Constellium to use Linde’s oxy-fuel tech in aluminum recycling and melting furnaces; targeting 50% cut in energy consumption
24 June 2015
Constellium N.V. and Linde Gases, a division of The Linde Group, signed a joint development agreement to use Linde’s oxy-fuel technology (earlier post) in Constellium’s aluminum recycling and melting furnaces, with a goal of cutting energy consumption by half while increasing melting rates by 20%. This announcement follows a long-term partnership with Linde in the area of energy-efficient re-melting technologies.
Air contains only 21% oxygen, the remaining 79% is ballast—mostly nitrogen. In combustion processes, all this ballast is negative; in other words, it does not contribute to the combustion, but has to be heated up, consuming unnecessary extra fuel.
If oxygen, not air, is used to combust a fuel, all the heat transfer mechanisms, convection, conduction and radiation, can be promoted at the same time. This results in a faster, more even heating process, which cuts the total heating time thus allowing for more production capacity and flexibility. The flue gas volumes are reduced by up to 80% with no more need for bulky flue gas systems or recuperators.
Low-temperature oxyfuel combustion technology occurs under a diluted oxygen concentration by mixing the furnace gases into the combustion zone. This process slows down the oxyfuel combustion reactions and results in lower flame temperatures, comparable to those of airfuel technology, which are below the point at which thermal NOx is created. The mixing of furnace gases into the flame also disperses the energy throughout the entire furnace for uniform heating and more efficient melting. The dispersed flame contains the same amount of energy but with a much more effective distribution. The overall result is more homogenous heating and melting, enabling not only a higher power input and thus higher melt rates, but also reduced formation of dross and NOx emissions.
The joint development agreement will build on the recent successful implementation of Linde's technology in Constellium’s finishing and recycling aluminium facility of Neuf-Brisach, France, where two of the four rotary tilting furnaces have been converted to low-temperature oxy-fuel combustion technology. Following this implementation, Constellium was able to achieve greater productivity and to accelerate progress on its sustainability roadmap. The conversion of the remaining furnaces at the France plant is scheduled to be completed by the end of 2016.
Linde has developed small burners to fit the lab-scale furnaces located in Constellium Technology Center, C-TEC. This effort has resulted in significant metal yield and further productivity increases at lab scale. The improved process is now under evaluation for implementation at industrial scale.
The implementation of the oxy-fuel technology in Neuf-Brisach is supported by the expertise of Constellium Technology Center, C-TEC. The R&T team is helping to define the required controls and operating conditions to reap the full benefits of the technology.
Constellium is a global sector leader that develops innovative, value added aluminium products for a broad scope of markets and applications, including aerospace, automotive and packaging. Constellium generated €3.7 billion of revenue in 2014.
Interesting for lower cost future aluminum ultra light e-vehicles and for a more efficient aluminum recycle industry.
Posted by: HarveyD | 24 June 2015 at 07:04 AM
Having worked extensively with oxyfuel-technology for power production for more than 7 years, I am puzzled by this article. The cost of separating the oxygen is very high, and can by no means be recovered just by lowering flue gas losses due to the lack of nitrogen, as indicated in this article. And if so, it implies that flue gas temperatures in the exhaust are extremely high and could be used to generate considerable power or utility steam. In a counter-current (bottom fired) melting furnace, the flue gases should not be much higher than the inlet temperature of the recycle material. However, I must confess I know very little about aluminium melting.
When the nitrogen is removed, there is no longer thermal NOx generation and thus less reason to burn at low temperature. Of course there could be other reasons, such as structural.
There is a hint of improved metal yield by using oxyfuel. It appears the primary mechanism is higher yield per furnace, which of course leads to improved top line income. But the cost of an air separation unit or oxygen delivery has to be subtracted before the result on the bottom line is seen.
Posted by: Thomas Pedersen | 24 June 2015 at 08:31 AM