the Siemens capability to optimize the
“heart” of the combined cycle by supplying its own gas and steam turbines
and taking full responsibility for plant
control and performance.
F-Class Success
Large combined-cycle plants using
natural gas emerged as the dominating
trend in electricity production in the
1990s. The driver for this development
was modern gas turbine technology. To
meet these market needs, Siemens developed an innovative, stationary gas turbine family based on advanced design
and technology features. The SGT5-
4000F (initially named V94.3A, at 265
MW) is the 50 Hz machine, whereas the
SGT6-4000F is the 60 Hz version, rated
at 180 MW. The SGT-1000F is a dual
50/60 Hz model, rated at 60 MW.
These turbines were developed using
proven technologies while incorporating the latest features in cooling, blade
and combustion technology. First commercially introduced at the Didcot
Power Station, England, in 1996, the
SGT5-4000F has become a successful
workhorse that matches customer
requirements, according to Siemens.
Now, after ten years of operating service of the fleet, the advanced family consists of over 150 gas turbines in operation, with over 60 units on order. As of
March 2007, it has over 4. 2 million and
12-months-average reliability values
between 99.3 and 99.7 show world-class reliability levels. The gas turbine
efficiency has evolved to 38.6%, and to
over 58% for plant efficiency — a record
value demonstrated at the Mainz-Wiesbaden combined-cycle plant in
Germany.
Ongoing market-driven engine evolution has continued for the original
design of the V94.3A engine, which
was the foundation for evolutionary
future development. Based on its predecessor, it combines simplicity and
robustness with high efficiency. The
continued development of the engine
was mainly driven by four factors:
• a focus on the gas turbine as the
most import element of the combined-cycle power application;
• the idea that fast turbine develop-
ment had to be embedded in the development of the overall plant, because the
optimized stand-alone gas turbine differs from a combined-cycle gas turbine
— for example exhaust gas temperature;
• the evolutionary development to
improve performance and flexibility;
• and the implementation of field
feedback to maximize reliability and
availability.
The evolutionary development is
characterized by rather small changes
based on a proven, existing design. That
means that once data from field experience becomes available, areas for potential improvements can be identified. This
information, in combination with output
from analytical tools, enabled Siemens to
develop new, improved features that are
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