Corrosion cause analysis and countermeasures for air cooler of sour water single-tower low-pressure stripper.

Leakage often occurs in the tube bundle of the overhead air cooler of the single-tower low-pressure stripper for sour water. The main media in the tube bundle of air cooler are H₂O, NH₃, H₂S, NH₄HS, etc. By analyzing the tube wall temperature, liquid phase H₂S concentration, liquid phase NH₃ concentration, gas phase H₂S partial pressure, gas phase NH₃ partial pressure and flow state of gas and liquid in tube bundle, it is concluded that the main cause of corrosion is chemical corrosion of high concentration NH₄HS or erosion corrosion of NH₄HS crystal solids. The following measures can reduce the corrosion rate of air cooler tube bundle: increase water injection to dilute local high concentration NH₄HS; upgrade material to titanium, Hastelloy C276 or Incoloy 800 to improve corrosion resistance; reduce the finned ratio of the tube bundle, partial reflux of air, and add the heating coils at the bottom of air cooler to increase the temperature of the tube wall; increase the frequency conversion and louvers of fan, set 10 mm/m gradient of tube bundle to prevent bias flow; control gas speed of the feedstock, etc. [ABSTRACT FROM AUTHOR]