Thermophysical properties of coal liquids. 1. Selected physical, chemical, and thermodynamic properties of narrow boiling range coal liquids

Abstract

Liquid products from the SRC-II processing of a high volatile bituminous coal were distilled into narrow boiling range fractions with average boiling points ranging up to 800 K. Liquid density, thermal conductivity, and viscosity were measured at temperatures to 505 K, and specific heat was determined to 600 K. Other property determinations included molecular weight, pour point, elemental analyses, water content and solubility, and hydrocarbon types. Both organic oxygen content and water solubility showed a pronounced maximum for the fraction having an average boiling point of 470 K and significantly Influenced density. A secondary distillation on six different fractions spaced over the entire boiling range yielded heart cuts spanning 4-26 K that were used for measurement of surface tension, heat of vaporization, and vapor pressure at temperatures to 755 K. Property data for all the fractions are compared with other published data and existing property correlations.

Vapor pressures and heats of vaporization of primary coal tars

“…Thus, the general opinion was that the UngerSuuberg correlation over-predicts boiling point, or under-predicts vapor pressure. [Gray et al, 1983[Gray et al, , 1985. The FGP correlation agrees with the measured vapor pressures of coal liquids and boiling points of pure compounds over a wide range of pressures [Fletcher and Kerstein, 1992].…”

Characterization of tars from Estonian Kukersite oil shale based on their volatility

“…4 suggests that if the tar consisted of a series of paraffinic compounds, the tar vaporization would be encompassed by vaporization of compounds with molecular weights between 150 and 750 g/mol (median at 450 g/mol). This is also a hint towards the well-known observation that chemical mixtures such as tars-and oils-derived from fossil fuels vaporize in distillation-like fashion and the volatility is a function of the molecular weight distribution of the tar or oil [11][12][13]. Figs.…”

Heat of re-forming a coal liquefaction product from distillate fractions

“…The liquids derived from hydrogenation of coal contain high concentrations of multi-ring aromatic compounds and of polar organic compounds with functional groups capable of forming hydrogen bonds (2)(3)(4). As a result of strong intermolecular interactions among these aromatic and polar compounds (5)(6)(7)(8), correlation procedures previously developed for petroleum fractions usually cannot be used for estimation of the thermodynamic properties of coal liquid distillates (9). The development of improved correlation procedures requires thermodynamic data for coal liquefaction products at temperatures and pressures relevant to post-liquefaction separation processes such as distillation.…”

“…Heat capacities and enthalpies of coal liquids have been collected for distillates covering the whole range of boiling temperatures of liquids obtained from different coals (7)(8)(9)(10)(11)(12)(13) predict the physical and thermodynamic properties of the liquids from easily measured parameters.…”

“…A case in point is the observation that distillate fractions from coal liquids sometimes have much lower boiling points than distillation temperatures (7). The AH values for re-forming the liquid from the several distillates should be useful in identifying and quantifying any strong intermolecular interactions that affect the distillation curve.…”