Coal conversion phases

These results indicate that the aliphatic portion of the coal is very important in the initial phases of coal conversion. Weak linkages must be associated with the aliphatics in coal though they have not as yet been completely identified. Both of the above methods show an increase in the aromatic methyl content of SRCs at short times which indicates that cleavage at a benzylic carbon is important in dissolving the coal. 

If the mobile phase is present in a significant concentration, as suggested by the results of solvent extraction studies (1,8), the practical meaning of the mobile phase to coal conversion processes may be profound. In coal liquefaction, two stage processes emphasizing the mobile phase and the macromolecular structure separately could well be most economical. In devolatilization kinetics, at least two sets of kinetic parameters are necessary to model the devolatilization phenomena associated with the mobile phase and the macromolecular structure respectively since the mobile phase components devolatilize at much lower temperatures than the macromolecular structure components 0. In addition, the mobile phase appears to have a significant influence on the thermoplastic properties of coal (0 and thereby on coke quality. 

Singer PC, Lamb JC III, Pfaender FK, et al. 1979. Treatability and assessment of coal conversion wastewaters. Phase I. Industrial Environmental Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC. 

Because ASPEN is to be used with coal conversion processes, its streams can be designated to carry an arbitrary number of solids or solid phases. This is done by specifying any number of substreams. In fact, the conventional vapor/liquid stream is normally assumed as a substream and solids can comprise other substreams. For the conventional vapor/liquid substream, process data is carried on component molar flows, total molar flow, temperature pressure, specific enthalpy, specific entropy, density, molar vapor fraction, molar liquid fraction, and molecular weight. For solid substreams, which are called "non-conventional substreams," the characterizing data is not as deterministic. The information associated with these substreams is called "attributes". Such attributes may be particle size distribution, ultimate and proximate analyses, or other material specific information. Another type of substream is an "informa-... 

The thermodynamics of corrosive alkali salt-oxide interaction is not well established. In an assessment of research needs for materials in coal conversion, the need for carbonate-silicate melt studies, including activity and phase equilibrium measurements, was stressed (31 ). The lack of thermodynamic data for fused salts, and their reactions with oxides and alloys leading to models of hot corrosion, was also indicated. 

Low sulfur fuel oils were prepared from a high volatile bituminous coal by hydrogenation under high temperatures and pressures. At a coal conversion of 80%, the ratio of oiU to-gas yields was about three, and 23% of the coal sulfur was contained in the oil. Sulfur content of the oil, however, remained the same at different coal conversion levels. The data obtained in the semi-continuous, dilute phase hydrogenation system showed that the whole oil can be directly used as a fuel oil where 1% sulfur is tolerated. Fuel oils containing 0,5 and 0,25% sulfur were produced by desulfurization of the whole oil, A preliminary economic evaluation indicated that low sulfur fuel oils can be produced from coal by hydrogenation at a manufacturing cost of about 5-6 per barrel. 

Kinetic Phases of Coal Conversion in Thermal Plasma... 

Kinetic Analysis of Thermal Plasma Conversion of Coal Kinetic Features of the Major Phases of Coal Conversion in Plasma... 

Pyrolysis is the first step of aU coal conversion processes and its understanding is essential for effective use of coal. The pyrolysis of coal consists of two series of reactions first is the primary decomposition that consists of the formation of radical fragments and their stabilization and the other is the secondary gas phase reaction of gaseous components produced by primary decomposition. The product yield during the pyrolysis depends on coal type and operating conditions of pyrolysis (Howard, 1981a,b Gavalas, 1982 Kawamura et al., 1993). 

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