Hold-up of fine particles in the packed dense bed of the multisolid pneumatic transport bed

Fan, Liang‐Shih; Takada, Masayuki; Satija, Sunil

doi:10.1016/0032-5910(83)80014-x

Cited by 25 publications

(10 citation statements)

References 4 publications

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“…The solenoid valve on the air inlet line acts simultaneously with the two shutters. Details of the design of the shutter plates have been given previously (Fan et al, 1983). In all the experiments, the shutters are activated at the point at which the height of the slugging dense bed is a maximum.…”

Section: Methodsmentioning

confidence: 99%

“…Liu et al (1979) used the Battelle cold model unit to investigate the heat-transfer properties, residence time of fine particles, and flow regimes for the dense bed in the MPTB. The holdup of fine particles in the packed bed of coarse particles in the MPTB was studied by Fan et al (1983). They found that the holdup was higher by up to a factor of 6 compared with that observed in pneumatic conveying systems without dense particles.…”

mentioning

confidence: 99%

“…The minimum fluidization velocity of the dense bed in the MPTB was measured by . They found that the minimum fluidization velocity initially increases and then decreases with an increase in the fine particle flow rate due to apparent drag reduction effects at low flow rates of fine particles in the defluidized packed bed of the MPTB (Fan et al, 1985). Satija and Fan (1985a) measured the terminal velocity of the coarse particles in the MPTB and found that the terminal velocity decreases with an increase in fine particle in flow rate.…”

mentioning

confidence: 99%

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Holdup of fine particles in the fluidized dense bed of the multisolid pneumatic transport bed

Kitano¹,

Wisecarver²,

Satija³

et al. 1988

Ind. Eng. Chem. Res.

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The production of NO, N20, and 03 in atmospheric coronas was experimentally investigated using a specially designed plasma reactor operated at a pressure of 0.1 MPa and a temperature of 300 K. The yields of NO, N20, and 03 were found to be (1.4 ± 0.7) X 1016, (1 ± 0.5) X 1017, and (4 ± 2) X 1017 molecules/J, respectively. There was also formation of N02 which was attributed mainly to the rapid reaction between NO and 03. The results from this study confirm the predictions of mathematical simulations of corona chemistry.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Holdup of fine particles in the fluidized dense bed of the multisolid pneumatic transport bed

Kitano¹,

Wisecarver²,

Satija³

et al. 1988

Ind. Eng. Chem. Res.

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“…In the past, various models have been proposed [2][3][4][5][6][7][8] to describe the gas and powder flow in packed beds, where the powder phase is treated as a continuous medium with properties analogous to those of a fluid. However, there is still poor agreement among these published studies of powder hold-up distribution.…”

Section: Introductionmentioning

confidence: 99%

Gas-powder flow in blast furnace with different shapes of cohesive zone

Dong

Pinson

Zhang

et al. 2006

Applied Mathematical Modelling

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With high PCI rate operations, a large quantity of unburned coal/char fines will flow together with the gas into the blast furnace. Under some operating conditions, the holdup of fines results in deterioration of furnace permeability and lower production efficiency. Therefore, it is important to understand the behaviour of powder (unburnt coal/char) inside the blast furnace when operating with different cohesive zone (CZ) shapes. This work is mainly concerned with the effect of cohesive zone shape on the powder flow and accumulation in a blast furnace. A model is presented which is capable of simulating a clear and stable accumulation region in the lower central region of the furnace. The results indicate that powder is likely to accumulate at the lower part of W-shaped CZs and the upper part of V-and inverse V-shaped CZs. For the same CZ shape, a thick cohesive layer can result in a large pressure drop while the resistance of narrow cohesive layers to gas-powder flow is found to be relatively small. Implications of the findings to blast furnace operation are also discussed.

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“…The transport characteristics of gas–solid (fine particles) flow through a bed of coarse particles have been investigated by a number of researchers both experimentally and numerically. ,− Most of these studies focus on the relationship between hydrodynamics (i.e., pressure drop over the bed, gas–solid mass flux) and the physical properties of the fine particles as well as the steady state permeability of the bed under either concurrent or countercurrent granular flow. ,,, In higher flow regime (coarse particles fluidized), Fan et al experimentally investigated the hydrodynamic characteristics ( U mf , U t , fine particle hold-up) of the multisolid turbulent bed (MSTB) system. − Applications of computational fluid dynamic (CFD) methods have advanced the understanding of the mixing behavior of such fully fluidized binary mixture particulates systems. − In the lower flow regime (coarse particles packed), Nemec et al reported that the migration of fine particles is subjected to diffusional resistance from the relative permeability in the packed bed (or “solid-phase friction factor”, i.e., packing density or void fraction of packed bed of coarse particles). , The diffusion rate may depend on the gas phase flow conditions described by the Reynolds number as well as the relative particle properties, such as the particle shape, density, and size. , Other studies ,,,− suggested that the relative particle size, the extent of cluster formation, and the local void fraction of the packed bed are closely related to the migration and transport of fine particles through the packed bed of staggered particles. The mass ratio of coarse to fine particles shall be considered according to Nastui et al, because stagnate fine cluster formation can be observed at the bottom of the packed bed when this ratio is sufficiently low .…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Transport Characteristics of Fluidized Geldart A/B Particles in a Geldart D Packed Bed

Wang

Fan

2016

Ind. Eng. Chem. Res.

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Redox reactions between fine solid fuels, such as pulverized coal powder, and coarse oxygen carrier particles can be carried out in a fixed/moving bed reactor chemical looping system. The migration pattern of the solid fuel powder and its contact time with coarse particles can significantly affect the reaction rate and the product yield. A number of challenges exist in transporting/mixing of fuel powder and in removing noncombustible waste (e.g., coal ash) from the reactor vessel in the chemical looping operation. Thus, it is important to understand the hydrodynamic behaviors of fine particles in such situations. This study describes an experimental approach that examines migration characteristics of fine particles (Geldart A/B), in both spatial and temporal aspects, in a packed bed of coarse particles (Geldart D). The experimental variables include the particle size distribution of the fine powder, the fine to coarse mass ratio, and flow conditions. At a given upward aeration flow within the range that is higher than the terminal velocity of the fine particles but lower than the minimum fluidization velocity of coarse particles (U t < U s < U mf,c), the fine particles may travel both upward and downward depending on the gas flow rate and the physical properties of particles and gas. The spatial transport pattern in terms of the upward and static transport partition (wt %) of Geldart A particles can be characterized as an exponential function of a group of dimensionless numbers (e.g., Stk*, Re p* and U s/U t). The time-dependent upward transport rate of fine particles is measured to determine the temporal migration characteristics. Cluster response time (τc) is introduced to describe how fast a cluster of fine particles in a packed bed respond to the ambient flow. This parameter is normalized by the response time of fine particle (τp) and further correlated with the pseudo-particle Reynolds number (Re p*) via an inverse power function with two coefficients.

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Hold-up of fine particles in the packed dense bed of the multisolid pneumatic transport bed

Cited by 25 publications

References 4 publications

Holdup of fine particles in the fluidized dense bed of the multisolid pneumatic transport bed

Holdup of fine particles in the fluidized dense bed of the multisolid pneumatic transport bed

Gas-powder flow in blast furnace with different shapes of cohesive zone

Experimental Investigation on Transport Characteristics of Fluidized Geldart A/B Particles in a Geldart D Packed Bed

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