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Yaakob, Najmiddin accepted dissertation 03-30-15 Sp 15.pdf (13.46 MB)
ETD Abstract Container
Abstract Header
Top of the Line Corrosion in CO
2
/H
2
S Environments
Author Info
Yaakob, Najmiddin
Permalink:
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1427716457
Abstract Details
Year and Degree
2015, Doctor of Philosophy (PhD), Ohio University, Chemical Engineering (Engineering and Technology).
Abstract
Top of the line (TLC) corrosion in sour (H
2
S) environments has not been well understood until now, since most reported TLC research has focused on sweet (CO
2
) conditions, with various models developed to predict corrosion rates and related phenomena in sweet systems. This has led to many unanswered questions relating to TLC mechanisms in CO
2
/H
2
S environments. In most sour environments, the nature of the FeS corrosion product layer is dependent on the concentration of H
2
S present in the mixed CO
2
/H
2
S environment. Therefore, the intent of this research is to determine the TLC behavior in marginally (less than 1 mbar/1000 ppm of H
2
S) and highly sour environments (more than 10 mbar/10000 ppm H
2
S), since both described conditions would lead to different TLC mechanisms. Experiments were conducted in custom designed autoclaves. Weight loss method for corrosion rate measurement, corrosion product analysis by SEM/EDX, optical profilometry, and condensed water analysis were used to investigate the TLC mechanisms. In marginally sour TLC between 0.015 mbar (15 ppm) to 0.03 mbar (30 ppm H
2
S), a non-homogenous FeS layer formed on the steel surface in shorter experiments (lasting a few days), with some areas being covered and others not. This localized corrosion which was not sustained, since pits were not seen in longer experiments lasting 28 days. Increases in H
2
S concentration between 0.08 mbar (80 ppm) to 0.15 mbar (150 ppm) did not lead to initiation of localized corrosion. The steel surface was uniformly covered by an FeS layer due to the greater scaling tendency that overcame the undermining by corrosion. Low general corrosion rate were found. Increase in water condensation rate lead to higher TLC rate due to saturation limits with respect to aqueous species required for formation of both FeCO
3
and FeS, phases that can confer a degree of protection against corrosion. In highly sour TLC, the main parameter which controls TLC behavior is the characteristics of the FeS layer formed on the steel surface. The formation of more coherent FeS layers was observed at higher steel temperature and conferred greater protectiveness regardless of the water condensation rate which is the main controlling factor in sweet TLC. Water condensation rate acts as a secondary effect that lowers the steel temperature. Finally, the TLC corrosion mechanisms in CO
2
/H
2
S environments (marginally and highly sour) were proposed through a descriptive model approach.
Committee
Srdjan Nesic (Advisor)
Pages
198 p.
Subject Headings
Chemical Engineering
Keywords
Sour TLC
;
TLC
;
Marginally Sour TLC
;
Highly Sour TLC
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Citations
Yaakob, N. (2015).
Top of the Line Corrosion in CO
2
/H
2
S Environments
[Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1427716457
APA Style (7th edition)
Yaakob, Najmiddin.
Top of the Line Corrosion in CO
2
/H
2
S Environments.
2015. Ohio University, Doctoral dissertation.
OhioLINK Electronic Theses and Dissertations Center
, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1427716457.
MLA Style (8th edition)
Yaakob, Najmiddin. "Top of the Line Corrosion in CO
2
/H
2
S Environments." Doctoral dissertation, Ohio University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1427716457
Chicago Manual of Style (17th edition)
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Document number:
ohiou1427716457
Download Count:
887
Copyright Info
© 2015, all rights reserved.
This open access ETD is published by Ohio University and OhioLINK.