Oxygenated_treatment

Oxygenated treatment

Oxygenated treatment

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Oxygenated treatment (OT) is a technique used to reduce corrosion in a boiler and its associated feedwater system in flow-through boilers.

With oxygenated treatment, oxygen is injected into the feedwater to keep the oxygen level between 30 and 50 ppb. OT programs are most commonly used in supercritical (i.e. >3250psi) power boilers. The ability to change an existing sub-critical boiler over to an OT program is very limited. "Common injection points are just after the condensate polisher and again at the deaerator outlet."[1] This forms a thicker protective layer of hematite (Fe2O3) on top of the magnetite. This is a denser, flatter film (vs. the undulation scale with OT) so that there is less resistance to water flow compared to AVT.[2] Also, OT reduces the risk of flow-accelerated corrosion.[3]

When OT is used, conductivity after cation exchange (CACE) at the economiser inlet must be maintained below 0.15μS/cm [4] this can be achieved by the use of a full-flow condensate polisher.[5]

Comparison of AVT to OT

More information Characteristic, All-Volatile Treatment (Reducing) ...

See also

References

  1. [1]
    Brad Buecker, "Flow-Accelerated Corrosion: A Critical Issue Revisited", 2007, Power Engineering, http://www.power-eng.com/articles/print/volume-111/issue-7/features/flow-accelerated-corrosion-a-critical-issue-revisited.doc
  2. [2]
    Mitsuhiro Yamagishi, Masamichi Miyajima, "Evaluation of Oxygenated Water Treatment" 14th International Conference on the Properties of Water and Steam in Kyoto, August 29-September 3, 2004
  3. [3]
    Daniels, D., "HRSG Failure Mechanisms - Waterside," Proceedings of the 22nd Annual Electric Utility Chemistry Workshop, Champaign, Illinois, May 7–9, 2002.
  4. [4]
    IAPWS Technical Guidance Document: "Volatile treatments for the steam-water circuits of fossil and combined cycle/HRSG power plants (July 2010) http://www.iapws.org/techguide/Volatile.doc"
  5. [5]
    Frank Gabrielli and Horst Schwevers, "Design Factors and Water Chemistry Practices - Supercritical Power Cycles" PREPRINT-ICPWS XV Berlin, September 8–11, 2008
  6. [6]
    Sharat Kumar and S.K. Gupta "Feed Water Treatment Optimization for Controlling Flow Accelerated Corrosion (FAC)" http://www.infraline.com/power/presentations/others/ntpc/n_50_fac_sharatkumar_chem.pdf
  7. [7]
    Frank Gabrielli and Horst Schwevers, "Design Factors and Water Chemistry Practices - Supercritical Power Cycles" PREPRINT-ICPWS XV Berlin, September 8–11, 2008, Page 10
  8. [8]
    Frank Gabrielli and Horst Schwevers, "Design Factors and Water Chemistry Practices - Supercritical Power Cycles" PREPRINT-ICPWS XV Berlin, September 8–11, 2008, Page 10
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