Type of CHP system: BFB boiler

Plant owner: UPM-Kymmene Oyj, Kaukas

Commissioned: (reconstructed):1979 (1996)

Status of plant: Commercial

Contractor details: Main supplier was A. Ahlström Oy. Steam turbine was supplied by Stal-Laval. Boiler conversion was supplied by Foster Wheeler Oy.

Power generation: Steam turbine

Power plant includes one recovery boiler (384 MW), wood fired fluidised bed boiler (109 MW), wood fired grate boiler (63 MW) and one waste heat boiler (76 MW). The total nominal capacity of the boilers is 631 MW and power production capacity is 131 MW.

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

The total use of fuels in power  plant (al boilers included) : 4548 GWh (black liquor 67%, wood fuels 16 %, natural gas for power plant 7 % and natural gas for paper production processes 9%). Indigenous fuels accounted for 84 % of total fuel consumption. Only the 109 MW fluidised bed boiler (KK1) is included in this study. The fuel consumption figures for KK1 are as follows: bark 83%, wood waste from wood processing industry 8% and natural gas 9 %.

Nominal capacities & efficiencies:

Thermal input, biomass & waste: 125 MW

Total thermal input, incl. fossil fuels: 125 MW

Gross electrical output: 25 MWe

Net electrical output: 20 MWe

Heat output: 84 MJ/s

Electrical efficiency, gross: 20 %

Electrical efficiency, net: 16 %

Power to heat ratio: 0,24

Power plant produces all heat energy needed in the processes of the mill. Half of electricity demand is met by own production. KK1 produces about 20% of the heat demand and 6% of the electricity demand.

How is plant controlled: By heat demand. Pressure of the backpressure net.

Heat backup: Process steam for paper mill is produced in a gas turbine when the production of other boilers is insufficient for plant needs.

Heat usage: Process steam

Energy usage:

Of total produced heat  22 % for paper mill, 70 % pulp mill, 5 % saw mill, 1 % for plywood mill and 2 % for other.

Of total generared electricity: 54 % for paper mill, 38 % for pulp mill, 3 % for sawmil, 2 % plywood mill and 3% for other. There are four different process steam pressures for production units: 3.5 bar, 10.5 bar, 12.5 bar and 15 bar.

Fuel storage: Fuels are stored on open fields. Fuel storage volume varies between 1000 and 30 000 m3 (loose).

Waste water: Waste water from plant is either led to sewage treatment plant or to sewage system, depending the type of waste water.

Ash discharge: Ash is discharged to plants own landfill.

Plant description:

Industrial boiler producing process heat and power for near-by mills: paper mill, pulp mill, saw mill and plywood mill. The boiler is  multifuel-fired boiler, able to fire all indigenous fuels. The  boiler conversion to fluidised bed boiler was carried out in 1996.

Fuel feeding system: Screw conveyors are used in fuel storage field. Fuel is transferred with belt conveyors to fuel silo and from silo to boiler by hydraulic bar unloader.

Boiler: 109 MW BFB boiler by Foster Wheeler.

Turbine: Backpressure  steam turbine. The steam turbine has been supplied by Stal-Laval. 1964/1979

Steam data: 40  kg/s (max), 500°C, 115 bar

Flue gas cleaning: Electrostatic precipitator and wet scrubber.

Staff: Operation personnel 3 persons in each shift, maintenance about 10 persons (steam power plant).

Data collected and quality assured by: VTT Processes.

Contact person: Kati Veijonen