Corrosion protection issues in the tops of refinery units
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In China, the practice of anti-corrosion treatment for the refining units in refineries generally involves \"one removal and four injections\" or \"one removal and three injections\"; these methods usually manage to keep the Fe2+ concentration in the reflux water at below 3 mg/l. However, some facilities have recently found that while iron ion levels in the reflux water from atmospheric pressure towers can be kept well under control, similar operating conditions and pH levels result in higher iron ion concentrations in the reflux water from vacuum towers, sometimes even exceeding 10 mg/l. Dear experts in the field, please discuss the similarities and differences in corrosion protection for the tops of atmospheric and vacuum distillation columns, as well as the appropriate procedures to follow in terms of process design.
It’s quite general. Has there been any change in the raw materials? The iron ion level at our factory under normal pressure is below 1 ppm
The production process of the vacuum distillation column, especially pH control, should be more stringent than that of the atmospheric pressure column.
Check whether the dosage of the chemical and its concentration are the same
What should the optimal pH value be? The corrosion inhibitors fed to the tops of the atmospheric and vacuum distillation columns come from the same tank; their concentration is the same, and the pH value is also kept at around 8.0. The requirements are met at the top of the atmospheric column, but the pH level there remains too high. Should there be a difference in pH control for atmospheric and vacuum distillation?