Flow of Fine Particles Entrained by Upward Gas Flow in Packed Beds of Coarse Particles.

Hidaka, Nobuyuki; Matsumoto, Tsunekazu; Kusakabe, Katsuki; Morooka, Shigeharu

doi:10.1252/jcej.32.197

Cited by 28 publications

(13 citation statements)

References 12 publications

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“…5,6) However, the result in Fig. 16 shows, on the contrary, that Δp increases more and more with gas velocity than the trend with pure gas.…”

Section: (3)mentioning

confidence: 77%

“…The pressure drop is distinctly large in lower section suggesting higher dynamic holdup in flow channel and this tendency is similar to the previous work. 6) In the period after t = 12-13 min., pressure drop does not show a distinct increase, resulting from that the blower is beyond the capacity as described before, and then the sudden decrease indicates no air supply due to perfect blockage of flow channel by fines. The accumulation of fines was visually observed at a limited region just on the lower flange.…”

Section: Effect Of Particle Diameter Ratio On Permeability Of Fines Flowmentioning

confidence: 99%

“…5) The study with various combination of fine material and packed coarse material indicated also the fines behavior was affected by the surface roughness of coarse material. 6) However, the steady flow defined as fines supplying rate is equal to fines discharging rate from packed bed, was chosen as the subject of those studies. Transient accumulation behavior of coke fines was also studied, 7) but limited to such a system as steady state could be secured.…”

Section: Introductionmentioning

confidence: 99%

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Permeation and Blockage of Fine Particles Transported by Updraft through a Packed Bed

2011

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The fines generated in iron making blast furnace bring about the unsteady or unstable gas/liquid permeability and solid motion. Fundamental experiment was carried out to investigate the inhomogeneous phenomena such as flow channel blockage by fine particles transferred by updraft through a fixed packed bed. The alumina sphere and coke were used for packed bed and fine particles transferred, respectively. Conclusion of this study is as follows. The principal factor controlling a criterion for the blockage is a particle diameter ratio of coke to alumina particle, and fines concentration is not a primary factor. Consideration on a hydraulic equivalent diameter of a regular packing model of spheres is effective to predict the critical diameter ratio and it resulted in good agreement with the experimentally determined. Locally blocked mass, that is, a cluster consisting of coarse alumina particles and fines through which gas is incapable of flowing is dispersed in the bed. The void fraction of packed bed being equivalent to the pressure drop, calculated from Ergun's equation, is considerably small compared with the initial value when the local blockage is in existence. Fraction of the local blockage calculated from the void fraction and static holdup of fines is 15-20% as far as the present experimental condition.

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“…5,6) However, the result in Fig. 16 shows, on the contrary, that Δp increases more and more with gas velocity than the trend with pure gas.…”

Section: (3)mentioning

confidence: 77%

Section: Effect Of Particle Diameter Ratio On Permeability Of Fines Flowmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Permeation and Blockage of Fine Particles Transported by Updraft through a Packed Bed

2011

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“…For this method fundamental flow mechanisms need to be formulated. Powder motion in packed bed had researched by several research groups to clarify traveling velocity of powder, [13][14][15] interaction force between powder and packed particles, [16][17][18][19][20][21] distribution of powder hold up 19,[22][23][24][25] and powder deposition behavior, 26,27) and their results were applied to simulate powder behavior [28][29][30][31] in shaft furnace, blast furnace mid zone, and so on. However, the effects of deadman structure and powder properties on powder and gas flows in the lower part of the blast furnace has yet to be discussed.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on Effects of Deadman Structure and Powder Properties on Gas and Powder Flows in Lower Part of Blast Furnace

et al. 2004

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Fig. 3. Calculated in-furnace distributions of standard condition. fraction of powder in the raceway zone decreases. In the deadman zone, liquid volume fraction decreases with going down because the liquid temperature increases mainly due to heat exchange with solid phase, and liquid viscosity decreases with this temperature rise, that results in higher liquid descending velocity.Regarding to the gas temperature, it shows the maximum around the raceway end zone due to the combustion of coke and pulverized coal. The high temperature region surrounded by 2 473 K isotherm shows almond nut shape. The gas temperature decreases with ascending in the furnace mainly due to heat exchange with solid phase. In the cohesive zone, exchanged heat from gas to solid is consumed as melting latent heat, cooling rate of gas phase gets quicker. In the stack region, central gas flow forms and cone shape temperature distribution is formed. In the wall region, gas temperature increases because increase in gas flow rate due to burden distribution and assumption of adiabatic wall.The evaluation parameters for this standard condition are follows. The penetration of high temperature gas at tuyere level and the maximum penetration are 2.86 and 3.50 m, respectively, and the height of maximum penetration is 3.28 m. Flow ratios of the gas and the powder phases are 45.1 and 72.7 %. The maximum powders volume fraction in the deadman is 0.096 %, and the average liquid temperature at tuyere level is 1 751 K. Effect of Deadman Coke DiameterFigure 4 compares gas temperature distributions calculated for various deadman coke diameter. The coke diameter is decreased from 40 (a) to 15 mm (d). The high temperature region surrounded by 2 473 K isotherm shrinks with decrease in deadman coke diameter. However, deformation of this region is small. This is considered that the deadman voidage for the smallest coke diameter case (15 mm) is still 0.445, and decrease in deadman permeability is small. The deadman cools with decrease in deadman coke diameter. The isotherm of 2 273 K encroached into the deadman region in smaller diameter cases, namely 20 and 15 mm. On the contrary, the deadman coke diameter has small effect on the temperature distribution in the upper half of the furnace is small. In Fig. 4(d), slightly higher temperature region appears in the central bottom region. This temperature increase is caused by numerical instability due to accumulation of powder in central bottom numerical grid. Although this phenomenon is observed in some other cases with low permeable deadman, it is confirmed that its effect on overall calculation results is small. Figure 5 shows the variations of evaluation parameters with deadman coke diameter extracted from calculated distributions of process variables. Both the maximum and tuyere-level penetrations of hot gas into deadman and maximum penetration height monotonically increases with increase in deadman coke diameter in accordance with variation of high-temperature region shape. The maximum volume fraction of powder p...

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“…In order to overcome these deficiencies, various experimen- ISIJ International, Vol. 47 (2007) tal 24,40,[100][101][102][103][104] and numerical 21,38,[40][41][42]96,[105][106][107][108][109] efforts have been made by various investigators in recent years. …”

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confidence: 99%

Modelling of Multiphase Flow in a Blast Furnace: Recent Developments and Future Work

et al. 2007

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An ironmaking blast furnace is a complex multiphase flow reactor involving gas, powder, liquid and solid phases. Understanding the flow behaviour of these phases is of paramount importance to the control and optimization of the process. Mathematical modelling, often coupled with physical modelling, plays an important role in this development. Yagi 1) gave a comprehensive review of the early studies in this area in 1993. Significant progress has since been made, partially driven by the needs in research but mainly as a result of the rapid development of computer and computational technologies. This paper reviews these developments, covering the formulation, validation and application of mathematical models for gas-solid, gas-liquid, gas-powder and multiphase flows. The need for further developments is also discussed.KEY WORDS: ironmaking; blast furnace; multiphase flow; two fluid model; discrete element method. Review development. Mathematical ModellingGenerally speaking, the existing approaches to modelling the multiphase flow in a BF can be classified into two categories: continuum approach at a macroscopic level and discrete approach at a microscopic level. In the continuum approach, phases are generally considered as fully interpenetrating continuum media and described by separate conservation equations with appropriate constitutive relations and interaction terms representing the coupling between phases. The general governing equations are based on the so-called two fluid model (TFM), originally developed for gas-particle flow, [29][30][31] given by:Conservation The so-called Model A and Model B result from the treatment of the fluid pressure. For example, for gas-solid flow, Model A assumes the pressure is shared between the two phases, while in Model B, the pressure is attributed to gas phase only. 31) Model A formulation has been widely used in multiphase modelling, especially in process metallurgy. Model B formulation was recently used in the so called combined continuum and discrete method for coupled flow of continuum fluid and discrete particles. 32) The continuum approach is suitable for process modelling and applied research because of its computational convenience and efficiency. Indeed, most of the BF modelling is based on this approach. However, its effective use heavily depends on constitutive or closure relations and the momentum exchange between phases. For Newtonian fluids (gas and liquid here), these relations can be readily determined. For non-Newtonian fluids such as solids and powder, general theories are not yet available. In the past, various theories have been devised for different flow regimes (three flow regimes have been identified: quasi-static regime, rapid flow regime and a transitional regime that lies inbetween). For example, models have been proposed to derive the constitutive equations for the rate-independent deformation of granular materials based on either the plasticity theory or the double shearing theory; the rapid flow of granular materials has been described by extend...

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Flow of Fine Particles Entrained by Upward Gas Flow in Packed Beds of Coarse Particles.

Cited by 28 publications

References 12 publications

Permeation and Blockage of Fine Particles Transported by Updraft through a Packed Bed

Permeation and Blockage of Fine Particles Transported by Updraft through a Packed Bed

Numerical Investigation on Effects of Deadman Structure and Powder Properties on Gas and Powder Flows in Lower Part of Blast Furnace

Modelling of Multiphase Flow in a Blast Furnace: Recent Developments and Future Work

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