Metsä Group is currently building a new bioproduct mill in Äänekoski in Central Finland. Important units like the recovery boiler and the superheater are equipped with Vallourec’s high-temperature grade tubes that contribute to increased process efficiency.
The Metsä Group’s mill will begin operations in the third quarter of 2017 and have an annual pulp production capacity of 1.3 MT. The new gasification technology and recovery boiler maximize the use of bioenergy and make the pulp mill totally fossil fuel free.
For this major project, Valmet teamed up with Vallourec for the delivery of nearly 5,000 tons of tubes made of special steel grades that offer resistance to high-temperature corrosion. The majority of the tubes were delivered in grades 16Mo3 and7CrMoVTiB10-10. They are applied inside the economizer, which is part of the heat recovery boiler, as well as for the superheater, where saturated wet steam is converted into superheated dry steam for power generation via a 260 MW turbine. All tubes delivered support high operating temperatures with grade specific maximums between 530° C and 650° C, which are crucial to the high overall energy efficiency and flexibility of the pulp plant’s different functional units.