Re-design and re-rating of turbomachinery

PCA's main activity is the design of new turbomachines, often of advanced design, both prototypes and products.

For many years, however, we have also been active in the re-rate market, both in the North America and in Europe, and this has now become a key part of our portfolio of operations. Re-rate refers to the re-design of some components of an in-service machine in order to effect a desired change in performance. Often re-rating of an older machine can be extremely cost-effective compared to the purchase of a new machine. Re-rate is best carried out during a routine overhaul.  Our partners in this activity are Sulzer Hickham in the USA and Sulzer Repco in Europe.

PCA’s re-rate activity has included the following machines:

• five-stage axial nitrogen expander
• three-stage axial nitrogen expander
• seventeen-stage steam turbine
  
• three-stage condensing steam turbine in a geothermal plant
• ten-stage axial compressor in a nitric acid plant
• centrifugal hydrocarbon gas compressor
• eight-stage steam turbine in an oil field plant
  

Ingersoll-Rand E-520 expander whose power output was increased by 10%

The picture above shows one of several Ingersoll-Rand E-520 axial flow nitrogen expanders rerated by PCA in conjunction with Hickham.  Mass flow and power increases of 10% or more have invariably been achieved, and at very small additional engineering cost during normal overhaul.  E-516 expanders have also been re-rated.

The picture on the right shows the rotor of a seventeen stage steam turbine whose power output was increased by 17% by virtue of a study involving meanline and throughflow analyses.  

17% power increase for this seventeen-stage steam turbine  

A 21% increase in power was achieved for a 10-stage steam turbine.  The picture shows the CFD-predicted Mach number contours for two of the stages.  CFD was used to optimise the profiles of a new set of blades for the machine.

CFD predictions used to optimise new plade profiles