FCC Overhead Line Failure
Situation: A section of pipe at a mix point between the propane purge from the Alky and the FCC Main Frac Overhead was failing (holing through) on a routine basis, each time of which required a unit shutdown to fix.
Action: Becht team worked over a weekend to design a Hastalloy quill that inject the purge stream in the FCC Overhead stream. This allowed for the sulfurous acid to be neutralized before it contacted the CS pipe, resulting in minimal cost and unit downtime.
Results: Becht concluded that SO2 contained in the purge stream reacted with water in the FCC stream to form sulfurous acid. The acid was neutralized by the NH3 in the FCC, but not before it corroded the pipe at the mix point.
The multidiscipline Becht team (Process, Corrosion/Materials, and Mechanical) quickly identified the root cause of the failure and a develop a unique solution (injection quill) that resolved the issue in a manner that required minimal capital cost and unit down time.
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