Continuous annealing and galvanizing line furnaces

ANDRITZ Metals offers a wide range of well-proven technologies to provide the required process for a large range of steel grades – from commercial quality to high-strength steels (HSS), advanced high-strength steels (AHSS) such as dual phase, Complex Phase and Quench & Partitioning steels, with different types of coating suitable for GI (galvanized), GA (galvannealed), GL (“galvalume”), Zinc-Magnesium, AlSi, and other products.

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

Heating technologies

ANDRITZ Direct Fired Furnace

The ANDRITZ Direct Fired Furnace (DFF) to heat the strip up to 680-750° 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 allow very homogeneous and accurate temperature regulation. A precise control of oxidation/reduction can be achieved for either strip cleaning, eliminating oil and iron fines,  or preparation of High Strength Steel to get good adherence during galvanizing or galvannealing process.

Some Direct Fired Furnace References:

Customer benefits:

• Better properties homogeneity
• Better control of strip oxidation
• Possibility to hot dip galvanise AHSS
• Easier reach of high annealing temperatures for 3rd gen. AHSS
• Operational flexibility

Radiant tube heating

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

Induction heating with different applications, used as a simple temperature boosting device in an air or furnace atmosphere of H2 and N2, which requires specific, patented technology to protect the coil from the atmosphere.

Electrical elements

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 :

• radiation cooling (air tubes) (2-10°C/s)
• slow jet cooling (10-20°C/s) with constant cooling rates
• medium jet cooling (20-60°C/s)
• rapid jet cooling (RJC) with cooling rates up to 70°C/s in 1 mm from 750°C down to 460°C
• ultra fast cooling called Differential Rapid Jet Cooling (DRJC) with cooling rates (with 5% H2):
  • up to 140°C/s in 1 mm from 750°C down to 460°C for HSS
  • up to 100°C/s in 1 mm from 870°C to 350°C for AHSS
  • DRJC design allows regulation flexibility in three directions (strip to nozzle, across strip width, along strip length) in order to get temperature uniformity profile and regular cooling rate

Using higher H₂ concentration allows even much higher cooling rates, without safety issues (in accordance with ATEX regulation).

Customer benefit

• wide design range for an optimum solution
• temperature uniformity across strip width
• high cooling rates with low operational constraints

After-pot jet cooling for different types of coating and for best strip stability.

Combined heating & cooling section

A chamber which can operate either in cooling mode or soaking mode without losing strip temperature

High-end technologies for optimum furnace solution

• Tightest sealing requirements for independent atmosphere control
• 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 of advanced high strength steel
• Mulit-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

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