Gas 2025 Issue

Figure 2 Amine foaming in pre-carbon filter, black debris on filter cartridges, and amine samples

selectively removes H 2 S. The facility believed it was receiv- ing unaccounted for mercaptans species, which were ulti- mately leading to the copper strip corrosion test failure. Operating with the new amine, the facility had few issues until December 2022. At this time, a technical service team was onsite to advise on a path forward to help with the copper strip corrosion test failures. The recommendation was to drain the water from the reflux drum on the overhead of the amine still tower and replace it with fresh water to the system. The system did see improvements from this recommendation; each time the reflux drum was drained, the copper strip test passed, and the operational issues in the amine still subsided. However, these gains in performance were temporary, with the opera- tional issues reappearing around five to seven days after the draining of the reflux drum. At this time, operations noted the appearance of black debris in the sight glasses on spent elements. Also, the pre-carbon bed filter housing was full of a stable foam, and the rich and lean amine became a dark amber to brown colour (see Figure 2 ). The source of the black debris was unknown at this time, but the facility determined that a shutdown would be required to fully clean the amine still. This led to a month of operation without any issues or failures of the copper strip corrosion test. However, operations soon reported that the

previous operational challenges had returned, and the amine still was once again filled with black debris (see Figure 3 ). The facility began a full troubleshooting campaign that ultimately concluded that the source of the black material was most likely FeS created during the reaction between the amine and H₂S present in liquid NGL. In this process, the sulphur ions released from H₂S during the reaction with the amine solvent react with the iron ions present in the steel used in the piping and vessels of the amine system to form FeS solid particulates. In many treating systems, these FeS particles form on the sides of vessels and piping in the amine system, creating a protective layer against corrosion. However, if the velocities of fluid moving through the vessels/piping are high enough, the FeS particles can be washed away or not allowed to deposit. This causes them to circulate throughout the sys- tem, contaminating amine and leaving the steel prone to potential sulphur corrosion. The facility’s team concluded that one of two issues was occurring in the system: u Foaming in the amine still led to improper regeneration of the amine and a failure to properly treat H₂S in the amine con - tactor, ultimately leading to a failed copper strip corrosion test. v Foaming in the amine contactor led to the carryover of rich amine into the downstream treated NGL. The down - stream NGL filter, which is designed to remove trace amounts of amine, was being overwhelmed with amine volumes exceeding design, leading to a failed copper strip corrosion test due to high concentrations of rich amine in the NGL post-filtration. At that time, the facility requested assistance with system diagnostics and recommendations for its filtrations and sep - aration challenges. System evaluation Once onsite, Transcend Solutions collected samples of the solid black debris from the facility’s amine system, as well as several of the spent pre-carbon filter elements. The sol - ids and elements collected underwent a variety of tests at Transcend’s lab to determine their composition.

Figure 3 Solid black debris recovered from the amine regeneration system

Gas 2025