Developments Toward an Intelligent Electric Arc Furnace at - Tenova

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3.25 3.20 3.15 3.10 3.05 3.00 2.95 2.90 2.85 2.80 41.00 40.50 40.00 39.50 39.00 38.50 38.00 37.50 37.00 36.50 36.00 35.50 2.95 2.96 2.97 Oct-05 Nov-05 Dec-05 Jan-06 EFSOP Evaluation Period, Feb 20 - Mar 19, 2006 40.56 Figure 10: Productivity, inventory cast ton / power on time, ton/min 40.49 40.41 Oct-05 Nov-05 Dec-05 Jan-06 EFSOP Evaluation Period, Feb 20 - Mar 19, 2006 Figure 11: Power On Time (POT), min 3.19 37.94 3.22 37.45
Yield (inventory cast ton per total metallic charge) increased by 0.5% during the evaluation period in comparison to January 2006. This increase is evident in Figure 9, where the average yield increased from 91.83% during Jan. 2006 to 92.33% during the evaluation period. As EFSOP ® only affects the operation during power-on-time productivity is calculated based on power-on-time and not on tap-to-tap time, as is typically done. The productivity (Inventory cast ton per minute power on time) is shown in Figure 10. It has increased during the evaluation period by 0.03 % compared to Jan-06, increasing from 3.19 ton/min to 3.22 ton/min. The increase in productivity comes from the increase in yield as noted above and from a reduction in power-on-time. In fact, POT was decreased by 0.49 minutes compared to Jan. 2005 as indicated in Figure 11. The economics for oxygen, methane, carbon and electrical usage have been evaluated in the usual straight-forward manner. Specifically, benefits are calculated as the product of the unit cost and the difference in average consumption during the baseline period compared to the evaluation period. Figure 12 is the average dollar cost per ton inventory cast contribution from electricity, natural gas, oxygen, and injected carbon. These costs dropped by 0.29 $/InvCastTon. As in the increase in carbon usage was suspect, an analysis was also considered without including carbon and found to be 0.52 $/InvCastTon. 24.80 24.60 24.40 24.20 24.00 23.80 23.60 23.40 23.20 23.00 24.65 24.46 24.37 Oct-05 Nov-05 Dec-05 Jan-06 EFSOP Evaluation Period, Feb 20 - Mar 19, 2006 Figure 12: Dollar Cost of Electricity, Natural Gas, Oxygen and Injected Carbon, $ / inventory cast ton The formula for evaluation of the benefits due to increases in production is presented below: 23.91 POT ty($ / InvCastTon) = NET * ( −1) POT productivi REF Where NET is the net earnings per ton billet sold and POTREF and POT are the power on time averages for the reference (Jan-06) and the evaluation periods, respectively. A value of $50/ton good billet was assumed. It is a measure of the additional profit made by being able to produce more (sell more) as result of improved productivity (lower POT and increased yield) using the same fixed costs. Figure 10 is the plot of the productivity improvement average dollar equivalent. The reference being Jan-06, therefore the productivity dollar equivalent is zero for January. The improvement in productivity during the evaluation period resulted in additional profit of 0.66 $ per ton inventory cast. 23.62
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Page 15 and 16: Figure 16 is a plot of a partial en
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Developments Toward an Intelligent Electric Arc Furnace at - Tenova

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