With good planning, suitable equipment and professional personnel, good results are achieved as planned – even in challenging board machine rebuild projects.
All the targets for the project were achieved. Runnability is better than before, and the efficiency is better, too,” says Rok Sustar, Technologist and Assistant to the Production Manager at Mayr-Melnhof Kolicevo mill in Slovenia. After more than a year, this positive atmosphere has not changed: the mill personnel are content with and confident about the improved coating section.
Before the rebuild, board machine BM 3 of Mayr-Melnhof Kolicevo Karton was facing challenges with runnability and efficiency. The coating section required improvements since the speed of the board machine was going to be increased and the existing coating technology was not suitable any longer. This resulted in the decision to rebuild the coating section.
Before the rebuild decision was made, the coating concept, coating color chemistry, and performance were tested at the Paper Technology Center in Järvenpää, Finland. Rok Sustar is convinced that finding the correct solution is easier with the chance to run a pilot. The decision does not have to be based on assumptions and conjecture when there is concrete proof before your eyes. “You can see the benefits and witness the good runnability,” Rok Sustar says.
Rok Sustar from MM Kolicevo (left) and Timo Nurmiainen from Valmet know the importance of pilot trials; they give the opportunity to test the papermaking process and coating chemistry
With clear targets in mind, a multilayer curtain coater and a blade coater started up after a very short shutdown period in the summer of 2015. A supply system for the two layers of the curtain coater was also installed. Sustar explains that the Valmet personnel were really professional. He continues: “The installation went according to plan. It was a short installation time, and there was a lot to do – like building it and testing it with water – but everything went well. The compact size of the curtain coater was also a real advantage in the rebuild.”
When everything is well planned, you are likely to get good results quickly. All the movements and hydraulics were tested at the workshop before the equipment was sent to the customer site. “In ten minutes, the board was saleable,” Sustar states.
The coating section has been easy to operate and more reliable since the rebuild. Curtain coating has a contactless coating application, which is good for runnability and reduces web breaks. “There is less second-rate board and fewer breaks at the coating section. Also, the day-to-day handling is a lot easier than before,” says Sustar.
To achieve high coating color quality, curtain coating requires a completely airless coating. This sets high standards for the OptiSupply machine circulation and its degasser. “The degasser in the supply system is working very well. We always reach the pressure we want to,” says Sustar. The maintenance requirements are relatively moderate: “We clean the degassers every two months in the longer shutdowns. They’re quite easy to clean. It takes less than two hours to open them, clean them with high pressure water, and close them – this includes everything.” A short, automatic cleaning sequence is used during the briefer shut-downs.
The Kolicevo mill has noticed that their customers are ever more demanding for higher quality and lower prices. Continuous improvement must be a constant state of mind for each producer.
A cost-effective rebuild with fast results is the only alternative. Any shutdown is a direct loss of income for the board producer. For good results, you need the correct concept choice, good planning, and proper raw materials to achieve the desired targets. A rebuild is always a challenge, but the risks are minimized with a good and reliable partner. “Valmet personnel are really professional,” summarizes Sustar.
Over the years, we have gathered plenty of experience and expertise in rebuilding all kinds of machines. We asked our experts to provide tips, advice, and industry insight to help you demystify the rebuild process and created a practical guide book.