A universal correlation between the heterogeneous ignition temperatures of coal char particles and coals

A universal correlation between the heterogeneous ignition temperatures of coal particles and coals is presented. A general index, Fz, for identifying coal ignition behavior has also been proposed. Although the values of coal proximate analysis are changeable, the coal ignition behavior is same for those with same Fz. The verification with 51 coals from different countries shows satisfactory results, so the prediction of ignition temperatures of coal char particles becomes suitable for engineering design. A table that is arranged in sequence of ignition difficulty is also given.