Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Sorbents For The Oxidation And Removal Of Mercury
Download Sorbents For The Oxidation And Removal Of Mercury full books in PDF, epub, and Kindle. Read online Sorbents For The Oxidation And Removal Of Mercury ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Sorbents for the Oxidation and Removal of Mercury by :
Download or read book Sorbents for the Oxidation and Removal of Mercury written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new modified carbon form containing reactive forms of halogen and halides. Optional components may be added to increase reactivity and mercury capacity. These may be added directly with the sorbent, or to the flue gas to enhance sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The sorbent can be regenerated and reused. Sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described.
Book Synopsis Mercury Control with Calcium-Based Sorbents and Oxidizing Agents by : Thomas K. Gale
Download or read book Mercury Control with Calcium-Based Sorbents and Oxidizing Agents written by Thomas K. Gale and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This Final Report contains the test descriptions, results, analysis, correlations, theoretical descriptions, and model derivations produced from many different investigations performed on a project funded by the U.S. Department of Energy, to investigate calcium-based sorbents and injection of oxidizing agents for the removal of mercury. Among the technologies were (a) calcium-based sorbents in general, (b) oxidant-additive sorbents developed originally at the EPA, and (c) optimized calcium/carbon synergism for mercury-removal enhancement. In addition, (d) sodium-tetrasulfide injection was found to effectively capture both forms of mercury across baghouses and ESPs, and has since been demonstrated at a slipstream treating PRB coal. It has been shown that sodium-tetrasulfide had little impact on the foam index of PRB flyash, which may indicate that sodium-tetrasulfide injection could be used at power plants without affecting flyash sales. Another technology, (e) coal blending, was shown to be an effective means of increasing mercury removal, by optimizing the concentration of calcium and carbon in the flyash. In addition to the investigation and validation of multiple mercury-control technologies (a through e above), important fundamental mechanism governing mercury kinetics in flue gas were elucidated. For example, it was shown, for the range of chlorine and unburned-carbon (UBC) concentrations in coal-fired utilities, that chlorine has much less effect on mercury oxidation and removal than UBC in the flyash. Unburned carbon enhances mercury oxidation in the flue gas by reacting with HCl to form chlorinated-carbon sites, which then react with elemental mercury to form mercuric chloride, which subsequently desorbs back into the flue gas. Calcium was found to enhance mercury removal by stabilizing the oxidized mercury formed on carbon surfaces. Finally, a model was developed to describe these mercury adsorption, desorption, oxidation, and removal mechanisms, including the synergistic enhancement of mercury removal by calcium.
Book Synopsis Fundamental Understanding of Mercury Removal from Coal Combustion by : Erdem Sasmaz
Download or read book Fundamental Understanding of Mercury Removal from Coal Combustion written by Erdem Sasmaz and published by Stanford University. This book was released on 2011 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coal-fired power plants are a major anthropogenic source of worldwide mercury (Hg) emissions. Since mercury is considered to be one of the most toxic metals found in the environment, Hg emissions from coal-fired power plants is of major environmental concern. Mercury in coal is vaporized into its gaseous elemental form throughout the coal combustion process. Elemental Hg can be oxidized in subsequent reactions with other gaseous components (homogeneous) and solid materials (heterogeneous) in coal-fired flue gases. While oxidized Hg in coal-fired flue gases is readily controlled by its adsorption onto fly ash and/or its dissolution into existing solution-based sulfur dioxide (SO2) scrubbers, elemental Hg is not controlled. The extent of elemental Hg formed during coal combustion is difficult to predict since it is dependent on the type of coal burned, combustion conditions, and existing control technologies installed. Therefore, it is important to understand heterogeneous Hg reaction mechanisms to predict the speciation of Hg emissions from coal-fired power plants to design and effectively determine the best applicable control technologies. In this work, theoretical and experimental investigations have been performed to investigate the adsorption and in some cases the oxidation, of Hg on solid surfaces, e.g., calcium oxide (CaO), noble metals and activated carbon (AC). The objective of this research is to identify potential materials that can be used as multi-pollutant sorbents in power plants by carrying out both high-level density functional theory (DFT) electronic structure calculations and experiments to understand heterogeneous chemical pathways of Hg. This research uses a fundamental science-based approach to understand the environmental problems caused by coal-fired energy production and provides solutions to the power generation industry for emissions reductions. Understanding the mechanism associated with Hg and SO2 adsorption on CaO will help to optimize the conditions or material to limit Hg emissions from the flue gas desulfurization process. Plane-wave DFT calculations were used to investigate the binding mechanism of Hg species and SO2 on the CaO(100) surface. The binding strengths on the high-symmetry CaO adsorption sites have been investigated for elemental Hg, SO2, mercury chlorides (HgCl and HgCl2) and mercuric oxide (HgO). It has been discovered that HgCl, HgCl2, and SO2 chemisorb on the CaO(100) surface at 0.125 ML coverage. Binding energies of elemental Hg are minimal indicating a physisorption mechanism. Noble metals such as palladium (Pd), gold (Au), silver (Ag), and copper (Cu) have been proposed to capture elemental Hg. Plane-wave DFT calculations have been carried out to investigate the mercury interactions with Pd binary alloys and overlays in addition to pure Pd, Au, Ag, and Cu surfaces. It has been determined that Pd has the highest mercury binding energy in comparison to other noble metals. In addition, Pd is found to be the primary surface atom responsible for increasing the adsorption of Hg with the surface in both Pd binary alloys and overlays. Deposition of Pd overlays on Au and Ag has been found to enhance the reactivity of the surface by shifting the d-states of surface atoms up in energy. The possible binding mechanisms of elemental Hg onto virgin, brominated and sulfonated AC fiber and brominated powder AC sorbents have been investigated through packed-bed experiments in a stream of air and simulated flue gas conditions, including SO2, hydrogen chloride (HCl), nitrogen oxide (NO) nitrogen dioxide (NO2). A combination of spectroscopy and plane-wave DFT calculations was used to characterize the sorption process. X-ray photoelectron spectroscopy (XPS) and x-ray absorption fine structure (XAFS) spectroscopy were used to analyze the surface and bulk chemical compositions of brominated AC sorbents reacted with Hg0. Through XPS surface characterization studies it was found that Hg adsorption is primarily associated with halogens on the surface. Elemental Hg is oxidized on AC surfaces and the oxidation state of adsorbed Hg is found to be Hg2+. Though plane-wave DFT and density of states (DOS) calculations indicate that Hg is more stable when it is bound to the edge carbon atom interacting with a single bromine bound atop of Hg, a model that includes an interaction between the Hg and an additional Br atom matches best with experimental data obtained from extended x-ray absorption fine structure (EXAFS) spectroscopy. The flue gas species such as HCl and bromine (Br2) enhance the Hg adsorption, while SO2 is found to decrease the Hg adsorption significantly by poisoning the active sites on the AC surface. The AC sorbents represent the most market-ready technology for Hg capture and therefore have been investigated by both theory and experiment in this work. Future work will include similar characterization and bench-scale experiments to test the metal-based materials for the sorbent and oxidation performance.
Download or read book Mercury Removal Sorbents written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Sorbents and methods of using them for removing mercury from flue gases over a wide range of temperatures are disclosed. Sorbent materials of this invention comprise oxy- or hydroxyl-halogen (chlorides and bromides) of manganese, copper and calcium as the active phase for Hg.sup.0 oxidation, and are dispersed on a high surface porous supports. In addition to the powder activated carbons (PACs), this support material can be comprised of commercial ceramic supports such as silica (SiO.sub. 2), alumina (Al.sub. 2O.sub. 3), zeolites and clays. The support material may also comprise of oxides of various metals such as iron, manganese, and calcium. The non-carbon sorbents of the invention can be easily injected into the flue gas and recovered in the Particulate Control Device (PCD) along with the fly ash without altering the properties of the by-product fly ash enabling its use as a cement additive. Sorbent materials of this invention effectively remove both elemental and oxidized forms of mercury from flue gases and can be used at elevated temperatures. The sorbent combines an oxidation catalyst and a sorbent in the same particle to both oxidize the mercury and then immobilize it.
Book Synopsis Novel Nano-structured Sorbents for Elemental and Oxidized Mercury Removal from Flue Gas by : Lei Ji
Download or read book Novel Nano-structured Sorbents for Elemental and Oxidized Mercury Removal from Flue Gas written by Lei Ji and published by . This book was released on 2008 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermally robust chelating adsorbents, 3-mercaptopropyltrimethoxysilane silica (MPTS-silica) and 3-aminopropyltiethoxysilane 2-mercaptobenzothialzole silica (APTS-MBT-silica), were proven to be very effective in capture HgCl2 from simulated flue gas at elevated temperatures in a fixed-bed mode. For MPTS-silica, a minimum of 58 mg/g HgCl2 capacity was observed. Pore size of the silica substrate does not have significant effect while particle size was found to have a significant effect on mercury capture; this effect was believed to be due to an enhanced channeling effect for the larger particle size adsorbent. A new approach for simultaneous removal of elemental and oxidized mercury from flue gas was successfully developed by using a room temperature ionic liquid (RTIL) coating layer. Six RTILs were synthesized and tested for their potential of elemental and oxidized mercury capture. These RTIL coating layers are all thermally stable above 160°C and the coating of these RTIL does not have any negative effect on the thermal stability of the chelating ligands. 1-butyl-3-methyl-imidazolium chloride ([bmim]Cl) was identified to be the most promising RTIL for simultaneous elemental and oxidized mercury removal from flue gas. 25 wt% [bmim]Cl coated MPTS-silica showed a 10 mg/g saturated elemental mercury capacity and a minimum of 38 mg/g oxidized mercury capacity in a fixed-bed mode. A low temperature selective catalytic reduction (SCR) catalyst, manganese oxide supported on titania, was tested as a sorbent for elemental mercury capture from flue gas at high temperatures. It was shown that this material showed high mercury capacity and remained active for mercury capture even after use for NOx reduction. Water vapor and manganese loading do not have a significant effect on mercury capture. However, SO2 has a strong negative effect on mercury removal process. Bed temperature was found to have a significant effect on mercury capture process. HgO formed during the mercury adsorption process by this material and it was believed that the mercury adsorption follows Mars-Maessen mechanism.
Book Synopsis Field Demonstration of Enhanced Sorbent Injection for Mercury Control by :
Download or read book Field Demonstration of Enhanced Sorbent Injection for Mercury Control written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Alstom Power Inc. has conducted a DOE/NETL-sponsored program (under DOE Cooperative Agreement No. DE-FC26-04NT42306) to demonstrate Mer-Cure{trademark}, one of Alstom's mercury control technologies for coal-fired boilers. Mer-Cure{trademark} utilizes a small amount of Mer-Clean{trademark} sorbent that is injected into the flue gas stream for oxidation and adsorption of gaseous mercury. Mer-Clean{trademark} sorbents are carbon-based and prepared with chemical additives that promote oxidation and capture of mercury. Mer-Cure{trademark} is unique in that the sorbent is injected into an environment where the mercury capture kinetics is accelerated. This full-scale demonstration program was comprised of three seven-week long test campaigns at three host sites including PacifiCorp's 240-MW{sub e} Dave Johnston Unit No. 3 burning a Powder River Basin (PRB) coal, Basin Electric's 220-MW{sub e} Leland Olds Unit No. 1 burning a North Dakota lignite, and Reliant Energy's 170-MW{sub e} Portland Unit No. 1 burning an Eastern bituminous coal. All three boilers are equipped with electrostatic precipitators. The goals for this Round 2 program, established by DOE/NETL under the original solicitation, were to reduce the uncontrolled mercury emissions by 50 to 70% at a cost 25 to 50% lower than the previous target of $60,000/lb mercury removed. The results for all three host sites indicated that Mer-Cure{trademark} technology could achieve mercury removal of 90%. The estimated mercury removal costs were 25-92% lower than the benchmark of $60,000/lb mercury removed. The estimated costs for control, at sorbent cost of $1.25 to $2.00/lb respectively, are as follows: (1) Dave Johnston Unit No. 3--$2,650 to $4,328/lb Hg removed (92.8% less than $60k/lb); (2) Leland Olds Unit No. 1--$8,680 to $13,860/lb Hg removed (76.7% less than $60k/lb); and (3) Portland Unit No. 1--$28,540 to $45,065/lb Hg removed (24.9% less than $60k/lb). In summary, the results from demonstration testing at all three host sites show that the goals established by DOE/NETL were exceeded during this test program. Mercury removal performance4 of greater than 90% reduction was above the 50-70% reduction goal, and mercury removal cost of 25-92% lower than the benchmark was above the 25 to 50% cost reduction goal.
Book Synopsis Aufrichtiger Hundertjähriger Haus-Kalender von 1834 bis 1934 hinsichtlich der Ostertabelle, Sonnen und Mondfinsternisse ... nach den berühmtesten Astronomen bearbeitet ... by :
Download or read book Aufrichtiger Hundertjähriger Haus-Kalender von 1834 bis 1934 hinsichtlich der Ostertabelle, Sonnen und Mondfinsternisse ... nach den berühmtesten Astronomen bearbeitet ... written by and published by . This book was released on 1839* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Mercury Oxidation and Adsorption Over Cupric Chloride-based Catalysts and Sorbents for Mercury Emissions Control by : Xin Li
Download or read book Mercury Oxidation and Adsorption Over Cupric Chloride-based Catalysts and Sorbents for Mercury Emissions Control written by Xin Li and published by . This book was released on 2012 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury emissions control is of great importance in environment protection as well as public health. Current mercury emissions control technologies are not well designed nor optimized, mainly due to the lack of fundamental understanding of adsorption and/or catalytic mechanisms and necessary kinetic modeling and reliable simulation data. This work aims to advance the fundamental mechanistic understanding of heterogeneous catalytic oxidation reaction and adsorption by using the reaction between Hg(0) vapor and CuCl2 and the subsequent adsorption of resultant oxidized mercury onto sorbents. XANES and EXAFS were used to determine mercury compounds formed on AC sorbents. The XANES study on raw and CuCl2-impregnated AC sorbents suggests that little or no elemental mercury is formed onto any spent sorbents and the chemisorption of Hg(0) vapor is very likely to be the dominant mechanism. HgCl2 is found to be a major oxidation reaction product when CuCl2 and HCl were impregnated onto raw AC regardless of the type of the carrier gas (i.e. N2 or O2). The adsorption isotherms of HgCl2 on DARCO-HG and CuCl2-impregnated AC were found to be of the Langmuir type. The kinetic adsorption constants were estimated by fitting the model simulation with experimental data. The breakthrough data from experiments are in good agreement with the calculation results from the modified kinetic model. The simulation results indicate that pore diffusion resistance significantly increases with an increase in sorbent particle size. HgCl2 adsorption removal performance was also predicted in an entrained flow system using a modified model. The CuCl2/[alpha]-Al2O3 catalyst possesses high activity for the oxidation of Hg(0) to Hg2+, with an excellent stability under the environment similar to the flue gas from coal-fired power plants. The CuCl2 crystallites formed onto [alpha]-Al2O3 were very stable up to 300oC, and undergo the thermal reduction process from Cu(II) to Cu(0) via Cu(I). In the absence of HCl and O2 gases, CuCl2 was found to follow a Mars-Maessen mechanism by consuming lattice chlorine of CuCl2 for Hg(0) oxidation and to be reduced to CuCl. In the presence of 10 ppmv HCl, 2,000 ppmv SO2, and 6% O2 gases, the CuCl2/[alpha]-Al2O3 sample works as an Hg(0) oxidation catalyst exhibiting>90% conversion with good resistance to SO2 at 140oC. The reduced CuCl was able to be re-chlorinated to CuCl2 under HCl and O2 gases by following the Deacon reaction. Multiple copper species were found to be formed when [gamma]-Al2O3 is used as a substrate as opposed to one Cu(II) species on [alpha]-Al2O3. The CuCl2/[gamma]-Al2O3 catalysts with low CuCl2 loading (
Download or read book Lüdin Max (1919-?). written by and published by . This book was released on 1939 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Zeitungsausschnitte.
Book Synopsis Fundamental Understanding of Mercury Removal from Coal Combustion by : Erdem Sasmaz
Download or read book Fundamental Understanding of Mercury Removal from Coal Combustion written by Erdem Sasmaz and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Coal-fired power plants are a major anthropogenic source of worldwide mercury (Hg) emissions. Since mercury is considered to be one of the most toxic metals found in the environment, Hg emissions from coal-fired power plants is of major environmental concern. Mercury in coal is vaporized into its gaseous elemental form throughout the coal combustion process. Elemental Hg can be oxidized in subsequent reactions with other gaseous components (homogeneous) and solid materials (heterogeneous) in coal-fired flue gases. While oxidized Hg in coal-fired flue gases is readily controlled by its adsorption onto fly ash and/or its dissolution into existing solution-based sulfur dioxide (SO2) scrubbers, elemental Hg is not controlled. The extent of elemental Hg formed during coal combustion is difficult to predict since it is dependent on the type of coal burned, combustion conditions, and existing control technologies installed. Therefore, it is important to understand heterogeneous Hg reaction mechanisms to predict the speciation of Hg emissions from coal-fired power plants to design and effectively determine the best applicable control technologies. In this work, theoretical and experimental investigations have been performed to investigate the adsorption and in some cases the oxidation, of Hg on solid surfaces, e.g., calcium oxide (CaO), noble metals and activated carbon (AC). The objective of this research is to identify potential materials that can be used as multi-pollutant sorbents in power plants by carrying out both high-level density functional theory (DFT) electronic structure calculations and experiments to understand heterogeneous chemical pathways of Hg. This research uses a fundamental science-based approach to understand the environmental problems caused by coal-fired energy production and provides solutions to the power generation industry for emissions reductions. Understanding the mechanism associated with Hg and SO2 adsorption on CaO will help to optimize the conditions or material to limit Hg emissions from the flue gas desulfurization process. Plane-wave DFT calculations were used to investigate the binding mechanism of Hg species and SO2 on the CaO(100) surface. The binding strengths on the high-symmetry CaO adsorption sites have been investigated for elemental Hg, SO2, mercury chlorides (HgCl and HgCl2) and mercuric oxide (HgO). It has been discovered that HgCl, HgCl2, and SO2 chemisorb on the CaO(100) surface at 0.125 ML coverage. Binding energies of elemental Hg are minimal indicating a physisorption mechanism. Noble metals such as palladium (Pd), gold (Au), silver (Ag), and copper (Cu) have been proposed to capture elemental Hg. Plane-wave DFT calculations have been carried out to investigate the mercury interactions with Pd binary alloys and overlays in addition to pure Pd, Au, Ag, and Cu surfaces. It has been determined that Pd has the highest mercury binding energy in comparison to other noble metals. In addition, Pd is found to be the primary surface atom responsible for increasing the adsorption of Hg with the surface in both Pd binary alloys and overlays. Deposition of Pd overlays on Au and Ag has been found to enhance the reactivity of the surface by shifting the d-states of surface atoms up in energy. The possible binding mechanisms of elemental Hg onto virgin, brominated and sulfonated AC fiber and brominated powder AC sorbents have been investigated through packed-bed experiments in a stream of air and simulated flue gas conditions, including SO2, hydrogen chloride (HCl), nitrogen oxide (NO) nitrogen dioxide (NO2). A combination of spectroscopy and plane-wave DFT calculations was used to characterize the sorption process. X-ray photoelectron spectroscopy (XPS) and x-ray absorption fine structure (XAFS) spectroscopy were used to analyze the surface and bulk chemical compositions of brominated AC sorbents reacted with Hg0. Through XPS surface characterization studies it was found that Hg adsorption is primarily associated with halogens on the surface. Elemental Hg is oxidized on AC surfaces and the oxidation state of adsorbed Hg is found to be Hg2+. Though plane-wave DFT and density of states (DOS) calculations indicate that Hg is more stable when it is bound to the edge carbon atom interacting with a single bromine bound atop of Hg, a model that includes an interaction between the Hg and an additional Br atom matches best with experimental data obtained from extended x-ray absorption fine structure (EXAFS) spectroscopy. The flue gas species such as HCl and bromine (Br2) enhance the Hg adsorption, while SO2 is found to decrease the Hg adsorption significantly by poisoning the active sites on the AC surface. The AC sorbents represent the most market-ready technology for Hg capture and therefore have been investigated by both theory and experiment in this work. Future work will include similar characterization and bench-scale experiments to test the metal-based materials for the sorbent and oxidation performance.
Book Synopsis Developments of Sorbents for Mercury Removal From Flue Gas by : Evan J. Granite
Download or read book Developments of Sorbents for Mercury Removal From Flue Gas written by Evan J. Granite and published by . This book was released on 2000 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development and Evaluation of Low-cost Sorbents for Removal of Mercury Emissions from Coal Combustion Flue Gas by :
Download or read book Development and Evaluation of Low-cost Sorbents for Removal of Mercury Emissions from Coal Combustion Flue Gas written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Determining how physical and chemical properties of sorbents affect vapor-phase mercury adsorption has led to potential approached for tailoring the properties of sorbents for more effective mercury removal. ... Objectives: to determine how physical and chemical properties of sorbents affect mercury adsoprtion; to develop more cost-effective sorbents"--P. v.
Book Synopsis Coal Fired Flue Gas Mercury Emission Controls by : Jiang Wu
Download or read book Coal Fired Flue Gas Mercury Emission Controls written by Jiang Wu and published by Springer. This book was released on 2015-03-17 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury (Hg) is one of the most toxic heavy metals, harmful to both the environment and human health. Hg is released into the atmosphere from natural and anthropogenic sources and its emission control has caused much concern. This book introduces readers to Hg pollution from natural and anthropogenic sources and systematically describes coal-fired flue gas mercury emission control in industry, especially from coal-fired power stations. Mercury emission control theory and experimental research are demonstrated, including how elemental mercury is oxidized into oxidized mercury and the effect of flue gas contents on the mercury speciation transformation process. Mercury emission control methods, such as existing APCDs (air pollution control devices) at power stations, sorbent injection, additives in coal combustion and photo-catalytic methods are introduced in detail. Lab-scale, pilot-scale and full-scale experimental studies of sorbent injection conducted by the authors are presented systematically, helping researchers and engineers to understand how this approach reduces the mercury emissions in flue gas and to apply the methods in mercury emission control at coal-fired power stations. Readers will arrive at a comprehensive understanding of various mercury emission control methods that are suitable for industrial applications. The book is intended for scientists, researchers, engineers and graduate students in the fields of energy science and technology, environmental science and technology and chemical engineering.
Book Synopsis Comparison of Sorbents for Mercury Removal From Flue Gas by : Evan J. Granite
Download or read book Comparison of Sorbents for Mercury Removal From Flue Gas written by Evan J. Granite and published by . This book was released on 2001 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Catalytic Oxidation and Heterogeneous Capture of Elemental Gas-phase Mercury by : Sandhya Eswaran
Download or read book Catalytic Oxidation and Heterogeneous Capture of Elemental Gas-phase Mercury written by Sandhya Eswaran and published by . This book was released on 2006 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability of three sorbents, activated carbon, char and mordenite, to adsorb mercury is determined using simulated flue gas containing 10-15 mu g/m3 of mercury, in a laboratory-scale, fixed-bed adsorption system. The adsorption performance of the three sorbents is compared by, adsorption rate, rather than the adsorption capacity. The effect of temperature, sorbent loading, mercury concentration and acid gases such as NO and SO2 on the adsorption rate is investigated and presented in this dissertation. The mercury adsorption rate is in the range of 3000 to 3900 ng/hr for all three sorbents and increases with temperature, mercury concentration and acid gas concentration. Temperature is the major factor affecting the mercury adsorption rate on activated carbon and char while the rate of mercury adsorption on the zeolite sorbent is more strongly affected by the mercury concentration in the flue gas stream.
Book Synopsis Development of New Sorbents to Remove Mercury and Selenium from Flue Gas. Final Report, September 1, 1993--August 31, 1994 by :
Download or read book Development of New Sorbents to Remove Mercury and Selenium from Flue Gas. Final Report, September 1, 1993--August 31, 1994 written by and published by . This book was released on 1995 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury (Hg) and selenium (Se) are two of the volatile trace metals in coal, which are often not captured by conventional gas clean up devices of coal-fired boilers. An alternative is to use sorbents to capture the volatile components of trace metals after coal combustion. In this project sorbent screening tests were performed in which ten sorbents were selected to remove metallic mercury in N2. These sorbents included activated carbon, char prepared from Ohio No. 5 coal, molecular sieves, silica gel, aluminum oxide, hydrated lime, Wyoming bentonite, kaolin, and Amberite IR-120 (an ion-exchanger). The sorbents were selected based on published information and B & W's experience on mercury removal. The promising sorbent was then selected and modified for detailed studies of removal of mercury and selenium compounds. The sorbents were tested in a bench-scale adsorption facility. A known amount of each sorbent was loaded in the column as a packed bed. A carrier gas was bubbled through the mercury and selenium compounds. The vaporized species were carried by the gas and went through the sorbent beds. The amount of mercury and selenium compounds captured by the sorbents was determined by atomic absorption. Results are discussed.
Book Synopsis Development and Evaluation of Nanoscale Sorbents for Mercury Capture from Warm Fuel Gas by : Raja A. Jadhav
Download or read book Development and Evaluation of Nanoscale Sorbents for Mercury Capture from Warm Fuel Gas written by Raja A. Jadhav and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Several different types of nanocrystalline metal oxide sorbents were synthesized and evaluated for capture of mercury (Hg) from coal-gasifier warm fuel gas. Detailed experimental studies were carried out to understand the fundamental mechanism of interaction between mercury and nanocrystalline sorbents over a range of fuel gas conditions. The metal oxide sorbents evaluated in this work included those prepared by GTI's subcontractor NanoScale Materials, Inc. (NanoScale) as well as those prepared in-house. These sorbents were evaluated for mercury capture in GTI's Mercury Sorbent Testing System. Initial experiments were focused on sorbent evaluation for mercury capture in N{sub 2} stream over the temperature range 423-533 K. These exploratory studies demonstrated that NanoActive Cr{sub 2}O{sub 3} along with its supported form was the most active of the sorbent evaluated. The capture of Hg decreased with temperature, which suggested that physical adsorption was the dominant mechanism of Hg capture. Desorption studies on spent sorbents indicated that a major portion of Hg was attached to the sorbent by strong bonds, which suggested that Hg was oxidized by the O atoms of the metal oxides, thus forming a strong Hg-O bond with the oxide. Initial screening studies also indicated that sulfided form of CuO/alumina was the most active for Hg capture, therefore was selected for detailed evaluation in simulated fuel gas (SFG). It was found that such supported CuO sorbents had high Hg-sorption capacity in the presence of H{sub 2}, provided the gas also contained H{sub 2}S. Exposure of supported CuO sorbent to H{sub 2}S results in the formation of CuS, which is an active sorbent for Hg capture. Sulfur atom in CuS forms a bond with Hg that results into its capture. Although thermodynamically CuS is predicted to form unreactive Cu{sub 2}S form when exposed to H{sub 2}, it is hypothesized that Cu atoms in such supported sorbents are in ''dispersed'' form, with two Cu atoms separated by a distance longer than required to form a Cu{sub 2}S molecule. Thus CuS remains in the stable reactive form as long as H{sub 2}S is present in the gas phase. It was also found that the captured Hg on such supported sorbents could be easily released when the spent sorbent is exposed to a H2-containing stream that is free of Hg and H{sub 2}S. Based on this mechanism, a novel regenerative process has been proposed to remove Hg from fuel gas at high temperature. Limited multicyclic studies carried out on the supported Cu sorbents showed their potential to capture Hg from SFG in a regenerative manner. This study has demonstrated that supported nanocrystalline Cu-based sorbents have potential to capture mercury from coal syngas over multiple absorption/regeneration cycles. Further studies are recommended to evaluate their potential to remove arsenic and selenium from coal fuel gas.
