Coal-Liquid Mixtures

At this point, it is appropriate to consider another form in which coal can be used as a fuel, and this is as COM or coal-water mixture (CWM). A coal-liquid mixture (CLM) consists of finely crushed coal suspended in varions liquids and typically small amounts of chemical additives that improve 

Stability and other physical properties. The primary purpose of CLM is to convert coal from a solid to an essentially liquid form, which, with certain equipment modifications, allows the coal to be transported, stored, and burned in a manner similar to fuel oil. 

In addition to COM and CWM, CLM technology has been extended to include mixtures of coal-methanol, solvent-refined coal-oil, petroleum-coke oil, and other solid-fuel-liquid mixtures. However, for the purposes of this text, the contents of this section are limited to the more mature technologies involving COM and to CWM (Morrison, 1980 Argonne, 1990c). 

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Albertsson (Paiiition of Cell Paiiicle.s and Macromolecules, 3d ed., Wiley, New York, 1986) has extensively used particle distribution to fractionate mixtures of biological products. In order to demonstrate the versatility of particle distribution, he has cited the example shown in Table 22-14. The feed mixture consisted of polystyrene particles, red blood cells, starch, and cellulose. Liquid-liquid particle distribution has also been studied by using mineral-matter particles (average diameter = 5.5 Im) extracted from a coal liquid as the solid in a xylene-water system [Prudich and Heniy, Am. Inst. Chem. Eng. J., 24(5), 788 (1978)]. By using surface-active agents in order to enhance the water wettability of the solid particles, recoveries of better than 95 percent of the particles to the water phase were obsei ved. All particles remained in the xylene when no surfactant was added. 

Shinn, J. H. Hershkowitz, F. Holten, R. R. Vermeulen, T Grens, E. A., "Coal Liquefaction in Inorganic-Organic Liquid Mixtures". Paper presented at Am. Inst. Chem. Engrs. annual meeting, Miami, Florida, November 1977. 

The separation of the components of a liquid mixture by treatment with a solvent in which one or more of the desired components is preferentially soluble is known as liquid-liquid extraction — an operation which is used, for example, in the processing of coal tar liquids and in the production of fuels in the nuclear industry, and which has been applied extensively to the separation of hydrocarbons in the petroleum industry. In this operation, it is essential that the liquid-mixture feed and solvent are at least partially if not completely immiscible and, in essence, three stages are involved ... 

The flame ionization detector (FID) can be used for the detection and quantitative estimation of components separated by the GC. Identification of major species can be achieved by a mass spectrometer which can not be used for quantitative analysis of complex mixtures such as coal liquids. 

Mass spectrometers used to be expensive and complex for routine use as a GC detector. The Ion Trap Detector (ITD, Finnigan) is a low priced mass spectrometer (MS) for capillary chromatography. Three analytical tools - SEC, GC, and ITD - are incorporated into a powerful analytical system for the analysis of complex mixtures such as coal liquids, petroleum crude and various refinery products. The instrumentation and the SEC-GC-MS analysis of a coal liquid are presented in this paper in order to demonstrate the technology. 

Oil, or petroleum, is a liquid mixture of medium-length hydrocarbons (shorter than the hydrocarbons in coal, but longer than the hydrocarbons in natural gas). It is usually black or dark brown and has a strong smell, but the characteristics of oil vary greatly, depending on its specific ingredients. 

Very commonly, however, the sample of interest is not a pure compound, but is a complex mixture such as a coal liquid. As a result, a specific structure determination for each molecular type is not practical, although it is possible to determine an average chemical structure. Features which may be determined include the hydrogen distribution between saturate, benzylic, olefinic, and aromatic sites. The carbon distribution is usually split into saturate, heterosubstituted saturate, aromatic + olefinic, carboxyl, and carbonyl types. More details are possible, but depend greatly on the nature of the sample, and what information is desired. 

In this paper, we present the results of an experimental study on the phase behavior of well-characterized binary mixtures which represent the more complex mixtures that arise in SCF extractions of petroleum residua and coal liquids. These binary mixtures consist of pentane and toluene with meso-tetraphenylporphyrin (TPP). Porphyrins occur naturally in crude oils (11,12) and represent an important class of high molecular-weight constituents of these oils, including those which contain heavy metals, such as nickel and vanadium. 

This reactor allows easy data collection for high-temperature, high-pressure reaction systems that have difficult flow properties. This includes reactants that are solid at room temperature or mixtures of solids and liquids. Typical reactions performed in autoclaves are coal liquefaction, petroleum residuals and coal liquids upgrading, and high molecular weight hydrogenation experiments. 

S- and 0-compounds, saturation of the N- and O-heteroatom ring was necessary prior to hydrodenitrogenation, HDN, but that this was not the case for S-compounds. This work suggests that the reaction network obtained for a model nitrogen compound will be the one that would occur in complex mixtures such as coal liquids.(7)... 

Microstructure. The characterization of coal-derived asphaltene is quite similar to that of petroleum-derived asphaltene. Since it is anticipated that coal-derived asphaltene will have acid/neutral and base characteristics (26, 36), the average structure of both must be considered. In Table III, Structure I is amphoteric (or slightly basic), and Structure II is an acid/neutral representation. A mixture of both may be typical of the average structure of a coal-derived asphaltene. At present, we will illustrate this by an asphaltene obtained from coal liquid of the Synthoil process. (The coal is hvAb, West Kentucky, Homestead Seam the coal liquid is obtained by catalytic hydrogenation at 450° C and 4000 psig having %C, 86.7 %H, 8.38 %N, 0.93 %S, 0.09 %Q, 3.2 and %Ash, 0.7.)... 

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