Full Thrust: Innovation
for Maintenance of High
Performance Industrial
Gas Turbines
Repair process based on EOS technology opens
new opportunities for industrial gas turbine
maintenance cost reduction
I
n 1852 James Prescott
Joule described for the first
time the physical principle
of the gas turbine – the
thermodynamic cycle, also known as
the Joule Process. The initial ideas and
concepts behind this invention date
back as early as 1791.
The Swedish-based company
Siemens Industrial Turbomachinery
AB (SIT) manufactures gas turbines
for power generation in industrial
and oil and gas applications. The
performance spectrum of Siemens’
industrial turbines ranges from 15 to
60 megawatts. Besides construction,
the Siemens subsidiary also provides
long-term service and maintenance
for these engineering masterpieces. In
an effort to help reduce maintenance
costs, Siemens is currently working on
the development and implementation
of Additive Manufacturing technology,
utilising EOS technology and
equipment.
Challenge
The gas turbine consists of air inlet,
compressor, combustor, turbine
and hot gas outlet. The compressor
compresses the air going through the
engine. In the combustion chamber,
compressed air is mixed with fuel and
During operations,
the components in
the engine’s hot gas
path are exposed to
high temperatures
burned in order to increase the kinetic
energy of the flow. In the turbine,
the kinetic energy of the flow is
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converted into mechanical energy. This
mechanical energy is used to turn the
gas turbine compressor and generator
(to generate electricity) or other driven
equipment (e.g. compressor to pump
the gas /oil through the pipe lines).
During operations, the components in
the engine’s hot gas path are exposed
to high temperatures, at times in
excess of 1,000 degrees Celsius (e.g.
blades and vanes). This, in turn, leads
to a high level of wear of the hot gas
path components.
This is also true for the burner tip –
the point at which the ignition of the
fuel-air mixture takes place. Here, the
effects of wear and tear can be clearly
seen and measured. The manufacturer
undertook rigorous testing to establish
a prescribed operating period after
which the burners typically need to be
repaired.
Conventional repair procedure required
prefabrication of a big portion of the
burner tip. This prefabricated burner
tip is used for replacement of the
burner tip after a specified operation
time (cut old and weld prefabricated
one). Conventional repair procedure
can be time-consuming with a
significant number of sub-processes
and examinations. To help simplify
and speed up the repair procedure
Additive Manufacturing technology was
implemented at Siemens.
Solution
Such an undertaking requires an
innovative partner. Siemens found
just that in EOS: In addition to having
the right Additive Manufacturing
technology, EOS was also able,
within a short time frame, to
individually adapt one of its in-house
machines – an EOSINT M 280 – for
this processing. The alterations
concerned, in particular, the scale of
the machine’s interior, which had to
be enlarged to accommodate the 800
millimetre burner. The manufacturer
also amended further hardware
components such as a camera system
and an optical measuring system and
made corresponding adjustments to
the software. EOS carried out the
extensive re-working of the EOSINT
system in less than a year.
From the outset it was
clear that the approach
would be reaping
benefits
From the outset it was clear that the
approach would be reaping benefits.
Rather than replacing a large portion
of the burner tip, Siemens began
by removing the damaged material
only. Moreover, during repair,
former versions of the burners
in the fleet could be re-built to
the latest design. So, theses
former versions of the burners
in the fleet could be not only
repaired, but also improved –
thus bringing new meaning
to the term Additive
Manufacturing.
Resul