Prediction of coal fouling using an alternative index under the gasification condition

► The experiment of coal gasification was carried out for verifying the coal fouling tendency in the drop tube furnace (DTF). ► Thirteen different coals compared with predictions using a wide range of empirical indices. ► Some traditional indices for anticipating fouling tendency are not co-related with this experimental result. ► A new approached index resulted in improved correlations between predictions and experimental observations. Coal gasification was carried out in order to verify the coal fouling tendency in the drop tube furnace (DTF), which can simulate an entrained-bed gasifier. Thirteen pulverized coal samples, in the range of bituminous and sub-bituminous, were utilized, and compared, with predictions using a wide range of empirical indices. Large discrepancies were noted in most cases, with respect to experimental results, ash deposition rates, and different indices. Some indices used for anticipating fouling tendency are not co-related with the results of this experiment. A newly approached index, which is especially important considering the diffusivity parameter, looks at the ratio of acid and alkali mineral matters injected into gasifier and heat flux, indicates that traditional expressions are modified to account for other parameters which influence the ash deposition phenomenon. The alternative index resulted in improved correlations between predictions and experimental observations.