Hydrogen transport during steam oxidation of iron and nickel alloys

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.

KEYWORDS:

• Hydrogen
• oxidation
• steam
• velocity
• pressure
• diffusion
• permeability

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

Portions of this report were prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

Additional information

Funding

This work was supported by the Office of Naval Research [N00014-12-1-0612];EPSRC Supergen Plant Life [EP/F029748];EPSRC Supergen Plant Life [GR/S86334/01];US Department of Energy [Advanced Alloy Development FWP].