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  • Outstanding reduction of NOx emissons in Kessales

NOx emissons reduction by 45% in Kessales

The site of Kessales near Liège hosts a continuous annealing line that produces mild and Ultra Hight Strength steels for automotive and industry clients throughout Europe. In 2011, the decision was taken to renew the technology of the burners of the line for quality, energy and environmental reasons.

One of the key-objectives was to reduce NOX (Nitrogen Oxides) emissions by reducing the temperature of the flames and the excess of Oxygen in the combustion.


 

In November 2011, the line was interrupted during 6 weeks in order to execute this 7 million Euros investment, which took place at various levels:

  • The burners were replaced by new ones
  • The casing and isolation of the oven was completely renewed
  • The radiant tubes in which the fumes circulate were also replaced by a new technology

One year and a half after these investments, the outcomes go beyond the initial expectations. Altogether, the new burners and radiant tubes, by allowing part of the fumes to circulate again in the tubes, diminish the oxygen brought into the combustion as well as the flame temperature and therefore NOX emissions. The new set-up allows also a better heating of the coil.

  • NOX emissions have been reduced from 470 in 2011 to 260 milligram per normo cubic meter in 2012, and 219 are expected in 2013. The European standard is at 500 mg/Nm3 for 3% of oxygen.
  • The energy efficiency of the oven has been increased, as the consumption was 1,31 Gigajoules of Natural Gas per ton and has dropped down to 0,8 Gj/ton in June 2013. This means saving 28kg of CO2 per ton of steel.

On top of that, the new state-of-the-art installation allows to reprocess 3 tons per hour of steam in average, both for the manufacturing process itself and also to heat the buildings. This represents 15% of the total consumption of steam of the Kessales site, an annual saving of  23500 Gigajoules of natural gas and 1311 tons of CO2.