ABSTRACT
Hydrogen is a reaction product during the oxidation of alloys in steam. A fraction of the hydrogen produced diffuses into the alloy, while the remainder is released back into the gas phase. Hydrogen permeation experiments on iron and nickel foils were made to quantify the fraction of hydrogen which permeated through the metal and the fraction which went back into the gas phase. Tests were conducted at 750 °C in Ar-3% H2O on one side of the foil to track hydrogen transport during oxidation. Exposure tests at 650 and 700 °C in atmospheric pressure steam on ferritic steel T23 and ferritic/martensitic steel T92, as functions of gas velocity and sample orientation, provide evidence that the transport of hydrogen back into the gas phase influences the oxidation kinetics. Boundary layer controlled hydrogen diffusion away from the scale and into the gas phase was modelled to predict the effects of gas velocity and pressure.
Acknowledgments
The authors wish to thank the UK Department of Energy & Climate Change and the US Department of Energy for their role in bringing together and supporting the US-UK Collaboration on Fossil Energy Research and Development. Portions of this work were performed in support of the US Department of Energy’s Fossil Energy Crosscutting Technology Research Program. The Research was executed through NETL Research and Innovation Center’s Advanced Alloy Development Field Work Proposal. One of the coauthors (G. H. M.) gratefully acknowledges the Office of Naval Research for support of his participation in this collaboration under Contract N00014-12-1-0612, Dr. Airan Perez, Scientific Monitor. Portions of this work at Cranfield University were supported by the EPSRC Supergen Plant Life Extension project (Grants GR/S86334/01 and EP/F029748) and associated industrial consortium that included the following companies: Alstom Power Ltd., Doosan Babcock, E.ON, National Physical Laboratory, Praxair Surface Technologies Ltd, QinetiQ, Rolls-Royce plc, RWE npower, Siemens Industrial Turbomachinery Ltd. and Tata Steel.
Disclosure statement
No potential conflict of interest was reported by the authors.
Disclaimer
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