drives improve power station efficiency

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www.worldpumps.com WORLD PUMPS October 2011 Applications 14 G rosskraftwerk 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 efficiency In 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 CO 2 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%.

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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.