Showing papers in "Fuel in 1988"

TL;DR: In this article, coal from lignite to anthracite was extracted at room temperature with CS2-N-methyl-2-pyrrolidinone (MP) mixed solvent (1:1 by volume), which was found to be a very efficient solvent for the extraction of bituminous coals.

TL;DR: In this paper, the authors considered the use of FT-i.r. spectra for the quantitative determinations of aliphatic hydrogen, H al, and aromatic hydrogen H ar, in coals.

TL;DR: In this paper, small angle neutron scattering has been used for studying the asphaltene macrostructure in liquid dispersions Thanks to modelling calculations, the experimental data have been interpreted in terms of flat particles or sheets with a diameter in the range (6-20 nm) and a mean thickness of about 06-08 nm.

TL;DR: In this article, a series of heterocyclic compounds present in coal volatiles have been pyrolysed in a flow reactor to obtain kinetic data on their thermal stability.

TL;DR: In this article, pyrolysis data from degraded wood and coalified logs or stems was examined for coalification and the results showed several stages of evolution during coalification, including the selective degradation of cellulosic components and preservation of lignin-like components, and the degradation of methoxyl groups with replacement by phenolic hydroxyls such that catechol-like structures are produced.

TL;DR: In this paper, chemical changes occurring during dry phase oxidation with air of a subbituminous coal have been investigated by FT-i.r. spectroscopy, and the results have shown that the aliphatic structure is more reactive than the aromatic one.

TL;DR: In this paper, the effects of variations in the maceral composition of coal, in association with rank, upon reactivity in combustion were examined using a simple reactivity test, and the reactivity ranges for two rank series of single seam coals were determined along with the reactionivity ranges obtained from studying lithotypes of various maceral concentrations of a single coal.

TL;DR: In this article, a series of derivatives of benzene with other functional groups was studied in a flow reactor to obtain a data set of thermal stabilities of coal-related compounds.

TL;DR: In this article, the authors measured densities, porosities and surface areas of coal macerals and concluded that only a fraction of the surface of coal is composed of hydrophilic sites.

TL;DR: In this article, it was shown that most of the CO2 uptake is not due to imbibing of CO2 within the coal structure but rather to CO 2 uptake in open and closed (to He) micropores.

TL;DR: In this paper, the reaction kinetics of char-CO2 gasification at atmospheric pressure were investigated in a thermobalance reactor using four coals of different rank, and the effects of coal rank (lignite to semianthracite), particle size (0.18 to 1.00 mm), reaction temperature (700 to 900 °C) and concentration (30 to 100 vol%) of the reactant gas (CO2) on the conversion rate of char gasification were determined.

TL;DR: In this article, three asphaltene dispersions have been studied by small-angle X-ray scattering, and the macrostructure model used for the curve simulations is based upon a distribution of thin discs which all have the same thickness (3.4 A) and a radius which follows a power law such as r β (13 A ⩽ r ⌽ 800 A ), which suggests that these membranes could result from the aggregation of small Yen's elementary units.

TL;DR: In this article, the effect of temperature, time, mineral matter and oxygen concentrations on low-rank coal has been investigated using synchronous fluorescence spectroscopy, showing that polyaromatic ring absorptions in these conditions occur in the 2, 3 range.

TL;DR: Vitrinite reflectance profiles have been constructed for twelve borehole sequences from the Carboniferous of the eastern and central Midland Valley of Scotland as discussed by the authors, which reveal extensive thermal aureoles that have modified organic matter for many tens of metres above and below the sill-sediment contacts.

TL;DR: In this paper, the principal features of wood charcoal particle gasification in CO2 gas environment at atmospheric pressure were investigated and correlated by an empirical relationship for the rate of gasification of the particle as a function of the variables investigated.

TL;DR: In this paper, the problem posed by sample compressibility and pore-filling as interacting processes in a mercury penetration experiment is discussed, and the fractal dimension is observed to be inversely correlated with pore volume and the volume of trapped mercury.

TL;DR: In this paper, the effects of char formation temperature, conversion, coal particle size and char particle size on the rates of coal chars derived from three different bituminous coals were measured at 500 °C.

TL;DR: In this article, a 0.3 m internal diameter combustor was used for spouted, fluidized and spout-fluid bed combustion of three bituminous coals or coal rejects of differing ash contents.

TL;DR: In this paper, the rate of formation of acetylene, the most interesting product of coal pyrolysis in hydrogen plasma, is determined by heat transfer to coal and by the kinetics of pyrotechnics and homogeneous gas phase reactions.

TL;DR: Goynuk and Seyitomer oil shales were pyrolysed using a Heinze retort at 520 and 900° C, producing high and medium oil yields, respectively.

TL;DR: In this paper, the authors proposed mechanisms for natural coalification and confined-system pyrolysis, where permanent contact between the components of the effluents released (some of them acting as H-donors, others as radical stabilizers) and the solid phase must be made.

TL;DR: In this article, the desulphurization of four samples of Central Anatolian lignites by treatment with aqueous NaOH was examined, and the results showed that organic sulphur was not removed from three of the samples but in the other lignite 12.5 wt% of the organic sulfur was removed by treatment at 70 °C for 8 h with 20 wt/v% NaOH solution.

TL;DR: The literature on microbial desulphurization of coal is reviewed in this article, which provides a compilation of the scattered information available on the salient features of this biogenic process and concludes that although the process is still in its infancy, it could be seen as a technology of the future.

TL;DR: In this paper, a mathematical model to predict spontaneous combustion in coal stockpiles is derived by breaking up the dump into three regions where different effects dominate, such as reaction, heat transfer and flow.

TL;DR: In this paper, the C-13 and H-1 n.m. method for estimation of the average molecular parameters of polycyclic aromatic compounds has been studied further, which can determine the bi-aryl linkages and the number of aromatic nuclei and has been applied to the characterization of pyrolytic pitch fractions.

TL;DR: In this article, an unstable catalytically-cracked distillate fuel has been analysed to identify compounds involved in the formation of sediment during its storage, and two groups of compounds, which react in the presence of acid to form the polar, highly coloured fraction of sediment, have been extracted from the fuel and characterized by t.l.r. and m.s.

TL;DR: In this paper, the emission spectra of the liptinites are discussed in terms of changing chemical composition at different levels of maturity, and the spectra clearly illustrate that the hydrocarbon-generating capacities of different liptinite macerals reach their maxima at different maturity levels.

TL;DR: Differential scanning calorimetry (d.s.c.) has been used to characterize crude petroleum and a thermal fingerprint can be obtained in a short time with a single experiment as discussed by the authors.

TL;DR: In this article, the authors measured the diffuse reflectance spectra of coal powders and found that the broad absorption bands can be attributed to the real electronic transitions of polycondensed aromatic hydrocarbons.

TL;DR: In this paper, the swelling properties of a rank range of eight coals were studied using two series of solvents, in terms of electron donor number and pK b values.