], and zone injection [23]. Because of the reduction of dissolved Hg 2+ and re-emission of Hg 0 in wet-FGD [24][25][26][27], the Hg 0 removal efficiency of oxidation/absorption is not high. Recently, several absorbents have been developed to oxidation and absorption Hg 0 from flue gas, including K 2 S 2 O 8 /Ag + /Cu 2+ solution [28], NaClO 2 [29], diperiodatocuprate (III) coordination ion and diperiodatonickelate (IV) solutions [30,31]. ...
Wet flue gas desulfurization (WFGD) system of coal-fired power station can synergistically remove arsenic from flue gas. However, the detailed mechanism of arsenic removal by desulfurization slurry and its further migration and transformation from gas to desulfurization products still remains unclear. In this study, two important factors, the Fe³⁺ concentration and the pH value, were investigated for their effects on arsenic removal, redistribution and transformation in a lab-scale reactor. The results show low Fe³⁺ concentration (≤1 mg L⁻¹) in slurry may lead to the decrease of particle size and the increase of Zeta potential of gypsum particles, thus promoting arsenic removal from flue gas, while more Fe³⁺ (10–500 mg L⁻¹) could reduce its removal due to the increase of mass transfer resistance. Arsenic removal efficiency decreases with pH value rising. The slurry with Fe³⁺ is easier to remove As(III) from flue gas than As(V) due to the strong polarity of AsCl3(g). Either increasing Fe³⁺ concentration (pH = 5.5) or rising pH value (Fe³⁺ concentration = 50 mg L⁻¹) can promote arsenic migration from desulfurization wastewater into gypsum. At any pH value, Fe-gypsum has a stronger ability to adsorb As(V) than As(III). Acid leaching model test indicates the arsenate incorporated into gypsum lattice can reach 12% without Fe³⁺, but the presence of Fe³⁺ hinders the arsenate doped into gypsum crystal, which is less than 1%. This raises the potential environmental risk of further utilization of gypsum due to the unstable arsenic speciation. The main arsenates substituting SO4²⁻ doped into gypsum lattice are HAsO4²⁻ and AsO4³⁻.
The environmental problem concerning Hg pollution has received worldwide attention. Coal fired power plants are responsible for large amounts of Hg emission and produce abundant by-products in particular gypsum which is capable of extensive use. In this study, the migration of Hg in the gypsum production process and effluent treatment process in a typical wet flue gas desulfurization (WFGD) system was investigated and the temperature programmed decomposition technique was applied to identified Hg species in these products. Hg concentration in both the solid and liquid fraction of samples obtained in wet flue gas desulfurization system were determined by atomic fluorescence spectroscopy. The results indicated that gypsum accounted for a small proportion (29.9%) of Hg while the majority of Hg was transported to effluent treatment process where over 99.6% Hg was removed. The amount of Hg discharged from WFGD in the drainage, gypsum, and desulfurization sludge were 0.04 t/yr, 13.56 t/yr, and 9.56 t/yr, respectively. Desulfurization environment promoted HgS formation and lead to HgS being dominant in gypsum. The alkaline environment in the effluent treatment process contributed to the formation of HgO which was regarded as the primary Hg compound and accounted for 49.5%, 54.8%, and 78.5% of the total Hg in the neutralization tank, precipitation tank, and flocculation tank, respectively. The occurrence of HgCl2 in the solid fraction attributed to absorption of solid particles when it precipitated and was enhanced by the addition of chemicals. There was no obvious difference in the proportion of HgSO4 in the effluent treatment process. Systematic studies on difference in the partitioning of Hg species enables a better understanding on Hg behavior and provides conferences on targeting removal of Hg species in WFGD system.
We investigated the distribution of 18 elements including non-volatiles (Al, P, Ca, Fe, Mg, K, Mn, Cu, Na, Cr, and Ni), semi-volatiles (Zn, Pb, Ag, As, and Cd), and volatiles (Hg and S) and compared their behaviors in two types of full-scale sewage sludge mono-incinerators, namely, a step-grate stoker (GS) and two fluidized bed incinerators (F-types), with the same feed sludge. Most of the non-volatile elements were enriched five-fold in all incinerated sewage sludge ash (ISSA), while the volatile S and Hg were barely enriched in ash due to the combustion components generated in the gas phase. While the semi-volatile elements were also enriched five-fold in the F-types, a different enrichment behavior was observed in the GS. Boiler and multi-cyclone dust in the GS showed higher enrichments of Pb and Cd compared to ash due to the combined effects of lower temperature and smaller particle size. Compared to the F-types, the GS generated ashes with lower toxicity as the major component (99.7%) and hazardous dust as the minor component. In the future, more attention should be paid to grate stokers in terms of recycling ISSA.
At present, wet flue gas desulfurization (FGD) systems offer insufficient control of the oxidation process. This study proposes to optimize the oxidation process of desulfurization slurry by an oxidation reduction potential (ORP) control strategy. By designing a L16(45) orthogonal test, the effects of temperature, concentration, rotation speed, air flow rate, and pH on ORP were investigated at different oxidation stages of CaSO3. Based on the analysis of variance, the order of contribution of different influencing factors at the specific oxidation stage was obtained. The influence degree of specific influencing factors on ORP was different, and the trend is explained for each different oxidation stage as well. The results indicate that only the temperature plays a significant role in the change of ORP during the whole oxidation process, which clarifies that the temperature affects the oxidation process of CaSO3 by affecting the dissolution of O2 and CaCO3 and the transformation of S(IV) to S(VI). The results also provide theoretical guidance for precise oxidation control of the FGD slurry system.
Characteristics of Hg0 re-emission in wet flue gas desulfurization (WFGD) system were investigated based on a bubble column. Five addition agents were used to inhibit Hg0 re-emission and improve removal of gaseous mercury. The results show that SO32- plays an important role in Hg0 re-emission in WFGD system. Hg0 re-emission is intensified sharply in the presence of SO32-, and further intensified with the increase of SO32- concentration. Hg0 re-emission is strengthened at a higher temperature of desulfurization slurry. However, the removal efficiencies of both Hg2+ and total gaseous mercury decrease significantly with increasing slurry temperature. And the decreasing amplitude of total mercury removal efficiency is slightly higher than that of Hg2+. In addition, re-emission rate of Hg0 declines first and then increases with increasing pH value. A least Hg0 re-emission is observed at a pH value of 5.5. Fenton reagent, NaClO, K2S2O8, Na2S and EDTA can inhibit Hg0 re-emission in different extents. Among them, Fenton reagent and EDTA exhibit better performance than that of NaClO and Na2S. The least inhibition effect is found for K2S2O8. For the sake of effective inhibition of Hg0 re-emission and gaseous mercury removal, a lower slurry temperature, a pH value in the range of 2.5~3.5 and a Fe2+ concentration of 50 mg/L are optimal in practical WFGD system.
Red mud and carbide slag which are industrial waste materials from alumina and chlor-alkali plants pose environmental risks due to the large production volume. However, reutilization has been limited due to their composition and structure and the large alkali concentration in red mud has hampered utilization of red mud. At the same time, flue gas produced during the process of coal firing is a major environmental threat causing greenhouse effects and fog haze. In this work, alkalis (Na2O) in red mud were released by the alkali and acid methods and carbide slags and flue gas were utilized to remove alkalis from red mud. The effects of the reaction time, temperature, and solid-to-liquid ratio on dealkalization of red mud by carbide slag were studied. Flame absorption and X-ray diffraction were employed to monitor the changes in the red mud before and after dealkalization. Under the optimal conditions, the residual Na2O amount in the red mud after dealkalization using the carbide slag diminished to less than 3 wt%, whereas that of Na2O dropped to less than 2 wt% using flue gas. The pH of the suspension was determined by the acid method. The hydroxysodalite (Na8Al6Si6O24(OH)2) structure in the initial red mud was destroyed and soluble sodium salts formed in the suspension could be easily replaced by carbide slag or flue gas reducing Na2O.
Recently, the Hg0 re-emission from flue scrubbing solutions has become a research focus. The objective of this study was to evaluate the influence of arsenite on Hg0 re-emission by investigating critical important parameters, including the arsenite ion concentration, pH values, solution temperature, fluorine ion concentration, and chlorine ion concentration. The experimental results indicate that arsenite could directly reduce Hg2+ to Hg0 and promote the decomposition of Hg(SO3)22-. High pH, temperature and chlorine ion concentration contributed to the inhibition of Hg0 re-emission, but the fluorine ions had little effect. The mechanism research suggests that the formation of unstable HgH2AsO3+ at low arsenite concentration accelerates Hg0 re-emission. For the Hg(II)-As(III)-S(VI) system, the formation of unstable HgSO3H2AsO3- than Hg(SO3)22- could increase Hg0 re-emission. With an increase in arsenite concentration, the formation of Hg(H2AsO3)2 (which comes from the reaction between HgSO3H2AsO3- and H2AsO3-) contributes to the suppression of Hg0 re-emission. The results of this study are conducive to providing new insight into Hg0 re-emission and mercury control.
Mercury released from wet flue gas desulfurization (WFGD) devices can be inhibited by additives that can transfer mercury to its solid phase. However, the use of additives increases the mercury content in desulfurization gypsum, and the mercury is released again during the calcination process. In this study, NaHS, 2,4,6-trimercaptotiazine, trisodium salt nonahydrate (Na3(C3N3S3)·9H2O, or TMT) and sodium dithiocarbamate (DTCR) were used as additives to control mercury emissions in simulated WFGD devices. Then, different calcination methods were adopted to study mercury release behaviors from calcination process. The transformation of mercury compound species on gypsum was also investigated to explain its behavior during calcination. The result showed that the mercury content in the solid phase increased significantly in the presence of additives. Among three additives, simulated desulfurization slurry with TMT had the highest trapping efficiency over mercury. The mercury thermal stability in gypsum increased in the order of using DTCR, TMT and NaHS. Due to the migration of mercury to the solid phase and the stronger thermal stability of resultants, the residual content of mercury in gypsum with additives after calcination were higher than that without additives. In general, using TMT coupled with slow-speed calcination had the best effect on controlling mercury contamination from WFGD slurry and WFGD byproducts. Moreover, it was verified by temperature programmed decomposition experiments that, after using NaHS, TMT and DTCR, the mercury compound in the gypsum was mainly in the form of HgS, Hg3(TMT)2, Hg(DTCR)2, respectively, which explained the mercury release behaviors during calcination.
Wet flue gas desulphurization (WFGD) technology is the most mature and widely applied desulphurization technique in the world at present. As divalent mercury (Hg2+) is easily dissolved in aqueous solution, the effect of WFGD on mercury transformation and removal efficiency has become a hot subject in the research of how to control mercury contamination with low cost. In this paper, the demercuration property of limestone–gypsum WFGD process is simulation studied by Aspen plus software, assessing the effect of different process parameters on demercuration efficiency. Results show that conventional WFGD system has a high removal efficiency for Hg2+ (>90 %) but ineffective at removing Hg0, and even Hg0 slightly increases due to reduction in Hg2+ by SO2 or SO3 2−. Mercury removal efficiency is negatively influenced by the increase in the temperature of flue gas, but can be enhanced by increasing the pH of slurry solution and the concentration of SO2 in flue gas. In addition, presence of chloride can lead to the formation of HgCl2 and ClHgSO3 −, which inhibits the re-emission of mercury.
This paper discussed the stability of ClHgSO3− complexes in desulfurization wastewater after it emitted from WFGD system. The results of experiments showed that the increase in temperature promotes ClHgSO3− complex decomposition which fitted the pseudo first-order kinetics principle, and the E
a
value was calculated to 19.93 J/mol. The increase of H+ concentration in the solution stimulates the decomposition of ClHgSO3− complexes. The result of competitive reaction indicated that Ca2+ was easier to react with SO32− than Hg2+ to form CaSO3, which is slightly soluble and stimulated the decomposition of complexes. SO42− ions inhibit the forward reaction of ClHgSO3− decomposition and promote ORP value of wastewater, which avoid the formation of unstable HgSO3. It was also found that Hg2+ concentration was relatively low in wastewater, and decomposition reaction cannot be evaluated by ORP change. Moreover, ORP value and variation negligibly reflect the stability of complexes.
The re-emission of elemental mercury was simulated in the lab-scale wet scrubber. Absorbing and dissolving of vapour Hg2+ were simulated in the slurry as HgCl2 standard solution was continuously injected into the slurry. Some factors such as oxidation models of wet flue gas desulphurization system, ratio of oxygen to sulphur and a trimercapto-s-trazine trisodium salt additive on elemental mercury re-emissions were investigated. Trends of oxidation-reduction potential and pH values of testing slurries with different SO2 concentrations and testing time were studied. Elemental mercury re-emissions occurred in reduction atmosphere when oxidation-reduction potential of the slurries were negative.
The slip ammonia from selective catalytic reduction (SCR) of NOx in coal-fired flue gas can result in deterioration of the utilities or even the environmental issues. To achieve selective catalytic oxidation (SCO) of slip ammonia, Ru-modified Ce-Zr solid solution catalysts were prepared and evaluated under various conditions. It was found that the Ru/Ce0.6Zr0.4O2(PVP) catalyst displayed significant catalytic activity and the slip ammonia was almost completely removed with the coexistence of NOx and SO2. Interestingly, the effect of SO2 on NH3 oxidation was bifacial, and the N2 selectivity of the resulting products was as high as 100% in the presence of SO2 and NH3. The mechanism of the SCO of NH3 over Ru/Ce0.6Zr0.4O2(PVP) was studied using various techniques, and the results showed that NH3 oxidation follows an internal SCR (iSCR) mechanism. The adsorbed ammonia was first activated and reacted with lattice oxygen atoms to form an -HNO intermediate. Then, the -HNO mainly reacted with atomic oxygen from O2 to form NO. Meanwhile, the formed NO interacted with -NH2 to N2 with N2O as the by-product, but the presence of SO2 can effectively inhibit the production of N2O.
This paper evaluates the influence of the main constituents of flue gases from coal combustion (CO2, O2, N2 and water vapor), in air and oxy-fuel combustion conditions on the re-emission of Hg(0) in wet scrubbers. It was observed that the concentration of water vapor does not affect the re-emission of mercury, whereas O2 and CO2 have a notable influence. High concentrations of O2 in the flue gas prevent the re-emission of Hg(0) due to the reaction of oxygen with the metals present in low oxidation states. High concentrations of CO2, which cause a decrease in the pH and the redox potential of gypsum slurries, reduce the amount of Hg(0) that is re-emitted. As a consequence, the high content of CO2 in oxy-fuel combustion may decrease the re-emission of Hg(0) due to the solubility of CO2 in the suspension and the decrease in the pH. It was also found that O2 affects the stabilization of Hg(2+) species in gypsum slurries. The results of this study confirm that the amount of metals present in limestone as well as the redox potential and pH of the slurries in wet desulphurization plants need to be strictly controlled to reduce Hg(0) re-emissions from power plants operating under oxy-fuel combustion conditions.
The free energy of formation of dimethyl sulfite in aqueous solution can be calculated as −91.45 ± 0.79 kcal/mol; this calculation required measurement of the solubility of dimethyl sulfite. From this value and the pKa of SO(OH)2, using previously reported methods, the free energy of formation of SO(OH)2 can be calculated to be −129.26 ± 0.89 kcal/mol. Comparison of this value with the value obtained from the free energy of formation of 'sulfurous acid' solutions, calculated from the free energy of formation of sulfite ion and the apparent pKa, values, permits evaluation of the free energy of covalent hydration of SO2 as 1.6 + 1.0 kcal/mol, in agreement with earlier qualitative spectroscopic observations. From the apparent pKa and the anticipated pKa values for the tautomers (SO(OH)2, pK1 = 2.3; HSO2(OH), pK1 = −2.6) it is possible to calculate the free energy change for tautomerization of SO(OH)2 to H—SO2(OH) as +4.5 ± 1.2 kcal/mol. All equilibrium constants required for Scheme 1, describing the species present in dilute aqueous solutions of SO2, have been calculated. In agreement with previous Raman studies the major tautomer of 'bisulfite ion' is calculated to be H—SO3−.
This paper evaluates an elementary reaction mechanism for Hg0 oxidation in coal-derived exhausts consisting of a previously formulated homogeneous mechanism with 102 steps and a new three-step heterogeneous mechanism for unburned carbon (UBC) particles. Model predictions were evaluated with the extents of Hg oxidation monitored in the exhausts from a pilot-scale coal flame fired with five different coals. Exhaust conditions in the tests were very similar to those in full-scale systems. The predictions were quantitatively consistent with the reported coal-quality impacts over the full range of residence times. The role of Cl atoms in the homogeneous mechanism is hereby supplanted with carbon sites that have been chlorinated by HCl. The large storage capacity of carbon for Cl provided a source of Cl for Hg oxidation over a broad temperature range, so initiation was not problematic. Super-equilibrium levels of Cl atoms were not required, so Hg was predicted to oxidize in systems with realistic quench rates. Whereas many fundamental aspects of the heterogeneous chemistry remain uncertain, the information needed to characterize Hg oxidation in coal-derived exhausts is now evident: complete gas compositions (CO, hydrocarbons, H2O, O2 NOx, SOx), UBC properties (size, total surface area), and the ash partitioning throughout the exhaust system are required.
This article introduces a predictive capability for Hg retention in any Ca-based wet flue gas desulfurization (FGD) scrubber, given mercury (Hg) speciation at the FGD inlet, the flue gas composition, and the sulphur dioxide (SO2) capture efficiency. A preliminary statistical analysis of data from 17 full-scale wet FGDs connects flue gas compositions, the extents of Hg oxidation at FGD inlets, and Hg retention efficiencies. These connections clearly signal that solution chemistry within the FGD determines Hg retention. A more thorough analysis based on thermochemical equilibrium yields highly accurate predictions for total Hg retention with no parameter adjustments. For the most reliable data, the predictions were within measurement uncertainties for both limestone and Mg/lime systems operating in both forced and natural oxidation mode. With the U.S. Environmental Protection Agency's (EPA) Information Collection Request (ICR) database, the quantitative performance was almost as good for the most modern FGDs, which probably conform to the very high SO2 absorption efficiencies assumed in the calculations. The large discrepancies for older FGDs are tentatively attributed to the unspecified SO2 capture efficiencies and operating temperatures and to the possible elimination of HCl in prescrubbers. The equilibrium calculations suggest that Hg retention is most sensitive to inlet HCl and O2 levels and the FGD temperature; weakly dependent on SO2 capture efficiency; and insensitive to HgCl2, NO, CA:S ratio, slurry dilution level in limestone FGDs, and MgSO3 levels in Mg/lime systems. Consequently, systems with prescrubbers to eliminate HCl probably retain less Hg than fully integrated FGDs. The analysis also predicts re-emission of Hg(O) but only for inlet O2 levels that are much lower than those in full-scale FGDs.
The purpose of this study was to investigate the dependence of mercury emissions on coal ranks and electric utility boilers equipped with Fabric Filter Baghouses (FF). A comparison of mercury emission rates and fly ash properties was made between a circulating Fluidized Bed Combustor (CFBC) with FF and a Pulverized Coal (PC) combustor with FF during the burning of all three ranks of American coals. The data were collected from the Environmental Protection Agency Information Collection Request (EPA ICR) and WKU ICSET's mercury testing program. A statistical stepwise regression procedure was used to determine significant factors such as coal rank and types of boilers equipped with FF on mercury emissions during coal combustion. The higher mercury emission rates were generally found in both CFB and PC units when lignite was burned. The lower mercury emission rates were generally found in both CFB equipped with FF and PC units equipped with FF when bituminous coal was burned. There was a statistically significant lower mercury emission in the CFBC equipped with FF than that in the PC units when sub-bituminous coal was burned. Lower mercury emission rates in electric utility boilers equipped with FF are due to the active fly ash generated with a larger specific surface area and pore volume. Higher mercury emission rates observed during lignite-fired boilers may be due to their lower specific area of fly ash, which results from lower LOI, as well as the pore blockage by selenium (Se) for Texas lignite; and sodium (Na) and potassium (K) for North Dakota lignite. There is no significant mutual benefit for the mercury captured by the addition of Spray Dry Absorber (SDA) or selective non-catalytic reduction (SNCR) in the CFBC system.
Elemental mercury (Hg0) re-emissions from slurries and solutions were evaluated in a lab-scale simulated scrubber. Oxidized mercury (Hg2+) standard solution was injected into the simulated scrubber at a desired rate to simulate absorbing and dissolving of Hg2+ in the flue gas across wet flue gas desulfurization (WFGD) systems. PS analytical mercury analyzer was used to continuously determine Hg0 re-emission concentrations in the carrier gas from the scrubber. Sulfite ion in the slurry of CaSO3 was validated to reduce Hg2+ to Hg0, while no Hg0 re-emission occurred from slurries of CaSO4 and CaO. Transitional metal ions with low chemical valence such as Fe2+, Pb2+, Ni2+, and Cu+ were used to prepare solutions with concentration levels of mmol·L−1. Reduction reaction of Hg2+ to Hg0 was observed from these solutions. Reduction capabilities for the different transitional metal ions in the solutions were: Pb2+>Cu+>Fe2+> AsO−2>Ni2+.
This paper describes a lab-scale simulated scrubber that was designed and built in the laboratory at Western Kentucky University’s Institute for Combustion Science and Environmental Technology. A series of tests on slurries of CaO, CaSO3, CaSO4/CaSO3 and Na2SO3 were carried out to simulate recirculating slurries in different oxidation modes. Elemental mercury (Hg0) re-emission was replicated through the simulated scrubber. The relationship between the oxidation–reduction potential (ORP) of the slurries and the Hg0 re-emissions was evaluated. Elemental mercury re-emission occurred when Hg2+ that was absorbed in the simulated scrubber was converted to Hg0; then, Hg0 was emitted from the slurry together with the carrier gas. The effects of both the reagents and the operational conditions (including the temperature, pH, and oxygen concentrations in the carrier gas) on the Hg0 re-emission rates in the simulated scrubber were investigated. The results indicated that as the operational temperature of the scrubber and the pH value of the slurry increased, the Hg0 concentrations that were emitted from the simulated scrubber increased. The Hg0 re-emission rates decreased as the O2 concentration in the carrier gas increased. In addition, the effects of additives to suppress Hg0 re-emission were evaluated in this paper. Sodium tetrasulfide, TMT 15, NaHS and HI were added to the slurry, while Hg2+, which was absorbed in the slurry, was retained in the slurry as mercury precipitates. Therefore, there was a significant capacity for the additives to suppress Hg0 re-emission.
This Topical Report summarizes progress on Cooperative Agreement DE-FC26-04NT42309, 'Field Testing of a Wet FGD Additive'. The objective of the project is to demonstrate the use of two flue gas desulfurization (FGD) additives, Evonik Degussa Corporation's TMT-15 and Nalco Company's Nalco 8034, to prevent the re-emission of elemental mercury (Hg°) in flue gas exiting wet FGD systems on coal-fired boilers. Furthermore, the project intends to demonstrate whether the additive can be used to precipitate most of the mercury (Hg) removed in the wet FGD system as a fine salt that can be separated from the FGD liquor and bulk solid byproducts for separate disposal. The project is conducting pilot- and full-scale tests of the additives in wet FGD absorbers. The tests are intended to determine required additive dosages to prevent Hg° re-emissions and to separate mercury from the normal FGD byproducts for three coal types: Texas lignite/Powder River Basin (PRB) coal blend, high-sulfur Eastern bituminous coal, and low-sulfur Eastern bituminous coal. The project team consists of URS Group, Inc., EPRI, Luminant Power (was TXU Generation Company LP), Southern Company, IPL (an AES company), Evonik Degussa Corporation and the Nalco Company. Luminant Power has provided the Texas lignite/PRB co-fired test site for pilot FGD tests and cost sharing. Southern Company has provided the low-sulfur Eastern bituminous coal host site for wet scrubbing tests, as well as the pilot- and full-scale jet bubbling reactor (JBR) FGD systems tested. IPL provided the high-sulfur Eastern bituminous coal full-scale FGD test site and cost sharing. Evonik Degussa Corporation is providing the TMT-15 additive, and the Nalco Company is providing the Nalco 8034 additive. Both companies are also supplying technical support to the test program as in-kind cost sharing. The project is being conducted in six tasks. Of the six project tasks, Task 1 involves project planning and Task 6 involves management and reporting. The other four tasks involve field testing on FGD systems, either at pilot or full scale. The four tasks include: Task 2 - Pilot Additive Testing in Texas Lignite Flue Gas; Task 3 - Full-scale FGD Additive Testing in High-sulfur Eastern Bituminous Flue Gas; Task 4 - Pilot Wet Scrubber Additive Tests at Plant Yates; and Task 5 - Full-scale Additive Tests at Plant Yates. The pilot-scale tests and the full-scale test using high-sulfur coal were completed in 2005 and 2006 and have been previously reported. This topical report presents the results from the Task 5 full-scale additive tests, conducted at Southern Company's Plant Yates Unit 1. Both additives were tested there.
Wet scrubber systems, depending on the form of gas-phase mercury, can provide cost-effective mercury emissions control. However, field- and bench-scale tests suggest that significant increases in elemental mercury (Hg0) concentration may occur across wet scrubbers. The Babcock & Wilcox Company (B&W) observed this phenomenon around 1997 and subsequently focused its research on finding solutions. During pilot-scale tests aimed at enhancing the mercury removal performance of wet FGD systems, B&W discovered the important role of Sulfides on the sequestration of soluble ionic mercury (Hg2+) and was subsequently awarded two patents utilizing sulfide chemistry. A detailed mechanistic interpretation of the role of sulfide on the sequestration of Hg2+ is presented here with the aid of a commercial electrolytic equilibrium model (OLI software, www.olisystems.com). B&W's pilot-scale results and OLI mechanistic modeling revealed the important role of transition metal ions (specifically iron) and soluble sulfites in exacerbating re-emission of Hg0 and the significance of the presence of Sulfides in suppression of this re-emission. The significant effect of scrubber pH on the consumption of sulfides by metal ions was another important finding of this study that has considerable field implications. One of B&W's patented technologies that utilizes sodium hydrosulfide has been applied on several operating wet scrubbers to prevent reemission of Hg0. The mechanistic information compiled by B&W has been used to further improve the performance of this technology in the field.
The aqueous sulfite ion reacts with Hg2+(aq) to form 1:1 and 2:1 coordination complexes. The Hg(SO3)22- complex is redox stable. However, dissociation of a sulfite ligand forms redox-unstable HgSO3. Under conditions where Hg(SO3)22- predominates, the rate of reduction of the mercuric ion to Hg0 by coordinated sulfite depends inversely on the concentration of uncoordinated sulfite, while it is unaffected by the amount of sulfite liberated by dissociation. Analysis of the kinetics yields the sequential sulfite binding constants K1 = 2.1 × 1013 and K2 = 1.0 × 1010 at μ = 0.10 M. These values lead to the prediction that HgSO3 is more abundant in clouds than is Hg(SO3)22- under virtually all atmospheric conditions. The product of the redox reaction appears to be a strongly bound Hg0·SO2 complex, which is at least 3 orders of magnitude more soluble than uncomplexed Hg0(aq). This finding may have important implications for the partitioning of atmospheric mercury from the gas phase into atmospheric water droplets prior to its wet deposition.
A series of laboratory scale experiments were conducted in an FGD-batch reactor. A synthetic flue gas was produced and directed through a CaCO3 suspension contained in a glass reactor vessel. The suspension temperature was set at 54 °C through a water bath. In order to observe the distribution of mercury species in the system, solid, liquid and gaseous samples were taken and analysed. For gaseous mercury determination, continuous measurements were carried out, up and downstream the reactor. Furthermore, the concentration of chlorine in the scrubber solution of the system was varied from 0 to 62 g/l under different oxidative conditions.In a first approach, a concentration drop of elemental mercury coming out of the system was observed. The latter occurs only when high concentrations of Cl− are present, combined with a high O2 availability in the scrubber. It was also observed that mercury species distribution in the different phases varies, depending on the available chemical form of chlorine and oxygen concentration.
The properties of fly ash in coal-fired boilers influence the emission of mercury from power plants into the environment. In this study, seven different bitumous coals were burned in a full-scale 100 MWe pulverized coal combustion boiler and the derived fly ash samples were collected from a mechanical hopper (MH) and an electrostatic precipitator hopper (ESP). The mercury content, specific surface area (SSA), unburned carbon, and elemental composition of the fly ash samples were analyzed to evaluate the correlation between the concentration of particulate-bound mercury and the properties of coal and fly ash. For a given coal, it was found that the mercury content in the fly ash collected from the ESP was greater than in the fly ash samples collected from the MHP. This phenomenon may be due to a lower temperature of flue gas at the ESP (∼135 °C) compared to the temperature at the air preheater (∼350 °C). Also, a significantly lower SSA observed in MH ash might also contribute to the observation. A comparison of the fly ash samples generated from seven different coals using statistical methods indicates that the mercury adsorbed on ESP fly ashes has a highly positive correlation with the unburned carbon content, manganese content, and SSA of the fly ash. Sulfur content in coal showed a significant negative correlation with the Hg adsorption. Manganese in fly ash is believed to participate in oxidizing volatile elemental mercury (Hg 0) to ionic mercury (Hg 2+). The oxidized mercury in flue gas can form a complex with the fly ash and then get removed before the flue gas leaves the stack of the boiler.
This paper is to discuss the recent observations of elemental mercury (Hg 0) reemissions from a pilot-scale limestone wet scrubber. Simulated flue gas was generated by burning natural gas in a down-fired furnace and doped with 2000 ppm of sulfur dioxide (SO 2). Mercuric chloride (HgCl 2) solution was delivered to the scrubber at a controlled rate to simulate the absorption of ionized mercury (Hg 2+). Testing results have shown that, after Hg 2+ was injected, elevated Hg 0 concentrations were soon detected both in the scrubber effluent flue gas and the hold tank air, which reflected the occurrence of Hg 0 reemissions in both places. When the HgCl 2 feed was stopped, the Hg 0 reemission continued for more than 2 h. In addition, a significant Hg 0 reemission was also detected outside the scrubber loop. In an attempt to understand the Hg 0 reemission increase across the wet scrubber system under transient and steady states and to understand the underlying relationship with the mercury complexes retained in the wet scrubber system, a mercury reemission model was developed. With this model, it was found that the Hg 0 reemission rate under the current testing conditions can be simulated by a first-order reaction, and only a portion of Hg · S(IV) complexes retained in the slurry were participating in the reemission reaction.
An inventory of mercury emissions from anthropogenic activities in China is compiled for the year 1999 from official statistical data. We estimate that China's emissions were 536 (±236) t of total mercury. This value includes open biomass burning, but does not include natural sources or re-emission of previously deposited mercury. Approximately 45% of the Hg comes from non-ferrous metals smelting, 38% from coal combustion, and 17% from miscellaneous activities, of which battery and fluorescent lamp production and cement production are the largest. Emissions are heaviest in Liaoning and Guangdong Provinces, where extensive smelting occurs, and in Guizhou Province, where there is much small-scale combustion of high-Hg coal without emission control devices. Emissions are gridded at 30×30 min spatial resolution. We estimate that 56% of the Hg in China is released as Hg0, 32% as Hg2+, and 12% as Hgp. Particulate mercury emissions are high in China due to heavy burning of coal in residential and small industrial settings without PM controls. Emissions of Hg2+ from coal-fired power plants are high due to the absence of flue-gas desulfurization units, which tend to dissolve the soluble divalent mercury. Metals smelting operations favor the production of elemental mercury. Much of the Hg is released from small-scale activities in rather remote areas, and therefore the activity levels are quite uncertain. Also, emissions test data for Chinese sources are lacking, causing uncertainties in Hg emission factors and removal efficiencies. Overall, we calculate an uncertainty level of ±44% (95% confidence interval) in the estimate of total emissions. We recommend field testing of coal combustors and smelters in China to improve the accuracy of these estimates.
Secondary atmospheric pollutions may result from wet flue gas desulfurization (FGD) systems caused by the reduction of Hg2+ to Hg0. The present study employed three agents: Na2S, 2,4,6-trimercaptotiazine, trisodium salt nonahydrate (TMT) and sodium dithiocarbamate (DTCR) to precipitate aqueous Hg2+ in simulated desulfurization solutions. The effects of the precipitator’s dosing quantity, the initial pH value, the reaction temperature, the concentrations of Cl− and other metal ions (e.g. Cu2+ and Pb2+) on Hg2+ removal were studied. A linear relationship was observed between Hg2+ removal efficiency and the increasing precipitator’s doses along with initial pH. The addition of chloride and metal ions impaired the Hg2+ removal from solutions due to the complexation of Cl− and Hg2+ as well as the chelating competition between Hg2+ and other metal ions. Based on a comprehensive comparison of the treatment effects, DTCR was found to be the most effective precipitating agent. Moreover, all the precipitating agents were potent enough to inhibit Hg2+ reduction as well as Hg0 re-emission from FGD liquors. More than 90% Hg2+ was captured by precipitating agents while Hg2+ reduction efficiency decreased from 54% to just less than 3%. The additives could efficiently control the secondary Hg0 pollution from FGD liquors.
Calcium-based scrubbers designed to absorb HCl and SO(2) from flue gases can also remove oxidized mercury. Dissolved mercury halides may have an appreciable partial vapor pressure. Chemical reduction of the dissolved mercury may increase the Hg emission, thereby limiting the coremoval of mercury in the wet scrubbing process. In this paper we evaluate the effects of the pH level, different gypsum qualities, and iron in flue gas desulfurization (FGD) scrubber suspensions. The impact of these parameters on mercury vapor pressure was studied under controlled laboratory conditions in model scrubber suspensions. A major influence is exerted by pH values above 7, considerably amplifying the mercury concentration in the vapor phase above the FGD scrubber suspension. Gypsum also increases the mercury re-emission. Fe(III) decreases and Fe(II) increases the vapor pressure significantly. The consequences of the findings for a reliable coremoval of mercury in FGD scrubbers are discussed. It is shown that there is an increased risk of poor mercury capture in lime-based FGD scrubbers in comparison to limestone FGD scrubbers.
Gas phase oxidation and catalytic oxidation of element mercury (Hg(0)) to bivalent mercury (Hg(2+)) were proposed to improve the mercury removal efficiency in the wet flue gas desulfurization (WFGD) system. However, the re-emission of Hg(0), generated by the reduction of absorbed Hg(2+), would lead to a damping of the total mercury removal efficiency. In this paper, the absorption and reduction behaviors of bivalent mercury in the Ca-based WFGD slurry were evaluated in our purpose-built device. According to our experimental results, the slurry chemistry (such as CaSO(3) content, SO(4)(2-), Cl(-) and pH value) had a strong influence on the reduction of absorbed bivalent mercury. And the inlet concentrations of SO(2) and O(2) contribute little to the mercury absorption. Within the typical pH value range of 4.5-5.5, about 70% of inlet bivalent mercury was converted to Hg(0). The re-emission of Hg would be greatly retarded with the increase of [SO(4)(2-)] due to the formation of HgSO(4) or Hg(3)O(2)SO(4). Moreover, it was found that Cl(-) would also inhibit the reduction of bivalent mercury through the ligands reactions between Cl(-) and Hg(2+).
Experimental data from a laboratory-scale wet scrubber simulator confirmed that oxidized mercury, Hg2+, can be reduced by aqueous S(IV) (sulfite and/or bisulfite) species and results in elemental mercury (HgO) emissions under typical wet FGD scrubber conditions. The S(IV)-induced Hg2+ reduction and Hg0 emission mechanism can be described by a model which assumes that only a fraction of the Hg2+ can be reduced, and the rate-controlling step of the overall process is a first-order reaction involving the Hg-S(IV) complexes. Experimental data and model simulations predict that the Hg2+ in the flue gas can cause rapid increase of Hg0 concentration in the flue gas across a FGD scrubber. Forced oxidation can enhance Hg2+ reduction and Hg0 emission by decreasing the S(IV) concentration in the scrubbing liquor. The model predictions also indicate that flue gas Hg0 increase across a wet FGD scrubber can be reduced by decreasing the pH, increasing S(IV) concentration, and lowering the temperature.
New US EPA regulations place caps on the levels of mercury that can be emitted from coal-burning power plants, with targets to hit in 2010 and 2018. To meet these targets, technologies already available to reduce other pollutants, such as SOâ and NOx, will probably be modified to reduce mercury as a cobenefit. The authors review the effectiveness of these technologies at holding the line on mercury and explore how they can be improved for deeper emission cuts. 19 refs., 3 figs., 1 tab.
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Evaluation of the Impact of selective catalytic reduction on Hg speciation for a power plant firing a blended coal at DTE Energy's Monroe Power Station
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Field testing of a wet FGD additive for enhanced mercury control-Task 5 full-scale test results. Topical report. DOE-NETL DE-FC26-04NT42309. Pittsburgh (PA): National Energy Technology Laboratory
- Blythe G Owen
Blythe G, Owen M. Field testing of a wet FGD additive for enhanced mercury control-Task 5 full-scale test results. Topical report. DOE-NETL DE-FC26-04NT42309. Pittsburgh (PA): National Energy Technology Laboratory; 2008. <http://www.netl.doe.gov/technologies/coalpower/ewr/mercury/control-tech/ pubs/42309/42309URSTask5TopicalReport.pdf>, available on Nov. 15, 2012. C.-M. Cheng et al. / Fuel 106 (2013) 505–511
United States Environmental Protection Agency Office of Air Quality Planning and Standards
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Evaluation of the Impact of selective catalytic reduction on Hg speciation for a power plant firing a blended coal at DTE Energy’s Monroe Power Station
- Laudal Dennis
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Role of sulfide in the sequestration of mercury by wet scrubbers. In: EPRI-DOE-EPA-AWWA Combined power plant air pollution control mega symposium
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Bench-scale kinetic study of mercury reactions in FGD liquors. Final report. DOE-NETL DE-FC26-04NT42314
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A mechanism for mercury oxidation in coal-derived exhausts
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