Authors:
Dr. Mariana de Albuquerque Lima Braulio | 4CAST | Brazil
Cassio Linhares | Alcoa Brazil | Brazil
Jose Ribamar F Cunha | Alcoa Brazil | Brazil
Austin Maxwell | Alcoa Australia | Australia
Dean Whiteman | Alcoa Australia | Australia
Prof. Dr. Victor Carlos Pandolfelli | Federal University of São Carlos | Brazil
Changing the refractory lining concept for any high-temperature equipment is not a straightforward task. It involves many steps, including materials’ selection, design adjustments, new procurement specifications, contractor application training, and so on. This work illustrates how this process took place for a circulating fluidized bed boiler in an alumina refinery, aiming to reduce the total overhaul time by decreasing the curing and drying time. This objective was attained by replacing cement-bonded castables by phosphate ones. Firstly, the selected materials were tested in lab conditions, to guarantee that the change would not affect the lining performance and the equipment reliability. After that, pilot trials were conducted in selected boiler areas to evaluate the materials’ behavior under operating conditions. Later, during the next overhaul, the new materials were applied in the whole maintenance selected regions, ensuring a reduction from original 64h to 30h in the dry out curve. The benefits of this modification were various: higher productivity (additional 34h of steam production), lower need to use an external contractor to manage the drying step, shorter curing time (5h for the phosphate-bonded castable versus 24h for the cement containing ones), increase in the products’ shelf life (from 6 to 18 months), lower amount of product’s types (2 instead of 4) and financial savings. Because of this systemic approach, it is not only expected shorter overhauls but also greater intervals among two consecutive maintenance halts, pointing out the advantages of a suitable materials’ selection.