The influence of flue gas temperature on lead chloride induced high temperature corrosion

Hanna Kinnunen, Markus Engblom, Daniel Lindberg, Mikko Uusitalo, Sonja Enestam, Patrik Yrjas

Research output: Contribution to journalArticleScientificpeer-review

18 Citations (Scopus)

Abstract

Firing of waste-​based fuels increases the risk for heavy metal-​induced corrosion in the furnace walls and in other low-​temp. heat transfer surfaces, such as primary superheaters.  Lead-​contg. compds., esp. alkali lead chlorides, were detected in the boiler water walls, causing severe corrosion.  Corrosion rate of chlorine-​induced corrosion is known to be dependent on the material temp. and the objective of this work was to study the influence of the flue gas temp. on lead chloride-​induced corrosion.  The expts. were carried out with full-​scale corrosion probe and deposit probe measurements in a recycled wood firing CFB boiler.  The material used in the corrosion probe measurements was low alloy steel EN10216-​2 16Mo3 and the material temp. was adjusted to 360°.  Two corrosion and deposit probes were used in different locations to expose the probes towards hot, 800°, and cooler, 490°, flue gas temps.  Changes of the wall thicknesses were measured and the samples were analyzed with SEM​/EDS and x-​ray diffraction for more detailed deposit characterization.  Corrosion was detected in both the hot and the cooler flue gas samples.  A low melting (T0 = 368°) alkali-​lead-​chloride mixt. was identified.  Findings from these measurements strongly indicate this mixt. to be the corrosion-​causing compd. at both flue gas temps.  However, the corrosion rate was higher in the hot flue gas sample compared to the cooler flue gas sample.  A much steeper deposit temp. gradient was calcd. for the hot flue gas sample, suggesting that the alkali-​lead-​chloride mixt. is in the molten form.  These findings, together with the higher proportion of the present alkali-​lead-​chloride mixt., are the potential factors for the higher corrosion rate in the hot flue gas sample compared to the cooler flue gas sample.
Original languageUndefined/Unknown
Pages (from-to)241–251
JournalFuel
Volume196
DOIs
Publication statusPublished - 2017
MoE publication typeA1 Journal article-refereed

Keywords

  • Water wall
  • High temperature corrosion
  • Superheater
  • Lead potassium chloride
  • Waste wood combustion
  • Low alloy steel

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