Siemens has launched a lightweight aero-derivative gas turbine designed specifically for the oil and gas industry, the first fruit of its purchase of the aero-derivative arm of Rolls-Royce. Designated the Industrial RB211-GT30, it it is optimised for the needs of the oil and gas industry, and its offshore applications in particular. It is based on the proven Industrial RB211 gas turbine which has accumulated over 34 million hours in service.
Over the last decade Rolls-Royce Energy and Dresser-Rand groups have supplied a significant share of the 20 to 40 MW offshore power generation on FPSOs (floating production storage and offloading vessels) worldwide. Now Siemens will be able to utilise this combined expertise.
Siemens has enhanced the RB211 design to 'set new standards of power density, reduced down time, and easy maintenance.' The RB211-GT30 drives a two-pole AC generator at either 60 Hz or 50 Hz with no need for a gearbox, with savings in weight and footprint. The package has a new lightweight construction that is 30 % smaller and lighter than its predecessor. It is designed specifically for offshore duty, with a three-point base mount and torque tube design. The package has been optimised to facilitate safe maintenance and reduce down time, even in challenging offshore conditions. The complete gas turbine can be removed from either side of the package and exchanged in less than 24 hours, thanks to an innovative rail system built into the package itself. The auxiliary systems are functionally unchanged, but have been optimised to improve maintenance access and maximise online maintenance while the unit is running.
The demand for FPSOs has increased recently owing to the the transfer of a large portion of global offshore oil exploration, drilling, and production from relatively accessible shallow water to increasingly deep and ultra-deep waters. Significant investment in fields off the Brazilian and West African coasts has driven demand for FPSOs and this trend is likely to continue to expand over the next decade. Southeast Asian projects will follow the same path, but with lower oil production volumes in shallower water.
FPSOs can produce crude oil, process it on the high sea, and store it until a tanker brings it to the coast. They have proven to be an efficient approach to offshore production because they can be moved from the production location in the event of storms, political unrest, or an alternate commercial opportunity. The main power loads on offshore installations are driven by electric motors rather than directly by gas turbines. This reduces capital costs by allowing power production to be centralised in a smaller number of larger gas turbine generators.
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