Pyrolysis, coal aromaticity, NMR parameters, cross-validation, coal char, coal tar


Simulations of large-scale coal combustors rely on accurate submodels to describe the chemical and physical changes in coal during reaction. Typically, simplified empirical submodels are tuned to experimental data to reduce the computational complexity. When data are not readily available, simplifying assumptions are used, which can create inaccuracies and biases in a large simulation. One such simplifying assumption in coal research is how to describe the elemental composition of primary pyrolysis products. This paper explores several different empirical model forms to predict the dry, ash-free fractions of C, H, O, N, and S in both the char and tar, using variables such as parent coal composition, reaction conditions (temperatures and particle residence times), and key coal structural parameters derived from NMR measurements to improve the treatment of coal chemistry in large simulations. These model forms were correlated to existing data using a wide range of experimental data using a cross-validation procedure. Since coal structural values can be expensive to measure, several correlations from the literature were used to estimate these values on the basis of information from the proximate and ultimate analyses of the parent coal, including a new correlation for the coal aromaticity. These model forms were tested against a set of measured elemental compositions of tar and char to find the best fit to use in the cross-validation process. The best empirical models are presented that predict the elemental composition of the coal char and tar after devolatilization. 1. INTRODUCTION Current areas of coal research have advanced the understanding of the processes involved in coal pyrolysis; however, little is

Original Publication Citation

Richards, A. P., C. Johnson, and T. H. Fletcher, “Correlations of the Elemental Compositions of Primary Coal Tar and Char,” Energy and Fuels, 33:10, 9520-9537 (2019). DOI: 10.1021/acs.energyfuels.9b01627

Document Type

Peer-Reviewed Article

Publication Date



ACS Publications




Ira A. Fulton College of Engineering


Chemical Engineering

University Standing at Time of Publication

Full Professor