Multi-stack Bell-type Annealing Furnaces (MBAF) for Silicon Steel Strip
Tenova LOI Thermprocess, with its predecessors Matthias Ludwig and Nassheuer, has been building bell-type annealing plants for more than 60 years. Throughout the world, more than 500 LOI multi-stack annealing bases have been installed. The world-wide market share during the past 10 years is virtually 100%.
In the production of grain-oriented electrical strip, the material is annealed at about 1,200 °C following decarburizing and coating to obtain defined grain growth and a specified surface layer on the electrical strip.
In contrast to their widespread use for carbon steel and stainless steel, single-stack bell-type annealing furnaces have not become as established solution for the annealing of grain-oriented electrical steel sheet. Most of the new plants constructed for these applications over the past 20 years have therefore been multi-stack bell-type annealing furnaces (MBAF).
Normally three or four individual charge stations are installed in a row under the heating hood. Small coils (usually ≤ 12 t) are often charged in two layers. In other words, two coils may be stacked on each other on self-supporting plates.
Larger coils (usually ≥ 12 t) are charged in one layer on a charge plate manufactured from a high-temperature-resistant alloy or positioned directly on the base.Throughout the world, it has become normal practice to install electrically heated MBAF-plants. Multi-stack plants for two-layer operation have already been constructed with gas firing system with significant lower operating costs.
Value for Money
- Solid annealing equipment design
- Low operational costs
- Excellent temperature uniformity
- Very uniform mechanical and magnetic properties of the electrical sheet
- High heat transfer mainly by radiation
- High efficient electrical heating or low NOx gas-fired burners
- Individual coolers
- TÜV proven safety strategy
- Sophisticated process control
- O2 concentration monitoring
- Long service life
- Sturdy base support design
- > 60 years of experience in Bell-type Annealing
- > 500 multi-stack annealing bases worldwide
- World-wide market share during the past 10 years virtually 100%
- Selection of alternative heating systems (electrical and gas-fired heating)
- Low NOx burners in case of gas-fired heating
- Fully automated control system
- Various software modules for optimization
- World's first gas-fired MBAF plant
- Flameless combustion technology
- Possibility to produce HiB-grades
HPH® Bell-type Annealing Furnaces for non-grain-oriented Silicon Steel Strip (NGO)For over 60 years LOI, has been a technical and economical market leader in Bell-type Annealing technology. A wide variety of innovative details and comprehensive process technology expertise are the result that customers can build on.