Reasons for high iron ion levels in acidic water in the residue hydrogenation unit

There are several possible reasons for the high concentration of acidic iron ions in the residue hydrogenation unit: 1. **System corrosion**: Even with the use of corrosion inhibitors, corrosion of equipment and pipelines can still occur, especially when certain inhibitors are not effective or are not applied evenly. Corrosion can cause iron ions to be released from equipment or pipeline materials into the water system. 2. **Issues with the selection or dosage of corrosion inhibitors**: The corrosion inhibitor used may not be suitable for the current system conditions, or the amount added may be insufficient, resulting in poor performance. 3. **Water quality issues**: The pH of the acidic water is actually around 10, indicating alkalinity, which may affect the effectiveness of corrosion inhibitors as well as the solubility and form of iron, thereby influencing the release of iron. Regarding control parameters, different factories and operating conditions may have varying requirements. Generally speaking: - **Iron ion concentration**: The typical range for control is below 1 mg/L, but the specific value should be determined based on actual conditions and the requirements of the equipment. - **pH value**: It is usually maintained at a neutral to slightly alkaline level, such as pH 7-9, to optimize the corrosion-inhibiting effect and prevent corrosion. It is recommended to examine and optimize the use of corrosion inhibitors, while also checking the overall integrity of the system and its operating conditions. If necessary, more detailed water quality analyses and system inspections should be carried out to identify the root cause of the increased iron ion concentration, so that appropriate adjustments can be made. .

As a supplementary point, corrosion existed in the pipes and equipment prior to the injection of the corrosion inhibitor, due to factors such as the advancement of cold zones and an increase in chloride ions