Type of CHP system: Dust fired boiler
Commissioned: (reconstructed):1985 (2001)
Status of plant: Commercial
Boiler unit: Ålborg Boiler/D. Babcock
Turbine unit: BBC
Precipitator: FLS miljø
FGD: Fläkt DK
Power generation: Steam turbine
Studstrupværket, unit 4, is fuelled with a combination of hard coal and straw in a pulverized coal fired boiler.
Main fuel: Co-firing (fossil + biofuel)
Hard coal is the main fuel. In 2001 the plant has been designed to utilise 100,000 tonnes of straw annually amounting to 10% of the fuel demand (energy basis). 4 of the 24 burners have been redesigned for straw. Oil can be utilised in the same boiler.
Nominal capacities & efficiencies:
Thermal input, biomass & waste: 62,9139072847682 MW
Total thermal input, incl. fossil fuels: 629,139072847682 MW
Gross electrical output: 285 MWe
Net electrical output: 260 MWe
Heat output: 484 MJ/s
Electrical efficiency, gross: 45,3 %
Electrical efficiency, net: 42,3 %
Overall efficiency, gross: 86,2 %
Power to heat ratio: 0,57
Gross output of 375 MWe can be obtained in condense mode.
Net output of 350 MWe can be obtained in condense mode. 260 MWe at full heat load.
The net power share from the straw is 35 Mwe.
How is plant controlled: Studstrupværket is controlled by a certain minimum of heat demand and beyond this, by the electricity demand.
Heat usage: Heating only
The power produced is fed into the electricity grid.
The heat is sold to the district heating network of Århus Municipal.
DH inlet temperature: 125 °C
DH return temperature: 50°C
Heat storage size: Storage capacity is 27000 m3/8500GJ.
(Common for 2 units of same size). m3
Fuel storage: The coal is stored in a coal yard.
Straw storage capacity: 1152 balles/576 tonnes, equal to 29 hours of operation at full load.
Waste water: In 2001 3726 m3 waste water from both units 3 and 4 were sent to the municipal sewage system from all the units at Studstrup.
Ash discharge: In 2001 120823 ton of fly ash from both units 3 and 4 were produced.
Studstrupværkets unit no. 4 is identical to unit 3. The plant was originally built as a coal fired unit for combined heat and power production. To meet the biomass agreement with the government one row of burners was modified to include burners for co-firing of coal and straw. The straw substitutes about 10% of the coal at full boiler load, related to energy input. The heat generated is supplied to the DH area of Århus.
Fuel feeding system:
The coal is conveyed from the coal yard into the silos of the unitand then feed into the coal mills for grinding. The pulverized coal is trans ported to the burners by means of primary air.
The straw is pre-treated in a shredder and hammer mill. The straw is cut into bits shorter than 30 – 50 mm, and then conveyed pneu-matically to each of the 4 burners in one row.
Boiler: Benson boiler
Turbine: Extraction turbine.
240 bar, 535/540 deg. C
Flue gas cleaning:
The unit is equipped with electrostatic precipitator.
Installed low Nox burners in 1993.
Cooling system: Sea water cooling.
Steam extraction for cooling by the DH-net
Data collected and quality assured by: FORCE Technology.
Contact person: Anders Evald