World first. Again.

Because it is now the only mill in the world with batch pulp cooking that also uses recycled secondary steam for woodchip pre-steaming. It also marks a major expansion by ANDRITZ in the world of batch cooking.

DARE TO BE DIFFERENT

Smurfit Kappa wanted to lower the mill’s environmental impact by reducing consumption of steam, as well as improving pulp yield. But part of it was simply that Nettingsdorfer’s ethos is to be innovating all the time (remember the shoe press?). Pulp Mill Manager, Gunter Leitgeb, explains that “Continuous improvement is in our DNA. We all have to find new ideas and implement them. We get measured on it.”

This was good news for ANDRITZ. Paavo Tolonen, Fiberline Director, ANDRITZ Pulp & Paper Services, says, “We are really convinced that this technology will work everywhere. But we needed to try it out in the real environment. It was important for us to find customers willing to share the risks in doing something new.” Leitgeb explains, “ANDRITZ did everything to make us feel comfortable, with studies and guarantees. It helped us to do something new.”

MOVING THE GOALPOSTS

And this really is something new.

The “continuous batch” system at Nettingsdorfer is basically batch pulp cooking, but with continuous liquor circulation, via a highly-developed system of interdependent tanks. Leitgeb says that before the recent upgrade with ANDRITZ, “our heat recovery system was already very good, near the world’s best. But we still had waste energy. We still had to cool our liquid emissions with cold water.” And on the quality front, the firm wanted to reduce the shives and the amount of uncooked chips by enhancing impregnation, which leads to improved pulp strength, a key selling point for kraftliner. The project also made it possible to compact the chips more, enabling the mill to increase chip density in the digester by 10% and creating flexibility for process optimizations. In short, the goals were to raise pulp quality and yield, while reducing energy consumption, and thereby cost and environmental impact. All while improving safety. Tolonen summarized, “In general, batch cooking has better flexibility with pulp quality and wood furnish, but worse energy consumption. The idea here was to combine (the best of) both.”

DIGGING DEEP

Tolonen also argues that this project reveals huge potential for other batch pulp mills. “A lot of batch mills have no secondary heat recovery or chip presteaming. And there has been little development of the digester screens for decades. We have developed continuous pulping technology for batch pulping.” He argues that although ANDRITZ is a relatively new entrant into the batch pulping space, it has “huge knowledge and decades of experience that we can bring to batch cooking.”

Leitgeb continues, “I would definitely suggest doing an audit with ANDRITZ, because they look for something new, not just safe. They go digging. They put their experience together with the mill and they are very advanced, with a lot of knowledge and experience. He concludes, “If you have liquids that can flash, then definitely go for it. You get benefits in safety, environment, quality, production, availability, and raw material savings. I can’t see a negative.”

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