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Continuous galvanizing line furnaces

ANDRITZ provides galvanizing furnaces (CGL) with a wide range of heating and cooling technologies to meet the process requirements for production of all steel grades.

Product description

ANDRITZ METALS offers a wide range of well-proven technologies to provide the required mechanical properties for a large range of steel grades – from commercial quality to high-strength steels (HSS), advanced high-strength steels (AHSS) such as dual phase and TRIP steels, with different types of coating suitable for GI (galvanized), GA (galvanealed), GL (“galvalume”), and other products.

ANDRITZ Selas provides equipment not only for the furnace with an atmosphere of HNx (mixture of N2 and H2), but also for the cooling tower and the post-treatment section in terms of heating and cooling. In order to fulfill the product requirements (building, house appliances, and automotive non exposed and exposed parts), ANDRITZ Selas defines the adapted furnace, which can be horizontal, vertical or L-shaped with vertical DFF.

In addition to the process requirements, we focus both on minimizing energy consumption as well as on optimizing transition times based on thermodynamic mathematical models and on design to suit all maintenance aspects.

Heating technologies

  • The Direct Fired Furnace (DFF) to heat the strip up to 720-780° C with its preheating pass (using its own waste gases) replaces up to 12 passes with radiant tube heating in a vertical furnace. ANDRITZ Selas burners and ultra low NOx emissions allow the atmosphere to be controlled very accurately in a temperature window, which is essential in the controlled pre-oxidization necessary for galvanizing AHSS or for cleaning the strip by reducing oxides and eliminating iron fines and oils. This happens in one heating pass with excellent uniformity of heating temperature across the strip width.
  • Radiant tube heating (RTH) to reach the annealing temperature up to 900-920° C, with ON/OFF recuperative or regenerative burners for I, U, W, P and PP thin radiant tubes.
  • Induction heating with different applications, used as a simple temperature boosting device for air or used inside a furnace with an atmosphere of H2 and N2, which requires specific, patented technology to protect the coil from the atmosphere.
  • Electrical elements, such as wires, strips, or radiant tubes adapted to the process.

Cooling technologies

A wide range of different designs are available to suit the process requirements to an optimum, starting at very slow and going up to very high cooling rates with perfect uniformity of temperature across the strip width in different atmospheres (N2, HNx at 5% H2 up to 95% H2) or using water for suitable applications.

  • Slow jet cooling for low cooling rates
  • Rapid jet cooling for high cooling rates
  • Differential rapid jet cooling for ultra-high cooling rates:
    This well proven design for HSS products and dual phase steel grade, in operation since 1995, – for instance at voestalpine Stahl – not only ensures highest cooling efficiency and homogeneous temperature via automatic control, but also guarantees strip stability and flexible operation.
  • Water sprayers, mist coolers (water and air), where applicable
  • After-pot jet cooling for different types of coating and for best strip stability

Customer benefits

Heating/cooling section

  • A chamber which can operate either in cooling mode or soaking mode without losing strip temperature
  • Tightest sealing requirements to separate chambers with different atmospheres
  • A combi-furnace, to run either as CAL or CGL without cutting the strip
  • DFF technology for fast and efficient heating of strip, selective pre-oxidation for the production at advanced high strength steel
  • Multi-functional furnace for many grades of steel
  • Low carbon steel for domestic appliances, automotive non exposed and exposed parts (multiphase steels, high strength steel, advanced high strength steel)
  • Multi zone furnace with individual temperature zone control for highest quality steel

Corresponding E&A models

All ANDRITZ line models

FVZ3 continuous galvanizing line

Voestalpine Stahl, continuous galvanizing line FVZ3

DFF continuous galvanizing line

Continuous galvanizing line DFF

FVZ4 continuous galvanizing line

Voestalpine Stahl, continuous galvanizing line FVZ4

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