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Author : Feng Guo
Publisher :
ISBN 13 :
Total Pages : 180 pages
Book Rating : 4.:/5 (392 download)
Download or read book Modeling of Adsorption and Desorption of Mercury on Sorbents in a Fixed Bed Absorber written by Feng Guo and published by . This book was released on 1997 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Youngkil Lee
Publisher :
ISBN 13 :
Total Pages : 240 pages
Book Rating : 4.:/5 (442 download)
Download or read book Kinetic Modeling of Mercury Desorption and Adsorption on Fixed-bed Sorbents written by Youngkil Lee and published by . This book was released on 1999 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 51 pages
Book Rating : 4.:/5 (946 download)
Download or read book Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed and Entrained-Flow Reactor written by and published by . This book was released on 2009 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO2, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO2, and NO2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and intraparticle diffusion. The Freundlich isotherm more accurately described in-flight mercury capture. Using these parameters, very little intraparticle diffusion was evident. Consistent with other data, smaller particles resulted in higher mercury uptake due to available surface area. Therefore, it is important to capture the particle size distribution in the model. At typical full-scale sorbent feed rates, the calculations underpredicted adsorption, suggesting that wall effects can account for as much as 50 percent of the removal, making it an important factor in entrained-mercury adsorption models.
Author : Amit Ghai
Publisher :
ISBN 13 :
Total Pages : 208 pages
Book Rating : 4.:/5 (366 download)
Download or read book Adsorption and Desorption of Mercury from Sorbents in a Hot Air Stream written by Amit Ghai and published by . This book was released on 1996 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : T. C. Ho
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (129 download)
Download or read book Modeling of Mercury Desorption from Activated Carbon at Elevated Temperatures Under Fluidized/fixed Bed Operations written by T. C. Ho and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed Reactor written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300- W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150oC. All methane, air, SO2, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO2, and NO2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and intraparticle diffusion. The Freundlich isotherm more accurately described in-flight mercury capture. Using these parameters, very little intraparticle diffusion was evident. Consistent with other data, smaller particles resulted in higher mercury uptake due to available surface area. Therefore, it is important to capture the particle size distribution in the model. At typical full-scale sorbent feed rates, the calculations underpredicted adsorption, suggesting that wall effects can account for as much as 50 percent of the removal, making it an important factor in entrained-mercury adsorption models.
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.
Author : Youngkil Lee
Publisher :
ISBN 13 :
Total Pages : 224 pages
Book Rating : 4.:/5 (55 download)
Download or read book Experimental and Kinetic Study of Mercury Adsorption on Various Activated Carbons in a Fixed Bed Adsorber written by Youngkil Lee and published by . This book was released on 2003 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Mark A. Bentley
Publisher :
ISBN 13 : 9781267320728
Total Pages : 132 pages
Book Rating : 4.3/5 (27 download)
Download or read book Mercury Adsorption and Desorption Kinetics written by Mark A. Bentley and published by . This book was released on 2012 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury emissions in the United States are regulated under the Clean Air Mercury Rule. Multiple mercury removal technologies have been investigated and at this time, activated carbon injection into flue gas has been considered to be an efficient and economically feasible method for the removal of elemental mercury. Also, chemical modifications to activated carbon have shown to increase its mercury sorption capacity and removal efficiency. In this study, adsorption of elemental mercury onto ferric chloride impregnated activated carbon was investigated. The results show that ferric chloride impregnated activated carbon has a higher mercury sorption capacity than raw activated carbon does. A chemisorption mechanism was proposed and confirmed based on the characterization tests of fresh and spent sorbents. A kinetic study for the regeneration of spent sorbents was also conducted. The activation energies of mercury desorption from various substrates were calculated and the corresponding mercury desorption profiles were mathematically modeled.
Author : Erdem Sasmaz
Publisher : Stanford University
ISBN 13 :
Total Pages : 195 pages
Book Rating : 4.F/5 ( download)
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.
Author : Thomas K. Gale
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (316 download)
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.
Author :
Publisher :
ISBN 13 :
Total Pages : 8 pages
Book Rating : 4.:/5 (684 download)
Download or read book COMBINED THEORETICAL AND EXPERIMENTAL INVESTIGATION OF MECHANISMS AND KINETICS OF VAPOR-PHASE MERCURY UPTAKE BY CARBONACEOUS SURFACES. written by and published by . This book was released on 2000 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall goal of this research program is to gain fundamental understanding of the important chemistry and physics involved in mercury adsorption on carbonaceous surfaces. This knowledge will then be used to optimize adsorption processes and operating conditions to maximize the uptake of mercury within the required contact time. An additional long-term benefit of this research is the basic understanding of the Hg adsorption process, which may facilitate the design of new adsorbents for more efficient and cost-effective removal of Hg from a variety of effluent streams. Molecular modeling of the adsorption of Hg on carbonaceous surfaces will greatly increase the insight into the physics of the adsorption process and combined with in situ rate measurements of mercury adsorption and desorption (conventional and pulsed laser) on graphite using linear and nonlinear optical probes with real time optical resolution have the potential to provide fundamental insight into the process of mercury uptake by carbonaceous surfaces. Besides accurate assessment of key parameters influencing adsorption equilibrium, fundamental understanding of the kinetics of mercury adsorption, desorption, and diffusion will be developed in this study. These key physical and chemical processes postulated through molecular modeling efforts and verified by in situ measurements will be utilized to select (or develop) promising sorbents for mercury control, which will be tested under dynamic conditions using simulated flue gas.
Author : T. Carey
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (47 download)
Download or read book Laboratory Investigation and Model Development of Flue Gas Mercury Adsorption Using Solid Sorbents written by T. Carey and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Grégorio Crini
Publisher : Presses Univ. Franche-Comté
ISBN 13 : 2848673044
Total Pages : 500 pages
Book Rating : 4.8/5 (486 download)
Download or read book Sorption Processes and Pollution written by Grégorio Crini and published by Presses Univ. Franche-Comté. This book was released on 2010 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Puze Yang
Publisher :
ISBN 13 :
Total Pages : 224 pages
Book Rating : 4.:/5 (416 download)
Download or read book Mercury Desorption from Sorbents at Elevated Temperatures written by Puze Yang and published by . This book was released on 1998 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Juan He
Publisher :
ISBN 13 :
Total Pages : 272 pages
Book Rating : 4.:/5 (896 download)
Download or read book Advanced Adsorbents for Capture of Vapor-phase Mercury and Other Toxic Components from Flue Gas written by Juan He and published by . This book was released on 2013 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: During coal combustion, mercury and arsenic are volatized and are present in multiple forms in the gas phase; similarly, the formation of nitrogen oxides in flue gas depends on nitrogen content of the coal and oxygen available to react with nitrogen. New approaches for cost-effective control of mercury and other pollutants are necessary. In this work, a group of room temperature ionic liquid coated nanostructured chelating adsorbents was developed and used for gas-phase mercury and arsenic adsorption; the simultaneous removal of mercury and nitrogen oxide using ceria-modified manganese oxide/titania materials was investigated. Three thermally robust adsorbents, 25 wt% [bmim]Cl coated-MPTS-Si, 25 wt% [bmim]Cl-MPTS-MCF and 25 wt% [bmim]Cl-Ambersep[superscript TM] GT74 were synthesized and demonstrated to be effective adsorbents for simultaneous capture of oxidized and elemental mercury at 160°C. Mercury from vapor phase dissolves in the [bmim]Cl ionic liquid layer;and subsequently bonds to the chelating ligands of MPTS or directly coordinates with the sulfur-containing groups from Ambersep[superscript TM]GT74 resin. In fixed-bed adsorption experiments, the 25 wt% [bmim]Cl-MPTS-Si exhibited the largest mercury (Hg2 and Hg0) capacity in an inert atmosphere. A mathematical model was developed to describe mercury removal based on the experimental data measured at laboratory-scale. To synthesize adsorbents for both mercury and arsenic capture, both [bmim]Cl and an amino acid-based RTIL, [TBP][Tau], were supported on a silica gel with high surface area and accessible mesopores. In both fixed-bed and batch adsorption modes, all of the RTIL-coated silica adsorbents can effectively remove Hg0 and As(III) simultaneously, and exhibited high As(III) capacities. Because of the high solubility of CO2 in the [TBP][Tau] RTIL, the presence of CO2 caused a negative effect on the Hg0 and As(III) adsorption performance of [TBP][Tau]-Si. High surface area ceria-titania materials are used as supports for manganese oxide for both warm-gas mercury capture and low temperature selective catalytic reduction. Remarkably, these materials exhibit high Hg0 adsorption capacities and excellent NO removal performance both in single-component tests and in combined NO and Hg0 removal experiments at 175°C. For the Hg0 adsorption, MnOx/CeO2-TiO2 adsorbents had large Hg0 capacities up to 37 mg g−1. SO2 inhibited Hg0 adsorption on the surface of MnOx, but the CeO2-TiO2 support retained most of its Hg0 capacity in the presence of 100 ppm SO2 The simultaneous capture of Hg0 and Hg2 at 175°C was observed using CeO2-TiO2 support. Both the NO adsorption and co-adsorption of NO + CO can be found over the surface of MnOx/CeO2-TiO2 materials. The results of XPS analysis suggest that the presence of lattice oxygen play important role on the mercury and NO adsorption, with great formation of HgO and nitrate species; in the presence of CO in the feed gas, mercury adsorption doesn't inhibit the SCR activity of NO. In summary, the nanostructured, RTILs coated chelating adsorbents and manganese supported on ceria-titania oxide materials were successfully developed and studied for removal of gas-phase mercury and other toxic components. The experimental results suggest these novel adsorbents could be technically feasible for multi-pollutants control in coal combustion.
Author : T. C. Ho
Publisher :
ISBN 13 :
Total Pages : 6 pages
Book Rating : 4.:/5 (43 download)
Download or read book Kinetic Study of Mercury Sorption/Desorption Process on Sorbents written by T. C. Ho and published by . This book was released on 1999 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:
