Dear Sir,
For Refinery CDU Overhead Corrosion Mechanisms, we also say that we need to maintain 25 percent more free water in CDU overhead after water dew point. I understand that it is not possible to completely remove water from crude feed so we will have aqueous corrosion anyways.
I am not able to understand why we need free water liquid always present in CDU . We are using Offsite Crude Feed tankages to drain water from tanks before feeding and then also desalter is removing salts, water also from crude feed , then why we need free water in overhead circuit ?
Can experts in this field explain the reasons in details.
Also Water Wash added in top section will force water dew point early ? We need to maintain Column top Temperature greater than water dew point temp ( this is for not condensing any water at column top) and also column top temp greater than Salt Formation Temp always ( to avoid ammonium chloride salt corrosion and subsequent fouling ) .
Water wash is added to force water dew point or wash away fouling deposits or to maintain 25 percent excess free water in overhead ? Also what should be location of Water wash?
Best Regards,
Edited by chetanhm2, 19 February 2022 - 03:21 AM.