Corrosion of inlet and outlet pipelines of the reconditioned regeneration caustic scrubber tower
Thread Content
There is localized corrosion at multiple locations, including the inlet and outlet of the alkali solution circulation pump at the bottom of the flue gas alkaline scrubber tower in the reprocessing plant’s regeneration system, as well as at the inlet and outlet pipes of the backup pump. The operating temperature is 36°C, the pH level is maintained between 8 and 10, and the concentration of the alkali solution is 75%. The pipeline material is carbon steel. Who can explain the mechanism of this corrosion?
This corrosion phenomenon may be caused by several factors: 1. **Unstable pH control**: Although theoretically, maintaining a pH level between 8 and 10 can prevent acidic or alkaline corrosion, in practice, if the pH level is not controlled properly, imbalances in acidity or alkalinity in certain areas can occur, leading to corrosion. 2. **High alkali concentration**: A 75% alkali concentration is high, and prolonged exposure can cause alkaline corrosion to carbon steel, especially in areas with low flow rates or long residence times. 3. **Pipeline material issue**: Carbon steel is used as the material for the pipelines in the caustic scrubber; this material has poor corrosion resistance in highly alkaline environments and is prone to chemical corrosion. 4. **Design and operation issues**: Problems in pipeline design, such as dead corners or areas with low pH levels, or improper operation of the circulation pump (e.g., frequent start-stop cycles or unstable flow rates), can all lead to increased localized corrosion. Solutions may include optimizing the pH control system, as well as increasing the frequency and accuracy of monitoring ； Consider using more corrosion-resistant pipeline materials, such as stainless steel or coated anti-corrosion pipes ； Improve pipeline design to avoid dead corners and areas where liquid can accumulate ； As well as improving equipment operation and maintenance strategies to ensure stable alkaline solution flow rate and pressure. .