Steam exploded pellets made from bark and residues - a new possible value stream for the pulp and paper industry

摘要

To reduce global warming and the negative impact on the climate, the world is turning away from fossil fuels and is increasingly looking for new and sustainable options to replace fossil fuels with renewable and sustainable raw materials. For thermal coal, the substitution is for example biomass such as woody residues or traditional white pellets. White pellets are relatively sensitive and require careful handling from production, all the way up until use of the product. A power plant requires substantial and costly rebuild to be able to burn white pellets. Another limitation with white pellet is that it can only be co-fired with coal in small percentages. Steam exploded black pellets is a new product which due to its characteristics has many advantages over white pellet, making it particularly suitable as an environmentally friendly and cost competitive substitution to coal. For example, Japan is undergoing a major shift in energy policy and is looking at alternatives to replace a large portion of approximately 120 000 000 ton of thermal coal used today. To drive the change away from fossil fuels, there is an incentive system in place, the so-called Feed-In-Tarif-System (FIT-system) which ensures the price paid for energy produced with renewables for a 20-year period. Australia, and the surrounding area with well managed forests and competitive transport distance to Japan, has excellent prospectives to capture this new and emerging business opportunity. Many of our pulp and paper customers are meeting increasingly challenging market conditions and finding new ways to optimize production. To increase the value of the available biomass is becoming all the time more important. The steam explosion process is well suited for integration to an industrial process which emits low temperature waste heat, for example a Kraft pulp mill. Energy from hot waste water is utilized for drying of biomass and medium pressure steam for the steam explosion reactor is extracted from the turbine. Raw-material for the pellet plant is bark and other residues from the operation. The presentation focuses on the feasibility of integration of steam exploded black pellet line to a pulp mill and the results of Valmet's trials using softwood bark as feedstock for the production of black pellets.