Applying hermetically sealed compressors in offshore platforms

MAN Diesel & Turbo in Zurich has been awarded a contract for a HOFIM compressor (High-Speed, Oil-Free, Integrated Motor). It is MAN's first hermetically-sealed compressor being installed on an offshore production platform – Ivar Aasen in the North Sea, run by Det norske oljeselskap ASA.

“From a conceptual point of view, this HOFIM compressor unit is very similar to MAN’s subsea compressors currently being under system integration tests in Norway,” states Mathias Scherer, Vice President Sales & Contracts in Zurich. “This compressor technology has a great business potential for platform operators as the offshore industry is asking for simple, robust and safe systems which can be integrated into cramped environments. Another important aspect is the improvement of total cost of ownership.”

MAN’s Business Unit Oil & Gas has supplied integrated turbocompressor systems for 25 years. The most significant aspects of this machine are the use of a high-speed motor and active magnetic bearings. There is no need for dynamic seals which makes the compressor system hermetically sealed and as a consequence offers many advantages. The absence of the dry gas seal system and of the complete oil system reduces the complexity and this leads to the improved system reliability. The required footprint significantly shrinks by 60 percent and weight on the compressor installation drops by 30 percent in mass compared to traditional compressor designs.

The order for Ivar Aasen comprises a multi-stage radial compressor (1x100 percent) arranged in tandem configuration around a centrally positioned 9.5 megawatts high-speed electrical motor.

The integrated active magnetic bearings are provided by MECOS, a company acquired by MAN Diesel & Turbo early 2012. MECOS is a leading company in the field of active magnetic bearing systems. Since 1988, MECOS has launched magnetic bearing solutions for compressors, turbines and other high-speed rotating machinery serving in various industrial applications.

The complete HOFIM unit will be delivered to the module packager SMOE Pte Ltd. in Singapore which is building the Ivar Aasen platform. In 2016 the module will be sailed away to the final site of operation: The Ivar Aasen field situated in the Norwegian sector of the North Sea. The compressor will export the produced gas from the platform to shore.