In spite of the potential advantages of atmospheric fluidized bed systems, experience has proved that, under certain environments and operating conditions, a given material employed for internal components could lead to catastrophic events. In this study, an attempt is made to establish material selection and operational criteria that optimize performance and availability based on theoretical considerations of the bed hydrodynamics, thermodynamics and combustion process. The theoretical results

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... may indicate that, for high-volatile coals with particle diameters (d^) of 1-3 mm and sand particle size (d^) of 0.674 mm, a considerable proportion of alkali chlorides may be transferred into the freeboard region of fluidized bed combustors as vapor phase, at bed temperatures {Ty ) < 840 °C, excess air {XSA) < 20 %, static bed height (HJ < 0.2 m and fluidizing velocity {UJ < 1 m/s. Under these operating conditions, a high alkali deposition may be expected to occur in heat exchange tubes located above the bed. Conversely, when the combustors operate at Tj, > 890 °C and XSA > 30 %, a high oxidation rate of the inbed tubes may be present. Nevertheless, for these higher Ty values and XSA < 10 %, corrosion attack of metallic components, via sulfidation, would occur since the excessive gas-phase combustion within the bed induced a local oxygen depletion. Liberación de sales alcalinas y volátiles del carbón que afectan componentes internos en sistemas de combustión de lecho fluidizado Palabras clave Deposición alcalina. Mecanismo de oxidación-sulfidación. Modelación de la combustión. Cinética de devolatilización. Lechos fluidizados.