Cent. Compressor Driver Sizing

[HamzaNossair]

Hello everyone,

Can each one share his experience over the selection of Centrifugal Compressor Driver size?

Fixed Speed Motor, 10% above the Max absorbed POWER?

VFD- Motor, should the compressor designed to deliver the Max flow at 105% speed curve? also, shall the Motor and VFD system sized at the 105% speed curve of the compressor?

Also, what's the basis for GT's and Steam Turbine?

 

[rotw]

Sizing according to what API ?
Basically 10% margin above max absorbed power (at motor shaft) of any of the specified operating conditions this is acc. API617.
VSD or fixed does not matter apart any start up issues that you have to be aware of. 10% margin when its a steam turbine.
Gas turbine : power is what you get at site that's it

 

[HamzaNossair]

Ok..Thank you,

The issue now is, If you have the Max Operating Power located at the 100% speed curve, if you applied the Affint. Laws as:

( Power@105% speed/Power@100% speed)= (105% speed/100% speed)^3....

The result Power is way above the Driver sized Power....

Does the VFD needs to have +Power Margin at the 105% speed curve, no matter if there is no process operating point alocated at the curve??