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POWER FPSOs AND GAS TURBINES generation, lean pre-mixed DLE system that can achieve berg is expected to be 99.5%. This is approximately 0.5% single digit ppm NOx and carbon monoxide (CO) levels higher than what is typically specifed for similar offshore down to a 20% load. applications.

Overall, the use of DLE combustion systems with weak To support high availability targets, the SGT-750 is and medium calorifc value fuels has been subject to rigor- equipped with online infrared monitoring of the turbine ous development programs. In addition to fundamental hot section. Each camera covers the pressure side, suction design and analytical work, comprehensive combustion rig side, and the platform. Before and after each inspection, testing along with core engine and full packaged unit test- measurement of the turbine blades’ surface temperature in ing has been completed. DLE engines are now capable of the compressor section can be performed while the ma- reliably operating on a wide range of fuel compositions chine is on load. and are considered an established technology for offshore The cameras allow for early, non-destructive detection production applications. of possible issues, such as cracks or blockage of cooling holes, before they lead to failure events. Infrared images 14 DAYS OF DOWNTIME OVER 17 YEARS also speed up service activities by providing technicians

Extending mean time between overhauls (MTBO) and with valuable diagnostic information. Other notable fea- reducing the duration of both planned and unplanned tures of the SGT-750 include: maintenance on rotating equipment is prioritized in off- shore production applications. This is particularly the case • Borescope ports for fve of the 13 compressor stages.

on Johan Castberg, as the gas reinjection train, which is • A door that allows access to the compressor at the front necessary for production, is operating in 1x100 confgura- of the air inlet chamber.

tion without backup. • An overhead crane inside the gas turbine enclosure.

When it comes to overhauling gas turbines, end-users The enclosure was designed with enough space for operat- generally have two options. The frst option is to conduct ing personnel to walk around the machine and exchange all maintenance activities on the core engine, auxiliaries, combustor components. and driven equipment onsite. The second is to perform • A gas generator that can be removed from either side of a rapid onsite engine exchange using a customer owned the installation. The generator is then disconnected from spare and then transport the existing engine core to an on- the air intake and power turbine and removed sideways on shore workshop or OEM facility for servicing. a rail assembly.

For the SGT-750, the second option results in total planned downtime of 14 days over 17 years. The core en- Johan Castberg offcially came on stream on March 31 of gine exchange can be performed in 24 hours from load this year. On June 17th, it reached its peak production ca- to load. Additionally, the compressors utilize modularized pacity of 220,000 barrels of oil per day. This increases energy 3 bundle concept, which minimizes the time needed to swap deliveries from the Barents Sea by 150% . Since the instal- out spares and reduces overall maintenance costs. lation, Siemens Energy has received three additional orders

Availability of the compression train on Johan Cast- for the SGT-750 from FPSO projects for power generation. 1 Equinor. Johan Castberg Anchored on the Field. September 2024. url: https://www.equinor.com/news/johan- castberg-anchored-on-the-feld 2 Bulat, Ghenadie , and Matthew Rickert. "Making the Case for Dry Low Emissions Technology in Offshore Oil and Gas Applications." Paper presented at the Abu Dhabi International Petroleum Exhibition & Conference,

Abu Dhabi, UAE, November 2019. doi: https://doi.org/10.2118/197830-MS 3 Equinor 24 OFFSHORE ENGINEER OEDIGITAL.COM