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1.
Feed coals and fly ashes from a coal-fired power station burning Alberta subbituminous coal were examined for a period of thirty-eight weeks to determine the variation in emitted mercury. Feed coal samples were analyzed for proximate, calorific value and Hg content, while fly ash samples were examined for C and Hg contents. The maceral content of the feed coal was also determined. The emitted mercury was calculated and compared to mercury emitted from the stack according to a mass-balance calculation from a previous study for the same station.Mercury contents ranged from 0.029 to 0.066 mg/kg for feed coal, and from 0.069 to 0.112 mg/kg for fly ash. The carbon/char in fly ash was separated into reactive (vitrinitic/bimacerate) and less reactive (inertinitic) chars using ZnBr2 at specific gravities of 1.7, 2.0, and 2.25 to 2.4. The result shows that there is a positive correlation between the carbon and mercury content of the fly ash. The reactive char particles in the fly ash may be responsible for the capture mercury in fly ash. The percentage of estimated captured mercury by fly ash increases with increasing carbon content (%) in fly ash. The percentage of emitted mercury for the period of 38 weeks is estimated to be within the range of 49% to 76% of the total input of mercury.  相似文献   

2.
Leaching characteristics of fly ash   总被引：6，自引：0，他引：6  
The disposal of fly ash as a byproduct of thermic power stations, results in significant environmental problems. The leaching of coal fly ash during disposal is of concern for possible contamination, especially for the aquatic environment when ash is in contact with water. The aim of this study was to investigate the leaching behaviour of fly ashes currently disposed in Kemerkoy Power Plant (Turkey) fly-ash-holding pond. The studies were conducted with fly ashes from the electrostatic precipitators (fresh fly ash) and from the fly ash pond (pre-leached fly ash). The fly ashes has alkaline in nature and pH ranges between 11.9 to 12.2. The pre-leached fly ash exhibited lower EC values (7,400 µS) than the fresh fly ash (10,300 µS). In contrast to Fe and Pb, the elements such as Cr, Cd, Cu and Co did not leach from the fly ash. The Ca and Mn concentrations decreased with increasing temperature whereas, Na and K concentrations increased. The results showed that the most important effects of fly ash leaching were pH, Na, Ca, K, Fe, Mg, Mn and Pb.  相似文献   

3.
The mercury and maceral content of subbituminous feed coals burned at six Canadian power plants was measured and compared to the mercury and carbon content of corresponding fly ashes. The fly ashes were collected from electrostatic precipitator (ESP) pollution controls used at the power plants. Four feed coals from the Upper Cretaceous to Tertiary age Scollard Formation were deposited in freshwater depositional environment and contain 35–44% inertinite. Two feed coals from the Upper Cretaceous age Horseshoe Canyon Formation were deposited in a brackish water environment and contain 14% inertinite.The data show that abundant inertinite equates to more unburned carbon in ESP fly ash, and to enhanced capture of mercury in cold-side ESP fly ash. This indicates that the inertinite content of a coal seam may be indicative of the percentage of unburned carbon and the percentage of mercury captured by a cold-side ESP.  相似文献   

4.
Fly ash generated by coal-fired power plants is in part collected by filters in the emission stacks while a small portion is vented into the atmosphere. Since many of the coalfired power plants in the western United States are located in the desnrt, the ability to monitor fly ash emissions requires a chemical tracer that utilizes desert soil and plant interactions with the fly ash deposited in the desert environment. This investigation presents the results of a controlled greenhouse experiment in which a native desert plant, the brittlebush (Encelia farinosa), was grown on admixtures of desert soils and fly ash. The fly ash is strongly enriched in Sr and the brittlebush is a Sr accumulator. The data demonstrate that (1) the brittlebush isotopically equilibrates with desert soils whose fly ash components are as low as 0.25% by weight, (2) the fly ash Sr is apparently more available to the plant, than Sr derived from the soils, and (3) the difference between the87Sr/86Sr ratio of the fly ash (0.70807) and soils (0.71097 to 0.71117) warrants further investigations in the natural environment to determine the practicality of this method as a natural tracer of fly ash in the environment.  相似文献   

5.
We present the first data on the mode of occurrence of Au in fly ashes from the Wulantuga and Lincang power plants in China, which burn high-Ge coal. Gold occurs as fine-grained drop-like particles with a size of n*0.01–0.2 μm on the surface of the glass globules. These features of the Au particles are proof for Au condensation from the gas phase and deposition on the surface of fly ash in the cooler zone of the electrostatic precipitator and baghouse filter.  相似文献   

6.
本文结合福州电厂粉煤灰室内试验结果分析，探讨粉煤灰扰动样现场取样及试验控制干密度的等问题，该电厂粉煤灰的沉积规律与其它电厂有所不同，灰料颗粒组细分布和距排灰口远近基本无关，取样也不能按以往经验进行。  相似文献   

7.
This study investigated the removal efficiency of pharmaceuticals from aqueous solutions supported on chemically treated fly ash. The coal fly ash was supplied by the electric power station in Krakow, Poland. There are plenty of studies showing the utilization of fly ash as a low-cost adsorbent for wastewater containing heavy metals or dyes. Adsorption and immobilization of pharmaceuticals and personal care products on fly ash is a relatively new method but it is a very promising one. In this study, the adsorptive removal of diclofenac, ketoprofen, carbamazepine, bezafibrate, bisphenol A, 17α-ethinyl estradiol and estriol by HCl- and NaOH-treated fly ash was assessed. Chemical treatment of fly ash changed structures of particles and enhanced specific surface areas. HCl-treated fly ash was characterized by the highest BET specific surface area 47.9 m2 g?1 and unburned carbon content 8.1%. Isotherms for all compounds except for 17α-ethinyl estradiol (EE2) and estriol (E3) were linear. Higher linear regression coefficients (R 2) obtained for isotherms of EE2 and E3 show that the Freundlich model better describes their sorption. Adsorption coefficients K d varied between 109.5 (L kg?1) for bisphenol A and 471.5 (L kg?1) for bezafibrate. Freundlich constants (K F) for EE2 and E3 were 62.3 and 119.9 (µg1?1/n L1/n kg?1), respectively. Acid treatment of fly ash increased adsorption of diclofenac, ketoprofen, carbamazepine, bezafibrate and bisphenol A. Comparison of the octanol–water partitioning coefficients (log K OW) with the partitioning coefficients normalized on unburned carbon content (log K UC) revealed similarities but no strong correlation. The increasing of unburned carbon increased sorption of compounds to fly ash.  相似文献   

8.
Mercury capture by fly ash C was investigated at five lignite- and subbituminous-coal-burning Bulgarian power plants (Republika, Bobov Dol, Maritza East 2, Maritza East 3, and Sliven). Although the C content of the ashes is low, never exceeding 1.6%, the Hg capture on a unit C basis demonstrates that the low-rank-coal-derived fly ash carbons are more efficient in capturing Hg than fly ash carbons from bituminous-fired power plants. While some low-C and low-Hg fly ashes do not reveal any trends of Hg versus C, the 2nd and, in particular, the 3rd electrostatic precipitator (ESP) rows at the Republika power plant do have sufficient fly ash C range and experience flue gas sufficiently cool to capture measurable amounts of Hg. The Republika 3rd ESP row exhibits an increase in Hg with increasing C, as observed in other power plants, for example, in Kentucky power plants burning Appalachian-sourced bituminous coals. Mercury/C decreases with an increase in fly ash C, suggesting that some of the C is isolated from the flue gas stream and does not contribute to Hg capture. Mercury capture increases with an increase in Brunauer-Emmett-Teller (BET) surface area and micropore surface area. The differences in Hg capture between the Bulgarian plants burning low-rank coal and high volatile bituminous-fed Kentucky power plants suggests that the variations in C forms resulting from the combustion of the different ranks also influence the efficiency of Hg capture.  相似文献   

9.
This study investigated the potential application of heavy oil burning fly ash as a precursor to prepare activated carbon. The raw fly ash obtained from a power plant is cleaned by nitric acid/hydrochloric acid and activated at 550–800 °C with hold times of 30 and 60 min to obtain fly ash activated carbon. The phosphoric acid is used as a chemical agent to improve the surface characteristics of the cleaned fly ash. The effects of process variables such as amount of chemical reagents, activation time and temperature were investigated according to two-levels full factorial design. The resultant activated carbons were characterized in terms of Brunauer, Emmett and Teller surface area and total and pore volume. The maximum specific surface area was found of 148.30 m2/g at 800 °C temperatures with 60 min holding time. The test showed that the surface area and pore volumes of the material are also significantly enhanced by the activation process.  相似文献   

10.
The isotopic compositions of S (δ34S) and C (δ13C) were determined for the coal utilized by a power plant and for the fly ash produced as a by-product of the coal combustion in a 220-MW utility boiler. The coal samples analyzed represent different lithologies within a single mine, the coal supplied to the power plant, the pulverized feed coal, and the coal rejected by the pulverizer. The ash was collected at various stages of the ash-collection system in the plant. There is a notable enrichment in 34S from the base to the top of the coal seam in the mine, with much of the variation due to an upwards enrichment in the δ34S values of the pyrite. Variations in δ34S and in the amount of pyritic S in the coal delivered to the plant show that there was a change of source of coal supplied to the plant, between week one and week two of monitoring, supporting a previous study based on metal and sulfide geochemistry for the same plant. The fly ash has a more enriched δ34S than the pulverized coal and, in general, the δ34S is more enriched in fly ashes collected at cooler points in the ash-collection system. This pattern of δ34S suggests an increased isotopic fractionation due to temperature, with the fly ash becoming progressively depleted in 34S and the flue gas S-containing components becoming progressively enriched in 34S with increasing temperatures. Substantially less variation is seen in the C isotopes compared to S isotopes. There is little vertical variation in δ13C in the coal bed, with δ13C becoming slightly heavier towards the top of the coal seam. An 83–93% loss of solid phase C occurs during coal combustion in the transition from coal to ash owing to loss of CO2. Despite the significant difference in total C content only a small enrichment of 0.44–0.67‰ in 13C in the ash relative to the coal is observed, demonstrating that redistribution of C isotopes in the boiler and convective passes prior to the arrival of the fly ash in the ash-collections system is minor.  相似文献   

11.
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12.
Raman spectroscopy was used as a supplementary method to characterise the thermal maturity of Ediacaran organic matter (OM) from the East European Craton. Because this method is based on organic particles measurement, it appears to be a good supplementary method in addition to the acquisition of biomarker data, which is based on extractable organic matter and may be affected by potential contamination. Raman spectroscopy seems to be particularly useful for lower Palaeozoic rocks, which do not contain vitrinite. Here, we compared C31 22S/(S + R) homohopane ratio results (obtained using gas chromatography – mass spectrometry), with various Raman parameters including: G_STA, Gmax position, Dmax/Gmax, FWHMG, RAR, D_STA, and PDmax. Close correlations were observed between C31 22S/(S + R) and G_STA, Gmax position, Dmax/Gmax, and FWHMG, reaching values of R2 = 0.5‒0.6, whereas no correlation existed between homohopane ratio and the RAR, D_STA, and PDmax parameters. Raman spectroscopy results divided Ediacaran samples into two distinctive groups: (i) immature (Russian, Lithuanian, and Belarusian), characterised by relatively higher values of G_STA, Dmax/Gmax, and FWHMG and relatively lower values of PGmax, and (ii) mature (Polish and Ukrainian), with relatively lower values of G_STA, Dmax/Gmax, and FWHMG and relatively higher values of PGmax. Within each group no statistically confirmed differences were found. However, significant discrepancies were observed between the hopane ratio and Raman parameters in Lithuanian samples, in relation to other samples from the group (i). Values of the C31 22S/(S + R) ratio for Lithuanian samples are close to those for the group (ii) and significantly higher than those for the group (i). However, all Raman parameters are the same as those of the rest samples from the group (i), indicating the immature character of OM from Lithuanian rocks. We interpret this discrepancy as representing contamination of the cores with drilling fluids, resulting in increased values for the C31 22S/(S + R) ratio. In this case, Raman spectroscopy is a useful tool for detecting extract contamination and appears to be an effective and decisive method in the case of rocks suspected of contamination.  相似文献   

13.
燃煤排放可吸入颗粒物的显微结构与物质组成研究   总被引：1，自引：0，他引：1  
对我国西南地区三个火电厂排放的可吸入颗粒物(PM10)的显微结构、矿物和化学组成等的研究表明,在PM10中,随着粒径的减小,非球形颗粒的比例增加;同原状飞灰相比,PM10以实心结构为主,多孔和空心结构较少;场发射扫描电子显微镜下,多数PM10颗粒的表面并不光滑,而是布满了次级微细颗粒;PM10的物相组成与燃煤煤种密切相关,小龙潭电厂PM10主要矿物包括石英、石灰、石膏和赤铁矿,而贵阳电厂PM10则以莫来石和石英为主;据单个PM10颗粒化学组成,将PM10分为硅质、铁质、Ca-铝硅质、Fe-铝硅质、Ca-Fe-铝硅质和硫酸钙六种颗粒类型;从不同采样点PM10元素组成看,从静电除尘器(ESP)前到ESP,PM10化学成分变化不大,到ESP后,元素Fe、Ca、Mg和Al的含量急剧减少,而Na的含量则迅速增高.  相似文献   

14.
Coal combustion in power plants in India produces large quantities of coal-related wastes, e.g. fly ash and bottom ash. Indian coals used in power stations are of high ash content, thus resulting in the generation of large amounts of fly ash (~100 million tons/year). Combustion of coal results in enhanced concentration of most radionuclides found in waste materials. In the present work, an attempt has been made to assess the radiological impact of the Kolaghat thermal power plant in West Bengal, India. The fly ashes and coal from the power plant were analysed for 238U, 232Th and 40K by a NaI (Tl)-based gamma-ray spectrometer. The results show that 226Ra and 232Th range from 81.9-126 and 132-169 Bq/kg in fly ash and 25-50 and 39-55 Bq/kg in coal. These results are high compared to those of other thermal power plants of India. Hence, the Kolaghat fly ash has a significant amount of radioactivity which, if not properly disposed, will be a serious threat to the ambient environment.  相似文献   

15.
A detailed assessment of elements was carried out at a power plant rated at approximately 760 MW of electricity using western Canadian subbituminous coal. The concentrations of elements of environmental concern (As, Cd, Cr, Hg, Ni, and Pb) in milled coals, ashes, stack-emitted materials. Speciation of As, Cr, and Ni were determined. The polyaromatic hydrocarbons (PAHs) emitted from the stack were also measured. The rates of input of elemental input for As, Cd, Cr, Hg, Ni, and Pb were 28, 0.94, 230, 0.44, 44, and 88 kg/day, respectively; of which only 0.16, 0.01, 0.40, 0.27, 0.15, and 0.04 kg/day, respectively, were stack emitted. The total stack emission of toxic elements is 1.02 kg/day, with Cr being the highest contributor to this group with 0.4 kg/day. However, Hg at 0.27 kg/day has the highest percentage rate of emission at about 60%, while Cd has the lowest at about 1%. The electrostatic precipitator (ESP) removes a significant portion of the elements indicated by their relative enrichment (RE) ratios greater than 0.7. The results show that most of the elements in milled coal are low compared to world coals and other Canadian milled coals.Mercury is mostly ( 81%) emitted as gaseous elemental mercury (GEM), with 19% as reactive gaseous mercury (RGM). Particulate mercury is very low and averages about 0.1% of the total mercury at this station. Most of the arsenic in the milled coal is primarily associated with pyrite or as arsenate in its less toxic form of As+5 (> 95%). In both bottom and fly ashes, more than 95% of the total arsenic is present as As+5. Chromium in the milled coal and bottom ash is mostly non-toxic (Cr+3). The more toxic Cr+6 comprise less than 5% of the total Cr in the ESP fly ash and the stack-emitted ash. Nickel in milled coal and ashes is in the form of non-toxic Ni+2, predominantly in coordination with oxygen.The emitted PAHs include acenapthene, fluorene, 2-methyl-fluorene, phenathrene, anthracene, fluoanthene, and pyrene; which are emitted from stack at the combined rate of 3.6 g/day. The concentrations of elements of environmental concern (As, Cd, Hg, Ni, and Pb) emitted to the atmosphere by the power plant in the zone of maximum impact at ground level are lower than those listed in the Health Guidelines of the USEPA and Canadian National Air Pollution Surveillance. This is based on stable meteorological conditions, down wind from the power plant for a maximum distance of 3 km.  相似文献   

16.
Geotechnical Properties of Low Calcium and High Calcium Fly Ash   总被引：1，自引：0，他引：1  
In this paper, a comparative study has been made for physical and engineering properties of low calcium and high calcium Indian fly ash. The grain size distribution of fly ash is independent of lime content. Fly ash particles of size >75 μm are mostly irregular in shape whereas finer fractions are spherical for low calcium fly ash. For high calcium fly ash, chemical and mineralogical differences have been observed for different size fractions. Compared to low calcium fly ash, optimum moisture content is low and maximum dry density is high for high calcium fly ash. Optimum moisture content is directly proportional and maximum dry density is inversely proportional to the carbon content. The mode and duration of curing have significant effect on strength and stress–strain behavior of compacted fly ash. The gain in strength with time for high calcium fly ash is very high compared to that of low calcium fly ash due to presence of reactive minerals and glassy phase.  相似文献   

17.
Coal, a fossil fuel, is the largest source of energy for the generation of electricity in India. In order to study the potential environmental hazards by coal based power plants, particulate matters were collected using Stack Monitoring Kit and gaseous pollutants by Automatic Flue Gas Analyzer. The morphological and chemical properties, mineralogical composition and particle size distributions have been determined by SEM–EDX, XRD and CILAS. The data revealed the presence of particulate matters, SO2, NOx in the range of 236–315, 162–238, 173–222 mg/Nm3 respectively. The emission of CO2 was in the range of 43,004–60,115 Nm3/h with an average of 52,830 Nm3/h. Among the elements, Fe > Mn > Al > Zn > B > Ni > Cr > Cu were present in substantially higher proportion than Pb > Mo > Cd > Se > As > Hg. It was found that most of the elements were concentrated on fly ash surface rather than coal, bottom ash and pond ash. This variation may be attributed to the fineness of fly ash particles with large surface ratio to mass. Mineralogical studies of coal and fly ash by X-ray diffraction revealed the presence of mullite, quartz, cristobalite and maghemite. Presence of mullite and quartz found in fly ash indicate the conversion of complex minerals to mullite and quartz at high temperature. Transfer Coefficient was calculated to determine the ratio of the enrichment of trace elements in fly or bottom ash with respect to coal and pond ash.  相似文献   

18.
Estimation of coal power plant emissions is a vital step to visualise emission trends with respect to specific policy implementations and technological interventions so that their effectiveness in terms of emission reductions and ambient air quality improvement can be quantitatively assessed. However, research work concerning stack emission estimations specifically for coal power plants in India is limited. To bridge the present gap, we present a plant-specific multi-year and multi-parameter Coal Power Stack Emission Model. This model has been developed to explore current and historical annual stack emissions from a coal-based thermal power plant taking into account essential variables such as coal characteristics, process attributes and control equipment aspects, which can significantly influence the stack emissions. This study concentrates on development of Coal Power Stack Emission model and its application for the estimation of plant and year-specific emission factors and stack emissions for a coal-based power plant at Badarpur, New Delhi, for the period of 2000–2008. The validation of Coal Power Stack Emission model has also been successfully carried out by comparing the trends of percentage change in annual emission estimates and observed ambient air concentrations of total suspended particles, PM10 and sulphur dioxide at two nearby air quality monitoring stations, namely Siri Fort and Nizamuddin.  相似文献   

19.
Seyitömer power plant comprises 4.8% of Turkey's total energy production. The fly ash produced has been deposited in the area, since the 1960s, by a dry disposal technique. In 1997, wet disposal was improperly exercised in the area causing ash flow over agricultural fields. This study is concerned with the chemical analysis of ash, soil and water samples collected in the area following ash-removal studies after the ash flow in 1997. The results reveal that Na, K, Ca, Mg, Mn, Al, Fe, Co, and Cr contents of soil and water are governed by basement lithology in the area, whereas Cd, Pb, Zn, and Cu contents are determined by fly ash from disposal sites. Although lithogenic Cr and Co contents are exceedingly high, comparison with the regulatory standards for drinking water, irrigation water and agricultural soils reveals no pollution pertinent to solid waste production in waters, whereas there is moderate pollution by Pb and Cu in soils.  相似文献   

20.
The discovery of Hadean to Paleoarchean zircons in a metaconglomerate from Jack Hills, Western Australia, has catalyzed intensive study of these zircons and their mineral inclusions, as they represent unique geochemical archives that can be used to unravel the geological evolution of early Earth. Here, we report the occurrence and physical properties of previously undetected CO2 inclusions that were identified in 3.36–3.47 Ga and 3.80–4.13 Ga zircon grains by confocal micro-Raman spectroscopy. Minimum P–T conditions of zircon formation were determined from the highest density of the inclusions, determined from the density-dependence of the Fermi diad splitting in the Raman spectrum and Ti-in-zircon thermometry. For both age periods, the CO2 densities and Ti-in-zircon temperatures correspond to high-grade metamorphic conditions (≥5 to ≥7 kbar/~670 to 770 °C) that are typical of mid-crustal regional metamorphism throughout Earth’s history. In addition, fully enclosed, highly disordered graphitic carbon inclusions were identified in two zircon grains from the older population that also contained CO2 inclusions. Transmission electron microscopy on one of these inclusions revealed that carbon forms a thin amorphous film on the inclusion wall, whereas the rest of the volume was probably occupied by CO2 prior to analysis. This indicates a close relationship between CO2 and the reduced carbon inclusions and, in particular that the carbon precipitated from a CO2-rich fluid, which is inconsistent with the recently proposed biogenic origin of carbon inclusions found in Hadean zircons from Jack Hills.  相似文献   

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