Superheater deposits and corrosion in temperature gradient – Laboratory studies into effects of flue gas composition, initial deposit structure, and exposure time
Loading...
Access rights
openAccess
publishedVersion
URL
Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
This publication is imported from Aalto University research portal.
View publication in the Research portal (opens in new window)
View/Open full text file from the Research portal (opens in new window)
View publication in the Research portal (opens in new window)
View/Open full text file from the Research portal (opens in new window)
Date
2021-08-01
Major/Subject
Mcode
Degree programme
Language
en
Pages
14
Series
Energy, Volume 228
Abstract
The heterogeneous nature of the ash chemistry of biomass fuels gives rise to challenges in predicting the deposit melting, sintering, and enrichment of corrosive ash species. An experimental method has been developed to study the evolution of ash deposit chemistry and morphology in temperature gradients simulating the conditions of real superheater deposits. The method is based on applying synthetic ash mixtures on an air-cooled corrosion probe, which is inserted into a tube furnace. The focus has been on how the melting behavior of alkali salt-rich deposits, i.e., KCl-K2SO4-NaCl-Na2SO4 mixtures, affects the chemistry and morphology. Intradeposit vaporization-condensation of alkali chlorides has been of interest. The interaction of reactive gas components (H2O+SO2), with the deposits, was also studied. The vaporization-condensation mechanism leads to enrichment of alkali chlorides in crevices and voids within deposits, leading also to build-up of chlorides on the steel surface, which causes accelerated corrosion, due to the formation of low-melting FeCl2 mixtures. Liquid-phase sintering and temperature gradient zone melting (TGZM) were the main mechanisms for the supersolidus sintering of the deposits. Iron and nickel oxides were found within the deposits and at the outer edge of deposits, due to the TGZM mechanism.Description
Keywords
temperature gradient, High-temperature corrosion, Sulfation, Alkali chlorides, Ash deposits
Other note
Citation
Niemi, J, Engblom, M, Laurén, T, Yrjas, P, Lehmusto, J, Hupa, M & Lindberg, D 2021, ' Superheater deposits and corrosion in temperature gradient – Laboratory studies into effects of flue gas composition, initial deposit structure, and exposure time ', Energy, vol. 228, 120494 . https://doi.org/10.1016/j.energy.2021.120494