An upstream oil and gas player, manages a gas exporting platform situated offshore Ivory Coast, Africa, where they operate two mechanical drive gas turbine units (5MW each) that drive compressors with high availability requirements.
The units are exposed to harsh environmental conditions that lead to spikes in pressure drop (dP) and excessive engine degradation from fouling and corrosion. As a result, the customer was forced to schedule unwanted shutdowns for maintenance.
Together with their OEM, the company contacted Camfil to evaluate a higher performance filtration system. Although the platform's limited available space restricted expansion of the filter housings, they requested higher efficiency grade filters at a lower dP and a longer life to meet their lower maintenance requirements. Camfil offered a compact, high-efficiency solution that met their challenging goals.
The offshore platform is subjected to high humidity and temperatures, sea salt in the air, among other contaminants from flare, supply vessels, process equipment, and contaminants from lube oil exhaust ventilation.
In addition to sea salt, the site is exposed to extreme dust as a result of Harmattan sandstorms that occur 4 months of the year between late November to mid-March. During this dry season, dust travels from the Sahara to the Ivory Coast and get transported hundreds of kilometers over the Atlantic Ocean onto the platform1. Although the systems are located between decks and are not exposed to direct rain or sea spray, with the right wind directions, the units are often challenged with saltwater and Harmattan storms, particularly Unit B.
The original intake system was a high velocity (31,298 CFM) configuration with nine M6 efficiency final filters (3W x 3H), per turbine.
Due to the extreme site conditions, Unit B's turbine performance significantly decreased.
During the bidding process, Camfil sent technical site representatives to evaluate the turbines. The OEM awarded Camfil with the project due to its track record of success with offshore medium velocity filter houses.
The company's objectives were to eliminate degradation and minimize maintenance requirements to once per year. To achieve this, Camfil recommended to redesign the filter house to the Compact EPA Filter Offshore solution consisting of:
A new filter house using nine pre-filters back to back with nine high efficiency filters to fit in the existing footprint.
To minimize downtime during the installation process, coordination effort was key. The Camfil team went onsite to supervise the installation work and on-the-spot troubleshooting. They assessed the equipment required and the manpower needed.
Figure 1 shows dP over time for both engines.
Engine B: Engine B is in a more challenging area on the platform, resulting in multiple dP spikes pre-upgrade, and exceeding more than 5.2” w.g. At each peak, an unplanned shutdown was required for filter replacement.
Once they upgraded to the Compact EPA Static solution, dP stabilized and did not exceed 2.0” w.g. The filters lasted the full year without any unscheduled shutdown.
Engine A: Engine A is in a cleaner area on the platform, resulting in a more stable dP and fewer spikes, pre- and post-upgrade. Despite its cleaner conditions, dP spiked to 3.1" w.g. pre-upgrade, whereas dP had not exceeded 1.7" w.g. with the Camfil installation.
The results are impressive since the upgraded solution delivers an EPA efficiency versus the original M6 efficiency. Where a typical E10 EPA filter solution is expected to have a higher dP than an M6 filter solution when using the same housing size, Camfil's Compact Static
Figure 1: Pressure Drop Over
EPA filter solution is able to deliver an EPA efficiency performance at a lower dP and with a longer service life, resulting in safer, more reliable and more productive operations.The site manager further confirmed a significant improvement in engine performance, allowing them to run a full year without any unwanted shutdowns that were previously caused by fouling and corrosion with the original system.
The Camfil Compact Static EPA system is designed to withstand the harshest environments with space constraints, using the unique high efficiency CamGT 3V-600 filter series. The deeper filter frame offers maximum filter media usage, allowing for unparalleled media area and low media velocity, providing the lowest dP and longest available life on the market.
Camfil’s patented construction featuring vertical pleating and interrupted hot melt separators for optimum water handling allows trapped water to drain freely from the filter during operation, thus avoiding re-entrainment of dissolved impurities and maintaining low and stable dP under high humidity conditions. Figure 2 shows that these features prevent corrosion, making the CamGT 3V-600 series the optimal choice for an offshore environment.
Traditional M6 high velocity systems coalesce and remove larger droplets well, but still let through about 20 lbs of salt per year.
A final multi-stage system lowers salt ingestion to approximately 0.04lbs per year, 99.9% less than a typical high velocity system.