drives improve power station efficiency
Post on 16-Sep-2016
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www.worldpumps.com
WORLD PUMPS October 2011Applications14
Grosskraftwerk Mannheim Aktienges-
ellschaft (GKM) operates one of
the most efficient coal-fired power
plants in Europe. While re-structuring the
boiler plant in Block 6 of this Mannheim,
Germany installation, two of the three boiler
feed pumps were fitted with high-efficiency
AC drives. The result has been a 25% energy
saving and a quick return on investment.
The GKM power plant (Figure 1) is a high-
efficiency coal-fired power plant that uses
the latest technologies. Given the block's
20-year life expectancy, the company’s
board of directors was attracted by the
short three-year’s return on investment.
As a result, it was decided to give the
go-ahead to the investment.
ABB received the order to modernize two of
the three boiler feed pumps, of which the
third pump serves as a stand-by. The main
part of the order was the supply of ACS
1000 medium voltage drives to operate the
plant’s boiler feed pumps.
For each of the two pumps, the customer
ordered a technical package including a
robust RESIBLOC input transformer, an ACS
1000 medium voltage AC drive, a star-delta
re-connection of the existing 6 kV machine,
plus its complete overhaul. The existing turbo-
clutch was replaced with a rigid transmission.
Because no suitable central electrical control
room was available near the boiler feed
pumps, the AC drives, which are water
cooled, are each housed within a dedicated,
fully air-conditioned container (Figure 2). In
order to protect the containers against any
flooding by the nearby Rhine river, these
containers are mounted on, and attached
to, one-metre high steel stilts.
The benefits
The benefits of this new installation into
Block 6 are substantial. Taking 1,000 kW of
savings and multiplying it by the operating
period of 6,000 hours each year, along with
the producer's price of around 0.05 €/kWh
(the accepted EEX electricity tariff ), the
annual energy saving is €300,000 per boiler
feed pump. This represents a large energy
saving of around 25%.
Power generation
Drives improve power station efficiencyIn the following case study, ABB fitted existing boiler feed pumps in a German coal-fired
power station with the company’s high-efficiency medium voltage AC drives. The aim was to
improve operational efficiency and this has been easily achieved, says Oskar Werner, with the
added benefit of lower CO2 emissions.
Figure1. GKM’s high-efficiency coal-fired Mannheim power plant uses the latest
technology. The efficiency has now been improved still further using ABB’s ACS 1000
medium voltage AC drives.
Figure 2. With the introduction of the ACS 1000 variable speed drives, considerable energy
savings have been achieved – up to 25%.
www.worldpumps.com
WORLD PUMPS October 2011Applications 15
The new boiler feed pump drive system also
brings the benefit of a considerably lower
environmental burden, such that the energy
savings of 1,000 kW reduce CO2 emissions
by approximately 850 kg/h.
Over 98% efficiency achieved
The ACS 1000 drive achieves the high
efficiency of 98.5%. Together with the high
efficiency transmission system at 98%, the
transformer at 99% and the machine at
around 97%, the total efficiency of the pump
drive system has been clearly improved at
around 98% overall.
A further efficiency improvement has been
achieved by optimizing Sulzer's pump
impeller. The lower energy requirement that
results also meant an improvement in the
total efficiency of this power plant.
Calculated savings potential
ABB service engineers put the first pump
into service during the summer of 2006.
It was followed three months later by the
second pump. In 2008, after two years of
operation, the calculated savings potential
and the actual operational savings were
almost equal.
Because of the project’s success, ABB has
been given a follow-up order for the modern-
ization of the entire drive technology for the
district heating water circulation pumps at
one of the two heating centres. From this
heating centre, GKM supplies heat energy
to the district heating grids of Mannheim,
Heidelberg and Schwetzingen.
www.abb.com
ACS 1000 key data
Inverter type Three-level voltage source inverter (VSI)
Power range Air cooling: 315 kW - 2 MWWater cooling: 1.8 MW - 5 MW
Output voltage 2.3 kV, 3.3 kV, 4.0 kV, 4.16 kV (optional: 6.0 kV - 6.6 kV with step-up transformer)
Maximum output frequency 66 Hz (optional: 82.5 Hz)
Converter efficiency Typically > 98%
Type of motor Induction motor
Figure 3. The water-cooled ACS 1000 medium voltage
AC drives were installed ready for connection in special,
fully air-conditioned containers.