Weight Percentage Of Carbon Research Articles

Sediment accumulation rates west of the Mid-Atlantic Ridge ([formula omitted

Although carbonate curves have a long history of use for temporal correlation, only limited agreement concerning the reasons for down-core carbonate variations has been reached. In this study these variations are examined by analyzing absolute accumulation rates of both carbonate and terrigenous sediment components. Carbonate content was determined in nine cores from approximately 3000–5000 m water depth. Down-core variation in carbonate was correlated to an oxygen isotope curve to establish a down-core time stratigraphy.Weight percent carbonate, carbonate accumulation rate, and terrigenous sediment accumulation rate were plotted as a function of water depth and time (0–130,000 yrs B.P.). The weight percent carbonate plot indicates that carbonate content decreases with increasing water depth. However, the carbonate accumulation rate data demonstrates that this decrease in weight percent carbonate does not result from a decrease in the carbonate accumulation rate in the deeper cores. The accumulation rate of carbonate actually increases in these deep cores. The increase in carbonate accumulation rate is offset by a larger increase in the accumulation rate of terrigenous sediment resulting in a decrease in weight percent carbonate. High accumulation rates of both carbonate and terrigenous sediment in cores below 4250 m appears to result from transport and redeposition of sediment. Most of the carbonate sediment deposited in these deep cores appears to be derived from shallow areas of the Mid-Atlantic Ridge (MAR); the terrigenous sediment probably results from deposition by deep currents.

Carbonate Dissolution on the Muir Seamount (Western North Atlantic): Interglacial/Glacial Changes

ABSTRACT Although the history of carbonate dissolution has been studied for many years, few records of dissolution through an entire glacial cycle are available for the western North Atlantic (North American Basin). Using 14 cores from the Muir and Siboney Seamounts, located about 240 km northeast of Bermuda, changes in carbonate dissolution were examined over the last 125,000 years. The core depth range spans more than 3000 m, 1780 m-4980 m, insuring that major changes in dissolution will be recorded. Weight percent carbonate was plotted as a function of water depth for five stratigraphically defined levels to determine temporal changes in the sedimentary lysocline and calcite compensation depth (CCD). During the Holocene, the lysocline is located between 4050 m and 4350 m; the CCD is not pre ent even in the deepest sample (4980 m). The late glacial ( 18,000 years B.P.) lysocline may have shoaled to about 2500 m, whereas during early glacial time ( 72,000 years B.P) it deepened to about 3400 m. The mid-glacial carbonate maximum ( 60,000 years B.P; interstadial?) is marked by a deepening of the lysocline to about 3800 m. During the entire glacial episode, the CCD aappears to have remained fixed at 4650 m. The last interglacial ( 125,000 years B.P) was a time favorable to carbonate preservation; the lysocline was deeper than 4650 m, the deepest core containing sediments of this age Increased glacial dissolution appears to result from changes in deep circulation. The establishment of the CCD during glacial time is interpreted as indicating increased Antarctic Bottom Water flow. The lysocline, on the other hand, may reflect the degree of stagnation of North Atlantic Deep Water.

Thermochemical conversion of biomass: Gasification by flash pyrolysis study

Thermal decomposition of the basic components of dried biomass (cellulose, lignin, wood) is studied in inert atmosphere. Glucose is studied for comparison. The experiments are performed in an alumina porous bed reactor heated at temperatures between 600 and 1000°C. Flash pyrolysis (heating rate 250°C/s) allows the production of a medium heating value synthetic gas with gas phase conversion thermal efficiency of up to 95 percent. The weight percent of carbon gasified during the pyrolysis reaches 90 percent for cellulose and 70 percent for wood. Light hydrocarbons (CH 4, C 2H 4, C 2H 2, C 2H 6) provide about 50 percent of the energy recovered in the gas. Ethylene represents 5 percent (vol) of the pyrolysis gas. The overall ethylene and acetylene yield is markedly increased at high temperatures for short gas residence times. The pyrolysis reactions are endothermic. The total amount of energy required for pyrolysing wood at 850°C roughly corresponds to 20 percent of its heating value.

Drill Stem Steels for Use in Geothermal Environments

Steels which are used in drill stem for conventional drilling have been selected primarily to satisfy certain static strength requirements and cost considerations. As the environments in which drilling is performed become more severe (e.g., in geothermal fluids) additional considerations must be given to the design of alloys which are resistant to general corrosion, stress corrosion, and corrosion fatigue. General design considerations for steel alloys which should provide an enhanced resistance to geothermal drilling operations are presented. These considerations include discussion of the chemistry and metallurgical substructure, and how their variation affects the mechanical and corrosion properties of steel used for drill stem applications. A duplex ferritic-martensitic steel has an advantageous combination of compositional and microstructural features which should lead to improved chemical resistance (particularly to hydrogen sulfide) as well as provide a good combination of strength and toughness properties. This duplex steel is based on the iron-2.0 weight percent silicon-0.1 weight percent carbon system, and offers the potential of enhanced performance in geothermal drilling as well as low alloy cost.

酸化鉄ペレットの溶鉄中への溶解速度

The melting rate of iron oxide pellets into iron melt and the reduction rate of pellets by carbon in iron melt were obtained by measuring the evolution rate of CO gas. The pellets were made from iron oxide powder by pressing and sintering and were not crushed into pieces when added onto the iron melt. The effects of the iron oxide phase, the oxide additives in pellets, and the temperature and the carbon content of iron melts on the melting and the reduction rates were investigated. The following results were obtained:(1)It has been found that the heat transfer was not the rate-determining step for the two rates. It is considered that the carbon diffusion in a boundary layer on the iron melt surface could be the rate-determining step.(2) The total reduction rate was constant for reduction degrees from about 20% to about 70%, where solid iron oxides were reduced by carbon dissolved in iron melt.(3) The apparent activation energy of the melting of pellets into the carbon saturated iron melt was 35 for Fe2O3; 18 and 41 for Fe3O4 above and below 1470°C, respectively; 44 and 79kcal/mol for FeO above and below 1470°C, respectively.(4) The melting rate of Fe2O3, Fe3O4 and FeO pellets into the iron melt at 1570°C was proportional to C0.57, C0.45 and C0.42 respectively, where C denotes the weight percentage of carbon in an iron melt. The minimum amount of CO gas evolved was obtained at about 2%C.

Melting Rate of Iron Oxide Pellets into Iron Melt

The melting rate of iron oxide pellets into iron melt and the reduction rate of pellets by carbon in iron melt were obtained by measuring the evolution rate of CO gas. The pellets were made from iron oxide powder by pressing and sintering and were not crushed into pieces when added onto the iron melt. The effects of the iron oxide phase, the oxide additives in pellets, and the temperature and the carbon content of iron melts on the melting and the reduction rates were investigated. The following results were obtained:(1)It has been found that the heat transfer was not the rate-determining step for the two rates. It is considered that the carbon diffusion in a boundary layer on the iron melt surface could be the rate-determining step.(2) The total reduction rate was constant for reduction degrees from about 20% to about 70%, where solid iron oxides were reduced by carbon dissolved in iron melt.(3) The apparent activation energy of the melting of pellets into the carbon saturated iron melt was 35 for Fe2O3; 18 and 41 for Fe3O4 above and below 1470°C, respectively; 44 and 79kcal/mol for FeO above and below 1470°C, respectively.(4) The melting rate of Fe2O3, Fe3O4 and FeO pellets into the iron melt at 1570°C was proportional to C0.57, C0.45 and C0.42 respectively, where C denotes the weight percentage of carbon in an iron melt. The minimum amount of CO gas evolved was obtained at about 2%C.

Diffusivity of carbon in iron and steels at high temperatures

Although the literature contains many measurements of the diffusivity of carbon in Fe and steels, recent progress in plasma carburizing has made this regime around 1050 °C and over 1% carbon concentration of great interest. We have measured the diffusivity of carbon in steel from 975 to 1075 °C up to 1.3% carbon concentration by the steady-state method. Our results are in agreement with previous measurements of Smith and Wells, Batz, and Mehl in the regime of low temperatures and carbon concentrations. Using activation energies determined over a wider temperature range by the latter authors, we derive as an empirical expression for D throughout the range of temperatures and concentrations investigated, D=0.47 exp (−1.6 C) ×exp[−(37 000−6600 C)/RT] cm2/sec. Here, C is expressed in weight percent carbon and the energies are in cal/mole.

Energy-Dispersive X-Ray Analysis for Carbon on and in Steels

Alpha-particle induced X-ray emission studies of steel samples have provided quantitative, non-destructive determinations of the carbon content in surface layers and in the bulk. The analyses were performed using the ALPHA-X™ technique of alpha-induced X-ray emission. Absolute carbon surface densities were determined directly from the ratio of the carbon X-ray count-rate for the unknown layers to that for standard free-standing carbon films. Assessment of the bulk detection limit was made using a steel standard with 0.5 weight-percent carbon. The threesigma minimum detection limits for twenty minute analyses were 0.1μg carbon/cm2 (equivalent to≃5 Å) in the layers and 1000 ppm carbon in the bulk.

Oil and Gas Generation by Laboratory Pyrolysis of Kerogen

Thermally immature mineral-free kerogens were pyrolyzed in the laboratory under air-free conditions at temperatures from 250 to 450°C for up to several weeks. Significant quantities of bitumen, gaseous hydrocarbons, water, and carbon dioxide were formed. Elemental composition of each kerogen type was measured before and after pyrolysis to monitor increased carbonization, decreased hydrogen/carbon ratios, and other elemental changes. Immature kerogens with atomic H/C ratios greater than 1.00 generate liquid hydrocarbons on pyrolysis, whereas those with lower atomic H/C ratios generate predominantly gaseous hydrocarbons. Principal generation of liquid hydrocarbons generally occurs when the weight percent of carbon in the kerogen is between 77 and 85%, and the atomic H/C ratio is above 0.80. Principal gas generation occurs between 85 and 89% carbon and between atomic H/C ratios of 0.40 and 0.80. Thus, principal gas generation occurs after principal oil generation. Actually, most kerogens have completed hydrocarbon generation when the carbon content reaches approximately 90% by weight and the atomic H/C ratio declines to 0.40. Kerogens with unusually high initial hydrogen contents undergo principal oil generation up o 87% carbon and principal gas generation up to 92% carbon, but within the same atomic H/C ratio limits as normal oil-generating kerogens. Pennsylvanian-age coal, which is composed of gas-generating kerogen with a very low hydrogen content, has principal gas generation from 88 to 93% carbon.

Interpretation of the chemical composition of bituminous coal macerals

Various methods of identifying and classifying macerals are evaluated on the basis of literature references and our own experimental results. Comparison of the diagrams H C vs O C , atomic C H ratio vs weight percentage of carbon, and atomic C H ratio vs atomic percentage of carbon demonstrates the advantages of the characterization of maceral composition by means of the atomic carbon percentage, which is a function of the content of all five organogenic elements that enter into the composition of the combustible matter of caustobioliths. Illustration by means of maceral analyses from the same seam, of results from pyridine extraction, and of humic acid composition further confirms this view.

Electrical conductivity of molten FeNiSC core mix

The electrical conductivity of liquid (Fe 90Ni 10) 3S 2 saturated with 2.6 weight percent carbon averages 2.7·10 5 mho/m at 1000°C and zero pressure. This may imply a slightly lower electrical conductivity for the earth's core than that obtained by extrapolating the properties of pure liquid iron and solid iron alloys to core pressures and temperatures. Although a sulphur-rich core would have a smaller proportion of sulphur, the effect of lowering the sulphur content of the FeNiSC liquid to about 15 weight percent would be unlikely to increase the conductivity above 5·10 5 mho/m.

Oil Shale - An Impending Energy Source

Recent political, technological, and economic developments lead to optimism for the commercial exploitation of oil slide as a source of energy. Although presently the production of oil by mining or aboveground retorting seems feasible, the production of oil by in-situ techniques or of pipeline gas by either aboveground or underground gasification is less probable for a while. Introduction Where is oil shale going now? After many years of research, during which enthusiasm for development has periodically waxed and waned, the climate for development seems once again favorable. This report attempts to tell why. It includes a review of the size, location, and characteristics of the deposits, an assessment of the status of the processing technology, and a description of a planning program for oil-shale development. An attempt to weigh positive and negative factors to develop a current outlook results in a moderate optimism for the near-term development of an oil-shale industry. The Oil-Shale Deposits Oil shales are widely distributed throughout the U. S., but only those of the Green River formation of Colorado, Utah, and Wyoming have received appreciable attention as a possible source of fuels and chemicals. The location of the Green River deposits is indicated on Fig. 1. They underlie an area of about 17,000 sq miles in four principal basins: the Piceance Creek basin of Colorado, the Uinta basin Piceance Creek basin of Colorado, the Uinta basin of Utah, and the Washakie and Green River basins of Wyoming. Their energy potential has been estimated at more than 1 trillion bbl of oil, with about 600 billion bbl represented by the richer deposits those that assay greater than 25 gal of oil per ton in continuous sections of shale 10 ft or greater in thickness. The shale deposits vary in accessibility from those with no overburden (outcrops) to very deeply buried shales in the western Uinta basin. The outcrop (called the Mahogany ledge because of its color) along the cliffs above the Colorado River at the southern edge of the Piceance Creek basin has been utilized to study mining and retorting processes. In this Colorado basin, continuous sections of shale several hundred feet thick occur. Oil-yield assays average more than 25 gal/ton.: In Utah and Wyoming the sections of rich shale are not so thick, and in Wyoming they are often interspersed with alternating beds of lean shale. Mineralogically, the oil shales vary in composition from rocks composed of illite clay to those containing dawsonite, nahcolite, and potash feldspar as the principal minerals or to those made up of calcite and principal minerals or to those made up of calcite and dolomite. The minerals often occur as small crystals. When the organic material is present in significant quantity, it seems to be the cementing agent that holds the rock together, so that removal of the organic material from a rich shale leaves a residue with little structural stability. A typical oil shale from the stratum called the Mahogany zone in Utah and Colorado has the following composition: Organic matter, percent of shale: 13.9 Elemental composition, weight percent Carbon 80.5 Hydrogen 10.3 Nitrogen 2.4 Sulfur 1.0 Oxygen 5.8.

Carbon Isotopes in Pelites of the Precambrian Uncompahgre Formation, Needle Mountains, Colorado

Carbon isotopic ratios and weight percentages of carbon were measured in 15 samples of slate, phyllite, and schist of the approximately 1500- to 1600-m.y.-old Uncompahgre Formation of the Needle Mountains, southwestern Colorado. Rocks with less than 1 percent total carbon, all of which is reduced, have δC 13 values of −23 to −28 per mil, whereas those with 1 to 6.4 percent carbon have δC 13 from −29 to −31 per mil. In general, the slates and phyllites contain more carbon and isotopically lighter carbon than do the schists of higher metamorphic rank. Increasing loss of C 12 -enriched methane with increasing intensity of metamorphism is suggested to account for these differences.

Flame ionization detector response for the carbonyl carbon atom in the carboxyl group of fatty acids and esters

The response of the carboxyl group in free fatty acids, although markedly less than the equivalent response for a methylene carbon atom in the lower fatty acids, approaches this value in acids with six or more carbon atoms. The relative responses for these higher fatty acids are then proportional to the relative weight percent carbon content on a weight basis. In esters a complex molar response pattern is evident, apparently due to scission of the ester linkage with the lower acids to give an alcohol with a response of half a methylene carbon atom, and an acid or carboxyl group fragment with little or no response. In the methyl esters of saturated fatty acids with nine or more carbon atoms the net loss in response falls to the equivalent of one methylene carbon atom and the relative response is the proportional to the relative weight percent carbon content based on the number of carbon atoms in the fatty acid chain. Formate esters apparently give slightly higher responses than other esters of the same net number of carbon atoms. This suggests that the difference observed in the various esters may be due in the cases of those esters with higher responses to formation of a hydrocarbon in lieu of an alcohol during the initial scission of the ester group linkages. Alternatively in the esters other than formates the carboxyl group may give an increasing response as the fatty acid chain length increases.

Statistical Study of Coals on the Basis of their Analytical Values (II)

In this third report, the reporter has studied statistically the relation between the moisture and the ultimate analytical values in various coals, examining the relation of the moisture to hydrogen content and that to oxygen content separately;he has eliminated the relation between these contents with partial correlation analyses.The infer ence drawn from the study is as follows:(1) In the area covering brown coal and anthracite, the retation of the moisture to the carbon weight percentage is similar to the relation of density to the carbon weight percen-tage.But the minimum value of the moisture slips off that of density in connection with the carbon weight percentage.(2) The moisture of coals whose carbon weight percentage is lower than that at its minimum has a positive interrelation chiefly with the oxygen content, and scarcely has any correlation with hydrogen.(3) In contrast to that, the moisture of coals whose carbon weight percentage is higher than at its minimum has a negative interrelation with hydrogen content.Excepting the coals in which is contained extremely small amount of hydrogen, i.e.whose H/C atomic ratio is less than 0.2, the amount of oxygen has scarcely anything to do with it.(4) In the low-coalification coals, physical adsorption prevails, whereas chemical ad-sorption comes to gain importance as the coalification proceeds.(5) In respect to the moisture too, peat and lignite are proved to have quite different qualities from the coals of the area covering brown coal and bituminous coal.(6) Though the moisture contained in peat has close relation with the chemical com-ponents of peat, such relation is hardly discerned in lignite.