Abstract:
Objective To improve the total acetate removal efficiency of the ethylene glycol recovery system and achieve corrosion protection at the top of the subsea wet gas pipeline in deepwater gas fields.
Method Firstly, an analysis was conducted on the status and influencing factors of acetate removal in the regeneration dehydration and monovalent salt removal units of the ethylene glycol recovery system, revealing that the pH of the mother liquor of the flash separator significantly affected the total acetate removal rate. Then, by optimizing the original NaOH injection process to increase the pH of the mother liquor in the flash separator, the total acetate removal rate was significantly enhanced. Finally, the injection point of NaOH was optimized to eliminate operational stability issues.
Result The total acetate removal rate of the rich ethylene glycol after passing through the monovalent salt removal unit of the ethylene glycol recovery system was increased from 30%-40% to 90%, and the total acetate mass concentration in the rich ethylene glycol from a certain deepwater gas field was controlled from more than 5 000 mg/L to a stable level less than 2 000 mg/L, satisfying pipeline top corrosion protection requirements.
Conclusion This study presents a new approach and practical solution to the corrosion problem exacerbated by acetate at the top of the subsea wet gas pipeline and can serve as a reference and precedent for the preliminary design and operation of similar projects.
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