Drive solution boosts energy efficiency at power plant

Medium-voltage drives have slashed the energy consumption of two boiler feed pumps at a coal-fired power plant in Germany by 25 percent. The solution increases plant revenues by $800,000 a year and reduces annual CO2 emissions by 10,200 tons.
The two ABB high-efficiency ACS 1000 medium-voltage drives control two boiler feed pumps at Unit 6 of the 1,675-megawatt GKM coal-fired power plant at Mannheim, Germany.

The pumps each have a rated output of 5.8 megawatts and were installed in the mid-1970s when Unit 6 was constructed. Prior to the ABB solution, the pumps were controlled by hydraulic clutches, which were operating with an efficiency of only 72 percent and were losing more than 1 megawatt of energy per pump.

When Unit 6 was revamped in 2006, GKM concluded that the poor efficiency and high energy losses of the pumps and clutches were no longer sustainable. GKM turned to ABB for a solution.

ABB proposed a modernization package for each pump, comprising an ACS 1000 medium-voltage variable speed drive, an ABB RESIBLOC dry-type transformer and a complete overhaul of the pumps.

The water-cooled ACS 1000 medium-voltage AC drives are housed in air-conditioned containers and on stilts to provide a safe and controlled environment and protect the drives from flooding by the nearby Rhine River.

After two years of trouble-free operation, GKM could confirm a reduction in pump energy consumption of 25 percent, energy that the plant can sell instead of consuming and which is worth $400,000 per pump per year in revenues.

The improvement in energy efficiency has had a corresponding impact on the plant’s carbon footprint, lowering its carbon dioxide emissions by 10,200 metric tons a year – a significant reduction for a fossil-fuel power plant.

And the overall efficiency of the new pump drive system is a near-perfect 98.5 percent, compared to the inefficient 72 percent of the previous system.

The installation has been so successful that GKM subsequently awarded ABB an additional two contracts to install medium-voltage drive systems for the feeder pumps and water circulation pumps at two of the plant’s other generating and district heating units.

Coal-fired power plants typically consume between 7 and 15 percent of the energy they generate, with motor-powered applications like pumps accounting for 80 percent of this parasitic consumption.

Click here to learn more about the MV drives solution for GKM.

For additional information, visit the ABB Web site at www.abb.com.