Thermochemical conversion of pulverized carbon carriers under super high heating rates and elevated pressures

Abstract

Understanding the thermochemical conversion of pulverized carbon carriers under high heating rates is vital for improving efficiency and reducing emissions in high-temperature industrial processes. Three coal types (anthracitic, bituminous, and sub-bituminous) are investigated under high heating rates (up to 106 K/s) and elevated pressures (2 bar(g)) using a novel pressurized entrained-flow reactor: the Alternative Reducing Agent (ARA) reactor capable to reproduce the intense thermal environment of blast furnaces. Heating rate effects are isolated during the experiments to investigate the effect of the heating rate on the thermochemical conversion. Burnout ratios, ash content, and particle size distributions were assessed via the ash tracer method and laser diffraction analysis. Scanning Electron Microscopy (SEM) provided insights into morphological transformations. The results demonstrate clear heating rate dependent conversion behavior. Burnout ratios increase with volatile content and are significantly higher in high heating rate and matching temperature experiments than in low heating rate experiments. Higher heating rates enhance coal reactivity, reduce char residue, and increase pore formation, particularly in bituminous and sub-bituminous coals. The anthracitic coal displayed less pore development and ash flake deposition. Matching temperature conditions yielded intermediate burnout levels but significantly more residue than the high heating rate cases, confirming the heating rate’s impact on reactivity. The ARA reactor’s capability to provide high heating rate conditions under controlled settings offers a valuable platform to validate and improve simulation models and supports the development of more sustainable industrial processes.