By advising researchers and technology suppliers to work together within a common R&D project, Canadian paper mill Papier Masson, after only six months, got the improved refiner control system the…
By advising researchers and technology suppliers to work together within a common R&D project, Canadian paper mill Papier Masson, after only six months, got the improved refiner control system they had aimed for. Papier Masson, a division of White Birch Paper, is a newsprint mill, and refiner control is key to both quality and production efficiency.
“The control we had earlier worked well, and gave us good functionality, as we needed a tool to be able to find the optimal targets. By combining Paprican and Metso technologies we know what we can go after and find the right process targets much faster,” says Clement Desrochers, a process engineer and one of those who primarily managed the project from the mill side.
Co-operation led the way
The reason why Papier Masson wanted to cooperate with both researchers and technology suppliers was that the combination would deliver the optimal solution. In 2000, Papier Masson started TMP production with CD refiners. This was followed by several years spent development their own control system. The mill is relatively small, but known to have a high level of technical competence. The mill wanted to be able to manage the technology they were buying and had high ambitions for product quality. In 2002, the mill chose to postpone buying the advanced control system because they wanted to improve their own knowledge first. When they decided to move forward with the project, finding the optimal partner was a crucial first step.
“We have had good contacts for many years with Paprican,” (now FPInnovations), says Sylvain Bussire, responsible for TMP production at Papier Masson. The industry has worked together with Paprican since 1996 to develop TMP technology. Paprican began work on the Metso CD refiners in 2003. “We had already started to use results from Paprican’s work on CD refiners to improve the control of our reject refiner, but we realized it would take us a number of years to bring this technology into the main production lines in our mill on our own. We could not wait that long.”
They chose instead to buy a control system from Metso Automation, AQC Solution (Advanced Quality Control). This is a model-based control system based on multivariable predictive technology, developed by PacSim, now Metso Automation. The AQC Solution is also running at Stora Enso’s Kvarnsveden newsprint mill in Sweden. This advanced control quickly translated to improved control, quality became more stable and Papier Masson got significantly better efficiency in its energy consumption -the latter a question of survival for most TMP-producing mills. At the same time, Paprican had developed a control algorithm for CD
refiners based on a fundamental understanding of the process. Papier Masson realized the management of the process would be even better if one could fully understand the relationships between fibre treatment, pulp viscosity and pulp quality. With this kind of knowledge, the operators would also better understand how the control system was working.
The solution for Papier Masson was to contact both Metso Automation and Paprican, and convince them of the benefits of a common project.
“Paprican is the source of most of the basic knowledge about how fibre quality is improved inside the refiner, and how refiner intensity can be controlled,” says Sylvain Bussire. Paprican was rewarded the Wallenberg Prize 1998 for this research. A joint project with Papier Masson, Paprican and Metso Automation, to combine Paprican’s algorithm with Metso Automations AQC system, produced the control system that now produces optimal results.
Success from the beginning
The project started in the beginning of 2006. June 14th of the same year marked the first attempt to include the Paprican algorithm for refining intensity into the AQC system at Papier Masson. And it worked right from the start!
“This didn’t really come as that much of a surprise for us,” says Gregory Fralic, project leader for Metso Automation in this project. “We realized their algorithm would fit well into the Metso Automation AQC system. But still, it is amazing that it worked so well.”
The advantage for Papier Masson is partly a quicker way to optimal quality after startup or after a change of product. Also, wood raw material mate rial is complex in Canada, as there are a variety of wood species to consider. The energy situation is such that mills sometimes stop and restart the refiner refin er lines, which is another reason for wanting to have a good startup every time. In total, the economic gain from the improved control system translates to roughly $300,000 Canadian dollars annually. The operators are very happy.
“Some operators are very proud people,” says Clment Desrochers. “They sometimes turn off the automatic system to run manually; we see that they are constantly checking the data coming from the AQC system. It is obvious that they now trust the data, and that they can see and understand the relations between process, data, and the way the system controls the process.”
Thomas Browne, program manager at Paprican, is happy to see the fast improvements at Papier Masson. “But you should know that Paprican has been working with these issues for almost 30 years. Keith Miles and Donald May got the Wallenberg prize already ten years ago, after building their knowledge for decades. The long-lasting support from both industry and government has given us the knowledge to produce a specific technology solution as quickly as we did in this project. The new algorithm was fully tested on Papier Masson’s reject refiner before moving to the mainline with Metso Automation, and the initial implementation worked right away because the mill staff and operators were comfortable with the approach we were taking.”
Clment Desrochers agrees that the basic research done at Paprican was critical. Paprican’s high level of expertise in control technology was also a vital component of the project’s success. The project was able to move into practical use quickly and smoothly because there was a control engineer to work with at Paprican, Lahoucine Ettaleb.
Industry can take initiative
The fact that Paprican’s knowledge was useful was not a surprise. Neither was the fact that Metso Automation engineers were able to build a functional control system. The unusual factor in this project was that the user had such pervasive knowledge about research and was able to take initiative and see how cooperation between scientists and people in system technology development could benefit the project. The project at Papier Masson shows that people with a strong interest in technology and R&D projects can help their company make money on a short term. The time might not ever be perfectly ripe for initiating this kind of a project, but it is definitely too late when you actually need the new technology. The earlier the better!
The Process: The Facts
Producing mechanical and thermo mechanical pulps, such as TMP, requires the grinding of wood chips in large refiners. CD-refining, used at Papier Masson, is a technology developed by Metso Paper. The refining zone is conical, allowing longer refining times and the opportunity to impact fibre in more than one step. This allows for a more rugged and binding fibre surface, without breaking the fibres. The key to more even impact lies in pulp viscosity, or fibre concentration. The Paprican algorithm is built on using the refiner as one big sensor, by comparing fibre quality and pulp viscosity before and after passage of the refiner.
The parametres used to control fibre quality are motor load, the gap between discs, and by water flow into the refiner. In the CD-refiner, water can be injected at two positions in the refiner, making the process easier to control. The main advantage of being able to control consistency is more even and full quality, attained quickly after an up-start. With rising energy prizes, energy efficiency in itself has become a v
ery important factor for paper mills producing mechanical pulp.
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