The effect of turbulence on the conversion of coal under blast furnace raceway conditions. (1st January 2023)

• Record Type: Journal Article
• Authors: Wartha, Eva-Maria; Haugen, Nils Erland; Karchniwy, Ewa; Bösenhofer, Markus; Harasek, Michael; Løvås, Terese
• Is Part Of: Fuel. Volume 331:Part 2(2023)
• Publication Date: 2023-01-01
• Subjects: Coal combustion -- Blast furnace -- Turbulence effects -- Kinetic-diffusion limited -- Computational fluid dynamics; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2022.125840
• Languages: English
• ISSNs: 0016-2361

Abstract

Abstract: The main production route for steel in Europe is still via the blast furnace. Computational fluid dynamics (CFD) can be used to analyze the process virtually and thus improve its performance. Different reducing agents can be used to (partially) substitute the coke and consequently reduce overall emissions. To analyze different reducing agents effectively using CFD, their conversion process has to be modeled accurately. Under certain conditions, coal particles can cluster as the result of turbulence effects, which further reduces the mass transfer to the coal surface and consequently the conversion rate. We analyze the effect of turbulence under blast furnace raceway conditions on the conversion of coal particles and on the overall burnout. The model is applied in RANS to polydisperse particle systems and this is then compared to the simplified monodisperse assumption. Additionally, the model is extended by adding gasification reactions. Overall, we find that the turbulent effects on coal conversion are significant under blast furnace raceway conditions and should be considered in further simulations. Furthermore, we show that an a-priori assessment is difficult because the analysis via averaged quantities is impractical due to a strong variation of conditions in the furnace. Therefore, the effects of turbulence need to be correlated to the regions of conversion. Highlights: Turbulent clustering effects of particles under blast furnace raceway conditions. Reduced conversion rates due to reduced mass transfer to particles in clusters. Effect of monodisperse versus polydisperse particle representation. Effect of char oxidation and gasification reactions.