Many gas compressor stations use multiple gas turbine driven centrifugal compressors. In many instances, the units are not identical. The challenge is to control the units such, that certain operational parameters, for example fuel consumption, pipeline capacity or maintenance requirements, are optimized.

The discussion includes the use and sizing of multiple units, the arrangement of units, the arrangement as push or pull compression, as well as examples of optimization strategies at various levels of sophistication, up to and including the integration of hydraulic and turbomachinery optimization.

The benefits of methods that control compressors for the same turndown, or to control all gas turbines for the same load. This methodology can be derived and discussed for the case of identical machines, and will be expanded for the case where the compressors and their drivers are not identical. The control system has to rely on measurable parameters, but the system has to be reliable even if parameters that are not directly measured change during operation.

The paper describes a variety of optimization methods, starting with a simple algorithm, then comparing equalization methods, and finally illustrating the capability of methods that combine turbomachinery optimization and the optimization of pipeline hydraulics. An example demonstrating the potential fuel savings of such an optimization is given.

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