TY - JOUR
T1 - Temperature gradient induced changes within superheater ash deposits high in chlorine
AU - Balint, Roland
AU - Engblom, Markus
AU - Niemi, Jonne
AU - Silva da Costa, Daniel
AU - Lindberg, Daniel
AU - Yrjas, Patrik
AU - Hupa, Leena
AU - Hupa, Mikko
N1 -
Funding Information:
The financing through a research grant awarded by the Fortum Foundation (Application 20190123) is highly acknowledged. This work is part of the project Clean and efficient utilization of demanding fuels (CLUE), with support from the industrial partners: ANDRITZ, Fortum, International Paper, UPM-Kymmene Corporation, and Valmet Technologies Oy, as part of the activities of the ?bo Akademi University Johan Gadolin Process Chemistry Centre. Additional support from the Academy of Finland project ?Understanding the dynamics of intradeposit chemistry and morphology for control of corrosion in high temperature processes? (Decision 310266) is highly appreciated. We want to thank Linus Silvander for carrying out SEM/EDX analyses.
Publisher Copyright:
© 2021 The Authors
PY - 2021/7/1
Y1 - 2021/7/1
N2 - Cross-sections of kraft recovery boiler superheater deposits were analyzed using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The observed deposit morphology can be explained by temperature gradient induced time-dependent processes such as diffusional transport of alkali chloride vapours, temperature gradient zone melting, formation of melt enriched in Cl and K, and movement of this enriched melt towards the steel. These processes have recently been identified on a laboratory scale under well-controlled conditions, and are now for the first time identified to take place also in actual boiler superheater deposits. The identified processes alter the local deposit composition and melting behaviour close to the steel. The local first melting temperature (T0) close to the steel is lower by 30 °C compared to that of the deposit bulk T0. The observations made in this work give new insight into the melting and ageing behaviour of superheater deposits, relevant for superheater corrosion.
AB - Cross-sections of kraft recovery boiler superheater deposits were analyzed using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The observed deposit morphology can be explained by temperature gradient induced time-dependent processes such as diffusional transport of alkali chloride vapours, temperature gradient zone melting, formation of melt enriched in Cl and K, and movement of this enriched melt towards the steel. These processes have recently been identified on a laboratory scale under well-controlled conditions, and are now for the first time identified to take place also in actual boiler superheater deposits. The identified processes alter the local deposit composition and melting behaviour close to the steel. The local first melting temperature (T0) close to the steel is lower by 30 °C compared to that of the deposit bulk T0. The observations made in this work give new insight into the melting and ageing behaviour of superheater deposits, relevant for superheater corrosion.
KW - Ageing mechanism
KW - Melt enrichment
KW - Superheater deposit
KW - Temperature gradient
UR - http://www.scopus.com/inward/record.url?scp=85103401578&partnerID=8YFLogxK
U2 - 10.1016/j.energy.2021.120439
DO - 10.1016/j.energy.2021.120439
M3 - Article
AN - SCOPUS:85103401578
SN - 0360-5442
VL - 226
JO - Energy
JF - Energy
M1 - 120439
ER -