Centrifugal compressors : Principles, Operation and design

Identify the four classifications of equipment in a centrifugal compressor train: driven machine, driver, transmission device, and auxiliary systems; apply this framework to design, revamps, troubleshooting, and inspection.

Examine axial flow compressors used in gas turbines and blast furnaces, where rotating and stationary veins on a drum enable high flow rates and adjustable performance by changing vein angles.

Analyze how the compressor head curve and system resistance curve intersect to set the operating point at 100 percent flow, and how system type affects stability.

Understand how impeller diameter and speed determine the head produced by a centrifugal compressor, and that deviations from the capacity curve by more than 10 percent signal maintenance needs.

Explore performance relationships for centrifugal compressors, linking head, efficiency, and horsepower to flow, inlet conditions, and gas composition, then understand impeller design and speed and mechanical tradeoffs.

Remind that ideal gas head equations relate to iso-thermal considerations, and that polytropic head is the usual choice among compressor vendors.

Compare the ideal reversible head for compressing from P1 to P2 with the actual head caused by losses to define compressor efficiency, equal to ideal energy divided by actual energy.

Define how the centrifugal compressor curve is generated and explain how dynamic machines produce head by imparting velocity to the fluid.

Explore how backward leaning blades and radial vanes shape centrifugal compressor performance, noting head rise, surge head rise, and how flow changes affect the head curve and operating point.

Surge is a rapid instability in centrifugal compressors causing flow reversals and rapid temperature rise; stonewall is the high-flow limit, with typical surge and stonewall operating ranges.

Surge in a centrifugal compressor arises from flow separation at low gas velocity in the inlet guide vane, impeller, or diffuser, triggering a surge cycle with backflow and reduced head.