POWER October 2014 - 35

TOP PLANTS
1. No lazy river here. Coal is delivered to Rotterdam on ships and then transported by
barge to Lünen, where cranes are used to unload it. Courtesy: Trianel Kohlkraftwerk Lünen
GmbH und Co. KG
perature of 605C (1,121F). The steam is first
directed to the high-pressure turbine, following
which it is reheated and directed to the
medium-pressure turbine, and then to two
low-pressure turbines.
Controlling Emissions
Lünen utilizes a DeNOx process between its
reheater and air preheater. In the process, nitrogen
oxides react with ammonia and, with
the help of catalysts, are transformed into
nitrogen and water vapor. The plant also has
an electrostatic precipitator with 40 hoppers
for particulate removal and a flue gas scrubber
to reduce SO2 emissions. The resulting
gypsum and fly ash are recycled for use in
the building materials industry and by cement
plants.
Although carbon capture and storage technology
is still being developed and tested
around the world, the facility was designed
with room set aside so the plant can be retrofitted
with such a system if it is proven to be
viable on a large scale in the future.
" Despite difficulties arising from the spenese
company-Matsuo Steel Structure
Co., Ltd.-was chosen to manufacture
the components under the watchful eye of
specialists from TÜV Rheinland and Trianel
employees. Because the accuracy and
quality of work was so important, Matsuo
assembled the entire boiler furnace roof in
Shanghai to test the dimensions and verify
a precise fit prior to shipping the pieces
to the plant.
Efficiency Is the Key
The plant features a Siemens SST5-6000
steam turbine, a SGen5-3000W generator,
and the SPPA-T3000 instrumentation and
control system. The highly efficient steam
turbine is well suited for baseload operation,
but its design characteristics are also
a good match for highly responsive ramping-an
important aspect due to the variability
of renewable resources and their
prevalence in Germany.
" In the coming decades, conventional
power plants will play a major role in the
German energy transition and will still be
the backbone of security of supply. They
guarantee supply during windless and sunless
periods, " said Stefan Paul, managing
director of Lünen.
Trianel expects Lünen to achieve an 80%
capacity factor during its first full year of
operation, providing electricity for about 1.5
million households, as well as supplying the
city of Lünen with district heating. With an
electrical efficiency of 45.95%, the plant is
the cleanest and most efficient hard coal-
fired power plant in Europe. Compared to an
average efficiency of 36% for older plants,
October 2014 | POWER
Lünen will emit about 1.2 million fewer tons
of CO2 per year.
" The highly efficient flue gas stream's
cleaning process allows us to significantly
remain below the German federal emission
guide values regarding air and waste water
and, thus, to minimize impact on man and
environment in the plant's catchment area, "
Paul said.
The plant requires about 2 million tons
of coal each year. The coal is sourced from
various mining regions around the world and
delivered to the port of Rotterdam by bulk
carriers. From there, it is loaded onto barges
(typically four per day) and delivered to the
plant by Rhenus SE & Co. KG via the Datteln-Hamm
Canal.
The coal is unloaded using cranes (Figure
1) at the plant-owned port and is stored dustfree
in two silos with a 200,000-ton total capacity-enough
to operate the plant for about
30 days at full load. Fugitive dust emissions
are virtually eliminated through the use of
fully enclosed conveyor systems.
The coal is conveyed from the silos to
four cast bunkers that can hold 800 tons each
in the steam generator building. It is then
pulverized and fed into Lünen's 70-m-tall
boiler. During the design phase, the company
contemplated using a relatively new alloy-
T24-to construct the boiler tubes, but in
the end, the more proven T23 was used. The
engineers now look back with no regret,
because other German plants have run into
problems with T24, some even having to replace
the material.
The plant operates with supercritical steam
at a pressure of 285 bar (4,134 psia) and temwww.powermag.com
cial
licensing situation for coal-fired power
plants in Germany, we have managed to
build a plant to the highest technical standards
that by far surpasses the contractually
agreed performance values for output and
efficiency, " said Rainer Hauenschild, CEO
of the Energy Solutions business unit at Siemens
Energy.
It Takes a Village to Raise a Plant
At the height of construction in 2011,
more than 1,400 workers were employed at
Lünen. The plant currently employs about
90 personnel, including Trianel, STEAG
management, and Microca port operations
employees. In addition to the permanent
plant staff, it is estimated that the facility
supports another 400 jobs through its suppliers
and contractual partners.
" Managing the state-of-the-art and most
efficient coal-fired power plant in Europe
not only inspires me as an engineer-it is
also a heartfelt matter. Together with our
employees and service providers, we are
working to an even more flexible reaction
on the volatilities of power demand and to
the site's optimal utilization. The benchmark
towards our 31 shareholders is the
steady technical and commercial improvement
of the plant, " said Paul.
Congratulations to Trianel, Siemens, and
all of the companies that completed the construction
and continue to support the operation
of the facility, which is a worthy recipient
of a POWER Top Plant award. ■
-Aaron Larson is a POWER associate
editor (@AaronL_Power,
@POWERmagazine).
35

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POWER October 2014

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