PTQ Q4 2025 Issue

performances. The best solvent for the amine unit consid- ers 48% MDEA and 2% piperazine with process conditions as outlined. If the facility had decided to not replace the current MEA with a formulated MDEA solvent, the following items are recommended: • 316L should be the stainless steel of choice in a facility operating at these elevated chloride levels. • The performance of the L/R exchanger needs to be upgraded to achieve a rich outlet temperature of at least 190°F (a must, even if there is a change of solvent in the future). • There must be sufficient hot oil flow/temperature to the reboiler to achieve a regenerator overhead temperature of at least 215°F (preferred >220°F). Overhead temperature can be adjusted immediately. However, the repair of the heat exchanger must take place as soon as possible. After the L/R heat exchanger is repaired, the steam to the regen- erator should be further adjusted to maintain the proper overhead temperature as indicated. • Continue to monitor iron, chromium, manganese, nickel, and chlorides to estimate current corrosion rate and risk. • Consider inspection and potential replacement of dam- aged internals in the regenerator column (outlet bucket) at the next available opportunity. • Improve amine regeneration to lower lean loading and lower lean amine corrosion. Conclusion Based on the data and findings reported in this article in addition to the information on Parts 1 and 2 of this paper, the plant decided to finally replace the MEA solvent with the MDEA/PZ solvent combination. After some initial chal- lenges, typically as a consequence of solvent change and after unit stabilisation and operational experience, the cor- rosion in the process was reduced significantly to negligible levels. In fact, as of 2025, corrosion events at the amine unit have been minimal, with very low rates of metal loss and no major impact to the process or the unit equipment. David B. Engel is Managing Director at Nexo Solutions. He has more than 25 years of industrial experience in various areas, including chem- ical synthesis, oil and gas, analytical methods, membranes, chemical additives, process chemistry, and process separation technologies. He has been awarded almost 21 patents and authored more than 100 papers and seminars. Engel holds a PhD in organic chemistry from Indiana University Bloomington. Email: david.engel@nexosolutions.com Scott Williams is a Process Engineer, responsible for research and development, engineering, marketing, and sales at Nexo Solutions based in The Woodlands, Texas. Williams holds a BS in chemical and biological engineering from University of Colorado at Boulder. Cody Ridge is a Chemical Engineer from Texas Tech and a lead pro- cess engineer at Nexo Solutions. He started his career as an operator and process engineer in the Permian Basin. He is responsible for field engineering, technology development, and operations. Ridge is the support engineer for the East Texas, Louisiana and Oklahoma region. He has more than five published papers and has consulted with more than 30 gas plants and refineries.

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