Type of CHP system: BFB boiler

Plant owner: E.ON Finland Oy

Commissioned: (reconstructed):1986 (2000)

Status of plant: Commercial

Contractor details:

The main boiler of the plant was commissioned by A Ahlström. Fluidised bed boiler revision was delivered by Fortum Engineering. Turbine: V/O Tecnoroexport LMZ.

Power generation: Steam turbine

The technology change in year 2000 made it possible to use large variety fuels. Also condensing power production is possible when heat demand is low.

Main fuel: Multifuel (more biofuels and/or peat)

Bark, sawdust, cutter chips, recycled fuels, landfill gas from the nearby landfill and peat. Total of 592 GWh/a of wood fuels, 464 GWh/a of peat, 7 GWh of heavy fuel oil, 5.7 GWh of biogas annually.

Nominal capacities & efficiencies:

Thermal input, biomass & waste: 204 MW

Total thermal input, incl. fossil fuels: 204 MW

Gross electrical output: 68 MWe

Net electrical output: 54 MWe

Heat output: 120 MJ/s

Electrical efficiency, gross: 33 %

Electrical efficiency, net: 26 %

Overall efficiency, gross: 85 %

Power to heat ratio: 0,45

Plant runs normally with a blend of wood fuel/peat, 50/50, or even 75/25. Max output is about 15 % higher if 100 % peat is used

How is plant controlled: Plant is controlled by the heat demand. More condensing power is produced when the electricity price is high enough in the Nordic electricity market.

Heat backup: There are no heat back-up boilers at the plant. Other local heating plants connected to the DH network produce heat for peak and back-up. Plant is also equipped with electrical boiler but it is only used for main boiler start-up.

Heat usage: Heating only

Energy usage:

Heat produced at the plant is used for supply district heating network of the city. Heat produced at the plant is used for supply district heating network of the city. 77 % of the buildings in the city of Joensuu get the heat energy from the district heating network. The city of Joensuu has got a district heating system already since 1950´s.

Annual district heat production is about 480 000 MWh/a, CHP power production 220 000 MWh and condensing power 10 000 to 130 000 MWh/a.

District heat coverage (% of total demand in DH network): 87 %

DH inlet temperature: 72-115 °C

DH return temperature: 45-50°C

Fuel storage: Fuel storage capacity is 10 hours (2500 m3).

Waste water: Sanitary water is led to the municipal sewage treatment. Waste water from processes is led to sedimentation basin and from there to water system.

Ash discharge: Plant has own banking field for ashes. Some ashes have been used for landscaping.

Plant description:

Plant is a multi-fuel plant. Originally the plant was equipped with pf-boiler, after retrofitting using fluidised bed boiler. Plant generates heat for DH-system of  the city of Joensuu.

E.ON Finland leads the way in the field of emission trading. It is the first one in Nordic countries to have started to test emission trading.

Fuel feeding system: Wood fuel and peat is unloaded to an intermediate storage. Storage is unloaded by a screw conveyor  and the fuel is led to the boiler with a flight conveyor.

Boiler: BFB boiler. Boiler efficiency: 88%.

Turbine: Back pressure turbine with condensing tail.

Steam data: 75 kg/s, 535°C, 110 bar

Flue gas cleaning: Electric precipitator.

Cooling system: River water

Staff: Total number of power plant personnel is 40. There are 3 persons working in night shift.

Electricity sale info: Variable costs for electricity production are calculated and it is compared to the price of Nord Pool. Electricity selling is analysed in hourly grade.

Data collected and quality assured by: VTT Processes.

Contact person: Kati Veijonen