Unbiased methods for the morphological description of char structures

This paper shows how the most relevant morphological parameters of chars can be accurately measured with the aid of standard image analysis techniques. The descriptions of char particles thus obtained allow a more precise application of most of the classification schemes in use to date, or the production of useful data for the modelling of p.f. combustion. The application of these techniques is illustrated with a simplified scheme for the classification of char structures, with emphasis on the discrimination of the main structural types considered in current classification systems. Data obtained from the application of the proposed techniques to char samples from three coals of different rank and maceral composition clearly reflect the differences that could be expected from the plastic properties of the parent coals. The accuracy and objectivity of the measurements by these techniques make them a valuable tool for improving the repeatability and reproducibility of char petrographic analyses. (C) 1997 Elsevier Science Ltd.