50ton Electric arc furnace
EAF-50t Electric Arc Furnace
The actual power consumption per ton of steel is 610-180-200-10=220 kWh
Namely, the actual electrical energy needed for melting, phosphorus removal and heating up to the tapping temperature of 50% scrap steel and 50% molten iron in the arc furnace, (1630℃) is 220 kWh/t (e.g. oxygen blasting~50Nm3, metal charging 60%, electrical consumption 160kWh/t).
4. Main technical and economic indexes of the electric furnace.
Main technical and economic indexes of the electric furnace are shown in Table 1-5.
Table 1-5 Main technical and economic indexes of arc furnace
Type of steel | transformer capacity /MVA | Average tapping output /t | Max tapping output /t | Cycle of smelting /min | Power consumption of smelting kWh/t | Electrode consumption /kg/t | Amount of oxygen blasting /Nm3/t | Time of oxygen blasting /min |
Structural Steel | 22 | 55 | 60 | 68 | 220 | <2.2 | ≥50 | ~45 |
The key points to achieve the above indexes are: 1) Oxygen lance in furnace door; 2) the secondary charging together with molten iron feeding thermal idle time should be less than 16 min.
The high-quality super high power graphite electrode shall be adopted.
II. Technical specifications and explanation of 50t electric arc furnace
1. Technical specifications for 50t electric arc furnace equipment
Technological conditions and technical parameters for 50t arc furnace
1.1 Technological conditions and main requirements
The process flow of electric arc furnace is: “50t arc furnace + 60tLF refining furnace + continuous casting” – “trinity” process flow. Such techniques as furnace wall burner and oxygen lance in furnace door are adopted in the arc furnace equipment and process. Carbon steel is mainly produced.
Requirements for main process technical parameters of 50t arc furnace are shown in Table 2-1
Table 2-1 Requirements for main technical parameters of 50t arc furnace
No. | Name | Unit | Parameter | Remark |
1 | Number of furnaces in workshop | Piece | 2 | |
2 | Nominal capacity | t | 50 | Alternating current |
3 | Average tapping of molten steel | t | 55 | |
4 | Max. tapping of molten steel | t | 60 | |
5 | EBT hot heel | t | 7~9 | |
6 | Tap to tap period | Min | 68 | Mix 50% iron melt |
7 | Rated capacity of transformer | MVA | 22 | |
8 | Burner | Piece | 3 | 3-5 MW/piece |
Requirements for main performance and technological guarantee values for the 50t arc furnace equipment see Table 2-2
Table 2-2 Requirements for main performance and process guaranteed values of 50t arc furnace equipment
No. | Items to be checked | Unit | Parameter | Remarks |
1 | Tap to tap period | Min | 68 | |
2 | Average tapping | T | 55 | |
3 | Average power factor | 0.8 | ||
4 | Three-phase impedance unbalanced coefficient | % | ≤5 |
1.2 Technical parameters on designing 50t arc furnace
According to Technological conditions and technical requirements, main technical parameters of 50t arc furnace see Table 2-3
Table 2-3 Main technical parameters of 50t arc furnace
No. | Name of technical parameter | Specification /requirement | Remarks |
1 | Nominal capacity | 50t | |
2 | Average tapping output | 55t | |
3 | Quantity of EBT hot heel | 7~9t | |
4 | Internal diameter of furnace shell | Φ5200mm | |
5 | Rated capacity of the transformer | 22MVA | Self-supply by user |
6 | Primary voltage of transformer | 34.5KV | Frequency 60Hz |
7 | Secondary voltage | 410V-320V-170V | |
8 | Voltage regulation mode | 17 grade electric pressure regulating on load | |
9 | Secondary rated current | 39.692KA | |
10 | Cooling mode | Forced oil circulative water cooling | |
11 | Three-phase impedance imbalance coefficient | ≤5% | |
12 | Graphite electrode diameter | Φ450 | Super high power electrode |
13 | Electrode pitch circle diameter | Φ1200 | |
14 | Electrode lifting speed | Auto: hoist 6m/min fall 4m/min Manual: hoist 9m/min; fall 6m/min | |
15 | Max travel of electrode lifting | 3700mm | |
16 | Tilting angle | EBT tapping 20°; slag tapping 12° | |
17 | Furnace tilting speed | Tapping; slag tapping 0~1°/s; return dumping ≥3°/S | |
18 | Hoisting height of furnace roof | 450mm | |
19 | Lifting time of furnace roof | Hoisting< 15sfall< 20s | |
20 | Max Rotary angle of furnace roof | 75° | |
21 | Rotary time of furnace roof | Out/back <50s | |
22 | Dimension of the furnace door | 1100mm×800mm | |
23 | Hydraulic system | ||
Working pressure | 12MPa | ||
Working medium | Water --glycol | Shenzhen Houghton Co., Ltd. | |
Electrode fluctuation | Oil tank – electro-hydraulic proportional valve | ||
24 | Pneumatic system | ||
Consumption | 5m3/min | ||
pressure | 0.4Mpa | ||
25 | Water-cooling system | ||
Flow | 620m3/h | ||
Intake pressure | 0.45~0.55MPa | ||
Intake temperature | ≤35℃ | ||
Temperature of backwater | <55℃ | ||
26 | Requirement for water quality | ||
PH value | 7~8.5 | ||
Total hardness | <10° DH | ||
Suspended solid | <10mg/L | ||
Alkalinity | <60mg/L | ||
Chlorine ion | Mean <60mg/L | ||
Sulfuric ion | <100mg/L | ||
Conductance rate | 50 mille Siemens /m | ||
27 | Hoisting weight of lower furnace body | 90t | The weight of refractory is included |