Oy Alholmens Kraft Ab, with its unique combination of owners, was founded for the purpose of building a power station at Pietarsaari on the west coast of Finland. The power utility companies initiated the co-operation with the saw-, pulp and paper mill owners with the goal of finding a solution which maximized biomass utilization through co-firing with other fuels, to produce steam and heat in a utility sized power plant. Concept development resulted in a 240 MWe circulating fluidized bed unit with a flexible and demanding combination of fuels. The Alholmens Kraft power plant supplies process steam to the nearby UPM-Kymmene paper mill, and for district heating in Pietarsaari. The plant produces electricity for the power company owners in Finland and in Sweden. The CFB boiler steam capacity is 550 MWth (1875 MMBtu/hr), giving a maximum electric power of 240 MWe. When commissioned in autumn 2001 the boiler was one of the largest CFB boilers in the world, and the largest biofuel-burning CFB. The Alholmens Kraft CFB boiler is a multi-fuel boiler, whose main fuels are bark, wood residue and peat, with coal as a back-up fuel. Due to its location at the pulp and paper mill, high reliability and low emissions were the most important design criteria for the boiler. Steam production for the mill must be ensured all year-round, apart from during the mill’s short annual service shutdowns. Another important design consideration was the controllability of the boiler due to Nord Pool electricity production requirements. Typical regular load variation is between day and night but sometimes the load change speed requirement is quite high. This paper presents the Alholmens Kraft power plant application, and its very smooth start-up and operational experience during the first year with different fuels and fuel combinations at various load levels. The paper also describes how well the large boiler has performed with regard to the strict emission limits. The selection of design fuel contributes well towards the target for net CO2 reduction, but it also places huge requirements in terms of fuel purchasing and logistics. The volumetric fuel consumption by the boiler at full load is 1000 m3/h (35 000 ft3) of biofuel. More coal, the support and reserve fuel, is used in spring as weather conditions may cause availability problems with peat, before the new peat can be harvested and dried at the peat bogs. Coal is always available at the site. This paper presents the first year’s operational experience of the fuel logistics chain. The successful Alholmens Kraft CFB boiler project is an excellent example of the very wide fuel flexibility that is possible in a CFB unit.

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