Type of CHP system: CFB boiler

Plant owner: Owned by Växjö Municipality

Commissioned: 1996

Status of plant: Commercial

Contractor details:

Boiler: Foster&Wheeler Finland

Turbine: Alstom Finspång (former ABB)

Flue gas cleaning: Alstom Växjö  (former ABB)

Power generation: Steam turbine

The plant is supplied with a flue gas condenser giving up to 25MW.

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

Biomass of different kinds are fired. The last seasons we have used 40 % forrest residual, 40 % sawdust, 10 % bark and 10 % peat. Aprox 650 GWh annually (¨330 000 tons)

Nominal capacities & efficiencies:

Thermal input, biomass & waste: 115 MW

Total thermal input, incl. fossil fuels: 115 MW

Gross electrical output: 38 MWe

Net electrical output: 35 MWe

Heat output: 86 MJ/s

Electrical efficiency, gross: 33 %

Electrical efficiency, net: 29 %

Overall efficiency, gross: 108 %

Typical MWe output is 35 MW, Flue gas condenser giving 25 MW

How is plant controlled: By the heat demand.

Heat backup:

Two oil fired boilers on 50 MW, but one of them rebuilt for biomass on 27 MW. One oil fired boiler on 75 MW rebuilt for wood powder

And one electric boiler on 25 MW

Heat usage: Heating only

Energy usage:

The electric power is sold to Östkraft AB partly owned by VEAB. Last year 148 GWh. Last years heat production was 490 GWh. Number of distict heat customers: 4400

Number of electricity distribution customers: 27 000

District heat coverage (% of total demand in DH network): 75 %

DH inlet temperature: 80-120 °C

DH return temperature: 40-55°C

Heat storage size: 2000 m3

Hours of full load that the heat storage can meet: 140 MWh – 10 hours summer, 1 h winter

Fuel storage: We store the fuel outdoors and can store approx 50 000 MWh   Normally we store fuel for one week.

Waste water: Waste water is treated with sandfilter and goes to the waste water treatment plant run by the municipality.

Ash discharge: Flyash is recycled, bottom ash used on landfill

Plant description:

The plant is almost exclusively fired with biomass but was built for a variarity of fuels from coal to biomass and can give reduced effect on oil. This is enabled by using the CFB technique. The boiler is of so called Compact model, with integrated, (square) cooled cyclones. It is operated during a period of September to May when the district heating demand is sufficient.

Water consumtion is for the whole plant site

Fuel feeding system:

The fuel feeding system is constructed by Vessme OY Finland as subsupplier to Foster&Wheeler. It has two separate lines ending with four screws entering the fuel to the boiler

Turbine: A Vax turbine constructed by former ABB Finspång. Design for high electric power efficiency

Steam data: 140 bar, 540 degree Celcius,146 tons/hr

Flue gas cleaning:

For removal of NOx we have a SNCR/SCR system with ammonia injected in the cyclone and a honeycomb catalyst in the fluegaschannel. Dust/particles are separated in a two chamber electrostatic persipitator.

Cooling system: Rest heat is collected in condensers for district heating.

Staff:

In the company there are 141 employees. At the production unit 45 persons (producing heat and power, not included maintainence of distribution net and grid, marketing etc.) During day normally 6 persons work directly with the production and 15 with maintainence and support. During night there are 3 persons at low season and four at high.

Electricity sale info: The tarif change with market price, each hour.

Total capital cost: € 45,000,000

Data collected and quality assured by: Swedish Biomass Association.

Contact person: Johan Vinterbäck