Chloride corrosion in biomass-fired boilers – Fe-O-Cl system thermodynamic analysis
AGH University of Science and Technology, Faculty of Energy and Fuels, 30 Mick iewicza St., 30059 Krakow, Poland
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The most common and easiest alternative technologies for conventional fossil fuel combustion are biomass combustion and co-combustion. However, high-chlorine fuels (Clar>0,2%) like: biomass, waste and high chlorine coals generate the risk of intensified corrosion process and a limited steel mechanical strength is observed.
The paper presents a thermodynamic analysis of chloride-induced corrosion in the Fe-O-Cl system. The ranges of the metallic, oxide and chloride phase stability are determined within the temperature range T = 750-1000 K. Based on the parametric equations the equilibrium concentration of gaseous phase determined by Deacon reaction are presented. The effect of H2O concentration in the gaseous phase on high-temperature corrosion process and gaseous NaCl influence on NaFeO2 formation in the passive oxide scale layer (FeO/Fe3O4/Fe2O3) are discussed as well. The results are correlated with available in the literature laboratory experimental data and industrial corrosion process observations. Presented thermodynamic analysis is compared with assumptions of “active oxidation” model. The results may be used for experimental research prediction and a corrosion prevention in the industry.
© The Authors, published by EDP Sciences, 2016
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