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Description
Injecting pulverized coal into the raceway zone of blast furnaces is a stat of the art process to optimize the operation of the furnace. Modeling the thermo chemical conversion of pulverized coal in the raceway zone is commonly used to investigate its effect on the blast furnace process or to optimize the coal injection process. The quality and accurateness of the employed models determine the reliability of the simulation results. In case of pulverized coal conversion, heat transfer rates control the initial drying and devolatilization stages and simulation results are sensitive to the employed heat transfer model. In particular, the high heat of evaporation of water and the endothermy of the thermal break down of volatiles cause the heat transfer control of the thermo-chemical conversion. Since coal conversion is a sequential process, changes in the drying and devolatilization will also affect the conversion rates and also the overall conversion duration. Overestimating the heat transfer rates would then result in coal particles being consumed within the raceway zone in simulations, while they could reach the bulk coke bed at low conversion.in reality.
To assess this effect, we evaluate the influence of the heat transfer model on the overall thermo-chemical conversion of pulverized coal. For this purpose, we first introduce common thermo chemical coal conversion models and heat transfer models, which is followed by a simplified test case to evaluate the heat transfer’s impact on the thermo chemical coal conversion. Finally, we verify these results using experimental data for coal combustion from literature.