L. Srinivasan et Vn. Kabadi, THERMODYNAMICS OF COAL-DERIVED FLUIDS .2. VAPOR-LIQUID-EQUILIBRIA OF COAL LIQUID FRACTIONS, Fuel, 73(5), 1994, pp. 714-722
A thermodynamic model for prediction of vapour-liquid equilibria (VLE)
in coal-derived fluids has been developed. The model uses group contr
ibution methods for property evaluations and a continuous thermodynami
cs approach for VLE computations. A coal fluid is defined by multiple
molecular weight distributions, and each distribution is represented b
y an average molecule with fixed relative proportions of different fun
ctional groups. Besides the hydrocarbon group, phenolic, pyridinic and
thiophenic groups are used to represent O, N and S heteroatoms. From
the results it is concluded that for low-boiling coal liquid fractions
the phenolic compounds need to be treated separately, as opposed to t
he use of a single average molecule to define the coal liquid. Compari
son with published data shows that the model is successful in predicti
ng boiling ranges for low-boiling fractions. Failure of the model at h
igher temperatures is attributed to the binary interaction parameters
in the UNIFAC model which are regressed from low-temperature binary VL
E data.