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The influence of coal rank, maceral composition, particle size, pressure, temperature and heating rate on the ignition of single coal particles was studied with a heated-grid apparatus (1400 K, 10 MPa) working in connection with a high-speed camera. Experimental conditions were chosen to simulate the conditions of p.f. combustion and to provide data for a kinetic description. The temperatures of...
Semiquantitative analysis of the infrared spectra from 650 to 4000 cm -1 of nine coal tar pitches supplies excellent information on the concentrations of several functionalities. Relations have been found between the infrared data and the solubility, coke yield and composition of the volatile fraction of these pitches. The results contribute to a better understanding of pitch structure.
The influence of initial pressure of hydrogen on the catalytic coprocessing of Bergueda lignite with a vacuum residue of petroleum was studied, using an Fe 2 O 3 catalyst. Coal conversion increased with initial hydrogen pressure up to 10 MPa, but there was no significant increase beyond this value. However, oil conversion increased with pressure up to 12 MPa. On the other hand,...
The response of three high-ash Spanish anthracites to agglomeration with n-heptane was evaluated by measuring the organic matter recovery, ash rejection and pyritic sulfur rejection. The influence of oil concentration and coal particle size on the agglomeration results was investigated. The combustible recoveries of these coals increased to a maximum as the n-heptane concentration is raised, and...
Autoclave tests confirmed that CO + H 2 O was superior to hydrogen for solubilization of Black Thunder subbituminous coal (80-88 wt% coal conversion versus 55 wt% with H 2 at 390°C for 30 min). Syngas could be substituted for pure CO as long as the proportion of other gases did not exceed one third of the total. Potassium carbonate was the preferred water gas shift catalyst from...
Comparative combustion studies were performed on particles obtained from pulverized bituminous coal and waste automobile tyres (rubber). Particle size cuts of 75-90 and 180-212 μm were burned in a thermogravimetric analyser, at low heating rates, and in an electrically heated drop-tube furnace, at high heating rates. The combustion of individual particles in the drop-tube furnace was observed with...
Residues from the liquefaction of Black Thunder subbituminous and Illinois No. 6 bituminous coals in an autoclave and a bench unit were examined petrographically. Optical microscopy proved valuable for ranking the samples on the basis of overall coal conversion and presence of vitroplast, granular residue and inertinite. It was observed that in the autoclave that runs on Black Thunder coal, K ...
The results obtained from a variety of techniques (vapour adsorption, selective adsorption of caffeine and immersion calorimetry) used to characterize activated carbons of industrial origin are compared. It is shown that gate effects due to constrictions, and often overlooked, can be revealed by simple experiments with larger molecular probes. Immersion calorimetry appears to be a simple and efficient...
The influence of the addition of SO 2 , Na 2 SO 3 or CaSO 3 1H 2 O to aqueous suspensions of Siersza coal-cleaning refuse on its chemical transformations during oxidative alkaline treatment was investigated. Experiments performed in a froth column under mild conditions (90°C, 0.1 MPa) resulted in (1) marked degradation of the coal to solubilized products including...
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