We operate a CDU with Mid-East Crude sulfur content of 1.9%. Our CDU is a two-stages condensation design. Crude oil exchange heat with overhead vapor in the first-stage condenser. The material used for the condenser is CS. We encounter severe corrosion in the first-stage condenser. The life time of the first-stage condenser is only 1%7E2 years. We inject Corrosion Inhibitor upstream of the condenser. We do not inject wash water for the condenser as the overhead temperature of crude tower is 155C. We found deposit accumulated on the external surface of the tube bundle. We have heard that two-stages condensation has severe corrosion problem. Which refinery has the same design and face the same problem as us. How to solve the problem?

Hi To control the corrosion at carbon steel condenser you chose to consider wash water injection two hours in a weekat the unit condenser. Also, in some refinery they use insert tube to prevent corrosion at the inlet of the condenser. The Maine key is the condensation here especially at the inlet of the condenser. Actually it seems to me your corrosion inhibitor is not working could you tell us about the crude unit through out put. I f you are running the crude unit overhead line at 90 ft/s or above the corrosion problem will not be stopped and never been controlled. Wondering if I inject corrosion inhibitor + neutralizer +wash water caustic injection why crude unit still suffering a corrosion problem. Your problem is a operation problem and the erosion is exited at your system if you eliminate it your system will be worked fine. Mark

Hello friend, Two-stage overhead system is an old design, and it seems to be not very happy one. I've red in one Norm Lieberman's article that amine salts continuous trapping and accumulation in such systems is a common problem - causing severe corrosion issues. He recommends switching to one-stage overhead system. One thing I can say for sure: low quality and poor control of chemical injections is as bad as injecting no chemical at all. Make sure you have proper installation - good quality dozing pumps, frequently controlled dosing rate (which means adequate process parameters control). "Power is nothing without control", remember?