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The formation of organic compounds during steam drying of bark chips in the exhaust steam was investigated as a function of time, with temperature and age of bark chips as independent parameters. The rate of formation strongly depends on temperature. The results suggest that the amount of organic compounds in the exhaust steam can be minimized by drying stored bark at low temperature, with a...
Three methods of preparing catalysts for direct coal liquefaction (DCL) are presented, using ferric sulfide as a precursor. Of these, one involves the physical mixing of the coal and the supercritically dried catalyst, and the other two involve impregnation of the catalyst in the coal. In one of the latter two, the catalyst is prepared in situ as well. The in situ impregnated sample (IIS) of catalyst...
The temperature dependence of average molecular mass and carbon content of the isotropic matrix prepared by heat treatment of coal tar pitch exhibits distinct local minima at 400°C. This temperature agrees approximately with the position of local extremes on viscosity curves, designated as maximum/minimum. The anomalies were attributed to accelerated mesophase formation affecting the chemical and...
Changes in the combustion reactivity of sets of chars from five coals have been determined as a function of increasing devolatilisation temperature, heating rate and pressure. Chars were prepared in wire-mesh pyrolysis reactors, where evolving volatiles are rapidly removed from the vicinity of the heating coal. Samples were heated at rates between 1 and 5000 Ks -1 to temperatures up...
Conversion of low-rank coal to liquid products in tubular reactors decreased sharply when the reactors were mounted other than horizontally. The effect was greater for reactions in the absence of solvent than for those in the presence of tetralin.
Organic sulfur removal from coal with supercritical methanol as solvent, combining extraction and reaction, was studied. Experiments were carried out in a 300 ml batch reactor with Illinois coal at a coal/methanol weight ratio of 1 : 1, 400-450°C and various solvent densities and reaction times. Coal loss, 25 wt%, was relatively insensitive to operating conditions. Sulfur removal was highest...
During the carbonization of coal-tar pitch the viscosity of the pitch decreased at 200-360°C, reached a minimum at 360-400°C, and then increased at 400-450°C. The decrease of the viscosity of the pitch after its melting may be attributed to the solubilization of benzene insolubles (BI) (β-resin and quinine insolubles) by the solvation of benzene solubles (BS) to BI, in addition to the increase of...
Primary and secondary reactions of cellulose pyrolysis are modeled through a semi-global, multi-step scheme based on lumping the different products into three groups: gas, tar and char. The description of chemical processes is coupled to an unsteady, one-dimensional, variable property model of transport phenomena including heat convection, conduction and radiation, volatile tar and gas transport...
Differential scanning calorimetry (DSC) has been used to investigate the thermal transitions occurring for a series of eight Argonne Premium coals. Each of the coals was subjected to different heating/cooling profiles in order to determine the effect of cooling at varying rates on the second order process and to determine the effect of temperature of exposure on the second order process. The variable...
1 3 C solid-state n.m.r. spectra of samples of 14 coals and their pyridine residues representative of the three depositions in the Shanxi province of the People's Republic of China are described in detail. The results confirm those of previous infrared spectroscopy in showing these vitrinite-inertinite coals to have similar chemical structures and aromaticities to coals of the same rank from...
In the liquefaction of Yallourn, Wyoming, Wandoan and Illinois No. 6 coals, using water and carbon monoxide as a hydrogen source, iron pentacarbonyl, Fe(CO) 5 , together with sulfur acts as an excellent catalyst precursor. The coal conversion and the oil and asphaltene yields depend greatly on the amount of added water, CO pressure and especially reaction temperature. The liquefaction of Yallourn...
The process of coal desulfurization by processing with air-steam mixture at 623-673 K was investigated. Three coals of different rank (high- and low-volatile bituminous and anthracite) and sulfur content were used. The degree of desulfurization of the coals was 58.2, 79.8 and 81.4% respectively, and the degree of pyritic sulfur removal 96.8, 98.4 and 99.4% respectively.
A base fuel having a cetaine number of 40.2 was split into nine batches. To eight of these batches, varying quantities of ignition improver were added, resulting in cetane numbers up to 62. The base fuel and each of the blends with ignition improver were used in a co-operative fuel research (CFR) diesel engine, and the exhaust emissions of NO x unburnt hydrocarbons (UHC) and smoke were measured,...
Reactivity profiles are defined and measured with thermogravimetry for a dense metallurgical Longyear coke, a polymer-derived porous active carbon, Carboxen 1000, and three flame-chars, Illinois #6, Pittsburgh #8 and New Mexico Blue #1. For each sample it is found that the reactivity profile can be separated into a chemical kinetics expression and a structural profile describing reactivity evolution...
The activity of haematite, magnetite, pyrite and pyrrhotite containing ore catalysts, modified by treatment in a tensile-energy planetary activator mill and by elemental sulphur additions, has been studied in lignite hydrogenation and coal-derived liquid hydrocracking processes. The application of modified ore catalysts resulted in a significant (by two to four times) increasing of lignite conversion...
Chemical structure changes in Condor shale oil during catalytic hydrotreatment were studied based on elemental analysis, 1 H-NMR analysis, TLC/FID and GCD. Catalytic activities of red-mud/sulfur and Ni-Mo catalysts were discussed as to the hydrogenation and hydrogenolysis of structure units in addition to the removal of heteroatoms.
The capture of H 2 S by both limestone and dolomite was studied with a pressurized thermogravimetric apparatus. The experimental conditions were chosen to correspond to the conditions typical in a pressurized fluidized bed gasifier. Depending on these conditions the limestone reacts either uncalcined (CaCO 3 ) or calcined (CaO), and the dolomite either half-calcined (CaCO 3 ...
The synergistic effect due to the addition of mixed lignosulfonate catalyst and the role of each catalyst component during steam gasification of a model char were evaluated quantitatively. The carbon matrix became saturated quickly with respect to calcium. However, this saturation does not generate any problem for the effectiveness of the sodium catalyst in this mixed catalytic system.
The quality of interfaces between reactive and inert textural components in cokes produced from three single coals with added petroleum coke and calcined anthracite were quantified by microscopy and expressed as an interface quality index, IQI. For interfaces involving the three inert components studied, the IQI decreased in the order: inherent inerts > petroleum coke > calcined anthracite...
The behaviour of bitumen was investigated by differential scanning calorimetry. It is shown that two glass transitions take place after cooling at constant rate. The magnitude and temperature of these transitions depend on the cooling rate. At low cooling rate, (< 1 K min -1 ) the glass transition at the higher temperature vanishes and an endothermic peak is obtained. From these...
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