Estudo termomecânico da fratura de blocos refratários eletrofundidos aplicados em fornos de fusão de vidro via simulações computacionais

Abstract

Currently there is a great motivation and need for advances in the understanding of the best operating conditions of industrial equipment. As far as glass production is concerned, one action field is the search for increasing the working life of the refractory lining of glass melting furnaces, directly associated with glass quality, process energy efficiency, cost and other factors. Electrofused AZS (Alumina-Zirconia-Silica) refractories are used for the lining of glass melting furnaces due to their corrosion resistance and mechanical properties. However, operating conditions can drastically alter the performance of this refractory, limiting the lifetime of the furnace. Computational simulations have proven to be a useful tool for analyses where in situ testing of the glass melting process is difficult and involves certain risk for experiments and validations. In view of this, the present study aimed to investigate AZS blocks with electrode support, which present a reduced lifetime due to cracking and intense erosion. With the software Abaqus, a thermomechanical analysis was carried out via finite element models (FEM) to determine the maximum principal stress in the block during the heating of the furnace. Which reached the rupture limit of the AZS block approximately 42 h after the start of furnace heating at 0.13 m from the hot face. Regarding the process parameters analyzed, the cooling system of the electrode had a positive effect only for its own life, reducing the oxidation of the material. The study of different thermal histories still did not prevent the crack initiation during the heating of the furnace. Changing the hole geometry affected the maximum principal stress field, and for this condition after 43 h the maximum principal stress reached the AZS modulus of rupture was 43 h. The critical point at which this maximum principal stress. In order to study the effects of material change in the thermomechanical simulations, thermodynamic studies were additionally carried out via FactSage, with the objective of analyzing the corrosion of different refractory compositions in contact with glass, to find out a potential composition to replace AZS. The results showed that zirconia-rich compositions present higher glass corrosion stability. Finally, a comparative thermomechanical analysis between AZS and commercial HZ (High Zirconia) was conducted via thermal and mechanical simulation.