Análise de degradação e confiabilidade de um forno de indução tipo coreless

Abstract

Induction furnaces are widely used in the foundry industries and are also one of the key equipment in a hot dip galvanizing line where both channel and coreless induction furnaces types are used. Channel induction furnaces are used in the main coating process, where the moving steel plate is dipped into the working pot to receive a protective alloy layer. To maintain the level of the melting bath, ingots are immersed directly into the main pot. Being in direct contact with the heated bath, these ingots are melted, thus replacing the metal that was consumed in the coating process. However, it may be necessary to use auxiliary furnaces only to melt these ingots separately, preventing this process from occurring directly in the main pot melting bath, what could compromise the coating quality. ArcelorMittal Vega Galvanization Line 2 utilizes an auxiliary coreless pot for the Galvalume® material process. Over time, the refractory lining of this pot tends to degrade to the point of rendering it inoperative. Ensuring the reliability of this pot has not been a simple task, as it cannot be emptied for inspection and its operation must be uninterrupted, as the metal bath may solidify and the entire installation may be lost, causing enormous damage to the production process. This work aims to make an analysis of the degradation of this refractory lining, from the electrical supply current of the coil, applying the theories related to the reliability engineering study, in order to anticipate eventual failures that may compromise the coreless induction furnace availability and reliability.