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Heat Exchanger Fouling and Cleaning: Fundamentals and Applications
May 18-22, 2003 - Santa Fe, New Mexico, USA
| Editors: |
Paul Watkinson, University of British Columbia, Canada
Hans Müller-Steinhagen, German Aerospace Centre (DLR) and University of Stuttgart
M. Reza Malayeri, German Aerospace Centre (DLR) |
The articles for these proceedings are peer-reviewed.
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Sodium Aluminosilicate Solid Phase Specific Fouling Behaviour
Jonas Addai-Mensah, University of South Australia
Jun Li, University of South Australia
Marek Zbik, University of South Australia
Scott Rosencrance, Westinghouse Savannah River Company
ABSTRACT:
Process heat transfer equipment fouling due to sodium aluminosilicate precipitation is a serious problem that confronts high-level nuclear waste liquor and Bayer process alumina processing plants. The fouling of 316 stainless steel substrate by thermodynamically stable and unstable sodium aluminosilicate polytypes: amorphous solid, zeolite A, sodalite and cancrinite crystals, been has studied in an isothermal, batch precipitation system at 65 °C.
Fouling invariably occurred via heterogeneous nucleation, crystal growth and particulate adsorption processes, accompanied by solution-mediated, phase transformation and morphological changes. For the thermodynamically stable cancrinite fouling, the amount of scale deposited increased systematically with increasing crystallization time before levelling off as a result of depleted supersaturation. Where the deposited scale involved a less stable phase (e.g., amorphous, zeolite A), transformation to a more stable phases (e.g., sodalite/cancrinite) occurred. The scale layer coverage/growth characteristically increased and then decreased in a periodic manner. The periodicity of this unusual behaviour appeared to be directly and kinetically related to polytypic phase transformation of amorphous to zeolite A, zeolite A to sodalite and sodalite to cancrinite.
Jonas Addai-Mensah, Jun Li, Marek Zbik, and Scott Rosencrance, "Sodium Aluminosilicate Solid Phase Specific Fouling Behaviour " in "Heat Exchanger Fouling and Cleaning: Fundamentals and Applications", Paul Watkinson, Hans Müller-Steinhagen, and M. Reza Malayeri Eds, ECI
Symposium Series, Volume RP1 (2003). http://services.bepress.com/eci/heatexchanger/11
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