World’s Largest Gas Turbine-(340MW)
The world’s largest turbine, with an
output of 340 MW. In combination with a downstream steam turbine, it will
help ensure that a new combined cycle power plant achieves a record-breaking
efficiency of more than 60 % when it goes into operation in 2011.
After assembly at Siemens’ gas turbine plant in Berlin
(above), the world’s largest gas turbine hits the road. Bottom: The turbine
arrives on a flatbed trailer at its destination
Residents of the town of
Irsching in Bavaria, came out in droves this year to witness the traditional
raising of their white and blue maypole. Three weeks later, they appeared in
droves again—this time out of concern for the pole, as an oversized trailer had
shown up carrying a new turbine for the town’s power plant. The residents were
worried that the turbine, which measured 13 m in length, five meters in height, and
weighed 444 t, could pose a threat to their beloved maypole. This was not
the case, however; specialists supervising the transport were actually more
concerned about a bridge at the entrance to the town, which they renovated as a
precautionary measure prior to the turbine’s arrival.
The world’s largest turbine, which was built at Siemens’ Power Generation (PG)
plant in Berlin, traveled 1,500 km to get to Irsching—initially by water
along the Havel river, various canals, the Rhine, and the Main. It then went
down the Main-Danube Canal to Kelheim, where it was loaded onto a truck for the
final 40 km. This odyssey was undertaken because the only way to truly
test such a large and powerful turbine is to put it into operation at a power
plant. "It was a nice coincidence that the energy company E.ON was
planning to expand the power station in Irsching," says Hans-Otto Rohwer,
PG project manager in Irsching.
Siemens will now build a combined cycle plant at the Bavarian facility
(Block 5) for E.ON Kraftwerke GmbH.The plant will house two small gas
turbines and a steam turbine. Siemens will also build the plant’s new
Block 4, where the giant turbine will be installed. The new turbine’s
output of 340 MW, which equals that of 13 jumbo jet engines, is enough to
supply power to the population of a city the size of Hamburg.
"Block 4 is our project at the moment," says Rohwer. Siemens will use
the existing infrastructure here, purchase gas from E.ON-Ruhrgas, and sell the
electricity it produces at the plant. That’s not that important now, however,
as the turbine first needs to be tested over the next 18 months. To this end,
the unit has been equipped with 3,000 sensors that measure just about
everything modern technology can register—from temperature and pressure to
mechanical stress and material strain. If a component is defective, or fails,
computers linked to the sensors call attention to the problem immediately. The
component will then be removed, replaced, or reworked.
Most of the measuring technology is hidden; the thing that stands out at the
facility is a section of 21 office trailers housing the measurement stations.
The trailers look tiny next to the turbine hall, which is 30 m high.
Despite its massive size, the new facility’s metal facade makes it seem light
and modern compared to the plant’s three old concrete towers from the 1960s and
’70s, each of which is 200 m high. "The hall is still a long way from
finished," says Rohwer, as he points to a big hole in the floor between
the turbine and generator. "This is where we’re going to install the oil
systems to keep all movable parts of the shaft assembly lubricated. This is
also where most of the smokestack, nearly all the electrical equipment, and the
gas tanks will be located."
Efficiency Record. Rohwer points to an opening in one of the
walls and explains that it is the connection to the air intake unit, which will
draw in fresh air from the outside. Equipped with a special housing, filters,
and sound absorbers, the unit will channel in 800 kg of air per second
when the facility operates at full capacity—an amount that would exhaust the
air inside the hall in just a few minutes. But it will be worth the effort
because the gas turbine and a downstream steam turbine will set a new world
record with an efficiency rating of over 60 %, two percentage points
higher than the previous titleholder, the Mainz-Wiesbaden power plant.
Relatively speaking, therefore, less fuel will be burned and 40,000 t less
carbon dioxide (CO2) per year will be emitted into the atmosphere
than would be the case with the Mainz-Wiesbaden plant. And compared to the
average coal-fired plant, which has an efficiency of 42 %, the new
facility in Irsching will emit around 2.3 million t less CO2
per year, while producing the same amount of electricity.
Weighing in at 444 t, the world’s largest turbine is
carefully positioned
There will still be plenty of work to do even after the plant has been
built, as technicians will have to test all systems to ensure that the gas
lines are pressure-tight, electrical cables are properly secured, and all
valves open and close quickly and reliably. It’s like a final check before a
space mission.
There’s good reason for Siemens’ decision to use one giant turbine rather than
the two smaller ones E.ON will put into operation next door. "The price
per megawatt (MW) of output and efficiency correlate with the size of the
turbine—in other words, the bigger it is, the more economical it will be,"
explains Willibald Fischer, who is responsible for development of the 8000H
turbine family. "In 1990, the largest gas turbine produced 150 MW,
and, in conjunction with a 75-MW steam turbine, had an efficiency of 52 %.
Our gas turbine has an output of 340 MW. In combination with a 190-MW
steam turbine it utilizes more than 60 % of the energy content of the gas
fuel."
Engineers at PG overcame two challenges while designing the turbine. They
increased the amount of air and combustion gases that flow through the turbine
each second, which causes output to rise more than the losses in the turbine,
and they raised the temperature of the combustion gases, which increases
efficiency. "It’s tricky when you send gas heated to 1,200 to
1,500 °C across metal turbine blades," says Fischer. "That’s
because the highest temperature the blade surfaces are allowed to be exposed to
is 950 degrees, at which point they begin to glow red. If it gets any hotter,
the material begins to lose its stability and oxidizes."
Ceramic Coating. Siemens engineers have been creative in
tackling this problem. One thing they did was lower the heat transfer from the
combustion gas to the metal by applying a protective thermal coating consisting
of two layers: a 300-µm-thick undercoating directly on the metal and a thin
ceramic layer on top of that, which provides heat insulation. The blades are
also actively cooled, as they are hollow inside and are exposed to cool airflows
generated by the compressor. The blades at the very front (the hottest part of
the turbine) also have fine holes, from which air is released that then flows
across the blades, covering them with a thin insulating film, like a protective
shield.
As turbine blades spin, massive centrifugal forces come into play. The end of
each blade is exposed to a maximum force of 10,000 times the earth’s gravitational
pull, which is the equivalent of each cubic centimeter of such a blade weighing
as much as an adult human being.
The blades are made of a nickel alloy. These used to be cast and then left to
harden. Later, crystallites were made to grow in the same direction as the
centrifugal forces.But now the blades on the giant turbine in Irsching contain
alloys that have mostly been grown as single crystals through the utilization
of special cooling processes. They are therefore extremely resistant to
breaking, as there are no longer any grain boundaries between the crystallites
in the alloy that can rupture.
Engineers also optimized the shape of the blades with the help of 3D simulation
programs, whereby the edges were designed to keep the gap between the blades and
the turbine wall as small as possible. As a result, practically all the gas
passes across the blades and is utilized. The blade-wall gap is made even
smaller due to the turbine’s operation in a cone. This means that the shaft can
be shifted several millimeters during operation until the blades nearly touch
the housing—a practice known as "hydraulic gap optimization."
Trial Run. Each off the measures mentioned above produces only
a fractional increase in efficiency or output. But taken together they add up
to a new record. Whether or not everything works as planned will be revealed by
the 18-month trial period.If preliminary test results are satisfactory,
engineers will sign off on the new mega-turbine, allowing Siemens to begin
marketing it.
After successful completion of all tests, things will quiet down in Irsching.
The turbine will then be overhauled and disassembled, and all of its components
will be thoroughly examined. If everything is found to be in order, the unit
will be reassembled minus its specialized measuring equipment.
During the overhaul, engineers will install an additional steam turbine on the
shaft at the end of the generator. The turbine will make use of the generator’s
600-°C gas to generate steam in a heat exchanger. Only through this combined
cycle process can the energy in the gas be so effectively exploited as to
achieve the record efficiency of 60 %.
Conventional gas turbine power plants are generally pure peak-load facilities
that can be turned on very quickly. But the Irsching plant is simply too good
for that. "If the gas turbine proves itself during the trial period, we’ll
assume control of the plant in 2011," says Alfred Beck from E.ON
Kraftwerke GmbH. "It’s high efficiency will make it profitable for use in
medium load operations, despite slightly higher gas prices." The facility
will then generate electricity for between 3,000 and 7,000 hours each year, and
will definitely be a superlative power plant.
World’s Largest Steam Turbine-(1750MW)
ALSTOM to build
biggest ever Steam Turbine for new EPR Nuclear Power Plant in France
ALSTOM has been chosen by French utility EDF to supply the turbine island* for
the world’s biggest European Pressurised Reactor nuclear power plant at
Flamanville, France. The order is worth more than 350 million euros to ALSTOM.
In
close partnership with EDF, ALSTOM will carry out the engineering, procurement,
construction and commissioning of the whole 1750 MW turbine island and directly
supply all the major turbine island components, including Arabelle steam
turbine, generator, condenser and moisture separator reheaters.
EDF
is the world’s major nuclear power generation company with 58 units in service,
all of which use ALSTOM technology in the turbine island. This order, won
against international competition, reflects EDF’s confidence in both ALSTOM
technology and engineering know-how.
Arabelle
turbine technology is installed in four 1750 MW units in the EDF nuclear
power plants located in Chooz and Civaux, and is currently being installed in
the extension of Ling Ao power plant in China. The Arabelle steam turbine at
Flamanville will be the biggest ever built in the world.
The
Flamanville turbine island will be designed to last for 60 years and will meet
exacting standards of reliability and availability.
Patrick
Kron, Chairman and CEO of ALSTOM, said: “The selection of ALSTOM by the
world-leading company in nuclear power generation is confirming our strong
technology leadership through our Arabelle turbines and our extensive
experience in the conventional islands of nuclear power plants. Participating
in this prestigious project further reinforces our worldwide position in the
re-emerging nuclear market.”
*
The turbine island comprises the steam turbine, the generator, the condenser,
the moisture separator reheaters and auxiliary equipment needed to convert
steam produced at the nuclear reactor into electrical energy
ALSTOM
sets the benchmark for innovative, environmentally friendly technologies in the
world of power and rail transport infrastructure. ALSTOM built the fastest
train and the highest capacity automated metro in the world, and provides
turnkey integrated power plant solutions and associated services for a wide
variety of energy sources, including hydro, gas and coal. The Group employs
60,000 people in 70 countries, and had sales of € 13,4 billion.
