Viscosity of Coal-Derived Liquids. 1. A Group Contribution Method for Pure Model Compound Liquids

Abstract

Viscosity of coal-derived liquids is an important property useful in the design of coal liquefaction processes as well as for understanding the flow characteristics of coal liquids. A new model for the prediction of viscosity of coal liquid model compounds has been developed. The model uses Andrade equation with the constants A and B given by a well-defined group contribution method. The group contribution method uses the group definitions, group parameters, and procedure for property calculation, such that all the heteroatom functionalities and some significant molecular structures prevalent in coal-derived liquids are included. The model was tested using experimental data from literature and the average error was determined to be 11.55%. Two of the prominent liquid viscosity models available in the literature were also evaluated using the same experimental data set of coal model compounds. These models could not be applied to all the compounds, as some model parameters were not available. Both the models resulted in errors a few percent higher than obtained from our model, indicating that for coal model compounds the correlation developed here is more widely applicable and more accurate than any other model in the literature. Future efforts will include extension of the correlation to mixtures of coal model compounds and description of a procedure to compute viscosities of appropriately characterized coal-derived liquids.