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In one of the client refineries which we are working with, they are facing severe corrosion in the 2nd and 3rd stage ejectors of the vacuum column. The current treatment program is adding CI and neutralizer before the 1st stage ejector and during inspection/shutdown there has been no corrosion observed in the 1st stage but huge corrosion observed in the 2nd and 3rd ejectors. Is there are any similar kind of issue faced in other refineries. If so what has been the solution measure taken?
 
Answers
11/06/2014 A: Vivek Ramaswamy, Chennai Petroleum Corporation Limited, vivekramaswamy.cpcl@gmail.com
The filming amine which is the corrosion inhibitor always takes the liquid stream as it is high in molecular weight and very less volatile. Hence the CI injected in Stage 1 ejector makes it way into the 1st stage condenser and into the hot well along with the liquid stream and is not available in the 2nd/3rd Stage ejector. So adding CI in the 2nd and 3 rd stages will definitely solve the problem. What neutralising amine do you use? Also what is the pH, Cl content and Fe content of the water in hot well boot? This can help us further analyse as to why the neutralising amine is not neutralising the acidic phase and letting it get carried over to the 2nd and 3 rd stages respectively.
25/04/2013 A: Berthold Otzisk, Kurita Europe GmbH, Berthold.Otzisk@kurita-water.com
The injection of a water-soluble filming amine and neutralizing amine is a common good practice to reduce the corrosion potential significantly. If no corrosion is observed in the 1st stage, but huge corrosion occurs in the 2nd and 3rd stage, it is an indication, that acidic gases were not neutralized completely before.
Both corrosion inhibitors should be sprayed via spraying nozzle into the overhead system. A water slipstream can help to provide a better distribution of the filming amine and neutralizing amine. The sourwater pH should be in the 5.5 to 6.5 range, while the iron concentration should be far below 1.0 ppm.