There are several things to consider when upgrading gas turbines. At the moment, the original equipment manufacturers (OEMs) prefer to offer large upgrades like new turbines, flange-to-flange upgrades, rather than better maintenance deals for older equipment. A flange-to-flange upgrade is preferable for OEMs for several reasons:
- their competitors cannot provide new parts or repairs
- they want their customers to enter full long term service agreements (LTSAs)
There is also a trend among OEMs to start maintenance and repairs on other OEM’s turbines. However, can the power plant owner be sure that they are up to the task?
The best upgrade option for a particular gas turbine will depend on its age, location, and operating cycle. Although the OEMs may show calculations that prove full flange-to-flange upgrades to be the way to go, their calculations may not take into account all conditions prevailing at the power plant. Furthermore, a full flange-to-flange upgrade may also mean that the whole power plant needs to be upgraded. The plant may just not be equipped to handle the flange-to-flange upgrade.
It might make more sense in the long run to upgrade individual components rather than the entire engine. Late-model gas turbines incorporate advanced technology anyway, so any comprehensive upgrades apply only to older gas turbines that are part of a series or model line that the OEM has redesigned, such as Frame 7 and 9 series by GE Power Systems, W251 and W510 series by Siemens Westinghouse Power Corp., etc.
Components, that can be upgraded, include
- improved compressor blades and vanes for more air flow and better efficiency
- improved seals for tighter clearances
- combustion hardware for better turndown ratio, better fuel flexibility and longer maintenance intervals
- turbine blades and vanes for higher firing temperatures and/or longer maintenance intervals
Upgraded components usually include also new coatings and coating methods like metallic and ceramic coatings. Special thermal barrier coatings can be applied to hot section parts and protective coatings to compressor blades (the “cold end” of the machine).
Any improvement in performance always means better operational flexibility. Now that the world is turning more and more to renewable energy as its source of power, operational flexibility is becoming one of the most important qualities in gas turbines.
Any improvement also always impacts the maintenance agreement and maintenance costs. With a full flange-to-flange upgrade, inspection intervals are usually longer. However, part repair and purchase costs may be considerably higher. Older parts may also become obsolete, although they might still have use in maintenance and repairs without a full upgrade.
When making any gas turbine upgrade plans and decisions, consider these:
- Are you optimizing inspection intervals or turbine performances (power output & heat rate, operational flexibility)?
- Are you calculating total cost of maintenance and return of investment over a longer period of time, say 10 years?
- Do you know the versions of your gas turbine components and remaining lifetime to assess what different kind of upgrades are possible for your engine?
Figure 1.
Do you know your gas turbine? If not, you cannot make informed decisions about cost-effective upgrades.
We recommend that you always use a third party for consults in evaluating an OEM’s cost-effectiveness calculations when it comes to full upgrades. We are happy to also consult on long term service agreements.
TMMonitor can also prove to be an invaluable tool in determining which upgrade option is the best one for you.