Climate-Neutral Production of Corrugated Board Through Thermal Optimisation of the Wet End

As part of the "OptiCorr" project, measures were developed to thermally optimise the wet end of a corrugated board production line with a view to producing more climate-friendly corrugated board. The production of corrugated board requires large amounts of thermal and electrical energy, with 85 % of this being thermal energy and 15 % electrical energy. The thermal energy is supplied by steam generated in fossil-fuelled steam boilers.

Initial Situation

In the first section of a corrugated board production line – known as the "single facer" – a smooth paper web is bonded to a corrugated paper web using adhesive. To this end, both webs are preheated using steam-heated heating cylinders, whilst the paper web to be corrugated is additionally moistened to improve its formability. To produce full-fledged corrugated board, which can consist of up to seven layers of paper, a further section of the line – the so-called double facer – combines a maximum of three so-called single-faced corrugated boards with another paper web. Due to the rigidity of the corrugated board, heating plates must be used here, through which steam flows in the same way as through the heating cylinders.

Objective

The aim of the project was to reduce the plants’ CO₂ emissions. Simply by optimising the steam-heated heat exchangers – heating cylinders and heating plates – CO₂ emissions could be reduced in the production of corrugated board, both directly and indirectly through the reduction of paper waste. Given an annual production of approximately 6 000 000 t of corrugated board in Germany, this would correspond to a CO₂ reduction of approximately 19 200 t.

Approach

"OptiCorr" essentially pursued two approaches to reducing CO₂ emissions associated with production. On the one hand, the aim was to optimise the existing steam-based heat exchangers in terms of material usage and heat requirements. On the other hand, the aim was to develop innovative, electricity-based technologies that would eliminate the need for steam and thus the combustion of fossil fuels.

The Fraunhofer ISE’s tasks included providing support in developing the measurement concept for recording all relevant energy consumption at the individual machines. In addition, the ISE supplied model components for the creation of a digital twin of the entire system and supported the development of novel heating technologies, including microwave heating, induction and heating cartridges.

The “OptiCorr” project is funded by the Federal Ministry of Economic Affairs and Energy (BMWE).