THE AVEDØREVÆRKET CHP PLANT

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1 The Avedøreværket CHP plant

2 DONG ENERGY THE AVEDØREVÆRKET CHP PLANT The Avedøreværket CHP plant is one of DONG Energy s ten central power plants. It is situated on Avedøre Holme south of Copenhagen and is one of the world s most efficient CHP plants. The plant consists of two units: the coal-fired- and oil-fired Avedøre 1 from 1990 and the multi-fuel-fired Avedøre 2 from Avedøreværket produces power to the Nordic power grid and district heat to the Greater Copenhagen area. The two units are capable of supplying approx 200,000 households with heat and approx 1.3 million households with power. This corresponds to approx 30 % of the power consumption in Zealand. Great emphasis has been placed on designing the two units to fit into the flat, embanked landscape at Køge Bay. Due to its untraditional architecture, Avedøre 1 has won several international awards during recent years. Power production The total power production from Avedøreværket is sold on market terms. This means that production may vary much from one year to another. The power production is solely determined by supply and demand on the Nordic power market and by the relation between fuel prices and power prices. If the power price is low due to a large domestic power production from wind turbines or large, hydro-electric power production in Norway, is reduced at Avedøreværket production. The power is sold on a daily basis at the Nordic power exchange, NordPool, where the price is detemined by supply and demand. 2

3 AVEDØRE 1 Since its commissioning in 1990, Avedøreværket has produced power to the power grid and district heat to one of Northern Europe s largest district heating systems in the Greater Copenhagen Area. The production at Avedøre unit 1 is primarily based on coal, but the boiler can also use oil as fuel. The unit s power production covers approx 12 % of the power consumption east of the Great Belt, and the district heat production corresponds to the consumption of approx 70,000 households. Approx 500,000 households are daily supplied from the district heating system which goes from Gentofte in the north to Solrød in the south and Roskilde in the west. KARA/NOVEREN CHP plant Waste-to-energy District heating system VEKS district heating supply area CTR district heating supply area Vestforbrænding district heating supply area District heating steam January 2007 The district heating system goes from Gentofte in the north to Solrød in the south and Roskilde in the west. 3

4 85 TONNES OF COAL PER HOUR At maximum production, the fuel consumption is approx 85 tonnes of coal per hour or approx 50 tonnes of oil per hour. Once a day the employees on the coal yard fill up the four coal silos with coal. This is done by transporting the coal on closed conveyor belts from the coal yard to the silos with a unit capacity of 800 tonnes. Each silo supplies a coal mill which pulverises the coal. Warm air blows the pulverised coal into the boiler burners through a piping system. When the pulverised coal is blown into the furnace, it is ignited and combusted at a temperature of approx 1,500 C. The use of a special low-nox burner type reduces the content of nitric oxides in the flue gas. The boiler walls consist of water-filled pipes. The high temperature in the boiler transforms the water into high pressure steam. The high-pressure steam is then led from the boiler to the turbine which consists of one high-pressure part, two intermediate-pressure parts and one low-pressure part. The steam expands in the turbine and makes the turbine shaft rotate by 3,000 revolutions per minute. The turbine turns the generator which produces power. Workflow 1. Boiler 2. Coal mills 3. Burners 4. Turbine and generator 5. District heat exchangers 6. Feed pump 7. DeNOx plant 8. Air preheater 9. Ash separator 10. Desulphurisation plant 11. Gypsum storage 12. Stack 4

5 The 50 metres high storage tanks at Avedøreværket. The power is led through a transformer and further into the high-voltage grid at a voltage of 132 kv. After having passed the turbine, the steam proceeds to either the district heat exchanger or to the condenser. In the district heat exchangers the district heating water is heated to C by the steam before it is pumped into the district heating system. If the steam proceeds to the condenser, it is cooled by sea water and in both cases the steam condenses to water which is pumped back into the boiler after which the process starts over. The coal is transported to Avedøreværket by barges. Once unloaded, the coal is spread out in the coal yard. The coal yard has a capacity of up to 600,000 tonnes of coal, corresponding to approx six months consumption. The two oil tanks have a capacity of 80,000 tonnes of oil. To obtain a higher flexibility in the production of heat and power, Avedøreværket has two 50 metres high storage tanks capable of storing the district heating water at times with a low district heat demand for instance at night. Together the two storage tanks have a capacity of 44,000 m 3 water Cogeneration of heat and power entails that up to 91 % of the fuel energy is utilised at maximum district heat production. 5

6 Efficient flue gas cleaning When the flue gas leaves the boiler, it passes a catalyst in a denox plant where the content of nitric oxides (NOx) reacts with ammonia. The reaction converts up to 85 % of the nitric oxides into water and pure nitrogen. The flue gas is then led through an electrostatic precipitator where more than 99 % of the fly ash is removed. The fly ash is a high-demand mineral product used for the production of cement and concrete as well as for road construction. Technical key data, Avedøre 1 Commissioned in 1990 Steam pressure at superheater outlet 250 bar Steam temperature 545 C Fuel Coal and heavy fuel oil Net output at full load 250 MW or 215 MWe and 330MJ/s heat Efficiency, condensation operation 42 % Efficiency, CHP operation 91 % All the fly ash is reused for these purposes. At coal-firing, Avedøre 1 produces up to 13 tonnes of fly ash per hour. From the electrostatic precipitator the flue gas is led to the desulphurisation plant where the flue gas is led through by a mixture of limestone and water which reacts with the sulphur dioxide in the flue gas. This reaction forms the mineral product gypsum. The gypsum is separated in purifiers before it is led to the gypsum storage and sold to gypsum board manufacturers. This process removes more than 98 % of the sulphur dioxide from the flue gas, and approx 4 tonnes of gypsum are produced per hour. 6 AVEDØRE 1

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8 AVEDØRE 2 Avedøre 2 is a so-called multi-fuel-fired plant. This means that the plant is capable of using several types of fuel: natural gas, oil, woodpellets and straw. Avedøre 2 is the world s most efficient CHP plant. As a result of cogeneration of heat and power, up to 94 % of the fuel energy is utilised at maximum district heating production. Avedøre 2 can cover the heat demand of approx 130,000 households and the power consumption of approx 1 million households. The process Unit 2 consists of three modules: a steam turbine plant with supercritical pressure, a gas turbine plant and a biomass plant. The steam plant is the heart of Avedøre 2 and consists of boiler, steam turbine, generator and flue gas cleaning plant. The fuel can be utilised more effectively by increasing the pressures and temperatures to a level never seen before. Prior to combustion, the woodpellets are pulverised in large mills. The steam produced in the boiler pipe walls operates the turbine which then produces heat and power as in unit 1. The plant is equipped with denox plant, electrostatic precipitator and desulphurisation plant. However, the flue gas cleaning is only necessary when firing pellets and oil because natural gas does not contain ash and sulphur compounds. The steam plant is connected to the two 55 MW gas turbines and a 45 MW biomass plant. The gas turbines function as peak-load plants. This means that they are put into operation if power demand increases significally, typically in the morning and in the evening. The heat in the gas turbines exhaust gas is used to heat the feed water for the boiler, utilising the thermal energy to the smaximum possible extent. This means that Avedøre 2 uses a relatively small amount of fuel to produce one kilowatt hour compared to old power plants. Avedøre 2 thus utilises up to 50 % of the energy in the fired fuel for power production whereas an old unit utilises only approx 35 %. Natural gas and oil are cofired with woodpellets in the almost 70-metres high steam boiler at a temperature of approx 1,500 C. 8

9 Avedøreværket fires up to 170,000 tonnes of straw on an annual basis. The biomass plant The straw-fired biomass plant consists of a straw storage, one boiler, an ash separator and a plant for processing of bottom ash and fly ash. The plant is the largest in the world so far. The biomass boiler supplies steam to the unit s main turbine. The capacity is 45 MWe and 50 MJ/s heat. At maximum production, 25 tonnes of straw are fired per hour, corresponding to 50 straw bales of 500 kg each. The straw, which is supplied by a number of farmers in Zealand and the southern islands, is transported from the straw storage to the boiler on four conveyor belts. A straw shredder placed at the inlet to the boiler, loosens the straw before it is fed into the boiler by feed screws. A better utilisation of the steam energy is obtained by leading the steam from the biomass boiler to the main turbine rather than by converting it in a separate steam turbine. This connection of the systems entails a synergy, making the plant the world s most flexible and efficient biomass plant of its type. The total degree of utilisation of the fuel reaches up to 94 %. Avedøreværket fires up to 170,000 tonnes of straw on an annual basis. 9

10 AVEDØREVÆRKET FROM ABOVE Technical key data Avedøre 2 Commissioned 2001 Steam pressure at superheater outlet Main boiler 300 bar Biomass plant 310 bar Steam temperature at superheater outlet: Main boiler C Biomass plant 580 C Fuel Natural gas, heavy fuel oil, wood pellets and straw Net capacity at full load: Without gas turbines 425 MWe With gas turbines 575 MWe Without gas turbines 355 MWe and 485 MJ/s heat With gas turbines 495 MWe and 575 MJ/s heat Efficiency, condensation operation 49.1 % Efficiency, CHP operation 93 % 1. Boiler house, unit 1 2. Boiler house, unit 2 3. Administration building 4. Gas turbines 5. Straw storege 6. Eco-plant, unit 1 7. Eco-plant and biomass boiler, unit 2 8. Cooling water inlet 9. Harbour 10. Sub-stations 11. Storage tank 12. District heating pump station 13. Oil tanks 14. Coal yard 15. Wood pellet storage 10 Avedøre 2

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12 THE CONTROL ROOM Avedøre 1 and 2 are controlled from a common control room in unit 1 The control room is manned by shift workers at all hours A total of 130 staff are employed at Avedøreværket Unit 1 is controlled and monitored from a number of monitors and control panels Avedøre 2 is controlled and monitored by an advanced large-area display screen. The control room. 12

13 THE POWER PLANTS Frederikshavn Central CHP plants Local CHP plants Waste-to-energy CHP plants Måbjerg Herning Grenaa Studstrupværket Esbjergværket Vejen Horsens Skærbækværket Asnæsværket Kyndbyværket Avedøreværket DTU Lyngby Svanemølleværket H.C. Ørsted Værket Odense Stigsnæsværket Ringsted Slagelse Haslev Køge Haderslev Enstedværket Masnedø Maribo-Sakskøbing 13

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15 DENMARK S NEW ENERGY COMPANY DONG Energy is Denmark s new energy company established in DONG Energy is active in all links of the energy supply chain from offshore oil rigs in the North Sea, power plants producing heat and power, and wind farms, to marketing the energy and transporting it all the way to our customers doorsteps in Denmark and abroad. This ensures a highly reliable supply of energy and gives us the necessary expertise for developing our company for the future. DONG Energy has many years of experience. For more than a hundred years we have been supplying power to the Danish consumers and developed the special, Danish tradition of combining the production of heat and power. We are also at the cutting edge in the development of renewable energy, not least in the establishment of offshore wind farms. DONG Energy has increased its international activities significantly and is now an international energy company focusing on the North European energy markets. On the liberalised market the customers are free to choose their energy suppliers and DONG Energy competes every day against other energy companies to be the consumers preferred supplier. Yet, still being a small player on international scale, DONG Energy is rapidly developing its activities in all aspects of energy supply to be well-positioned for future competition on the energy market. Since the beginning of the 1980s, we have also supplied oil and natural gas to the Danish market. Innovation is a natural part of how we work. We have been involved in the extraction of the North Sea s reserves of oil and natural gas for 25 years, and our power plants are some of the most efficient and eco-friendly in the world. 15

16 Pay a visit to Avedøreværket Avedøreværket welcomes groups and schools and invites you to participate in a tour of our heat and power producing facilities. If you would like to have more information about the visits, please contact Avedøreværket at tel DONG Energy Avedøreværket Hammerholmen Hvidovre Denmark Tel Fax