Thermal Conductivity of Gas Mixtures

Lindsay, Alexander L.; Bromley, LeRoy A.

doi:10.1021/ie50488a017

Cited by 327 publications

(95 citation statements)

References 4 publications

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“…The reducing gas is introduced through the circumferentially distributed inlets and discharged from the top, and its properties, such as viscosity, thermal conductivity, are calculated based on the previous researchers' works. [30][31][32][33][34][35] On the other hand, charged from the top, the burden solid gradually descends to the bottom, where a man-made deadman is established to facilitate the discharge of direct reduced iron (DRI) located in the central region. The average diameter of the solid particle is 15.4 mm and the voidage of the moving bed is fixed as 0.4 according to the measurement in the laboratory experiments.…”

Section: Model Formulationmentioning

confidence: 99%

Numerical Analysis of the Characteristics Inside Pre-reduction Shaft Furnace and Its Operation Parameters Optimization by Using a Three-Dimensional Full Scale Mathematical Model

Kou

et al. 2013

ISIJ Int.

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Numerical simulation is considered to be an important method to study the inner characteristics of metallurgical processes, thus providing effective strategies for practical smooth operations. A three-dimensional full scale mathematical model considering mass, momentum, energy transfers and chemical reactions under steady state is developed in the present work to describe the characteristics inside the pre-reduction shaft furnace of COREX smelting reduction ironmaking process. The uneven gas and solid flow distributions in both radial and axial directions not only restrain the gas utilization but also cause the difference in the solid metallization between the center and near wall to reach as high as 0.4. Predicted by the established model, the CO-CO2-H2-H2O reducing gas with the temperature 1 050-1 100 K, the volume fraction of CO+CO2 around 70%, the ratio of CO to CO2 5-7, as low as possible H2O content, and the reasonably matched burden solid charging rate to control the top gas consumption per ton burden solid (TGC) in the range of 800-1 000 Nm 3 /t, are the optimal operation conditions to further improve furnace efficiency.

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Section: Model Formulationmentioning

confidence: 99%

Numerical Analysis of the Characteristics Inside Pre-reduction Shaft Furnace and Its Operation Parameters Optimization by Using a Three-Dimensional Full Scale Mathematical Model

Kou

et al. 2013

ISIJ Int.

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“…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.…”

Section: Phase Propertiesmentioning

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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“…Heidenreich (1994) presented another model for condensational growth. The author used the Lindsay-Bromley correlation (Lindsay and Bromley 1950) to calculate the temperature and composition dependencies of the thermal conductivity of the gas mixture and also accounted for the thermal diffusion and the Dufour effect. Temperature dependence of the diffusion coefficient was neglected in that study.…”

Section: Resultsmentioning

confidence: 99%

Evaporation and Condensational Growth of Liquid Droplets in Nonisothermal Gas Mixtures

Nadykto¹,

Shchukin²,

Kulmala

et al. 2003

Aerosol Science and Technology

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A theoretical study and coupled analytical model of the growth rates of a droplet in a nonisothermal gas mixture are presented. The derived model explicitly accounts for the influence of the properties of the gaseous media on the transport processes in an aerodisperse system. The Stefan flux as well as temperature and composition dependencies of the transport coefficients are accounted for simultaneously, still resulting in a convenient analytical expression. Such an expression is especially useful to use in a numerical GDE solution routine, in which much time cannot be spent in the individual physical processes. The results of previous studies are compared to our model predictions. Numerical calculations are performed for a wide range of saturation ratios for the water droplet-humid air system and compared with experimental data. The presented new model is an improvement on the existing ones, especially in cases in which the mass transfer rates are large, resulting in a nonuniform temperature field.

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Thermal Conductivity of Gas Mixtures

Cited by 327 publications

References 4 publications

Numerical Analysis of the Characteristics Inside Pre-reduction Shaft Furnace and Its Operation Parameters Optimization by Using a Three-Dimensional Full Scale Mathematical Model

Numerical Analysis of the Characteristics Inside Pre-reduction Shaft Furnace and Its Operation Parameters Optimization by Using a Three-Dimensional Full Scale Mathematical Model

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

Evaporation and Condensational Growth of Liquid Droplets in Nonisothermal Gas Mixtures

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