Infrared radiation shortens the drying process of paper production

New thesis shows that IR technology can be used to achieve higher drying speed and to study the drying behaviour of individual fibres.

The drying process is responsible for a great share of energy used in the paper machine, especially when it comes to premium tissue products such as toilet and kitchen towels. The dewatering is then performed by through air drying technique (TAD) which provides better absorption and softness. A new thesis now shows that supplied energy via infrared radiation increases the drying rate and reduces the need for fossil fuels. Consequently, premium products could be produced with less environmental impact and at lower cost.

In his thesis, Through Air Drying - Thermographic Studies of Drying Rates, Drying Non-uniformity and Infrared Assisted Drying, Aron Tysén has investigated parameters related to drying rate and non-uniformity in through air drying. The measurements showed that the air flow through the samples varied with grammage and pulp type, where softwood pulp demonstrated much higher permeability compared to hardwood pulp. At low grammages, relevant to tissue, no connection was found between the amount of air flow and the drying rate.

“Because the air is the process’ medium for energy transport, it means that we have encountered some form of bottleneck for how quickly we can dry with room-tempered air. I could then get past the bottleneck by adding energy via infrared radiation and thus achieving higher drying rates, says Aron.

According to Aron, IR technology could also be used to characterize the drying process with any paper-based product. Within the framework of his doctoral thesis, he developed a thermographic method that makes it possible to determine spatial local drying times with high resolution.

“With the right infrared camera, one should be able to see the drying behaviour of individual fibres in the sheet,” he explains.

Now, Aron Tysén enters a new role at RISE as Senior Research Associate, but with continued focus on process variability.

“Infrared radiation is an interesting method that we will look into in several different projects, including the Vinnova co-financed project “Online variability analysis of the total production of paper and board for process optimisation” and the programme areas “Tissue products and processes” and “Product Variability and Advanced Analytics in Papermaking” within the Bioeconomy Research Programme 2018-2020”, says Paul Krochak, Director Paper Technology at RISE.

Aron Tysén defended his dissertation on May 22 at Karlstad University. The study was performed as part of the Industrial Graduate School VIPP (Values Created in Fiber Based Processes and Products) at Karlstad University, with the financial support of the Knowledge Foundation.

For more information:

Aron Tysen, aron.tysen@ri.se, +46 768 767497

Paul Krochak, paul.krochak@ri.se, +46 768 767372