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

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Hanna Kinnunen Merja Hedman, Markus Engblom, Daniel Lindberg, Mikko Uusitalo, Sonja Enestam, Patrik Yrjas
Publisher: Elsevier
Publication year: 2017
Journal: Fuel
Volume number: 196
Start page: 241
End page: 251
eISSN: 1873-7153


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.


Keywords

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

Last updated on 2019-22-10 at 04:45