Type of CHP system: Grate fired boiler

Plant owner:

Elsam A/S

Overgade 45

DK-7000 Fredericia


Commissioned: (reconstructed):1982 (2002)

Status of plant: Commercial

Contractor details:

Boiler unit: BWE

Turbine unit: ABB

Precipitator: Research Cottrell

Power generation: Steam turbine

Herningværket is fuelled with a combination of wood chips on a vibrating grate and natural gas in gas burners.

Main fuel: Co-firing (fossil + biofuel)

Natural gas is the main fuel, wood chips being the secondary. The plant is designed for utilising 200,000 tonnes of wood chips annually with a input of 47 tonnes/h.

Nominal capacities & efficiencies:

Thermal input, biomass & waste: 140 MW

Total thermal input, incl. fossil fuels: 300 MW

Gross electrical output: 95 MWe

Net electrical output: 89 MWe

Heat output: 174 MJ/s

Electrical efficiency, gross: 31,7 %

Electrical efficiency, net: 29,7 %

Overall efficiency, gross: 89,7 %

Power to heat ratio: 0,51

Max. wood chip input of 140 MWth can be maintained in a range of 60 to 85 % boiler input. At higher load the wood chip is steady substituted by natural gas and to natural gas only at 100 % load.

How is plant controlled: Herningværket is controlled by the heat demand in the district heating system in Herning, Hammerum and Ikast.

Heat usage: Heating only

Energy usage:

The power produced is fed into the 60kV grid.

The heat is sold to three District heating companies: Sunds Heating Plant, Ikast Heating Plants and Energigruppen Jylland, Herning. Herningværket covers 75% of the heat demand in the Herning DH network as well as the major part of the demand in Sunds and Ikast.

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

DH inlet temperature: 90 °C

DH return temperature: 35°C

Heat storage size: Heat storage capacity is 35000 m3/ 6900GJ. m3

Fuel storage:

Wood chip storage is 13,000m3 or 3 days of operation.

Fuel oil storage is 19000 m3 or30 days of operation.

Waste water:

In 2001 the following amounts of waste water was sent to the municipal sewage system:

466 m3 from sanitary use

5953 m3 from the plant operation

Ash discharge: In 2001 no ash was produced. In the future the ash generated from the utilisation of wood chips will be about 1 – 1,5 % of the wood chip input and is for landfill.

Plant description:

The unit was commissioned to cover a heat demand in the Herning/ikast area. The unit was ajusted to fit into an existing district heating grid.

The unit was designed to cover 85% of the total heat demand. The original fuel was coal and oil. Has been modified twice, first (in 2000) for natural gas and since for wood chip (in 2002). This modifications have contributed to improvement of the environmental impact.

Fuel feeding system: Natural gas is supplied from the gas grid.

Wood chip: 75% is delivered as wood chip and 25% is delivered as trunks and chipped at the plant.

Boiler: Grate fired drum boiler

Turbine: Backpressure turbine with 2 extractions for heat production in 2 stages.

Steam data:

424,8 t/hr

115 bar, 525 deg. C

Flue gas cleaning:

The unit is equipped with electric precipitator.

Cooling system: Cooling by district heating water

Data collected and quality assured by: FORCE Technology.

Contact person: Anders Evald