b'Heavy Equipment | Engineer Innovation160 160 160 160Distance from load bottom, mm Distance from load bottom, mm Distance from load bottom, mm Distance from load bottom, mm140 2 140 140 2 140 22120 120 120 120100 100 100 100180 80 1 80 80160 60 60 6040 40 40 40120 20 20 2000 0.10.20.30.40.5 0.60.70.80.91.0 00 0.10.20.30.40.5 0.60.70.80.91.0 00 0.10.2 0.30.4 0.50.60.7 0.80.91.0 00 0.10.2 0.30.4 0.50.60.7 0.80.91.0Relative distance from load axis Relative distance from load axis Relative distance from load axis Relative distance from load axisTime step #3, 100 sec Time step #4, 120 sec Time step #5, 140 sec Time step #10, 240 secFigure 9: Load profile variation during a furnace heat. 1-soliid load, 2-molten loadshowing variation of load temperature(T)100with time. 9080Load Utilization, %The graph is fixing the molten load front70location. That gives the necessary data for60load meniscus calculations. Figure 750shows the procedure of meniscus40calculation. The calculation of the shape30of the load meniscus requires an iterative20approach, so the meniscus data is10passing, as feedback, into its own0 010 20 30 4050 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240Time, SecSimcenter MAGNET model. Nominally,Figure 10: Furnace load utilization coefficient.the load meniscus calculation comes to finding out a molten load shape with hydraulic pressure that is equal to theThe coil location produced conflicting electromagnetic pressure of the coilresults: it is impossible to find one optimal magnetic field. location of coil for all variants. The design decision was made to move the induction The third profile is an ellipsoid of secondcoil in the process from the top of the order with a bottom diameter equal tofurnace heat to the bottom.the solid load diameter and volume of the molten load. The Simcenter MAGNETThe change can be done synchronously block has the distribution of thewith time steps or continually. This variant magnetic field in the zone of moltenwas explored and shows satisfactory load, particularly, in the zone of outerresults. Some examples of the load diameter of the molten load. Theprofiles calculations are shown in Figure 9.intensity of the magnetic field in this zone can be used to determine the initialThe developed method efficiency can be meniscus height and its bottom diameterdefined by estimation of load level (Figure 7, Curve 2). utilization of the furnace. The Load Utilization (LU) coefficient may be used Curve 2 in Figure 8 is incompatible withfor the goal. The LU coefficient is defined the electromagnetic pressure curve thatas a ratio between mass of molten load Simcenter MAGNET produces (See Figureoutput and mass of furnace charge. As 8a). The two curves have a goodthe Figure 10 shows, at the use of coincidence on its ends, but not in themovable induction coil, the LU coefficient middle. There are two ways to improveis more than 90 percent.compatibility of the curves: a) induction coil design; b) induction coil location. ConclusionThe represented method of the induction The coil design method was used fromfurnaces with the cold crucible calculation the beginning, this design uses aallows for the design of furnaces with combination of cylindrical and conical coilminimal contact between the molten turns. This design showed satisfactorymetal and the furnace crucible, which in results in the initial stages. The curves onreturn dramatically reduces the the Figure 8b show good agreement.contamination of the load. n37'