Coil Ambient Temperature and Its Influence on the Formation of Blocking Layer in the Electromagnetic Induction-Controlled Automated Steel-Teeming System

doi:10.1007/s40195-018-0831-4

Abstract

Abstract:

Ambient temperature of induction coil is an important factor to influence the implementation of the electromagnetic induction-controlled automated steel-teeming (EICAST) technology. Meanwhile, it also affects the formation of Fe-C alloy blocking layer, which determines the length and installation position of induction coil. An experimental platform was designed to imitate actual working conditions in a ladle with the EICAST system. Ambient temperature of induction coil under high-temperature condition was measured to verify the accuracy of numerical result. After containing molten steel for 120 min and steel teeming for 40 min, the ambient temperature on the upper side of induction coil is 791 °C. In addition, the position of blocking layer in a 110 t ladle was measured by sand-collection and steel-pour methods, and the criterion temperatures of blocking layer in numerical simulation process were corrected. When the refining temperature is 1600 °C and the containing time of molten steel is 120 min, the thickness of blocking layer is 130 mm, and the distance between the upper surface of blocking layer and the upper surface of nozzle brick is 154 mm. When the criterion temperatures are 919 °C and 428 °C, the numerical results can be used to confirm the position of blocking layer and the installation position of induction coil.

Key words: Clean steel, EICAST technology, Heat transfer, Blocking layer, Coil ambient temperature

Ming He, Xian-Liang Li, Xing-An Liu, Xiao-Wei Zhu, Tie Liu, Qiang Wang. Coil Ambient Temperature and Its Influence on the Formation of Blocking Layer in the Electromagnetic Induction-Controlled Automated Steel-Teeming System[J]. Acta Metallurgica Sinica (English Letters), 2019, 32(3): 391-400.

Figures/Tables 18

Fig. 1 Schematic illustration of electromagnetic steel-teeming experimental devices. 1—resistance furnace; 2—induction coil; 3—thermal insulation material; 4—compressed air; 5—collecting device; 6—support structure; 7—nozzle brick; 8—K thermocouple; 9—upper nozzle; 10—experimental platform; 11—induction power supply

Table 1 Composition of Fe-C alloy particles

Fe-C alloy	C	Si	Mn	P	S	Cu	Ni
Components	0.07-0.13	0.17-0.37	0.35-0.65	≤ 0.035	≤ 0.035	≤ 0.25	≤ 0.25

Fig. 2 Schematic illustration of sand-collection method: a collecting device, b measuring device

Fig. 3 Schematic illustration of steel-pour method

Fig. 4 Simulation model: a three-dimensional model, b relevant dimensions

Table 2 Physical parameters of several materials

Materials	Density (kg m^-3)	Specific heat capacity (kJ kg^-1 °C^-1)	Thermal conductivity (W m^-1 °C^-1)
Nozzle brick	3040	1.13	2.9
Fe-C alloy	7830	Fig. 5	Fig. 5
Coil (copper)	8930	Fig. 6	Fig. 6

Fig. 5 Specific heat capacity and thermal conductivity of Fe-C alloy

Fig. 6 Specific heat capacity and thermal conductivity of copper coil

Fig. 7 Temperature curve of the upper surface of nozzle brick

Fig. 8 Temperature variation curve of coil ambient temperature

Fig. 9 Temperature distribution inside nozzle brick before steel teeming (t = 330 min)

Fig. 10 Temperature distribution inside nozzle brick after steel teeming

Fig. 11 Height of the Fe-C alloy original layer at different refining temperatures

Fig. 12 Position and thickness of the Fe-C alloy blocking layer

Fig. 13 Temperature variation of Fe-C alloy at different time

Fig. 14 Mechanism analysis of thickness and position difference of blocking layer

Fig. 15 Criterion temperatures of Fe-C alloy plugging layer

Fig. 16 Position of Fe-C alloy blocking layer after different containing time

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