Type of CHP system: Grate fired boiler

Plant owner: Owned by Tranås Energi AB, which is owned by Tranås Municipality

Commissioned: 2003

Status of plant: Commercial

Contractor details: Wärtsilä OY (boiler, buildings) Vaporel (turbine)

Power generation: Steam turbine

Flue gas condenser, 3,5 MW. Delivered by Radscan AB.

Main fuel: Bark

Bark75% (moist 55%), Sawdust 25% (moist 50%) , Annual consumption biomass 57 GWh

Nominal capacities & efficiencies:

Thermal input, biomass & waste: 12 MW

Total thermal input, incl. fossil fuels: 12 MW

Gross electrical output: 1,8 MWe

Net electrical output: 1,6 MWe

Heat output: 12,1 MJ/s

Electrical efficiency, gross: 15 %

Electrical efficiency, net: 13 %

Overall efficiency, gross: 116 %

Heat capacity 8,5 MW. Flue gas condensor 3,5 MW.

How is plant controlled: By heat demand

Heat backup: 20 MW biomass fired boilers, with flue gas condensors. 2×25 MW oil boilers.  Electric boiler 8 MW. Landfill gas boiler 1 MW.

Heat usage: Heating only

Energy usage:

The boiler is connected to the city of Tranås district heating system. Energy sold in the district heating system 128.000 MWh/year. 800 customers. (Approx80% to households and 20% to industries.)

District heat coverage (% of total demand in DH network): 50 %

DH inlet temperature: 70-115 °C

DH return temperature: 40-55°C

Heat storage size: Accumulation tank 2000m3 m3

Hours of full load that the heat storage can meet: 2 hours

Fuel storage: Maximum allowed storage is approx. 2.400 MWh. Approx 8 days of full load operation.

Waste water: From flue gas condenser, pH-adjustment and sandfilter. 25.000 m3/year

Ash discharge: Depony, landfill

Plant description:

Tranås Energi AB district heating network in Tranås is today 45 kilometers long. The new combined heat and power plant

is built next to the already existing district heating plant, which has four boilers that together produce 78 MW of district heat. Now

the combined heat and power plant is completed and the old plant will become a stand-by and peaking facility The existing

plant will also be used as a top-up facility.

Fuel feeding system: Different sorts of fuel is carried by a tractor to a 450m3 storage in the ground outside. From the storage:   scrapeconveyers,1 screw,

Boiler: Wärtsilä biograte

Turbine: Tuthill Nadrowski B5-S5

Steam data: 15,2 bar, 345 degree Celcius 13,6 tons/hr

Flue gas cleaning: Elctrostatic precipitator, flue gas condenser

Staff: Daytime:3 persons, weekends daytime: 1 persons. No persons at night

Electricity sale info: Follows Nordpool spotprice (hour).

Total capital cost: € 6,400,000

Data collected and quality assured by: Swedish Biomass Association.

Contact person: Johan Vinterbäck