Pori Energia Mill

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  • Pori Energia’s CFB boiler for electricity production of bio mass.
	  Lindab’s large flue gas silencer allows an airflow of 51.3 m3/s and lowers the noise level with 30 db (A).
  • The new flue gas silencer can handle continuous gas temperatures of 150°.
  • Flue gas silencer’s top section with its 12 baffles.
  • Flue gas silencer’s middle section with its 12 baffles.
  • Flue gas silencer’s bottom section with its 12 baffles.

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Story in short:

Giant Attenuator for Silent Energy Production

There are silencers and there are silencers. Most of them, at least in the case of ventilation systems, are circular or rectangular standard silencers in easy-to-handle sizes. But there are silencers in a class by themselves, fully developed and adapted for very demanding and specific customer needs. It was this kind of industrial solution from Lindab that solved Pori Energia’s needs of a new flue gas silencer for its CFB boiler, with optimal sound attenuation and fast, smooth installation. This giant silencer’s cross section dimensions of 4.0 x
5.5 m and airflow of 51.3 m3/s (184,700 m3/h) attenuates the sound level with a full 30 db(A).


Pori Energia Oy

Radanvarsi 2

28100 Pori



Pori Energia is a local producer and distributor of electricity that has been operating for over 100 years in Pori, Finland. In 2008, Foster Wheeler delivered a CFB boiler to Pori Energia for combus­tion and power production of biomass. “For this project our earlier customer delivered fans for both inlet and flue gases,” explains Piia Kyrönlahti, Technical Sales Manager Lindab. “IVK-Tuote Oy, in turn, delivered all of the silencers, including the very large flue gas silencer.” IVK-Tuote Oy was acquired by Lindab in 2010 and is today the Group’s unit for various types of special noise attenuators.

Biogas combustion, as CFB technology is about, generates noise from the actual combustion process, which produces an undesirable environmental effect that must be minimized to meet current environmental requirements.


Numerous improvements and smooth installation

“In 2015, the maintenance technicians of Pori Energia experienced whistle sounds coming from the 4 x 5.5 x 2.1 meter flue gas silencer,” Piia Kyrönlahti continues. “At the next maintenance stop, it was found that the splitters of the silencers were moisturized and swelled and that the re­quired noise reduction of 30 dB (A) from 125 to 95 db (A) could no longer be maintained. Shortly afterwards, Valmet Technologies sent us a request for a new flue gas silencer and we immediatly started calculations and dimensionings of this.”

After negotiating with Valmet Technologies on the solution, Lindab was able to deliver the new 4 x 5.5 x 2.3 m large flue gas silencer in August 2016. The large dimensions of this attenuator allow for an airflow of 51.3m3/s. This is the same volume of air that would be required to ventilate 1,000 flats! The new silencer that was delivered in three sections, was welded and assembled on site and has a number of improvements.

“We have used Lindtec mineral wool covered with 1 mm perforated steel plate, divided into 12 splitter sections, as compared to the previous 4,” explains Piia Kyrönlahti. “The splitter casing thickness is 1.25 mm which is 0.35 mm more than in previous attenuator, with all splitters riveted to the casing, allowing the installation to take place according to the strict schedule.”


Perfect delivery with all requirements met

“We are very pleased with Lindab’s delivery,” says Risto J. Huovinen from installer Valmet Tech­nologies. ”Even though we have not yet made any definite sound measurements, the prelimi­nary measurements show levels even better than the old, now replaced, silencer. In addition, the installation itself could be made on right time and completely without problems, a very important factor considering the fact that the plant is shut down for maintenance and repair for two weeks only each year.”

Unfortunately the plant had a fire shortly after, and due to a longer stand-still, no sound mea­surements have been possible, but Lindab’s new flue gas silencer is ready for immediate opera­tion and fully specified sound attenuation.