Blast furnace phenomena and modelling

I: Phenomena in the Blast Furnace.- 1 Dissection of Quenched Blast Furnaces.- 1.1 Introduction.- 1.1.1 Background to the present study.- 1.1.2 Methods of quenching and their effects.- 1.1.3 General in-furnace situations and peculiar phenomena.- 1.2 Relation Between Behavior of Descending Burden and State of Combustion Zone.- 1.2.1 Fundamental descent behavior of burden in the shaft.- 1.2.2 Asymmetrical descent of burden.- 1.3 Behavior of the Core.- 1.4 Situations in and Around the Combustion Zone.- 1.4.1 State in front of the tuyere nose.- 1.4.2 Formation of shell and movements at the lower part of the raceway.- 1.4.3 Conditions inside the furnace and the shape of the raceway.- 1.5 Shape of Cohesion Zone and Relation to Distribution and Movement of Burden.- 1.5.1 Formation of the cohesion zone.- 1.5.2 Relation between shape of the cohesion zone and operation conditions.- 1.6 Behavior of Circulating Elements.- 1.6.1 Effect of water quenching on the circulating elements.- 1.6.2 Behavior of circulating elements and amounts of circulation.- 1.7 Changes in Properties of Burden Materials.- 1.7.1 Macroscopic changes.- 1.7.2 Microscopic structural and composition changes.- 1.7.3 Effects of circulating elements on the behavior of the cohesion zone.- 1.8 Reactions in the Hearth.- 1.8.1 Slag formation reactions.- 1.8.2 Changes in the metal composition.- 1.9 Concluding Remarks.- 1.10 Addendum.- 1.10.1 Arrangement inside the furnace.- 1.10.2 Changes in properties of the burden.- 2 Measurements in Operating Blast Furnaces.- 2.1 Objectives of Blast Furnace Measurements.- 2.2 Development of Measurements for Clarification of Furnace Reactions.- 2.2.1 Standard instrumentation for blast furnaces a decade ago.- 2.2.2 Development of instrumentation since the introduction of blast furnace dissection.- 2.3 Relationship Between Furnace Measurement and Furnace Operation (Actual Examples).- 2.3.1 Relationship between measurements before blowing out of blast furnace and results of dissection.- 2.3.2 Measurements and estimations of the cohesive zone.- 2.3.3 Development and use of the latest sensors to study furnace interiors.- 2.4 Future Development of Blast Furnace Measurements.- II: Modelling of the Blast Furnace.- 3 Global Formulation.- 3.1 Review of Blast Furnace Models.- 3.1.1 Reichardt diagram.- 3.1.2 Operation diagram.- 3.1.3 Kinetic model.- 3.1.4 Control models.- 3.1.5 Models for estimating internal situations based on observed data.- 3.2 One-dimensional Static Model.- 3.2.1 Overall reaction rates.- 3.2.2 Overall material balance.- 3.2.3 Temperatures of gas and solid at the top of the furnace.- 3.2.4 Flow rate and composition of gas at tuyere level.- 3.2.5 Theoretical flame temperature.- 3.2.6 Temperature of gas and coke at tuyere level.- 3.2.7 One-dimensional mathematical formulation for internal state of blast furnace.- 3.2.8 Effect of various operating conditions on productivity and situation in blast furnace.- 3.2.9 Some applications of the model.- 3.3 Layered Structure Model.- 3.3.1 Radial distribution of flow rate of gas.- 3.3.2 Mathematical-kinetic model of blast furnace.- 3.3.3 Numerical analysis of blast furnace operation.- 3.3.4 Computed results.- 3.3.5 Steady-state two-dimensional modelling.- 3.3.6 Governing equations for cylindrical polar coordinates.- 3.3.7 Some auxiliary relations.- 3.3.8 Numerical solution of two-dimensional model.- 3.4 Two-dimensional Model for Gas Flow, Heat Transfer and Chemical Reactions.- 3.4.1 General concept of the radial distribution model.- 3.4.2 Momentum transfer.- 3.4.3 Mass transfer with chemical reactions.- 3.4.4 Heat transfer.- 3.4.5 Input conditions.- 3.4.6 Method of analysis.- 3.4.7 Simulation results.- 3.5 Two-dimensional Formulation by Finite Element Method.- 3.5.1 Flow analysis of gas.- 3.5.2 Computed results for gas flow.- 3.5.3 Simultaneous analysis of gas flow and heat transfer.- 3.5.4 Computed results on the simultaneous gas flow and heat transfer.- 3.6 Model for Estimating the Profile of the Cohesive Zone.- 3.6.1 General description of the mathematical model.- 3.6.2 Relation between indices estimated using the mathematical model and from blast furnace operation (cohesive zone analysis with 4000 m3 class blast furnace).- 3.6.3 Analysis of operation with decrease in production.- 3.6.4 Future direction.- 3.7 One-dimensional Dynamic Model.- 3.7.1 Outline of mathematical simulation model.- 3.7.2 Applications to blast furnace operations.- 3.8 Notation.- 4 Flow of Gas, Liquid and Solid.- 4.1 Flow of Solids During Charging and Control of Burden Distribution.- 4.1.1 Burden distribution of bell top furnaces.- 4.1.2 Burden distribution of bell-less top furnaces.- 4.2 Flow of Solids in the Upper Part of the Furnace.- 4.2.1 Information from dissected blast furnaces.- 4.2.2 Burden descent model.- 4.2.3 Decrease in angle of layer inclination with burden descent.- 4.2.4 Influence of some other factors.- 4.3 Flow of Solids in the Lower Part of the Furnace.- 4.3.1 Basic phenomena.- 4.3.2 Formation of mixed zone in the peripheral region near the wall.- 4.3.3 Movement of coke to the raceway.- 4.3.4 Movement of coke in dead coke zone and hearth.- 4.4 Theoretical Approach to the Flow of Burden Material in the Furnace.- 4.4.1 Stress distribution in the blast furnace.- 4.4.2 Inclination of the dead coke zone boundary.- 4.4.3 Notation (Sections 4.3 and 4.4).- 4.5 Numerical Simulation of Radial Gas Flow Distribution.- 4.5.1 Burden distribution model.- 4.5.2 Two-dimensional gas flow in the blast furnace.- 4.5.3 Outline of results of calculation.- 4.5.4 Concluding remarks.- 4.5.5 Notation.- 4.6 Flow of Gas and Liquid in the Dropping Zone.- 4.6.1 Counter-current flow region.- 4.6.2 Cross flow region.- 4.6.3 Concluding remarks.- 4.7 Flow of Slag and Metal in the Hearth During Tapping.- 4.7.1 State of coke bed in the hearth.- 4.7.2 Flow of slag during tapping.- 4.7.3 Flow of metal during tapping.- 4.7.4 Mathematical simulation of hearth flow.- 4.7.5 Concluding remarks.- 5 High Temperature Properties of Iron Ore Agglomerates.- 5.1 Reduction Behavior in Lumpy Zone.- 5.1.1 Estimation of reducibility in lumpy zone.- 5.1.2 Determination of reaction rate constant of reduction and comparison with blast furnace operation.- 5.2 Change of Mineral Phases in Blast Furnace.- 5.2.1 Change of mineral phases during reduction.- 5.2.2 Mineral phases in reduced iron ore agglomerates.- 5.2.3 Change of gangue minerals.- 5.3 Flow Resistance of Gas Through the Fused Packed Bed.- 5.3.1 Measurement of pressure drop in fused packed bed.- 5.3.2 Numerical calculation of gas flow resistance through a fused packed bed by use of an orifice model.- 5.3.3 Equation of pressure drop in fused packed bed.- 5.3.4 Quantitative determination of softening properties.- 5.4 Effects of High Temperature Properties of Burden on Blast Furnace Operation.- 5.4.1 Factors for evaluating high temperature properties of burden.- 5.4.2 Relationship between high temperature properties of burden and blast furnace operating performance.- 5.5 High Temperature Properties of Burden with Cohesive Zone Model and Direct Measurement of Cohesive Zone.- 5.5.1 Estimation of cohesive zone with theoretical models.- 5.5.2 Effect of softening properties on gas permeability.- 5.5.3 Evaluation of softening properties of sinter.- 5.5.4 Direct measurement of cohesive zone.- 5.6 Notation.- 6 The Raceway.- 6.1 Measurement and Observation of the Blast Furnace Raceway.- 6.1.1 Movement of coke particles in the raceway.- 6.1.2 Condition near the raceway.- 6.1.3 Reactions in the raceway.- 6.2 Mathematical Model of the Raceway.- 6.2.1 One-dimensional model.- 6.2.2 Two-dimensional model.- 6.3 Notation.- 7 The Lower Region of the Blast Furnace and the Slag-Metal-Gas Reaction.- 7.1 Reaction of Silicon.- 7.1.1 Introduction.- 7.1.2 Behavior of silicon in the blast furnace.- 7.1.3 Kinetics of silicon transfer.- 7.2 Other Reactions.- 7.2.1 Manganese.- 7.2.2 Titanium.- 7.3 Application of Reaction Models of Silicon to Blast Furnace Operation.- 7.3.1 Review of silicon reaction models.- 7.3.2 Partition reactions of Si, S and Mn.- 7.3.3 Mathematical model of silicon reactions in the blast furnace.- 7.4 Notation.- III: Flexibility and Adaptability of Blast Furnace.- 8 Blast Furnace Ironmaking Technology in the Near Future.- 8.1 Flexible Operation.- 8.2 Increase of Furnace Life.- 8.3 Mechanization of Cast-house Operation.- 8.4 Technology Development Related to Innovative Steelmaking Process.- 8.5 Use of Blast Furnace for Producing Other Metals.