POWER-GEN Europe
30th May – 01st June 2006
Cologne, Germany
Turbine and Condenser Modernization in
the Farge Power Plant as an example of
One Source of Competence
Richard Bednorz
Siemens Power Generation (PG)
Mellinghofer Str. 55
45473 Mülheim, Germany
Fritz Henken-Mellies
Kraftwerk Farge
Berner Fährweg 2
28777 Bremen, Germany
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© Siemens AG 2006. All rights reserved.
1. Introduction
Farge Power Plant is located in the north of Germany in Bremen. It is owned by the
German power supplier E.ON.
Farge PP is a 350 MW , coal fired power station with a Siemens PG Steam Turbine
consists of HP, IP and 2 LPs and a Siemens PG hydrogen cooled generator. The
station was commissioned in 1967. After more then 30 years of operation it has
accumulated approximately 200.000 working hours with nearly 4400 starts and stops.
Farge staff operate also the Huntorf Power Plant which is located close by. It is an air
storage gas turbine peak load power plant with a capacity of 290 MW.
2.1 Efficiency increasing measures
After more then 30 years of operation, in the year 2004 a number of measures for
efficiency improvement and power increase should be realized at the Farge Power
Plant.
With the planned measures the project should fundamentally improve the market
position of the plant and extend its life time.
The intension was to get more than 22 MW with following measures:
• New IP-/LP- turbines (rotors and inner casings each)
• New Condenser
• Maintenance of the HP Turbine
• Flow optimization at DeSOx
• Flow optimization at overheater
• Soot blower optimization
• Other smaller improvements
Figure 1 shows all the area in the plant where measures for efficiency improvement
were planed.
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Figure 1 Efficiency increasing measures at Farge Power Plant
At the end of 2002 Siemens PG received an order for the modernization of the turboset
incl. Condenser in 2004. The Siemens PG scope included the replacement of the IPand the two LP-Turbines with a modernization of the condenser.
After the placement of the order for the modernisation of the IP/LP-Turbines and the
condenser E.ON decided to place the order for the maintenance of the HP Turbine to
Siemens PG also for the same year.
With this, the customer was able to minimize interface issues between the turbine and
the condenser.
2.2 Project execution
The engineering and manufacturing was done at the Siemens PG Steam Turbine
Factory in Muelheim an der Ruhr in Germany, using the Siemens PG manufacturing
network. As a result, the project engineering and manufacturing interfaces were
minimized. As original manufacturer Siemens PG could use its own original
documents. Even the staff, who was involved in the installation and commissioning
phase more than 30 years ago, could be integrated into the team and supported the
engineers with their specific plant knowledge.
Consequently, the owner built a team to support the project as well as to bring in the
know-how from the power plant.
2.3 New turbines design
The modernisation of the turbines comprise the replacing of the rotors and inner
casings with new stationary and moving blades.
For the IP- and LP turbines Siemens PG used the last development of steam turbine
blading. In particular significant improvements in efficiency can be achieved with fully
three-dimensional designed bladings (High Tech Turbine Blading)
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Figure 2 shows an overview of the used features.
Figure 2 Turbine upgrade
The intention of the blade design for the new turbines is to minimize the blade profile
losses, over the entire blade path. This, of course, means that benefit can be gained
from reducing the profile losses at all points of the turbine. The so-called secondary
losses (which are the losses due to turning of boundary layers along the hub and
casing) is of significant magnitude especially in the forward region of the HP turbine. It
is expedient to reduce these losses. Leakage losses are relatively high at the admission
section to the HP and IP turbines. Leak-proof design, for instance a one-piece
admission segment, can therefore bring efficiency gains at these locations.
The present stage in blading development for enhanced efficiency is the so-called 3DS
blade. This new blade type was specially designed for use in the front stages of HP
and IP turbines. The three-dimensional geometry of the vane reduces the secondary
losses at the root and tip of the blade.
The last stages of HP and IP turbines and the first stages of LP turbines are usually
equipped with twisted blades featuring integral shrouds. Given the relatively long height
(span) of these blades, 3DS corrections at the root and tip of the blade yield no
significant advantage, as the influence of the secondary flow declines with increasing
blade height.
As already mentioned, the first rows of the LP blading, like the last rows in the HP and IP
turbines, are designed as twisted blades with shrouds. The last stage (i.e. L-0) in the
exhaust region is, however, quite different: the rotating blades are free-standing, without
shrouding or damping elements. The last row of stationary blades consists of hollow
blades that can incorporate suction slots for drawing off surface moisture or with hot
steam supply for blade heating purpose.
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Drains are provided on the circumference of the inner casing for the last stage of the LP
turbine . One highly effective way of avoiding droplet impact erosion at the last stage is
to use slotted hollow blades for the last stationary blade row. The water film on the blade
surface can then be drawn off through the slots.
2.3 New condenser design
The design of the new condenser had to take into account the transportation and
installation requirements as well as the improvement of the efficiency. Therefore
Siemens PG designed a tailor-made optimized tube bundle arrangement.
Figures 3 and 4 shows the basic difference between the old and new bundle
arrangement.
Figure 3 Old module - out
Figure 4 New module – in
The performance improvement and the efficiency increase were achieved with the
condenser design by:
•
Reduction of the steam pressure losses due to smaller steam velocity and
optimized tube arrangement;
•
Optimization of the air removal to improve its capacity;
•
Optimization of the air cooler bundle, centrally located and shielded from the
steam side;
•
Horizontal bundle at the bottom for deaeration by upward flow of steam and
create a boundary for air line system.
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Figure 5 Optimized tube bundle arrangement
With a design computation the engineers confirmed the efficiency of the tube bundle
arrangement. Figure 6 shows the plot of the calculated static pressure within the
bundle. The lowest pressure area is at the air cooler and ensures an efficient air
removal. There is no danger of air blanketing.
Figure 6 Plot of the calculated static pressure
The manufacturing of the condenser was at the Siemens PG manufacturing network.
The new bundles are of stainless steel, also the base plates. The tubes are rolled and
welded to the base plates
2.4 Installation and commissioning
The installation took place in the summer of 2004.
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The plant was shut down on 15. August 2004. After 5 days of cooling down the unit,
the works started.
The condenser modules were delivered to site before the outage. The despatch of the
turbines was handled on time due to the relatively short distance from the factory in
Muelheim to the Plant in Bremen.
Of special significance was the exchange of the complete condenser module boxes.
The old boxes, installed beneath the turbines, were cut, pulled out through an opened
wall in the turbine hall and replaced by new modules.
Figure 7 Pulling out the old condenser module from the turbine hall
Figure 8 Pushing the new condenser module into the turbine hall
At the end of September the modernization scope was finished as planed.
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© Siemens AG 2006. All rights reserved.
The maintenance works on the HP turbine exceeded the planned schedule due to
unforeseen findings. An essential part of the HP turbine had reached its life time and
required modification. But only 10 days later the unit could be started up.
After commissioning and achieving full load operation the power plant E.ON proceeded
to carry out performance tests according to the standard DIN 1943. The test confirmed
the given performance guarantees fully.
The actual power increase only from the modernization of the IP/LP-turbines and
condenser of 21,6 MW exceeded even the expectations of the client to his complete
satisfaction.
3
Summary
With only the replacement of the IP- and the two LP-Turbines with a modernization of
the condenser E.ON could nearly meet the planned target of 22 MW.
All together with the additional power improvement measures done by the customer
the Farge Power Plant reached the power output increase of 27 MW and an efficiency
of 42%.
These results brought the Farge Power Plant to the top position within of the power
producers of the E.ON group.
By the way, the power output increase of 27 MW are effective “green watts” and
consequently an E.ON contribute to the environment protection program.
The key to the success of this modernization project was the close cooperation and
openness between the engineering, field service experiences and the customer
operational know-how.
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© Siemens AG 2006. All rights reserved.