A Solution for the Increasing Amine Cycle in Refinery Operations

Tramp amines are a growing issue for the refining industry. They impact desalter performance, increase the potential for overhead corrosion, decrease neutralizer effectiveness and increase loadings on the wastewater treatment plant. Levels as low as 5 ppm of certain tramp amines can have a dramatic impact on salt points and associated corrosion in the atmospheric section.

Desalting problems begin with an increase in the aqueous phase pH driven by the tramp amines.  The higher pH results in increased amine partitioning to the oil phase. It also stabilizes the emulsion at the oil/water interface and extends the rag layer. Water carryover increases to the crude which results in increased chlorides in the crude tower overhead. Oil under carry is also increased which impacts the wastewater treatment plant. Increased corrosion of overheads is due to more than the higher chlorides from water carryover. Excess amine carryover buffers the overhead and makes it more difficult to control and maintain desired pH targets and thereby negating the effectiveness of neutralizers. Also the excess amines combined with the reduction of operational flexibility creates very high salt points. Salt deposition problems can result when the Salting Point exceeds the tower top temperature.

Lowering levels of tramp amines is very difficult because there are multiple sources of amines. In addition to H₂S scavengers and corrosion inhibitors in the incoming crude oil, amines are introduced through the sour water stripper, amine scrubber and from corrosion inhibitors used in steam production and refinery corrosion management.  And with increased water recycling, amines and ammonia levels in the stripped sour water will tend to increase over time.  This process can be described as the tramp amine cycle. 

Conclusion

This paper will present a detailed overview of the cost of the amine cycle in the refinery, the solutions to break the amine cycle and provide supporting test and case study data.