Fuel Arc Furnace (FAF) for Effective Scrap Melting (eBook)

Introduction 6
Contents 8
1 EAF in Global Steel Production Energy and Productivity Problems
Abstract 11
1.1 Production of Steel from Scrap Is EAF’s Mission 11
1.2 Melting a Scrap as a Key Process of the Heat 13
1.3 Unjustified High Electrical Energy Consumption 13
1.4 Problems of Ultra-High Power (UHP) EAFs with Regard to Energy 14
1.5 High Productivity or Low Costs? 15
References 16
2 Analysis of Technologies and Designs of the EAF as an Aggregate for Heating and Melting of Scrap 17
Abstract 17
2.1 Melting a Scrap by Electric Arcs. Function of Hot Heel 17
2.1.1 Single Scrap Charging 18
2.1.2 Telescoping Shell 19
2.2 Heating a Scrap by Burners in the Furnace Freeboard 19
2.2.1 Specifics of Furnace Scrap Hampering Its Heating 19
2.2.2 Stationary Burners and Jet Modules 20
2.2.3 Rotary Burners with Changing the Flame Direction 24
2.2.3.1 Slag Door and Oriel Rotary Burners 25
2.2.3.2 Roof Rotary Burners 27
2.2.4 Two-Stage Scrap Melting. Industrial Testing of the Process 29
2.2.4.1 Two-Stage Process in 100-t and 200-t EAFs 30
2.2.4.2 Two-Stage Process in Plasma Furnaces 31
2.2.5 Twin-Shell EAFs 32
2.2.5.1 Twin-Shell Shaft Furnaces 34
2.3 EAF with Preheating a Scrap by Off-Gases and Melting of Preheated Scrap in Liquid Metal 35
2.3.1 Conveyor Furnaces of Consteel-Type 35
2.3.2 Shaft Furnaces with Fingers Retaining Scrap 39
2.3.2.1 Calculation 41
2.3.2.2 EAF Quantum 42
2.3.2.3 EAF SHARC 44
2.3.3 Shaft Furnaces with Pushers of the COSS-Type 45
2.3.3.1 Shaft Furnaces of ECOARC-Type 46
2.4 Factors Hindering Wide Spread of Shaft Furnaces 47
2.4.1 Calculation of the Maximum Values of the Power of the Heat Flow of Off-Gases and Temperature of Scrap Heating by These Gases in the Shaft 48
References 49
3 Experimental Data on Melting a Scrap in Liquid Metal Required for Calculation of This Process 50
Abstract 50
3.1 Features of Scrap Melting Process 50
3.2 Studies of the Melting Process by the Method of Immersion of Samples in a Liquid Metal. Analysis of the Results 52
3.2.1 Melting of Single Samples of Scrap with a Solidified Layer and Without Solidifying 52
3.2.2 Co-melting of Multiple Samples 57
3.2.3 Porosity of Charging Zone and Bulk Density of Scrap 59
References 59
4 Calculations of Scrap Melting Process in Liquid Metal 60
Abstract 60
4.1 Scrap Melting Time 60
4.2 Adaptation of Experimental Data Obtained by the Method of Melting Samples to Real Conditions of Scrap Melting 61
4.2.1 Equivalent Scrap 61
4.2.2 Correction Coefficients KP, KL, Kts and K? 62
4.2.2.1 Coefficient KP, Adjustment of Porosity P in the Charging Zone 62
4.2.2.2 Coefficient KL, Adjustment of Temperature of Metal tL 62
4.2.2.3 Coefficient Kts, Adjustment of Scrap Preheating Temperature tS 62
4.2.2.4 Coefficient K?, Adjustment of Metal Stirring Intensity 63
4.3 Calculation Method of Scrap Melting Time in Liquid Metal 64
4.3.1 General Characteristic of the Method 64
4.3.2 Examples of Calculations of Scrap Melting Time 64
4.3.2.1 Conveyor Furnace Consteel 64
4.3.2.2 Shaft Furnace Quantum 65
4.3.2.3 Influence of Scrap Quality 66
4.3.3 Specific Scrap Melting Rate 67
References 68
5 Increasing Scrap Melting Rate in Liquid Metal by Means of Oxygen Bath Blowing 69
Abstract 69
5.1 Preliminaries 69
5.2 Tuyeres with Evaporation Cooling Embedded in the Lining 71
5.3 Roof Water-Cooled Tuyeres for Bath Blowing at Slag-Metal Interface 74
5.3.1 Thermal Operation of Tuyeres: Heat Flows, Temperatures 74
5.3.1.1 Operation of Tuyeres with Local Water Boiling 77
5.3.1.2 Jet Cooling 79
5.3.2 Roof Tuyere with Jet Cooling Design, Basic Parameters
5.3.2.1 Controlling the Optimal Position of Roof Tuyere Relatively to Slag-Metal Interface 84
References 86
6 High-Temperature Heating a Scrap in a Furnace Shaft 87
Abstract 87
6.1 Preliminary Considerations and Evaluation of Some Parameters 88
6.1.1 Calculation of Scrap Heating Time with off-Gases in the Quantum Shaft 89
6.2 Scrap Preheating System by High-Power Recirculation Burner Devices 90
Reference 93
7 Fuel Arc Furnace—FAF 94
Abstract 94
7.1 Concept of the Fuel Arc Furnace 94
7.1.1 Selection of the Quantum Constructive Scheme as a Base for FAF 95
7.1.2 Calculations of Main Parameters and Performances of the FAF 96
7.1.2.1 Data on Parameters and Operating Conditions of the furnace Required for Calculations 96
7.1.2.2 Calculation of Scrap Preheating Time 97
7.1.2.3 Required Transformer Power and Electrical Energy Consumption 97
7.1.2.4 Power of Burner Devices and Natural Gas Flow Rate 98
7.1.2.5 Tap-to-Tap Times and Hourly Productivity 98
7.2 Advantages of Fuel Arc Furnaces FAF of Quantum-Type 98
Reference 99
Index 100