(28a) Crude Unit Overhead Corrosion at Sincor

The SINCOR Upgrader crude oil column had shown several corrosion problems since startup early 2002. Design conditions did not considered the risk of having free water inside the column neither salt formation inside the tower, this was not considered to be a problem until after 10 months of operation, overhead condensers started to fail. Preliminary investigations indicated that at operating conditions and enough NH3 levels the salt formation inside the column was something to be expected to happen. The complexity of this system is due to the presence of NH3, HCl, H2S, and Light Organic Acids (LOA) that competed amongst them.

Due to Heavy Crude characteristics, LOA formation well above 200 ppm is expected when running the outlet of the heaters around 374 C (design condition) and was not considered in design either. Some other tests indicated presence of NH3 in the formation water in the crude, and evolution of H2S in more than 50 ppm in the Overhead water.

New operating conditions were set at 135 C (min top temperature), top P/A return temperature of min 127 C, and continuous wash water injection to keep overhead condensers clean. The column will be monitored and gamma-scanned frequently until next T/A to follow up the packing conditions when operating at these conditions.