Case Study:

Pleated bags installed in shaft furnace at steel plant




Shaft furnace for pellet firing

Dust type:

Ferric oxide, manganese oxide


  • The overall steel group is focusing on lowering emission
  • Emission was about 20mg/m3, which is above the emission standard.
  • Goal: emission lower than 5mg/m3


Replacing 1.152 bags with 1.152 pleated bags.

Installed October 2018.



  Bag filter Pleated bag solution
Airflow in unit  280.000 m³/hour
Dusttype  Ferric oxide, manganese oxide. Shaft furnace for pellet firing
Collector running hours/year  8.000
Filter model Filter bag CPB
Media/cloth type  Polyester+PTFE  Polyester w. PTFE membrane
Length  6.000 2.000
Number of bags/cartridges  1.152 1.152
M² in each bag/cartridge  3,00 5,60
M² in unit  3.456 6.400


By replacing the existing filter bags with Pleated Bags from Nordic Air Filtration the following results were obtained:

  • Decreasing of filter length, 2m vs 6m = 4m higher drop-out box underneath the filters
  • The PU-top fit easily to the tube sheet
  • Spunbund polyester, which is a surface filtration media, is more efficient for pulse cleaning keeping deltaP low for substantially longer than the felt media
  • As a consequence of upgrading to pleated bag filters, the filter surface area has increased by 50%
  • Weldtech technology (ultrasonic welded bands) ensures perfect fit of the bands and equal pleatdistance
  • Lower emission than with conventional filter bags. Emission after: 3,9mg/m3
  • Lower air-to-cloth ratio and lower dP, 700pa (after) vs 1800pa (before), provide significant cost saving of fan

Solution after: 

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