| dc.description.abstract | High Pressure Ratio Compressor (HPRC) technology is based on an innovative architecture that combines unshrouded and shrouded
impellers on a single high-speed shaft to achieve pressure ratios and efficiency levels higher than other available technologies. In the
final step of the product development and validation, a test campaign has been carried out with the aim to test the performance and
explore the operability of the new machine.
Surge exploration tests have been also performed allowing an evaluation of the transient behavior and the mechanical robustness of
the compressor even during a critical event such as Surge.
Compressor Surge has been analyzed under different conditions, forcing the operating point to move beyond the performance
envelope in full speed, at low and high pressure levels, and during emergency shut-downs. Thanks to the complex arrangement of the
gas loops and several valves used to recycle back the compressed gas, different levels of Surge intensity were induced upon
emergency shut-down.
The explorations of a fast event like Surge called for special instrumentations, configured to acquire process data both in direct and
reverse flow conditions in the most reliable way, with a high frequency sampling for an oil and gas environment.
The result of this work is a breakthrough for the tuning of a centrifugal compressor model – not only HPRC ones – to be used for
dynamic simulations and prediction of compressor dynamics during Surge events (like Surge cycle frequency and absorbed torque
during Second Quadrant operation) in a more reliable and robust way.
Surge exploration tests results analysis, in terms of vibrations and thrust loads, together with development of a compressor enhanced
dynamic model, allowed a change from a Surge acceptance criterion - based on the time spent on the left of the Surge Limit Line
during an Emergency Shutdown event - to a more physics based criterion - based on the acceptable number of Surge cycles, thus
increasing selection optimization of additional protections, such as hot/cold gas bypass valves. | en |
