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Stora Enso Imatra: The only way is up

Stora Enso’s Imatra Mill, located in eastern Finland, is one of the world’s largest producers of liquid packaging board. Now, thanks to the latest ANDRITZ flash drying technology, the mill is also able to fully utilize its BCTMP plant, which can now produce dry pulp for its internal use, as well as for the market.

In late 2017, and after a lot of deliberation and analysis, it was decided that Stora Enso’s Imatra Mill could better utilize its BCTMP plant. What was needed was the flexibility to be able to feed the board and paper machines with whatever capacity they needed, and then any extra could be diverted to a drying line. This would then get the needed result of the extra baled pulp, which could be used internally, or sold on the market. But there were challenges; the new drying line would have to be squeezed into a tight space between the BCTMP plant and the board machines. This meant a lot of creative engineering design, as really, the only way was up.

“Before we installed the Flash Dryer from ANDRITZ we had a lot of capacity in the BCTMP plant that we were not using,” explains Kalle Mäkelä, Production Manager, BM4 and BCTMP, Stora Enso Imatra Mills.

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“We were feeding wet pulp straight to the board and paper machines, but because of the extra capacity we knew we could be doing more and, of course, that meant making more pulp.

KALLE MÄKELÄ

Production Manager, BM4 and CTMP, Stora Enso

A TRIO OF TOP DEWATWERING AND DRYING TECHNOLOGY

As the leading supplier of flash drying systems with numerous installed bases around the world, ANDRITZ was selected by Stora Enso to deliver the latest in drying technology for the project. The scope of supply included a Twin Wire Press, HC- Fluffer, and Flash Dryer – all wellproven ANDRITZ technologies.

 

  • In the case of the Flash Dryer, ANDRITZ technology gives maximum energy efficiency and minimum environmental impact.
  • The Twin Wire Press has been proven in many applications for all types of pulp and is particularly pulps that are difficult to dewater and to reach high discharge dryness – a prerequisite for obtaining lower thermal energy consumption in the flash dryer.
  • The HC-Fluffer breaks up fiber particles with very low energy input, and thus has no negative impact on fiber properties. The fluffed pulp, with its large accessible fiber surface, is a crucial requirement for high and even dryness out of the subsequent flash drying stage.

 

The Twin Wire Press and the HC-Fluffer combined with the Flash Dryer make the perfect combination when it comes to consistent and high-quality pulp drying.

 

Close cooperation is vital in order to secure a successful execution and operation of the installation: Magnus Holmqvist, Area Sales Manager, ANDRITZ and Kalle Mäkelä, Production Manager BM4 and CTMP, Stora Enso.

© Riku Isohella

Stora Enso Imatra and ANDRITZ together developed how to locate the Flash Drying plant in an efficient space in the mill. The new Flash Drying Line was fitted into the overall layout.

© Riku Isohella

The ANDRITZ Twin Wire Press has been proven in many applications for all pulp types and is the best suited thickening equipment prior to a Flash Dryer.

© Riku Isohella
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“This project was a challenge due to the tight space we had, and really the only way was up in the design of the drying line in terms of making it fit the space.”

HEIKKI KANGAS

Project Manager, Technology & Investments, Stora Enso

FLEXIBILITY IS THE KEY

Commissioning and start-up of the new drying line took place in early January 2019 and went mostly according to plan, with the start-up of the Twin Wire Press and Flash Dryer, particularly going well

according to Mäkelä, who said, “What “What we were most impressed with was the start-up curve; we quickly ramped up production to maximum level, and the quality of the pulp we are producing is superb.

“The most important feature for us is the one of flexibility, as we were very dependent on what happened on the board and paper machines. We now have a BCTMP plant that we can run continuously at high capacity, which is a lot more economical than increasing or decreasing capacity, depending on the demand of the board machines.”

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