10 Dynamics of Centrifugal Compression Systems

Compression systems employed in gas processing plants and in gas pipeline transmission systems provide vital function to the overall operation of both systems, and therefore, must be vigilantly attended to in order to ensure a high level of operational reliability. The majority of these compression systems employ centrifugal compressors, either single- or multi-staged, driven by either gas turbines or electric motors with/without gearboxes. These compression systems are required to not only withstand uninterrupted operation for extended periods of time but also be able to cope with flow and pressure transients associated with surge control, startup and emergency shutdown (ESD) [1–8]. During these transients, the centrifugal compressors interact dynamically with system components around them, i.e. piping, fittings and equipment, drivers, as well as the associated control protocols. Fluid inertias and compressor/driver rotor inertias play an important role in either stabilizing or destabilizing the system dynamics [9]. The compressors’ performance characteristics have also an important role in the system dynamics behaviour [10]. Ensuring reliable and safe operation of the various aspects of these compression systems requires a good understanding of their dynamic behavior, which enables sound system design, operation and control.