Successful implementation of turbo fan technology at two pulp plants in Scandinavia has demonstrated the potential of Mechanical Vapour Recompression (MVR) designs in liquor recovery applications.

MVR designs incorporating turbo fans developed by ABB Fläkt Oy in Finland are now able to compete successfully against conventional compressor systems traditionally used in liquor recovery systems. Proven performance at plants in Norway and Finland show that MVR fans are applicable to both sulphate and sulphite mills. They can be used in pre-evaporators or evaporators.
At the Kaukas pulp mill in Finland, owned by UPM Kymmene, the MVR turbo fan acts a pre-evaporator that then feeds a conventional multi-stage liquor recovery system.

Part of improvements
Hannu Kytö, head of operations at the UPM Kymmene pulp mill at Kaukas, says that the installation of the MVR unit has helped the mill meet increasing production demands. The pulp mill has a capacity of 625,000 tonnes of pulp annually. This feeds two paper machines producing around 500,000 tonnes of LWC paper a year.
"The pre-evaporator is part of an overall investment in upgrading our recovery system," says Kytö. "The attractive investment cost and technical solution were factors in the choice of the MVR system."
He adds," The fan was easier to connect to the existing evaporation system than a compressor and it has helped us remove a bottleneck in production by increasing the capacity in the recovery system. Without this capacity, our pulp production would be limited." The system has to be reliable with more than 8,000 hours of operation a year.

Clear benefits
At the Borregaard sulpite pulp production plant in Norway, part of the Orkla group which is one of that country's largest listed companies, there were also clear benefits in adopting the fan approach. "We think this technology is more reliable, offers better up time, and lower maintenance costs due to the slower rotation rates", says Rune Hillström, executive vice president, at this speciality pulp plant. "By doing this we have been able to increase capacity of the evaportion plant by 15 per cent. It is also less sensitive to process disturbances compared to conventional turbo compressor technology."
As a consequence of these benefits, the turbo fan design has also been in used to recover the alkaline component of the bleach plant effluent to minimise emissions to water, says Hillström.

Simple construction
The main reason for the success of such fans, says Göran Tallberg, ABB Fläkt marketing manager, is their simplicity of construction when compared to the complexity of traditional designs incorporating compressors. This makes maintenance easier and helps control manufacturing costs.
ABB Fläkt Oy Industrial Fans, part of the ABB group, is one of the leading industrial fan manufacturers world-wide delivering its products to more than 100 countries.

Captions:

Figure 1. The incorporation of a Mechanical Vapour Recompression (MVR) turbo fan in the pre-evaporator at the Kaukas pulp mill in Finland by ABB Fläkt has helped avoid production bottlenecks.

Figure 2. Reliability, better up time, and lower maintenance costs were factors in using ABB Fläkt's turbo fan within the liquor recovery system at Borregaard's sulphite mill in Norway.

For more information contact:

South Africa, France, the Netherlands, Australia:
Göran Tallberg, Marketing Manager
E-mail: goran.tallberg@fiflo.mail.abb.com

Acia Pacific, China, Germany, Switzerland:
Markku Kerminen, Export Engineer
E-mail: markku.kerminen@fiflo.mail.abb.com

United Kingdom, Sweden:
Jarkko Hietaoja, Area Export Manager
E-mail: jarkko.hietaoja@ fiflo.mail.abb.com

Brazil, Latin America Regional, Canada, USA:
Risto Erholtz, Area Export Manager
E-mail: risto.erholtz@ fiflo.mail.abb.com

ABB Fläkt Oy
Industrial Fans
P.O.Box 5
FIN-02621 Espoo
Finland
Tel: +358 10 22 2000
Fax: +358 10 22 23480

Press release images