The growth in use of centrifugal compressors in chemical process industries (CPI) applications in recent decades has been brought about by four factors: 1) advances in dry gas seal technology; 2) modern aerodynamic, rotor-dynamic and thermodynamic knowledge and techniques; 3) advanced manufacturing methods to producing accurate rotating parts and various complex components with reasonable costs; and 4) the ability to simplify the control and anti-surge systems of a centrifugal compressor (and its driver) through the use of modern control and variable-speed technologies.
With these advances, and because of their simplicity, reliability, light-weight, and compact design, centrifugal compressors have become much more popular for use in CPI plants.
Figure 1. This cutaway diagram shows the internals of a process centrifugal
compressor with a multi-impeller, between-bearing design
As CPI plant sizes increase, the pressure to improve reliability is very high because of the large economic impact of a nonscheduled shutdown. Today, the run time between centrifugal compressor overhauls is three to six years or more.
Figures 1 and 2 show examples of centrifugal…