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Alkali and sulfur balances in the blast furnace. Mikko Helle Åbo Akademi. Alkali IN and OUT flows (BF1). Inputs: sinter (incl. pellets), coke, scrap (BF1), other Outputs: slag, dust Alkali analysis, daily values, interpolated if missing. Alkali IN and OUT flows (BF2).
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Alkali and sulfur balances in the blast furnace Mikko Helle Åbo Akademi
Alkali IN and OUT flows (BF1) • Inputs: sinter (incl. pellets), coke, scrap (BF1), other • Outputs: slag, dust • Alkali analysis, daily values, interpolated if missing
Alkali IN and OUT flows (BF2) • Inputs: sinter (incl. pellets), coke, other • Outputs: slag, dust
Alkali balance • Cumulative balances • Contain errors • Inaccurate massflows and analysis Similar trends can be seen
Alkali input and output • Filtered sums of in- and outflows • Explains the drifting in cumulative balances
Alkali input and output • Same inputs Similar total balances • Sinter and slag can explain some overall changes
Removing drift • Original balance curve (blue) is filtered (red) • ”Corrected” balance =blue-red
Corrected balances • Similar behavior can be seen between BF1 & BF2 • Errors in analysis of input materials? • Note the scale, ±15t
Influence of filtering on correction • Differences can be seen better when using less filtering, but real changes should not be eliminated
Sulfur IN and OUT flows (BF1) • Inputs: coke, oil, sinter (incl. pellets), scrap, other • Outputs: slag, iron, dust, (gas 40 ppm)
Sulfur IN and OUT flows (BF2) • Inputs: coke, oil, sinter (incl. pellets), other (very little) • Outputs: slag, iron, dust, (gas 100 ppm)
Sulfur balances • Cumulative balances • Drifting can be decreased by playing with the gas sulfur content • Hard to estimate sulfur content in gas • ”Correcting” with filtering gives same information
Corrected balances • Drift removed with filtering • Similarities can be seen between BF1 & BF2
Explaining errors • Outflow decreases before inflow and in both BFs?!? • Inaccurate sulfur content of oil?
Oil sulfur content • Calculating the ”correct” sulfur content of oil • If every other flow is correct, what should the S in oil to be for IN=OUT • Filtered values compared with the used one
Hearth volume and sulfur S-rich skull melts in the hearth Outflow of S increases and returns to original level when skull melting stops
Future • Information from balances will be used in efforts to explain BF behavior together with information on coke properties