FFRC member Valmet is a leading global developer and supplier of technologies, automation and services for the pulp, paper and energy industries. Valmet’s offering for the energy sector includes boilers, flue gas cleaning, automation and services for efficient combustion of biomass, waste, and co-combustion of biomass and waste derived fuels.

Efficient heat and power production from biomass and waste is challenging, requiring detailed knowledge in many fields such as combustion chemistry, corrosion and process modelling. Valmet has a long history of doing research together with universities and in recent years the cooperation has been intensified through several Valmet employees making their PhDs as a part of their work and personal development plan as experts in the company.

One recent example is Combustibility and corrosion expert Hanna Kinnunen, who defended her thesis “The role and corrosivity of lead in recycled wood combustion” in August 2019.

Recycled wood has become a popular substitute for virgin wood due to its CO₂ neutrality and relatively low price. However, recycled wood has a heterogeneous nature, as it might derive from several different sources and elevated concentrations of heavy metals such as lead, and chlorine may exist. These elements contribute to corrosion, fouling and slagging during combustion, each of which reduces the boiler efficiency.

Hanna’s work explains the detailed corrosion mechanisms caused by lead in combustion of recovered wood. The results are implemented in the Valmet boiler design and will enable a further increased efficiency and availability for Valmet’s state of the art boilers.