Intraparticle Temperature of Iron-Oxide Pellet during the Reduction

Hara, Yukiaki; Tsuchiya, Masaru; Kondo, Shinichi

doi:10.2355/tetsutohagane1955.60.9_1261

Cited by 44 publications

(31 citation statements)

References 5 publications

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“…The three-interface unreacted core model 10,27) is applied to obtain the chemical reaction rate R n with the expressions of equilibrium constant, reaction rate constant and effective diffusivity from Takahashi's work. 28,29) Meanwhile, given the model not considering solid phase composition in the corresponding expressions, the judgment of local species' mass fraction is necessarily established when creating the mathematical model.…”

Section: Mass Transfermentioning

confidence: 99%

Basic Characteristics of the Shaft Furnace of COREX® Smelting Reduction Process Based on Iron Oxides Reduction Simulation

Yang

et al. 2010

ISIJ Int.

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A two-dimensional mathematical model is developed to describe iron oxides reduction in the shaft furnace of COREX ® smelting reduction process. Combined with mass, momentum and heat transfers between gas and solid phases in steady state, the model calculates and demonstrates the basic characteristics of the shaft furnace, such as velocity, pressure, temperature fields of relevant phases and species' mass fraction distributions. The reduction from magnetite to wustite occupies most part of the furnace, and the reduction degree of burden located near wall is comparatively higher than that close to centre. The model also considers the influence of down pipe gas, driven by the pressure drop between the shaft furnace and melter gasifier, on the reduction behaviors inside furnace. Compared with the base case, the down pipe gas featuring higher temperature prefers to flow toward the symmetry axis, where both gas temperature and solid metallization are promoted remarkably.KEY WORDS: shaft furnace; mathematical model; iron oxides reduction; down pipe gas.The assumptions in the two-dimensional, axisymmetric mathematical model are given as below:(1) The volume fraction of gas in the packed column is set as constant 18) ; (2) Ignoring the wall effect as the gas flows near the wall; (3) The solid flow velocity is uniformly distributed in both radial and axial directions; (4) The solid particle diameter and shape factor always keep constant; (5) The flux decomposition reactions, non-iron oxides reduction reactions and other reactions are not considered in the basic model. Conservation EquationsThe fundamental conservation equations of continuity, momentum, energy and species transport for steady state could be described by Eq. (3). 19) .......... (3) The variable f, dependant diffusive term G f and source term S f all varies with different kinds of conservation equations as summarized in Table 1. Phase PropertiesAccording to the ideal gas equation, the density of gas phase is a function of local temperature and pressure. The viscosities and thermal conductivities of species in gas phase are obtained by Sutherland's law 20,21) and the modified Eucken equation 22,23) respectively with the relevant data from Eckert and Drake's work.24) Based on each specie's viscosity or thermal conductivity and mole fraction, both the gas mixture viscosity or thermal conductivity could be derived from Eq. (4), which is in accordance with Wilke's work. where, V represents viscosity or thermal conductivity;As for solid phase including lump ore and pellet, the average apparent density and particle diameter are measured by experiment with the results as 4 190 kg/m 3 and 0.154 m respectively. The solid viscosity is 6 kg/m · s and its thermal conductivity is 0.8 W/m · K. 10)All species' thermodynamics data, such as heat capacity, enthalpy and entropy, are all from Perry's book, 26) and the gas or solid phase thermodynamic data are computed based on a simple mass fraction average of the species' if needed. Mass TransferDue to iron oxides multi-stage s...

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Section: Mass Transfermentioning

confidence: 99%

Basic Characteristics of the Shaft Furnace of COREX® Smelting Reduction Process Based on Iron Oxides Reduction Simulation

Yang

et al. 2010

ISIJ Int.

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“…Here, C COb , C CO(0) : CO gas concentrations in the bulk gas and at the surface of the sample particle, [12][13][14]17) Relationships among the rates shown above can be derived by seeing Table 1 and the conceptual figure for the present unreacted-core shrinking model for six interfaces, given in Ref. 18).…”

Section: Diffusion Process In a Gas Filmmentioning

confidence: 99%

“…10) interfaces, the rate equation for each process given below can be written by making reference to the previously reported unreacted-core shrinking model for three interfaces, [12][13][14]17) as follows:…”

Section: Formulation Of Layers and Rate Parametersmentioning

confidence: 99%

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Gaseous Reduction Model for Sinter in Consideration of Calcium Ferrite Reaction Process (Unreacted-core Shrinking Model for Six Interfaces)

et al. 2015

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“…Both gas and solid phases considered in present work are 33) while the water gas shift reaction rate is considered with rate equations and rate constants determined by Takahashi et al. 34) Momentum source is derived from gas-solid drag determined by Ergun's equation and energy source is derived from heat exchange between gas and solid phase determined by Ranz-Marshall equation and enthalpy change accompanying chemical reactions.…”

Section: Model Formulationmentioning

confidence: 99%

Prediction of Pre-reduction Shaft Furnace with Top Gas Recycling Technology Aiming to Cut Down CO2 Emission

Yagi

et al. 2011

ISIJ Int.

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Top gas recycling is considered as one of the highest potential technologies to improve reduction efficiency and correspondingly to reduce carbon consumption. As a typical nitrogen free ironmaking process, pre-reduction shaft furnace of COREX ® process (COREX ® shaft furnace) for short is suitable to adopt the technology aiming to cut down CO2 emission. Under the premise of constant total injection volume, three kinds of reducing gas injection methods are numerically studied by employing a two-dimensional mathematical model. The method that 20% of total reducing gas in volume fraction is blasted through normal inlet (NI) while the rest through down pipe inlet (PI) rather than deadman inlet (DI) could apparently improve gas flow in the inactive zone located near the bottom direct reduced iron (DRI) outlet, thus increasing DRI reduction degree to 61% under present calculation conditions. Meanwhile, either decreasing the vertical height of PI or increasing its diameter makes further improvement on furnace efficiency. After adopting top gas recycling to the shaft furnace by NI+PI method with optimal parameters, CO utilization ratio reaches above 46% when DRI reduction degree correspondingly increases by 12%, what's more, CO2 emission from the whole process is reduced by about 540 Nm 3 /tHM. The results prove that top gas recycling technology promotes reduction efficiency inside shaft furnace and greatly reduces the greenhouse gas emission, which will contribute to suppressing global warming.

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Intraparticle Temperature of Iron-Oxide Pellet during the Reduction

Cited by 44 publications

References 5 publications

Basic Characteristics of the Shaft Furnace of COREX® Smelting Reduction Process Based on Iron Oxides Reduction Simulation

Basic Characteristics of the Shaft Furnace of COREX® Smelting Reduction Process Based on Iron Oxides Reduction Simulation

Gaseous Reduction Model for Sinter in Consideration of Calcium Ferrite Reaction Process (Unreacted-core Shrinking Model for Six Interfaces)

Prediction of Pre-reduction Shaft Furnace with Top Gas Recycling Technology Aiming to Cut Down CO2 Emission

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