The air heater is a rotary regenerative heat exchanger which recovers heat from the outgoing hot gases of the boiler and transforms it to the incoming air needed for combustion process. This system is composed of large numbers of heat transfer elements made from corrosion-resistant material (Corten) or enamel coated in order to resist acid dew-point corrosion. In this study, a root cause failure analysis of heating elements was carried out. Visual inspection, chemical analysis, and microscopic examinations of the heating elements, enamel coating, and depositions were conducted. Sulfuric acid dew-point temperature (ADPT) was determined to be 138–142 °C based on the sulfur dioxide of the flue gases. Moreover, temperature distribution across the air heater matrix was simulated using Fluent software. The failures of the heating elements were mainly due to sulfuric acid dew-point corrosion and under-deposit pitting corrosion. The corrosion products were mainly iron sulfate, iron oxide, and iron sulfide. In the case of enamel-coated elements, the failure was attributed to the existence of a large number of cracks and big bubbles in the coating, allowing the penetration of corrosive elements into and beneath the surface of coating and thus the detachment of coating.
Failure analysis Air preheater Heating elements Sulfuric acid dew-point corrosion Enamel coating Bubbles
This is a preview of subscription content, log in to check access.
The authors highly appreciate the financial support provided by Ramin Power Plant, Ahvaz, Iran. The project was also partially supported by the Shahid Chamran University of Ahvaz, Iran.
I. Warren, Ljungstrom heat exchangers for waste heat recovery. J. Heat Recovery Syst. 2(3), 257–271 (1982)CrossRefGoogle Scholar
D. Reay, A review of gas-gas heat recovery systems. J. Heat Recovery Syst. 1(1), 3–41 (1981)CrossRefGoogle Scholar
J.M. Blanco, F. Peña, Increase in the boiler’s performance in terms of the acid dew point temperature: environmental advantages of replacing fuels. Appl. Therm. Eng. 28(7), 777–784 (2008)CrossRefGoogle Scholar
S. Matsuda, T. Kamo, A. Kato, F. Nakajlma, Deposition of ammonium bisulfate in the selective catalytic reduction of nitrogen oxides with ammonia. Ind. Eng. Chem. Prod. Res. Dev. 21(1), 48–52 (1982)CrossRefGoogle Scholar
Y. Wang, Q. Zhao, Z. Zhang, Z. Zhang, W. Tao, Mechanism research on coupling effect between dew point corrosion and ash deposition. Appl. Therm. Eng. 54(1), 102–110 (2013)CrossRefGoogle Scholar
B. ZareNezhad, A. Aminian, Accurate prediction of the dew points of acidic combustion gases by using an artificial neural network model. Energy Convers. Manag. 52(2), 911–916 (2011)CrossRefGoogle Scholar
A. Bahadori, Estimation of combustion flue gas acid dew point during heat recovery and efficiency gain. Appl. Therm. Eng. 31(8–9), 1457–1462 (2011)CrossRefGoogle Scholar
X.Q. Cheng, F.L. Sun, S.J. Lv, X.G. Li, A new steel with good low-temperature sulfuric acid dew point corrosion resistance. Mater. Corros. 63(7), 598–606 (2012)Google Scholar
V. Linsa, E. Guimaraes, Failure of a heat exchanger generated by an axcess of SO2 and H2S in the sulfur recovery unit of a petroleum refinery. J. Loss Prev. Process Ind. 20(1), 91–97 (2007)CrossRefGoogle Scholar
F. Barreras, J. Barroso, Behavior of a high-capacity steam boiler using heavy fuel oil, part II: cold-end corrosion. Fuel Process. Technol. 86(2), 107–121 (2004)CrossRefGoogle Scholar
F.S. Shieu, K.C. Lin, J.C. Wong, Microstructure and adherence of porcelain enamel to low carbon steel. Ceram. Int. 25(1), 27–34 (1999)CrossRefGoogle Scholar
X. Yang, A. Jha, R. Brydson, R. Cochrane, The effects of a nickel oxide precoat on the gas bubble structures and fish-scaling resistance in vitreous enamels. J. Mater. Sci. Eng. A 366(2), 254–261 (2004)CrossRefGoogle Scholar
M. Kim, S. Chang, O. Oh, J. Won, H. Park, Failure analysis of enamel-coated carbon steel heating elements of gas-gas heater for flue gas desulfurization system. Eng. Fail. Anal. 14(4), 686–693 (2007)CrossRefGoogle Scholar
A. Zhang, S. Jiao, Z. Jiang, D. Wei, Bubble structures, fishscaling resistance and adhesion of vitreous enamel to low carbon steel. Prog. Adv. Mater. Res. 409(1662–8958), 736–742 (2011)CrossRefGoogle Scholar
Standard specification for steel, sheet, for porcelain enameling, ASTM-A424-06, ASTM International, 2000, p 1–3Google Scholar
A. Heidari-Kaydan, E. Hajidavalloo, Three-dimensional simulation of rotary air preheater in steam power plant. Appl. Therm. Eng. 73(1), 397–405 (2014)CrossRefGoogle Scholar
Y.K. Son, C.J. Lee, J.M. Lee, B.M. Kim, Deformation prediction of porcelain-enameled steels with strain history by press forming and high-temperature behavior of coating layer. Trans. Nonferrous Met. Soc. China 22(1003–6326), 838–844 (2012)CrossRefGoogle Scholar
N.T. Shardakov, EKh Kurumchin, G.K. Vdovin, V.A. Deryabin, Effect of the steel substrate on the composition of gases in enameling. Glass Ceram. 53(1–2), 46–47 (1996)CrossRefGoogle Scholar