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Thermochemical Wear of Refractory Linings Associated With Gas Firing in Metallurgical Plants

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Abstract

The present paper deals with the corrosive interaction between the atmosphere and the refractory lining as well as in one case the steel shell for two industrial facilities. In one of the following cases a magnesia carbon lining is partly decarburized by the atmosphere during preheating of a steel ladle. In the other case, the flue gas from blast furnace gas heating of a hot blast stove causes a nitric attack on the cold side of the refractory lining at the steel shell. Investigation of these mechanisms rely on computational fluid dynamics (CFD) simulations which quantify the flow and temperature field as well as the species transport during heat release from the gas combustion in both plants. Furthermore, the heat exchange between hot gas and refractory is estimated and thereby associated chemical reactions with/within the refractory material. In both CFD case studies a non-premixed approach was applied to model the combustion process and to characterize the flue gas composition. The follow-up reactions with refractory lining and the steel casing are discussed specifically for each case. The calculated oxygen content in flue gas during ladle preheating is estimated to 15%vol. The maximum heat transfer between hot gas and refractory takes place in the bottom region of the ladle due to convection. The radiative heat exchange plays the most important role in the zone of magnesia-carbon lining. Within the investigation of carbon burnout kinetics limiting factors like diffusion and mass transfer coefficient of oxygen were defined and (partially) determined. The NO formation during the blast stove heating period strongly depends on the dome temperature which is an important blast process control value. Calculated NO emission loads showed promising agreement with real plant data and literature trends.

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