Production process

Modernisation and new technologies

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Needs that change and responses that adapt. Machine manufacturers must be able to provide ‘smart’ solutions to the needs of today’s paper mills, caught between market changes that require new skills and adaptations, and a pandemic that brings about a new way of managing work.

The last few years have been years of great change for the paper industry – in particular for some sectors – which have imposed changes in direction and forced companies in the sector to adapt to a profoundly changed market.

The main case is the decline of printing papers on the one hand and the growth of packaging papers on the other. In addition to these changes, the vicissitudes of the Covid-19 pandemic have led to the need to deal with an entirely new reality.

However, technology is already able to come to the rescue and help companies in this process of rewriting their working methods. «The unprecedented moment calls for unprecedented measures» says Igor Oleshchuk, vice president paper and Board at Andritz. «We have to learn how to work and how to communicate in a new way. And, fortunately, there are technologies available that allow us to do that, focusing on small changes to achieve big results». Changes, says the vice president, «small in terms of investment, cost and time, but big in terms of efficiency, quality and capacity.»

At the Aticelca 2021 Congress he talked about just that and about «smart» solutions to the industry’s big challenges, to have paper machine builds, conversions and innovations in terms of efficiency and cost.

Small interventions, big benefits

One of the challenges facing the industry is the inversely proportional trend in graphic and packaging papers. A situation which even accelerated during the pandemic and which meant technology conversions and new production capacity. On top of this, the paper industry is also suffering from what Oleshchuk calls «the challenge of zero waste». For the machine builders, this represents a new area of competition.

«At Andritz» says the vice-president, «we have a lot of experience in complex rebuilds. Over the last ten years we have accumulated expertise in converting different machines and different paper grades, from more or less standard solutions, such as super calendered papers for newspapers, to packaging paper, but also specialty papers such as coated and kraft. At the same time, however, we have also learned that sometimes a small rebuild can have a big impact on the efficiency and additional capacity of a machine». «Smart» answers which, for a small investment, can bring great benefits.

New concepts for checkouts

Today there are a large number of headboxes on the market that have been installed for years; Andritz itself, says Oleshchuk, started producing them in the 1950s. These are now no longer up to date with the requirements of the market in terms of sheet formation, adaptability and so on. Today’s requirements in the sector, therefore, are to work on the existing. To this end, the company has developed a special programme aimed at modernising the headboxes. An interesting innovation is the new PrimeFlow AT family «a technology that provides superior flow profile uniformity through an accelerating trapezoidal tube bundle». But the real innovation is the introduction of the new «soft-layering» concept. This is a kind of fibre dilution. «This solution is able to dilute the headbox fibre by adding alternative materials, such as fibres and fines, fillers or others. What’s interesting is that soft-layering can be added to the primary headbox flow at virtually any time». However, the main advantage of this system is its simplicity of construction and its very low investment cost.

It is therefore possible to improve the performance of the headbox with minimal interventions such as adding new accelerated trapezoidal tubes to replace the old ones, adding slats or dilution control.

The formation section

«In formation technology» continues Oleshchuk, «we have achieved a new result. Andritz has a long history in GAP training, with the PrimeForm family». Among the most recent references, the vice-president remembers the 2020 modernization of a paper machine for kraftliners with the realization of a 9.2-meter-long machine capable of operating at a speed of 1,400 m/min and producing more than 80 t/h of paper with a grammage over 200 g/m^2.

«On the existing GapFormer we implemented the forming section with a vertical blade shoe press. We were able to reuse the existing beams, thus leaving the structure unchanged, with the added possibility of adding a paper grade to be produced or changing the paper grade completely».

The company has also adopted a similar approach to the GapFormer with regard to the hybrid forming section, «to easily switch from flatbed forming to high-capacity, low-intensity hybrid forming». The PrimeForm HB hybrid former was rebuilt with a new design and new elements were added. «By reusing the existing equipment as much as possible, we tried to keep the investment cost as low as possible and provide a high production capacity». So the GapFormer can be positioned very close to the headbox, within 5 metres, and have a low input consistency of 1% to 2%.

Several reconstructions have been made on this line. Oleshchuk gives three examples, highlighting the impact on quality achieved by acting on capacity.

The first application concerns a PM for a high-capacity testliner, «one of the best in Europe, a machine that produces wrapping paper. On this installation we were able to increase the burst by 5% and the capacity of the secondary headbox by 30%. All this with a rather limited scope of work carried out».

In the second example, which involved a cartonboard machine, «we achieved an improved formation of 25% and an increase in headbox throughput of 25%, thanks to a reduction in infeed consistency from 2 to 1.1-1.4%».

Finally, the application case of a PM for solid bleachboard in North America. «With the ‘smart’ solution we have been able to improve formation by 30-40% and the Scott Bond by 20%. In addition, the flow rate from the headbox has been increased by 20% due to the increased drainage of the hybrid former».

The press section and drying

One of the most interesting innovations, however, concerns the press and drying section. The 2,000 kN/m PrimePress X shoe press has been in operation for two years now and is producing very satisfactory results. It was built and installed by Andritz at an Italian paper mill with which the Austrian company has had a longstanding partnership. It is a highly customised solution, explains Oleshchuk. «With this installation we have been able to achieve an even 59% dryness» he says. The runnability of the machine has increased significantly, while energy consumption has been reduced significantly. «More importantly, this installation, which has been in operation for some time, has shown that it has maintained the life of the felt unchanged. This gives us a valuable indication of the wear and tear on the parts».

Also in the drying section, a plus for Andritz is the PrimeDry steel drying cylinders. This is a common technology today, but one that the Austrian company has been developing since the mid-1990s and continually updating. «In this area we have worked on exceeding the industry standard, which until now was limited to 10 bar, so that today we have been able to create cylinders with a pressure of up to 14 bar and we can also process cylinders with large diameters of up to 2.2 m. By changing these two factors – pressure and size – we have been able to improve the output of the drying unit by more than 20% at the same length».

Surface finishing tools

Continuous improvement work has also been carried out on one last type of machinery, those intended for paper surface finishing. «We have a whole family of coating and calendering machines, and a long history of developing and supplying these machines to the market» continues the vice president. «In recent years we have focused on revamping these machines and having simple, compact installations with a plug and play design». In particular, PrimeCoat Curtain features a layout with a 40% smaller footprint, a solution that makes it easy to install the machine in any space or on existing equipment. «In addition to this, we have also developed the design with a protected nozzle, which means that paper mills no longer need to have a spare nozzle, as this remains protected even during maintenance».

Once again, this is an example of a smart solution with a relatively low investment that can solve a number of problems. In essence, says Oleshchuk, «a relatively low input can sometimes lead to a high output». And he emphasises that, at Andritz, they are a machine manufacturer, but they don’t stop there, «we have experience in digitisation, maintenance, training and logistics. Our long collaboration with our customers» he concludes, «has given us the experience and data repository to develop these solutions to meet today’s challenges».

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