Showing papers on "Coal published in 1999"

Health impacts of domestic coal use in China

Abstract: Domestic coal combustion has had profound adverse effects on the health of millions of people worldwide. In China alone several hundred million people commonly burn raw coal in unvented stoves that permeate their homes with high levels of toxic metals and organic compounds. At least 3,000 people in Guizhou Province in southwest China are suffering from severe arsenic poisoning. The primary source of the arsenic appears to be consumption of chili peppers dried over fires fueled with high-arsenic coal. Coal samples in the region were found to contain up to 35,000 ppm arsenic. Chili peppers dried over high-arsenic coal fires adsorb 500 ppm arsenic on average. More than 10 million people in Guizhou Province and surrounding areas suffer from dental and skeletal fluorosis. The excess fluorine is caused by eating corn dried over burning briquettes made from high-fluorine coals and high-fluorine clay binders. Polycyclic aromatic hydrocarbons formed during coal combustion are believed to cause or contribute to the high incidence of esophageal and lung cancers in parts of China. Domestic coal combustion also has caused selenium poisoning and possibly mercury poisoning. Better knowledge of coal quality parameters may help to reduce some of these health problems. For example, information on concentrations and distributions of potentially toxic elements in coal may help delineate areas of a coal deposit to be avoided. Information on the modes of occurrence of these elements and the textural relations of the minerals and macerals in coal may help predict the behavior of the potentially toxic components during coal combustion.

A Compilation of Physical, Spectroscopic and Photophysical Properties of Polycyclic Aromatic Hydrocarbons

Abstract: Polycyclic aromatic hydrocarbons (PAH),t also known as polynuclear aromatic hydrocarbons or polyarenes, constitute a large class of organic compounds. They are formed and released into the environment through natural and man-made sources. Natural sources include volcanoes and forest fire, while the man-made sources come from wood burning, automobile exhaust, industrial power generators, incinerators, production of coal tar, coke, asphalt and petroleum, incomplete combustion of coal, oil, gas, garbage, tobacco and charbroiled meat. Polycyclic aromatic heterocyclic analogs containing one or more nitrogen, oxygen or sulfur atoms are also present in substantial quantities in coal tar and petroleum residues produced during the refining process. In the atmosphere, they are principally generated from the combustion of fossil fuels, wood or forest burning, refuse burning and coal tar. Although anthropogenic sources account for the major portion of atmospheric PAH pollution (l), vehicle emissions are believed to be responsible for 35% of the total PAH emission in highly populated and industrialized urban areas of the United States (2). Deposition of PAH in surface and ground waters can take place from a variety of sources such as airborne PAH, municipal wastewater discharge, effluents from wood treatment plants and other industries, oil spills and petroleum pressing. Accumulation of PAH in soils is believed to result from atmospheric deposition after long-range transport. The concentration of PAH found in soil around urban and industrialized areas are sometimes up to two orders of magnitude higher than those in less-developed areas (derived from forest fires and airborne pollution). Once released into the environment, PAH can partition between air, water, soil or sediments. An extensive body of work on this subject has appeared in the literature in recent years. Representative examples include partitioning of PAH between the gas and suspended particle phase (3,4), aidwater

Life Cycle Assessment of Coal-fired Power Production

Abstract: Coal has the largest share of utility power generation in the US, accounting for approximately 56% of all utility-produced electricity (US DOE, 1998). Therefore, understanding the environmental implications of producing electricity from coal is an important component of any plan to reduce total emissions and resource consumption. A life cycle assessment (LCA) on the production of electricity from coal was performed in order to examine the environmental aspects of current and future pulverized coal boiler systems. Three systems were examined: (1) a plant that represents the average emissions and efficiency of currently operating coal-fired power plants in the US (this tells us about the status quo), (2) a new coal-fired power plant that meets the New Source Performance Standards (NSPS), and (3) a highly advanced coal-fired power plant utilizing a low emission boiler system (LEBS).

Biotechnology and microbiology of coal degradation

Abstract: For several years it has been known that fungi and bacteria can attack and even liquefy low rank coals. This review covers the progress in coal biotechnology and microbiology, mainly during the last decade, from describing the first effects to elucidating the mechanisms used by the microorganisms. More than one mechanism is responsible for microbial coal degradation/liquefaction: oxidative enzymes (peroxidases, laccases), hydrolytic enzymes (esterases), alkaline metabolites and natural chelators. Due to the heterogeneous structure of coal, which is described in one section, and for economic reasons the review focuses on the enzymatic depolymerization of brown coal. Approaches which seem not so promising are discussed (anaerobic, reductive pathways, chemical pretreatment). Finally the possible applications and products in this field are summarized, as lignite with a worldwide production of about 940 million tons a year will continue to play an important economic role in the future.

Energy from Biomass: A Review of Combustion and Gasification Technologies

Abstract: Biomass materials have properties that differ from those of conventional solid fuels such as coal. A major difference is the high content of volatile matter in biomass materials, whereas coal has less than 20 percent. The design of a combustion or gasification system depends heavily on the specific biomass material - its morphology, moisture content, and mix of contaminants. The last determines which flue-gas cleaning systems will be applied. Combustion systems based on steam cycles are technically mature and commercially available. Gasification systems are commercially available. However, small-scale applications need much supervision and suffer from frequent interruptions. Advanced integrated gasification and combined heat and power concepts are promising but still not demonstrated. A demonstration plant has been built but is not yet in full operation. Comparisons have been made between gasifier/engine and steam-cycle concepts with capacities of 1 MWe (Megawatt electric). Production costs for the gasifier/engine capacities for the considered base are lower than that of the steam cycle. However, some uncertainty is involved in assumptions of the base case, and sensitivity analyses show that change in those assumptions is larger than the difference in costs between the two concepts. Therefore, one cannot conclude that one concept is more attractive than the other. Rather, feasibility studies must be performed to determine which system is most suitable.

Trace elements in coal: environmental and health significance.

Abstract: Trace elements can have profound adverse effects on the health of people burning coal in homes or living near coal deposits, coal mines, and coal-burning power plants. Trace elements such as arsenic emitted from coal-burning power plants in Europe and Asia have been shown to cause severe health problems. Perhaps the most widespread health problems are caused by domestic coal combustion in developing countries where millions of people suffer from fluorosis and thousands from arsenism. Better knowledge of coal quality characteristics may help to reduce some of these health problems. For example, information on concentrations and distributions of potentially toxic elements in coal may help delineate areas of a coal deposit to be avoided. Information on the modes of occurrence of these elements and the textural relations of the minerals in coal may help to predict the behavior of the potentially toxic trace metals during coal cleaning, combustion, weathering, and leaching.

The estimation of mercury emission from coal combustion in China.

Abstract: In this paper,the mercury emission of coal combustion and mercury content of coal were studied in China. The average mercury content of coal is 0.22mg/kg.By founding monitor program,the mercury emission factors of coal-fired boiler were measured,which were from 64.0% to 78.2%. Basing on other data,the total amount of mercury emission from coal combustion was 302.9 tons in 1995, including 213.8 tons in atmosphere and 89.07 tons in ash and cinder. From 1978 to 1995 mercury emission had been increasing at average 4.8% per year and 2493.8 tons mercury had been emitted into atmosphere during the process of coal combustion;and the mercury emission intensity is high in Beijing,Shanghai and Tianjin.Mercury emission from coal combustion is a important environmental problem in China.

Effects of Heating Rate and Ion-Exchangeable Cations on the Pyrolysis Yields from a Victorian Brown Coal

Abstract: A Victorian low-rank coal (Loy Yang) was acid-washed and ion-exchanged with Na and Ca to prepare the H-form, Na-form, and Ca-form coal samples. Two more H-form samples were also prepared by rewashing the Na-form and Ca-form samples with acid. These coal samples were pyrolyzed in a wire-mesh reactor where the secondary reactions of the evolved volatiles were minimized. The ion-exchanged coal samples were found to give very different tar yields from those of the raw coal samples. While the tar yields from the pyrolysis of the raw and H-form coal samples were observed to be very sensitive to changes in heating rate, the tar yields from the Ca-form and Na-form samples showed little heating rate sensitivity. Unlike higher rank coals studied previously, the tar yields from the pyrolysis of the raw coal and the H-form coal samples at 600 °C were found to increase much more than the corresponding increases in the total volatile yields as the heating rate was increased from 1 to 2000 K s-1. Reexchanging Na in the ...

Global emissions of hydrogen chloride and chloromethane from coal combustion, incineration and industrial activities: Reactive Chlorine Emissions Inventory

Abstract: Much if not all of the chlorine present in fossil fuels is released into the atmosphere as hydrogen chloride (HCl) and chloromethane (CH3Cl, methyl chloride). The chlorine content of oil-based fuels is so low that these sources can be neglected, but coal combustion provides significant releases. On the basis of national statistics for the quantity and quality of coal burned during 1990 in power and heat generation, industrial conversion and residential and commercial heating, coupled with information on the chlorine contents of coals, a global inventory of national HCl emissions from this source has been constructed. This was combined with an estimate of the national emissions of HCl from waste combustion (both large-scale incineration and trash burning) which was based on an estimate of the global quantity released from this source expressed per head of population. Account was taken of reduced emissions where flue gases were processed, for example to remove sulphur dioxide. The HCl emitted in 1990, comprising 4.6 ± 4.3 Tg Cl from fossil fuel and 2 ± 1.9 Tg Cl from waste burning, was spatially distributed using available information on point sources such as power generation utilities and population density by default. Also associated with these combustion sources are chloromethane emissions, calculated to be 0.075 ± 0.07 Tg as Cl (equivalent) from fossil fuels and 0.032 ± 0.023 Tg Cl (equivalent) from waste combustion. These were distributed spatially exactly as the HCl emissions, and a further 0.007 Tg Cl in chloromethane from industrial process activity was distributed by point sources.

Development and Application of a Correlation of 13C NMR Chemical Structural Analyses of Coal Based on Elemental Composition and Volatile Matter Content

Abstract: 13C NMR spectroscopy has been shown to be an important tool in the characterization of coal structure. Important quantitative information about the carbon skeletal structure is obtained through 13C NMR spectral analysis of coal. Solid-state 13C NMR analysis techniques have progressed beyond the mere determination of aromaticity and can now describe features such as the number of aromatic carbons per cluster and the number of attachments per aromatic cluster. These 13C NMR data have been used to better understand the complicated structure of coal, to compare structural differences in coal, tar, and char, and to model coal devolatilization. Unfortunately, due to the expense of the process, extensive 13C NMR data are not available for most coals. A nonlinear correlation has been developed that predicts the chemical structure parameters of both U.S. and non-U.S. coals generally measured by 13C NMR and often required for advanced devolatilization models. The chemical structure parameters correlated include (i)...

IN VITRO EFFECTS OF COAL FLY ASHES: Hydroxyl Radical Generation, Iron Release, and DNA Damage and Toxicity in Rat Lung Epithelial Cells

Abstract: Oxygen radical generation due to surface radicals, inflammation, and iron release has been suggested as the mechanism of adverse effects of quartz, such as emphysema, fibrosis, and carcinogenic effects. Therefore, we measured iron release, acellular generation of hydroxyl radicals, and oxidative DNA damage and cytotoxicity in rat lung epithelial (RLE) cells by different coal fly ashes (CFA) that contain both quartz and iron. Seven samples of CFA with different particle size and quartz content (up to 14.1%) were tested along with silica (alpha-quartz), ground coal, and coal mine dust (respirable) as positive control particles, and fine TiO(2) (anatase) as a negative control. Five test samples were pulverized fuel ashes (PFA), two samples were coal gasification (SCG) ashes (quartz content <0.1%), and one sample was a ground coal. No marked differences between SCG and PFA fly ashes were observed, and toxicity did not correlate with physicochemical characteristics or effect parameters. Stable surface radicals were only detected in the reference particles silica and coal mine dust, but not in CFA. On the other hand, hydroxyl radical generation by all fly ashes was observed in the presence of hydrogen peroxide, which was positively correlated with iron mobilization and inhibited by deferoxamine, but not correlated with iron or quartz content. Also a relationship between acellular hydroxyl radical generation and oxidative DNA damage in RLE cells by CFA was observed. Differences in hydroxyl radical generation and oxidative damage by the CFA were not related to iron and quartz content, but the respirable ashes (MAT023, 38, and 41) showed a very extensive level of hydroxyl radical generation in comparison to nonrespirable fly ashes and respirable references. This radical generation was clearly related to the iron mobilization from these particles. In conclusion, the mechanisms by which CFA and the positive references (silica, coal mine dust) affect rat lung epithelial cells seem to be different, and the data suggest that quartz in CFA does not act the same as quartz in silica or coal mine dust. On the other hand, the results indicate an important role for size and iron release in generation and subsequent effects of reactive oxygen species caused by CFA.

The lead content and isotopic composition of british coals and their implications for past and present releases of lead to the UK environment

Abstract: More than 60 coal samples, predominantly from the principal coalfields of England and Wales (25) and Scotland (30), were analysed for lead by AAS and for stable lead isotopes by ICP‐MS While the average lead content of Scottish coal, 239 mg kg−1, was more than double that of coal from England and Wales, 110 mg kg−1, the corresponding mean 206Pb/207Pb ratios (± 1 sd) were nearly identical, at 1181±0011 and 1184±0006, respectively In the light of the lead isotopic signatures of British coals and of both indigenous (206Pb/207Pb ∼ 117) and imported Australian (206Pb/207Pb ∼ 104) lead ores, an approach based on estimated lead emissions from these sources and the deconvolution of the historical lead and 206Pb/207Pb records preserved in lake sediments, peat bogs and archival herbage material indicates that coal combustion became an increasingly significant contributor to atmospheric lead deposition in the UK during the period 1830–1930, especially after the onset of England’s decline as a major location of lead mining and smelting in the late‐19th Century Since 1930 and the introduction of leaded petrol, the atmospheric 206Pb/207Pb ratio in the UK has been strongly influenced by car‐exhaust emissions of comparatively 206Pb‐depleted lead of predominantly Australian origin, counter‐balanced to some extent by coal‐combustion emissions of lead, although these have fallen dramatically since the mid‐1950s Nevertheless, with the introduction and substantial uptake of unleaded petrol in the UK during the last decade, even the declining releases from coal, along with contributions from other sources, are continuing to affect the atmospheric lead content and 206Pb/207Pb ratio

Effect of Coal Minerals on Chlorine and Alkali Metals Released during Biomass/Coal Cofiring

Abstract: The combustion behavior, gaseous emissions, and alkali metals released during the combustion of several biomass/coal blends were investigated using a direct sampling, molecular beam mass spectrometer (MBMS) system in conjunction with a high-temperature alumina-tube flow reactor. Pittsburgh No. 8 and Eastern Kentucky coals were blended with various biomass samples such as red oak wood chips, Imperial wheat straw, and Danish wheat straw. The coal/biomass blends were 15% biomass on an energy input basis. All pure fuels and blends were subjected to combustion in 20% oxygen in helium at a furnace temperature of 1100 °C, and the products were monitored with the MBMS. The amounts of NO(g) and SO2(g) detected during the combustion of the coal/biomass blends suggested that any change was the result of diluting the nitrogen and sulfur present in the fuel blend. The amount of HCl(g) detected during the combustion of the coal/wheat straw blends was higher than expected based on the combustion results for the pure fue...