High-sulfur coals

Schwefel-kobalt, m. cobalt sulfide, -kohle, /. sulfurous coal, high-sulfur coal, -kohlen-saure, /. sulfocarbonic acid (trithiocarbonic add, HaCSa). -kohlenstoff, m. carbon disulfide. -kolben, m. retort for distilling sulfur, -kora, -kbrachen, n. sulfur granule, -kuchen,... 

Properties. The properties of char products from two possible coal feeds, a low sulfur Western coal, and a high sulfur Midwestern coal, are shown in Table 11. The char derived from the low sulfur Western coal may be direcdy suitable as plant fuel, with only minor addition of clean process gas to stabilize its combustion. Elue gas desulfurization may not be required. Elue gas from the combustion of the char derived from the high sulfur Illinois coal, however, requires desulfurization before it may be discharged into the atmosphere. 

Industrial Wastewater Treatment. Industrial wastewaters require different treatments depending on their sources. Plating waste contains toxic metals that are precipitated and insolubiHzed with lime (see Electroplating). Iron and other heavy metals are also precipitated from waste-pidde Hquor, which requires acid neutralization. Akin to pickle Hquor is the concentrated sulfuric acid waste, high in iron, that accumulates in smokeless powder ordinance and chemical plants. Lime is also useful in clarifying wastes from textile dyeworks and paper pulp mills and a wide variety of other wastes. Effluents from active and abandoned coal mines also have a high sulfuric acid and iron oxide content because of the presence of pyrite in coal. 

Fig. 9. Measured coal-fired flow faciUty (CFFF) NO emissions where ( ) represents high sulfur coal, (e) low sulfur coal, (A) low sulfur coal having K2/S = 1.15, and ( ) LMF5-G. A, Illinois No. 6 coal (3% S) B, Montana Rosebud coal (1% S), and the NSPS range is between the dotted lines. To...

R. Markuszewski and T. D. Wheelock, eds.. Processing and Utilispition of High-Sulfur Coals, Vols. 1—111, Elsevier Science, Inc., New York, 1990. 

Coking coal is cleaned so that the coke ash content is not over 10%. An upper limit of 1—2 wt % sulfur is recommended for blast furnace coke. A high sulfur content causes steel (qv) to be brittle and difficult to roU. Some coal seams have coking properties suitable for metallurgical coke, but the high sulfur prevents that appHcation. Small amounts of phosphoms also make steel brittle, thus low phosphoms coals are needed for coke production, especially if the iron (qv) ore contains phosphoms. 

More recendy, the molten caustic leaching (MCL) process developed by TRW, Inc. has received attention (28,31,32). This process is illustrated in Eigure 6. A coal is fed to a rotary kiln to convert both the mineral matter and the sulfur into water- or acid-soluble compounds. The coal cake discharged from the kiln is washed first with water and then with dilute sulfuric acid solution countercurrendy. The efduent is treated with lime to precipitate out calcium sulfate, iron hydroxide, and sodium—iron hydroxy sulfate. The MCL process can typically produce ultraclean coal having 0.4 to 0.7% sulfur, 0.1 to 0.65% ash, and 25.5 to 14.8 MJ/kg (6100—3500 kcal/kg) from a high sulfur, ie, 4 wt % sulfur and ca 11 wt % ash, coal. The moisture content of the product coal varies from 10 to 50%. 

Cobalt—molybdenum alloys are used for the desulfurization of high sulfur bituminous coal, and cobalt—iron alloys in the hydrocracking of cmde oil shale (qv) and in coalhquefaction (6). 

Fluidized beds are ideal for the combustion of high sulfur coals since the sulfur dioxide produced by combustion reacts with the introduced calcined limestone to produce calcium sulfate. The chemistry involved can be simplified and reduced to two steps, calcination and sulfation. 

The sulfur content of coals available to utilities ranges from about 4 percent in high-sulfur coals to less than 1 percent in some Western coals. Although transportation costs maybe higher for Western coals, many Eastern utilities elect to burn Western coals to comply with increasingly stringent SO, regulations. 

Projects in the CCT program demonstrated innovative applications for both wet and dry or seniidry FGD systems. The wet FGD systems, which use limestone as an absorber, have met or exceeded the 90 percent SO, removal efficiency required to meet air quality standards when burning high-sulfur coal. The di"y or semidry systems use lime and recycled fly ash as a sorbent to achieve the required removal. 

EC Directive levels for SO2, NOx and lead have recently been incorporated into UK legislation in the form of the Air Quality Standards Regulations 1989. SO2 is generated when high-sulfur fossil fuels are burned. It is thus a factor of the amount of coal and heavy oil (predominantly) being burned. 

The principal source of sulfur dioxide, the precursor of sulfuric acid, is high-sulfur coal. Coal used in power plants can contain up to 4% sulfur, mostly in the form of minerals such as pyrite, FeS2. Combustion forms sulfur dioxide ... 

Fluidized bed combustion boilers are often conventional boilers but with unconventional, specially designed furnace beds. Fluidized bed combustion boilers are used to burn solid fuels, such as low-grade, high-sulfur crushed coal. The benefit of this process is its ability to provide 95 to 100% combustion (depending on the reactivity of the fuel) combined with reduced emissions of sulfur dioxide (S02) and nitrogen oxides (NOx). 

Acid precipitation, or acid rain, can causes significant impacts on freshwater, coastal, and forested ecosystems (e.g.. Likens et ai, 1996). Both NOi", from NO emissions, and SO from SO2 emissions contribute significantly to acid rain. The relative ratio of SO /NOf in precipitation will be substantially determined by the regional emissions of SO2/NO3. In developed countries, uncontrolled combustion of coal and high-sulfur fuel oil led to significant emissions of SO2, relative to NO Due to strict control of smokestack SO2 emissions in some regions and increasing NO emissions from automobiles, the relative contribution of NOi is expected to increase (Sirois, 1993 Mayewski et ai, 1990). 

Although pyridines and quinolines were first produced during the carbonization of coal, they are now available by synthesis in quantities that far exceed those by the former. Phosphorylated ribosides of hydroxylated and aminated pyrimidines and purines make up the basic structure of ribonucleic and deoxyribonucleic acids. The polycyclic oxaarenes are plant metabolites, while thiaarenes are primarily important components of high-sulfur petroleum that must be removed. 

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