Download or read book Mercury Emission Behavior During Isolated Coal Particle Combustion written by Madhu Babu Puchakayala and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Of all the trace elements emitted during coal combustion, mercury is most problematic. Mercury from the atmosphere enters into oceanic and terrestrial waters. Part of the inorganic Hg in water is converted into organic Hg (CH3Hg), which is toxic and bioaccumulates in human and animal tissue. The largest source of human-caused mercury air emissions in the U.S is from combustion coal, a dominant fuel used for power generation. The Hg emitted from plants primarily occurs in two forms: elemental Hg and oxidized Hg (Hg2). The coal chlorine content and ash composition, gas temperature, residence time and presence of different gases will decide the speciation of Hg into Hg0 and Hg2. For Wyoming coal the concentrations of mercury and chlorine in coal are 120ppb and 140ppb. In order to understand the basic process of formulation of HgCl2 and Hg0 a numerical model is developed in the current work to simulate in the detail i) heating ii) transient pyrolysis of coal and evolution of mercury and chlorine, iii) gas phase oxidation iv) reaction chemistry of Hg and v) heterogeneous oxidation of carbon during isolated coal particle combustion. The model assumes that mercury and chlorine are released as a part of volatiles in the form of elemental mercury and HCl. Homogenous reaction are implemented for the oxidation of mercury. Heterogeneous Hg reactions are ignored. The model investigates the effect of different parameters on the extent of mercury oxidation; particle size, ambient temperature, volatile matter, blending coal with high chlorine coal and feedlot biomass etc, . Mercury oxidation is increased when the coal is blended with feedlot biomass and high chlorine coal and Hg % conversion to HgCl2 increased from 10% to 90% when 20% FB is blended with coal. The ambient temperature has a negative effect on mercury oxidation, an increase in ambient temperature resulted in a decrease in the mercury oxidation. The percentage of oxidized mercury increases from 9% to 50% when the chlorine concentration is increased from 100ppm to 1000ppm. When the temperature is decreased from 1950 K to 950 K, the percentage of mercury oxidized increased from 3% to 27%.

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.

Download or read book Mercury Emission and its Control in Chinese Coal Fired Power Plants written by Jinsong Zhou and published by Springer. This book was released on 2015-01-13 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Mercury Emission and its Control in Chinese Coal-Fired Power Plants" focuses on investigating mercury emissions samplings and measurement in Chinese coal-fired power plants, mercury emission estimations and future trends, mercury speciation transformation during coal combustion, mercury control and mercury stability in byproducts. The book not only introduces mercury emissions from actual coal-fired power plants, but also presents studies on the mechanism of mercury emission and its control. This is a valuable reference for engineering thermal physicists, thermal engineers, and chemical engineers. Jinsong Zhou, Zhongyang Luo, and Mengxiang Fang are Professors in the College of Mechanical and Energy Engineering, Zhejiang University, China. Yanqun Zhu is Associate Professor in the College of Mechanical and Energy Engineering, Zhejiang University, China.

Download or read book Fine Particle and Mercury Formation and Control During Coal Combustion written by Xiaofei Wang and published by . This book was released on 2014 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pulverized coal combustion is widely used worldwide for the production of electricity. However, it is one of the primary emission sources of air pollutants, including particulate matter (fly ash) and mercury (Hg), into the atmosphere. This dissertation investigated three aspects of pollutant formation and control from the coal combustion process: (1) organic aerosol formation during coal combustion, (2) mercury removal during coal combustion by injection of Vanadium Pentoxide (V2O5), and (3) submicrometer particle formation during oxy-coal combustion. Part. 1. While the characterization and formation of the mineral matter component of aerosol during coal combustion has been well studied and understood, the characterization and fate of corresponding organic matter content was not examined in detail earlier. The first part of this dissertation studies the formation mechanism of organic aerosols during coal combustion. Pilot-scale experiments were conducted in a 1 MW coal combustor, and showed that black carbon aerosol formation was greatly enhanced by increasing the fuel-air equivalence ratio. However, organic carbon aerosol formation was lowered by increasing the fuel-air equivalence ratio, which was opposite to the trend of black carbon aerosol formation. This phenomenon indicates that the formation mechanism of organic carbon aerosol is different from black carbon (soot) aerosol. Detailed organic aerosol formation mechanisms have been studied in a laboratory-scale system. Aerosol mass spectrometry techniques were applied to characterize both coal combustion aerosols from a drop-tube coal combustor and coal pyrolysis products from a flat-flame coal pyrolyzer. The chemical composition of major species for both combustion organic aerosols and pyrolysis products are hydrocarbons, carboxylic acids and aromatic compounds. The similarities of the chemical compositions demonstrate that the products from coal pyrolysis, (the initial step of coal combustion), are the precursors of organic aerosols. More carboxylic acids and oxygenated organic compounds were found in the combustion aerosols, indicating that many pyrolysis products are oxidized before they are converting to organic aerosols. A strong correlation between inorganic and organic aerosol formation mechanisms has been found in this work, demonstrating that inorganic particles play a critical role as carriers of organic species. Sulfate species in inorganic aerosols play a particularly important role in organic aerosol formation. Enhanced organic aerosol formation during the combustion of high sulfur content coal has been observed for the first time. High resolution mass spectra analysis shows the presence of amine-like organics in the aerosols. The correlation between particulate sulfate and organics suggests that acidic sulfate particles may absorb basic amine-like organics, a major coal pyrolysis product, from the gas phase into the particle phase via acid-base neutralization reactions. Part. 2. Coal combustion is a major source of atmospheric mercury. High-temperature sorbent injection is an efficient method to capture metallic species during combustion. This part of the study examines the performance on Hg capture from pulverized coal combustion in a drop-tube furnace. V2O5 was tested as a sorbent and demonstrated good performance on elemental mercury capture, which results from the formation of ultrafine V2O5 particles during the combustion process. It is proposed that the ultrafine V2O5 particles catalyzed Hg0 oxidation on their large surfaces. Hg2+, the oxidation product, may condense on fly ash particle surfaces or on tubing surfaces, thereby being removed from the flue gas. Part. 3. Coal combustion is the largest single contributor to global anthropogenic CO2 emissions. Oxy-coal combustion replaces the air with oxygen and uses recycled flue gas (RFG) as a diluent, resulting in a higher concentration (>98%) of CO2 in the exhaust, which promotes more effective control, capture, and possible conversion of CO2. This part of the dissertation investigates the effects of recycling (up to recycle ratios of 60%) on submicrometer particle formation in a drop-tube furnace system. The recycled exhaust gas containing lower O2 concentration and higher CO2 concentration suppressed submicrometer particle formation. However, it was found that water vapor in recycled exhaust gas greatly enhanced the formation of submicrometer particles. The gas composition changes that result from exhaust-gas recycling significantly affected the size distribution of submicrometer particles at the exit of the combustor. Differences in the particle size distribution with and without the filtration of recycled exhaust gas were insignificant. The composition of the resultant particles in oxy-coal combustion and conventional coal-air combustion as determined by X-ray diffraction was similar.

Download or read book Energy Conversion and Resources written by and published by . This book was released on 2007 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mercury Control written by Evan J. Granite and published by John Wiley & Sons. This book was released on 2015-01-20 with total page 479 pages. Available in PDF, EPUB and Kindle. Book excerpt: This essential handbook and ready reference offers a detailed overview of the existing and currently researched technologies available for the control of mercury in coal-derived gas streams and that are viable for meeting the strict standards set by environmental protection agencies. Written by an internationally acclaimed author team from government agencies, academia and industry, it details US, EU, Asia-Pacific and other international perspectives, regulations and guidelines.

Download or read book A Theoretical Analysis of Single Coal Particle Behavior During Spontaneous Devolatilization and Combustion written by Shabi Ulzama and published by . This book was released on 2007 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 and Halogens in Coal written by and published by . This book was released on 2012 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fate of Trace Mercury in the Combustion of Coal written by R. C. Diehl and published by . This book was released on 1972 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mercury and Halogens in Coal written by Jeffrey Charles Quick and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Submicrometer Particle Formation and Mercury Capture During Powder River Basin Coal Combustion written by Marina Smallwood and published by . This book was released on 2005 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Behavior of Pulverized Coal Particles During Early Stages of Combustion written by Sangmin Choi and published by . This book was released on 1985 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Combustion Emissions written by Keith Schofield and published by Academic Press. This book was released on 2020-01-10 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combustion Emissions: Formation, Reaction, and Removal of Trace Metals in Combustion Products presents the latest scientific knowledge on combustion, with a particular focus on the behavior of elements in this high temperature method of energy generation. The book describes methods of control and establishes a solid base of understanding for future research. Encyclopedic in style and consistent in format, each chapter systematically presents a complete analysis of the combustion behavior of each element and guides the reader in resolving specific problems. This includes source levels in fuels and fuel usage, emission and pollutant release into the environment and environmental effects, and more. Societal impacts and environmental concerns are considered throughout, highlighting sustainability aspects across a diverse range of applications, such as within power plants, automobiles and propulsion. - Presents the latest research in a very systematic way - Includes methods of control and establishes a base of understanding for future research in energy systems - Analyzes the individual behavior of 34 elements, considering their chemistry, nature and environmental impacts

Download or read book Mercury and Air Toxic Element Impacts of Coal Combustion By product Disposal and Utilizaton written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The University of North Dakota Energy & Environmental Research Center (EERC) conducted a multiyear study to evaluate the impact of mercury and other air toxic elements (ATEs) on the management of coal combustion by-products (CCBs). The ATEs evaluated in this project were arsenic, cadmium, chromium, lead, nickel, and selenium. The study included laboratory tasks to develop measurement techniques for mercury and ATE releases, sample characterization, and release experiments. A field task was also performed to measure mercury releases at a field site. Samples of fly ash and flue gas desulfurization (FGD) materials were collected preferentially from full-scale coal-fired power plants operating both without and with mercury control technologies in place. In some cases, samples from pilot- and bench-scale emission control tests were included in the laboratory studies. Several sets of 'paired' baseline and test fly ash and FGD materials collected during full-scale mercury emission control tests were also included in laboratory evaluations. Samples from mercury emission control tests all contained activated carbon (AC) and some also incorporated a sorbent-enhancing agent (EA). Laboratory release experiments focused on measuring releases of mercury under conditions designed to simulate CCB exposure to water, ambient-temperature air, elevated temperatures, and microbes in both wet and dry conditions. Results of laboratory evaluations indicated that: (1) Mercury and sometimes selenium are collected with AC used for mercury emission control and, therefore, present at higher concentrations than samples collected without mercury emission controls present. (2) Mercury is stable on CCBs collected from systems both without and with mercury emission controls present under most conditions tested, with the exception of vapor-phase releases of mercury exposed to elevated temperatures. (3) The presence of carbon either from added AC or from unburned coal can result in mercury being sorbed onto the CCB when exposed to ambient-temperature air. The environmental performance of the mercury captured on AC used as a sorbent for mercury emission control technologies indicated that current CCB management options will continue to be sufficiently protective of the environment, with the potential exception of exposure to elevated temperatures. The environmental performance of the other ATEs investigated indicated that current management options will be appropriate to the CCBs produced using AC in mercury emission controls.

Download or read book The Effects of Carbon in ash on Mercury Capture from Flue Gas written by Kyung Man Kim and published by . This book was released on 2010 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury existing as a trace element in coal is an important pollutant because coal burning is increasing around the world for energy production and coal-fired plants are the largest anthropogenic source of mercury emission to the environment. Mercury behavior in the homogeneous conditions of cooling flue gas is characterized using equilibrium study and fundamental mercury kinetics depending on the time-temperature history. Up-to-date version of mercury oxidation based on quench rate is plotted with revised mercury mechanism. Slow quench rates show better mercury oxidation at the typical cooling rate in power plant. Mercury capture mostly occurs under heterogeneous conditions between sorbent particles and gaseous mercury, and this study is mainly devoted to understanding the role of carbon-in-ash on mercury capture from flue gas. Coal flyash samples are characterized by loss-on-ignition (LOI), surface area (BET) tests, and scanning electron microscopy (SEM). Flyash sorbents are injected using an in-flight configuration and then mercury concentration is measured by Hg CEMS. The unburned carbon is one main factor for capturing mercury. However, mercury uptake is shown to be relatively low when using flyash from high rank coal such as anthracite because of the small surface area coming from the non-porous structure. Therefore, when flyash is used as a sorbent for mercury capture, quantitative surface area should be compared and coal rank also should be considered. Non-carbon zeolite injection showed that carbon has physico-chemically favorable structure to capture mercury as well as creating high surface area with the ash. A detailed diffusion mechanism for the mercury capture process was examined using a relatively simple 1-D model. Porosity and Knudsen diffusivity are very important in intra-particle diffusion based on the investigation of sensitivity of diffusion factors. Under the conditions of this study, it appears that elemental mercury can be more readily captured than oxidized mercury because of its lower molecular weight.

Download or read book Combustion of Dense Streams of Coal Particles written by and published by . This book was released on 1992 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ignition of the high volatile isolated coal particles in vitiated environment seems to occur heterogeneously at the leading edge of the particle. Volatiles are observed to be ejected upward as jets in the direction of the convective flow but only after heterogeneous ignition. The volatiles burn in the gas phase homogeneously and form a wake flame; a black inner zone (unburned volatile) is formed (see Fig. A.3 for many common characteristics of isolated flames). Intermittent volatile ignition and combustion are observed to occur during the combustion process for a few of the isolated particle combustion experiments on high volatile non-swelling coal. The medium volatile coal particles ignite faster than the high volatile coal; but the intermittent ignition is not observed. The low volatile isolated coal particles combust in shorter time. The isolated char particles ignite at the surface of the particle heterogeneously with little volatile ejected, yet are not sufficient to form a volatile flame, resulting in a subsequent heterogeneous combustion. A group flame is formed for the two-particle arrays at closer interparticle spacing (Fig. A.4). Also, intermittent ignition does not occur for the high volatile particles when the two particles are at farther distances which suggests that radiation interaction between the particles might be occurring. However this conclusion is purely speculative. The char arrays experience heterogeneous ignition at the leading edge; combustion proceeds heterogeneously.