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Reducing costs and downtime at the Hot Strip Mill |
Previous Example |
| Downtimes of the reheat furnaces at the Hot Strip Mill result in loss of production. Consequently, there is a continuous quest for possibilities to minimize maintenance downtime, e.g., by increasing refractory life times and applying faster repair methods. Alternatively, the heating and cooling rates of the furnaces could be increased. An additional advantage of increased rates is that less burner gas is used. Currently, these rates are limited by preventing stresses to occur in the refractory lining. |
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Model picture of a roof anchor (middle image) and photographs of damaged roof anchors: Left, two anchor bricks have been 'decapitated' at the stress region indicated by the left arrow; Right, at the next maintenance stop, additional damage is observed at the stress region indicated by the right arrow. |
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| The project goals were: |
- Investigate the thermo-mechanical load of the refractory lining (i.e., determine the operating limitations of the furnaces);
- Formulate the optimised cooling and heating procedures, whilst minimizing damage risks;
- Recommendations for optimization of the construction and materials, such that even higher cooling and heating rates can be applied.
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| By means of thermo-mechanical modelling, we have established what the influence is of cooling and heating rates on the magnitude of the stresses and at what stage they occur. This knowledge has resulted in considerably reduced cooling and heating procedures, saving for major maintenance stops approximately 20 hours per furnace and a corresponding amount of gas. In addition, the risk of damage is reduced by avoiding stress peaks appearing in the current procedures. |
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| In summary, the results are a reduction of: |
- Maintenance costs and downtime (20 hours)
- Production losses
- Gas consumption
- Damage risk
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Previous Example |
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