Press releases

Seco/Warwick finishes commissioning on four double chamber furnaces

Furnaces were delivered to ASSAN Aluminium Sanayi ve Ticaret A.S. Turkey at 2007 and assign for coil annealing various sizes of coils, equipped with high convection Vortex® Jet Heating. ASSAN ALUMINIUM endeavors to be at the forefront of implementing and developing next generation technologies in the aluminium rolled products industry. Recognizing the productivity and quality gains offered by the Vortex® Jet Heating System compared to conventional technologies, ASSAN ALUMINIUM made the choice for the patented innovative solution. The furnaces are part of the ASSAN ALUMINIUM’s large-scale investment programme for renovation and expansion of Standart Aluminium (Ex-Nasas) assets to a 100,000 tpy aluminium complex for foil and specialty products.

The heating system incorporates recuperative burners for maximum energy efficiency. The complete installation includes an automatic charging machine for furnace loading, unloading, and load transportation between furnaces and load tables.

Vortex® Jet Heating Process Technology

Aluminium annealing requires an advanced convective heating system to obtain the shortest possible cycle without any loss of quality in the material. Quality problems typically appear at the strip edges, and are represented by non-uniform material properties like hardness, and discolorations of the strip surface, as in the case of 5xxx and 7xxx alloys caused by Mg- or Mn-bleeding, cracking of residual milling oil from coil degreasing, or coil surface melting. These problems are caused by overheating at the coil edge resulting from non-uniform impingement of the air flow. The governing parameter describing the temperature uniformity of a convective heating system is the ratio of maximum to minimum heat transfer coefficient (HTC). This parameter limits the heat up time since the smaller the HTC ratio the higher the average temperature that can be obtained without exceeding the maximum tolerable local heat transfer.

The Vortex® Jet Heating System incorporates arrays of 4 round inclined nozzles that generate a spiral vortex motion of air that results in high heat transfer without producing hot spots in the coil. The high volume flow of this nozzle system in conjunction with a unique semi-axial fan design allows the coil to be heated more uniformly by a larger mass of atmosphere. The effective thermal conductivity in a strip coil is much lower in the radial direction than in the axial direction, therefore, the most effective way of heating the coil is through the edges of the coil wraps. The difference between the thermal conductivity for the two directions is caused by the heat insulating effect of the gas and milling oil layers in the coil between the strip layers. This technology provides many benefits compared to older technologies:

Reduced heat-up time without local overheating.
Improved uniformity of material properties.
Minimizes local cracking and staining of milling oil
Reduced electrical consumption because the fan operates at a lower speed rather than a higher volume flow.