Full Load Testing Of A 12.5 MW Vertical High Speed Subsea Motorcompressor
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In late 2006 Authors’ company was awarded a contract for the motorcompressor for the Ormen Lange Subsea Compression Pilot. This Pilot represents the first subsea motorcompressor unit ever built in a fully marinized version and tested in a water pit, which was developed specifically for the project at the customer’s site (Nhyamna, Norway). The prototype unit is a 12.5MW (16763HP) integrated motorcompressor, which runs up to 10.5krpm in a vertical configuration with the following features: Single casing; High-speed motor rigidly coupled to a multistage centrifugal compressor (3 journal bearings shaft line); Canned Active Magnetic Bearings (AMBs); Process gas used as cooling fluid for the Electric Motor; Internal separation system (to protect the bearings and the electric motor from the intrusion of solid and liquid materials); Fully marinized AMBs control system; The design and validation plan for this complex equipment were developed through a four years program where many challenging milestones were achieved. The Ormen Lange Subsea Compression Pilot motorcompressor has successfully completed an intensive full load testing campaign in the Authors’ Company plant including the following: Static-dynamic tuning of the AMBs; Mechanical Running Test; Compressor Performance Test (ASME PTC-10 Type 2 + Full Load test); Electric Motor Performance Test; Overall cooling system check; Landing test (partial landing and full speed delevitation test). The test campaign has fully demonstrated the functionality of this prototype unit capable of operation in the service conditions. The Next step will be the shipment to the costumer site where the submerged testing will be conducted. This paper will provide a detailed description of the main test results of the subsea motorcompressor covering all aspects of the test program including rotordynamic behaviour, compressor thermodynamic performance, axial load variation versus operating conditions (monitored thanks to the thrust AMB), electric motor cooling system behaviour, electric motor performance, AMBs and control system operability. Of special interest is the rotor delevitation test from full speed consisting in the two ton rotor running at 10.5krpm dropping onto the mechanical emergency bearings until the machine reached a complete stop condition. This test, which was repeated 5 times, provided a full-scale verification of the landing numerical simulation developed by the authors (Ransom et al., 2009).
Vannini, Giuseppe; Masala, Andrea; Camatti, Massimo; Neri, Massimiliano Ortiz; Bondi, Sergio; Evangelisti, Silvia (2011). Full Load Testing Of A 12.5 MW Vertical High Speed Subsea Motorcompressor. Texas A&M University. Turbomachinery Laboratories. Available electronically from