Study of NH 4HS concentrating mechanism in air cooled heat exchanger tubes

Kazuhiro Toba, Koji Kawano, Kotaro Tanaka, Hirohito Iwawaki, Jun'ichi Sakai

    Research output: Contribution to journalArticlepeer-review

    2 Citations (Scopus)


    Highly concentrated NH 4HS causes significant corrosion. In high pressure plants such as hydrodesulfurization units operated under NH 4HS environments, leakage caused by corrosion could result in catastrophic disaster. Therefore, in the design phase, corrosion prevention techniques should be considered. In this study, based on the severe NH 4HS corrosion observed selectively in the vapor phase inside air cooled heat exchanger tubes, the NH 4HS concentrating model was developed to discern the difference in NH 4HS concentration between the vapor phase and the liquid phase. We elucidated that NH 4HS concentration in the condensed area in the vapor phase can be much higher than the liquid phase due to the difference of the heat transfer coefficient. This result quantitatively demonstrated the cause of corrosion observed in the air cooled heat exchanger tubes. In addition, this study indicated that the design of the air cooled heat exchanger tube where NH 4HS corrosion shall be concerned should consider a flow regime, air temperature or predicted NH 4HS concentration in the condensed area in the vapor phase.

    Original languageEnglish
    Pages (from-to)304-311
    Number of pages8
    JournalZairyo to Kankyo/ Corrosion Engineering
    Issue number6
    Publication statusPublished - 2011


    • Corrosion
    • Heat transfer coefficient
    • Hydroprocessing
    • NH HS
    • Refining
    • Vapor phase

    ASJC Scopus subject areas

    • Electrochemistry
    • Materials Chemistry
    • Metals and Alloys
    • Surfaces, Coatings and Films


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