In practice: Smurfit Kappa's £120m onsite sustainability drive
With one eye on a key carbon reduction goal for 2020, paper-based packaging company Smurfit Kappa recently undertook a multi-million-euro investment into new boiler and steam turbine systems at one of its major manufacturing facilities in Austria which will significantly reduce emissions.
Manufacturing equipment and technology used in the production of paper-based packaging has been approaching the renewal stage at Smurfit Kappa’s Nettingsdorf Paper Mill in Austria. And, as the paper producer closes in on its sustainability targets, it became clear that the company would need to upgrade some of its systems to cater for a potential increase in production whilst significantly reducing carbon emissions.
Despite opening in 1851, Smurfit’s Nettingsdorf facility has already claimed ‘industry-leading’ sustainability credentials in the sense that it has the lowest energy consumption in the paper industry for the production of ‘Kraftliner’, a material made from virgin fibre which is used to manufacture containerboard.
The challenge now is to build on this sustainability success and continue driving environmental improvements at the mill while growing the business. As Smurfit Kappa’s latest sustainability report notes, the company has cut overall emissions by 23% on the way to meeting a 25% reduction target by 2020. As such, new power systems would significantly improve on efficiencies within the Nettingsdorf facility, taking the company a step closer to its overarching goals.
In July 2017, Smurfit Kappa announced a €134m (£120m) investment in new technology at its Nettingsdorf Paper Mill that it believes will significantly reduce emissions while increasing production.
The investment includes the development of a new, state-of-the-art recovery boiler, which will be integral to the chemical production methods used to produce Kraftliner products. The boiler, which will be operational by 2020, will also produce biomass to help power the mill.
Smurfit Kappa’s investment also includes the implementation of a new, more efficient steam turbine by 2022.
Once operational, the new boiler and turbine system will produce around 22MWh of electricity and 130 tonnes of steam per hour. The investment will help reduced emissions at the mill by 40,000 tonnes – representing a 1.5% in Smurfit’s total carbon emissions and bringing the company to within 0.5% of its carbon emissions goal.
The manufacturing process
Due to economic incentives and high chemical recovery efficiency, Kraftliner manufacturing processes have several sustainability advantage over other pulping processes. For example, chemicals used to generate the paper pulp have a recovery rate of around 97%.
During the manufacturing process, wood is dissolved alongside spent pulping chemicals to form ‘black liquor’. This liquor can be separated from the pulp and sent to the recovery boiler where inorganic chemicals are recovered to be reused in the pulping process, while dissolved organics are used as fuel to generate steam.
Studies have claimed that black liquor is the fifth most important fuel in the world behind coal, oil, natural gas and gasoline. Around 1.3 billion tonnes of black liquor is processed globally and burnt in recovery boilers to recover 50 million tonnes of cooking chemicals and around 700 million tonnes of high-pressure steam. The recovery process minimises the environmental impact of waste material and chemicals from the pulping process because they can be reused. The energy recovered is classified as ‘renewable’ as it is coming from biomass materials, such as the spent wood.
Most pulping processes see black liquor sprayed into the lower compartment of a recovery boiler, and then burnt. Once the remaining black liquor is dissolved in water it is classed as ‘green liquor’. At this point, it is sent to a causticizing system to be converted into ‘white liquor’, using lime. This white liquor is then sent back to digesters to be reused in the pulping process.
Any heat released during the combustion phase of the black liquor can be recovered as high-pressure steam in the top compartment of the recovery boiler. The high-pressure steam is transferred to the steam turbine, where it is separated by pressure levels, with higher-pressure steam used for energy generation and lower-pressure steam used throughout various other processes in the mill, such as drying paper.
The generation of biofuels onsite at the Nettingsdorf facility has lessened the reliance on using fossil fuels for energy. Of the 4,727 terajoules (TJ) of fuel used annually at the mill, 3,592TJ is derived from biofuels.
More than 90% of Smurfit Kappa’s waste is generated across its paper mills, usually from the recovery paper pulping and screening processes. The Nettingsdorf facility recovers more than 18,000 tonnes of the 22,000 tonnes of waste that it generates. A large portion of Smurfit Kappa’s waste has a water content of 50% or more, meaning that using steam to evaporate the water reduces the overall volume and weight of the waste.
Smurfit Kappa is not yet able to share the exact specifications of its new boiler, but the benefits of such a system are likely to follow that of other new recovery boilers, which can burn black liquor at a solid content of more than 75%. This increases the amount of steam that can be generated, which improves combustion stability and reduces emissions as a result.
Overall, Smurfit Kappa produces more than 450,000 tonnes of virgin fibre containerboard every year at the Nettingsdorf mill, 90% of which is certified by FSC or PEFC standards. The mill is also certified to the ISO 9001 and 14001 standards.