OPET Finland ENERGIE The world´s largest biofuel CHP plant Alholmens Kraft, Pietarsaari § exploitation of pulp and paper mill and saw Project background mill by-products as fuel Pietarsaari, founded in 1652, is located on the § optimisation of the plant size and process Swedish-speaking west coast of Finland. The parameters total area is 93 km2 and there are 19 600 § sufficient fuel resources within economical inhabitant living in Pietarsaari. 56% of the transportation distance working population are employed by service The main innovation sector, 1% by forestry and agriculture and 40% by the industry, the biggest employer being the Alholmens Kraft Ltd builds the worlds largest pulp and paper mill of UPM-Kymmene. biofuelled power plant and the CFB boiler one of the biggest. The plant is an industrial CHP During the last years the utilisation of biofuels plant producing steam for forest industry and as on large scale has been focused on forest a utility producing district heat for the industry sites where large amounts of biomass is municipality. The wood fuel procurement available. system is also innovative and based on bailing the forest residues. Alholmens Kraft Ltd aims to When the planning of Alholmens Kraft new use annually 300 000 bales of forest residues. power plant (AK2) was started, the most important objectives were: Project description § electricity production with competitive Alholmens Kraft power plant introduces the price “best-practise” biomass/fossil fuel cofired § exploitation of process steam in the paper power plant concept with extremely diverse fuel mill and in town’s district heating selection – suitable to be replication almost anywhere in Europe. OPET – Organisations for the Promotion of Energy Technologies Contact: [email protected] www.tekes.fi/opet/ The main objective of the work is the Low emissions demonstration of new multifuel power plant § NOx emission minimisation with air staging concept. The aim is to demonstrate novel and ammonia injection technology for solid multifuel and low emission Boiler capacity 550 MW cogeneration in new commercial size. The plant th shall be pro-environmental and cost-effective. Steam production 194 kg/s The concept allows utilisation of fossil fuel with Steam pressure 165 bar cofiring biomass and waste. Steam temperature after the 545 °C superheaters and reheater The planning of the construction project was Boiler efficiency 92% started in 1996. At the beginning of 1997 Alholmens Kraft Ltd was founded. When the The full load is achieved with peat and wood investment decision was made in February residue mixture and/or coal combustion. It is 1999, the construction work was started also possible to reach the full load when immediately. The commercial operation is relatively dry wood fuel is used. There are scheduled to start in October 2001. altogether 11 fuel feeding points in the boiler. The requirement set on fuel feeding system is very high since it has to supply almost 1000 m3 Plant description of fuel in hour. Alholmens Kraft power plant is being built in The power plant's turbogenerator is a three the vicinity of UPM Kymmene pulp and paper casing, reheated, condensing turbine with mill. This enables the power plant to utilise extractions to district heat and process steam. wood based fuels provided by the pulp and Hydrogen cooled generator has output rate 306 paper mill and also to produce process steam for MVA. the mill. Turbine The power plant is combined condensing and Live steam 194 kg/s, 162 bar, 545°C CHP plant. The CFB boiler is manufactured by Reheat 177 kg/s, 37 bar, 545°C Kvaerner Pulping. There are about 50 persons working in the plant The dimensioning of the turbine plant allows operation and maintenance. In addition to that pure condensing mode. In that case the process the plant gives work to more than 400 persons steam and district heat are produced by the working in fuel production and transportation. existing power plant. Annual fuel consumption 3500 Technical details GWh/a Fuel Source Share Power 240 MW e Wood based Pulp and paper mill 30-35% Capacity to produce process 100 MW fuels th steam Sawing and Sawmills within 5-15% District heating capacity 60 MW forest residues short distance, th forestry sector Peat Production sites 45-55% Boiler is about twice as big as the solid close to the plant biofuelled boilers in average. Coal or oil Imported fuel, 10% mostly for start-up The boiler was chosen to be a CFB boiler. It is or support fuel possible to burn mixtures of the design fuels or single design fuel. Optimal fuel for this boiler Peat 45% design is biomass. The furnace cross-section is 8.5 x 24 m and height 40 m. Kvaerner Pulping Alholmens Heat production Finland was in charge of the design and 700 GWh manufacturing of the boiler. Highlights of the Bark and Kraft Power boiler: wood Plant residues 45% Electricity High efficiency and availability production 1300 § Stable steam generation with variable load GWh (paper mill and district heating) Heavy fuel oil § Efficient and reliable homogenisation of and coal 10% fuel mixture § Minimum slagging, fouling and corrosion Annual fuel utilisation and energy production risk with optimal fuel mixtures and material selection OPET – Organisations for the Promotion of Energy Technologies Contact: [email protected] www.tekes.fi/opet/ Procurement of the forest Baling of forest Forest haulage of bales residues is connected into residues by a forwarder timber harvesting On-road transportation by log trucks Chipping of forest residues on road-side Piling of forest residues at stand Alholmens Kraft Power plant Forest haulage of forest residues by forwarder On-road transportation Crushing of bales at the plant by lorries Forest fuel supply chain from forest to the plant. VTT Energy. Fuel One of the starting points of the power plant design was the maximum exploitation of bark and other wood based fuels, peat resources from neighbouring areas and existing commercial port and the possibility to import coal. The share of a particular fuel may vary seasonally. The plant is aimed to use 150 000–200 000 solid-m3 of logging residue annually. The logging residue is hauled to the plant as loose material or as bales. The plant owner A bundler collecting and compressing the forest participates in a project, which aims to develop residues. Timberjack. a new logging residue harvesting method, where the logging residues are baled in the stand. The main idea is to use traditional timber harvesting equipment. Four forest contractors has acquired already baling machine and are in the commercial use. It produces some 20 bales per hour. The volume of one bale is about 0.5 solid m3 (450–500 kg, 3.3 m long). An ordinary timber truck is used and it can take 60 to 70 bales at one load. Totally there is will be 5–6 baling chains in action. The plant has already Pulp, sawlogs and forest residue bales. stored 80 000 bales at the plant and in the forests. The bales or loose logging residues are crushed at the plant. Production costs of the baling method are estimated by Metsäteho to be about 45–55 FIM/MWh (7.2–9.2€/MWh), when the maximum transportation distance is 80 km and forest haulage distance 300 m. An annual working period is 10 months and working is carried out in two shifts. Loading of bales into the log truck. OPET – Organisations for the Promotion of Energy Technologies Contact: [email protected] www.tekes.fi/opet/ CFB boiler of the plant manufacturer by Kvaerner Pulping. stone is smaller since the alkalis in ash react Economical data with fuel sulphur resulting lower sulphur The total investment cost was about 1 billion dioxide emission. Fly ash and the gypsum from FIM (170 million €). The investment’s degree sulphur retention reaction are aimed to be of domestic origin is about 70%. The project utilised in recycling. was supported by the EU´s THERMIE programme. Nitrogen oxide emission is controlled by using low-NOx technologies. If the emission reaches Environmental impact the limit of 50 mg/MJ ammonia spraying is started in cyclones. By firing biomass the CO2 emissions can be reduced. The concept applies improved Emission discharge limits efficiency of SO and NO removal 2 x SO 100 mg/MJ technologies. 2 NOx 50 mg/MJ 3 Particle discharges 30 mg/m n In addition to electricity the plant produces process steam to the UPM-Kymmene Oyj Owner Wisaforest site and district heat to the City of Pietarsaari. The project shall end up with a fully Alholmens Kraft Ltd is owned by the Swedish developed and demonstrated multifuel fired power companies Graninge and Skellefteå Kraft power plant with high efficiency, low emissions and Finnish power companies Pohjolan Voima and environmental load. (PVO), Kattenö, Oulun Seudun Sähkö and Revon Sähkö. UPM-Kymmene, Katternö, Fossil fuels, coal and heavy fuel oil, are only Kokkola city, Päijät-Hämeen Voima own the used for start-up and support purposes. Pohjolan Voima shares. Users When high sulphur fuels, peat or coal, are used in the plant, lime stone is used to absorb sulphur Process steam is used to the UPM Kymmene so that the SO2 emission does not exceed the Wisaforest pulp and paper mill and heat is limit of 100 mg/MJ. When the share of wood supplied to district heating company of the city based fuels is higher, the mass flow of lime of Pietarsaari. Electricity is produced to owners. OPET – Organisations for the Promotion of Energy Technologies Contact: [email protected] www.tekes.fi/opet/ Builder and constructor Automation Automation DCS Oy Alholmens Kraft Ab Metso Automation Networks Inc.