TY - CONF
T1 - Causes of low-temperature corrosion in combustion of bituminous coal
AU - Vainio, Emil
AU - Vänskä, Kyösti
AU - Laurén, Tor
AU - Yrjas, Patrik
AU - Zabetta, Edgardo Coda
AU - Hupa, Mikko
AU - Hupa, Leena
N1 - Funding Information:
This work has been carried out within CLIFF (2014-2017) as part of the activities of Åbo Akademi Johan Gadolin Process Chemistry Centre. Other research partners are VTT Technical Research Centre of Finland Ltd, Lappeenranta University of Technology, Aalto University and Tampere University of Technology. Support from the National Technology Agency of Finland (Tekes), Andritz Oy, Valmet Technologies Oy, Amec Foster Wheeler Energia Oy, UPM-Kymmene Oyj, Clyde Bergemann GmbH, International Paper Inc., and Top Analytica Oy Ab is gratefully acknowledged. The work was partly financed by the project ‘Low temperature corrosion in combustion – old problem, new approaches’ (Decision No. 289869) financed by Academy of Finland and is gratefully acknowledged.
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2017
Y1 - 2017
N2 - Maximizing energy recovery by keeping flue gas temperatures as low as possible is of great interest in the power business, as higher recovery leads to higher plant efficiency. However, minimum allowable temperature is often limited by the presence of sulfuric acid. Condensation of sulfuric acid on steel surfaces could lead to severe corrosion. Hygroscopic deposits may also cause severe corrosion by taking up water and thus leading to wet corrosion. In this study, the risk of sulfuric acid corrosion and corrosion caused by hygroscopic deposits was studied in a full-scale circulating fluidized bed (CFB) boiler. The boiler was run both with and without limestone addition to reveal the effect of limestone on sulfuric acid corrosion and the effect of limestone on wet deposit corrosion. Furthermore, the effect of load on corrosion was studied. The measurements were performed before and after the electrostatic precipitator (ESP). A KCl salt method, which has been developed to detect trace concentrations of gaseous sulfuric acid, was used to study the risk of sulfuric acid corrosion. Furthermore, an acid dew point meter was used to determine the dew point temperature in the flue gases. Additionally, an air-cooled short-term corrosion probe was used to measure the corrosion rate of carbon steel at various material temperatures. Windward, side, and leeward side deposits were collected from the probe and analyzed by means of scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Fuel and fly ash samples for the different test cases were collected and analyzed. The work revealed new interesting findings on the causes of low-temperature corrosion in combustion of bituminous coal. The different operational parameters of the boiler had a significant impact on deposit composition and on expected corrosion risk. In this paper, we discuss the risks of sulfuric acid corrosion as well as corrosion caused by hygroscopic deposits. Furthermore, the influence of boiler parameters on deposit composition and chemistry will be discussed.
AB - Maximizing energy recovery by keeping flue gas temperatures as low as possible is of great interest in the power business, as higher recovery leads to higher plant efficiency. However, minimum allowable temperature is often limited by the presence of sulfuric acid. Condensation of sulfuric acid on steel surfaces could lead to severe corrosion. Hygroscopic deposits may also cause severe corrosion by taking up water and thus leading to wet corrosion. In this study, the risk of sulfuric acid corrosion and corrosion caused by hygroscopic deposits was studied in a full-scale circulating fluidized bed (CFB) boiler. The boiler was run both with and without limestone addition to reveal the effect of limestone on sulfuric acid corrosion and the effect of limestone on wet deposit corrosion. Furthermore, the effect of load on corrosion was studied. The measurements were performed before and after the electrostatic precipitator (ESP). A KCl salt method, which has been developed to detect trace concentrations of gaseous sulfuric acid, was used to study the risk of sulfuric acid corrosion. Furthermore, an acid dew point meter was used to determine the dew point temperature in the flue gases. Additionally, an air-cooled short-term corrosion probe was used to measure the corrosion rate of carbon steel at various material temperatures. Windward, side, and leeward side deposits were collected from the probe and analyzed by means of scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Fuel and fly ash samples for the different test cases were collected and analyzed. The work revealed new interesting findings on the causes of low-temperature corrosion in combustion of bituminous coal. The different operational parameters of the boiler had a significant impact on deposit composition and on expected corrosion risk. In this paper, we discuss the risks of sulfuric acid corrosion as well as corrosion caused by hygroscopic deposits. Furthermore, the influence of boiler parameters on deposit composition and chemistry will be discussed.
KW - HSO
KW - Hygroscopic deposits
KW - Low-temperature corrosion
KW - So
KW - CFB, low-temperature corrosion, coal
UR - http://www.scopus.com/inward/record.url?scp=85052323994&partnerID=8YFLogxK
M3 - Paper (not published)
AN - SCOPUS:85052323994
SP - 663
EP - 670
T2 - 12th International Conference on Fluidized Bed Technology, CFB 2017
Y2 - 23 May 2017 through 26 May 2017
ER -