Gravimetric analysis results while rental vessel in service
Unit/vessel
Inlet
Outlet (mg/L)
Removal
(mg/L)
Rental Vessel Sample 1 Rental Vessel Sample 2
10.7 10.7
0.5 0.4
95% 96%
Table 2
equipment and piping, forming a protective layer to corro- sion between the treatment process and the steel constitut- ing the equipment. Since the velocities in the facility’s system design were not conducive to this, it became necessary to install a filter specifically designed to remove FeS from the amine stream, meeting the appropriate size and media specifications. Once FeS particulates were adequately removed from the amine stream in the amine treater system, the foaming wit- nessed in the amine subsided, and subsequently so did the unit’s operational issues and downstream Y-grade specifica- tion failures. However, regardless of the mechanism, the issues expe- rienced at the facility were primarily due to FeS production within the amine treating unit and its inability to be removed due to inadequate and undersized filtration. Adequate vessel sizing and filtration design are both essential for effectively removing particulates from the amine stream and maintain- ing fluid quality. With adequate element design, effective filtration can sometimes be achieved with undersized vessels; this was not the case at the South Texas facility. An undersized vessel and improperly designed filtration elements both contrib- uted to the process failure. Even if the vessel had been sized correctly for the system, the existing element design would not have achieved the desired amine quality. It would have required an upgraded filter element that was appropriate for the fluid and particulate challenge. It is important to fully understand the filtration application and what is trying to be achieved with the filtration process. Design concepts or best practices that should be considered for new capital projects or optimising an amine filtration pro- cess in the facility include: u Always design for full flow filtration on both the lean and rich sides of the process. v The vessels should be designed in a horizontal orienta- tion with quick opening and closures on vessels. This is more ergonomic and efficient for operations, requiring less man- power and fewer work hours for filter changes. When considering filter elements, always select a filter with a specific micron rating and avoid nominal rated filters such as sock or string-wound elements. The filter should be constructed with material that is compatible with the pro- cess’s fluids and amine with an O-ring type sealing surface. Selecting the best filter for the application allows for con- tamination control in the process and maximum throughput. Nicholas Brownrigg is Sr Staff Engineer at Howard Energy Partners. Orbie Harris IV is in business development with Transcend Solutions LLC. Email: orbie.harris@trnscnd.com
Figure 7 Installed rental vessel
Transcend’s rental fleet to help remediate the FeS problem and the immediate need to resolve the copper strip corrosion test failures. The second step was to design a fit-for-purpose filtration unit that could handle the fluctuating particulate load present in the system while minimising the amount of work required by facility operators during filter changes. The rental filter designed to operate in lieu of the existing pre-carbon filter is shown in the process flow diagram in Figure 6 . The rental filter was equipped with 36 10-micron Transcend Tetra Endur coreless proprietary filter elements, utilising high-efficiency proprietary Novacel media. With the rental vessel online (see Figure 7 ), the amine stream began to clean up and allow the facility’s copper strip corrosion test to return to passing results. In approximately three weeks, the facility was able to return to full process capacity. Additional testing was performed while the rental vessel was in service to provide an update on amine fluid clean- liness. Table 2 provides the data that was collected from gravimetric testing. A custom-designed permanent filter was then designed for the amine treater system to replace the existing carbon pre-filter. This filter was designed to minimise piping and skid rework on the existing skid, which in turn helped keep installation costs low. Additionally, the size and number of elements in the filter were optimised to give operations an improved run life between filter changeouts. The permanent filter vessel with Tetra Endur elements, utilising proprietary high-efficiency Novacel media, has been operating since December 2023 with no operational issues and no copper strip corrosion test failures. Particle liquid filtration best practices The treatment of H₂S with amines in carbon steel vessels leads to the production of FeS particulates that can become entrained in the amine stream. This results in significant foaming in the amine, which jeopardises its ability to be properly regenerated in conventional amine regeneration systems. Additionally, foaming amine can be carried out of the amine contactor tower to the downstream system, risk- ing potential recontamination of treated fluid. Ideally, in amine systems treating H₂S, FeS particles would be handled by designing the unit such that velocities remain low enough that the FeS passivates the walls of the
36
Gas 2025
www.digitalrefining.com
Powered by FlippingBook