Pumps, blowers, and compressors provide the driving force for fluids to move through process facilities. Collectively, these devices are major consumers of energy in most production facilities, thus making their efficient operation a priority. They are characterized by a combination of relationships derived from basic principles and test data in the form of pump performance curves and compressor maps. This book only examines devices in the centrifugal and related categories, but includes the more complex configurations where two or more are operated in parallel or in series. The topics fall into the following categories:
Pumps. Control of both fixed-speed and variable-speed pumps relies on the pump performance curves and the system curve.
Compressor characteristics. The relationship between flow and head as presented on the compressor map is explained. The system curve is presented for both variable speed and constant speed compressors.
Compressor surge. The control logic used to prevent surge is developed from the basic principles and the compressor map, including the effect of gas density (molecular weight).
Capacity control, including limits on the compressor operation. The objective of capacity control is usually to maintain suction pressure, maintain discharge pressure, or maintain flow through the compressor, often in face of constraints from the compressor, the drive, and/or the process.
Compressors in parallel. Operation of compressors in parallel usually requires control logic to rationally distribute the load between the compressors currently in operation.
Steam turbines. The discussion is restricted to steam turbines that serve as the drive for a compressor.
