20 HEIMBACHANDRITZ
Pulp Paper & Logistics
Generate a cleaner dryer section More efficient cleaning is possible with a new dryer fabric developed by Heimbach. PPL reports
at Heimbach. Of particular importance is to find not only an effective solution by talking to customers, but also to ensure that the solution is sustainable. The growing share of board and packaging paper on the world market at the expense of reduced consumption of graphic papers has led to a decline in the quality of waste paper that is now available. This has led to paper machines and clothing increasingly suffering from contamination due to impurities in the stock. The reason for this is the
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decreasing proportion of fresh fibre content and rising contamination due to foreign material and adhesives in the re-cycled paper. This is particularly noticeable in the dryer section, where deposits occur on the fabrics and rolls. Says Yvonne Raschka, Product Manager at Heimbach: “As a
Figure 1: Deposits on the rolls are the result of contaminated dryer fabrics
consequence, the contaminated rolls lead to increased wear of the dryer fabric and therefore reduce its lifetime.” Peaks in the moisture profile of the sheet pose another problem
caused by uneven contamination. In order to balance these out the drying process needs to be intensified, which frequently leads to partial over-drying.
Figure 2: Dirt in the dryer fabric tends to be deposited on the MD yarns in the forward positions
September/October 2016
What is needed is a ‘contamination resistant’ dryer fabric It was this notion of an ‘ideal dryer fabric’ that prompted Heimbach to focus on a new solution and develop a dryer fabric with high contamination resistance and improved cleanability – a universal, solution-oriented approach that required detailed investigation. Analysing randomly-selected samples of contaminated used dryer fabrics revealed that, particularly in the early parts of the dryer section, dirt particles
are deposited on the machine direction (MD) yarns on the paper side. It is in these early positions that the degree of contamination of the fabric is most pronounced, due to the large contact area between dryer fabric and sheet generated by the MD yarns, resulting in more dirt being deposited. “This discovery gave us the idea of developing a design with the least area of attack, that is, a reduced contact area,” said Raschka.
The result should be efficient and sustainable Raschka and her colleagues developed a prototype based on the early findings. “We didn’t only want to develop a fabric that was more resistant to
lacing great value on product development and continuous improvement is key
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