KONA Powder and Particle Journal
Online ISSN : 2187-5537
Print ISSN : 0288-4534
Volume 4
Showing 1-21 articles out of 21 articles from the selected issue
Front Cover
Explanation of the Cover Photograph
Message from the Editor
Original Report
  • Michitaka Suzuki, Toshio Oshima, Hisaki Ichiba, Isamu Hasegawa
    1986 Volume 4 Pages 4-12
    Published: 1986
    Released: June 30, 2014
    JOURNALS FREE ACCESS
    Experimental measurements and computer simulation are reported on the void fraction of multi-component randomly packed beds with log-normal, log-uniform, Rosin-Rammler or Andreasen (Gaudin-Schuhmann) size distributions. Packing experiments were done by two methods, i.e. prodding and tapping. Glass beads (spherical particles) and crushed glass (irregularly shaped particles) were used for these experiments.
    The following results were obtained from the experiments and the simulations. A minimum void fraction of a packed bed with Andreasen distribution exists in the range of Fuller constant q = 0.5-0.8, and the void fractions of packed beds with the other three distributions decrease as the size distribution spreads.
    The experimental and the simulated results for void fraction were compared with values calculated by our model and agreement between them was fairly good. This model is useful for estimating the void fraction in a multi-component randomly packed bed of spherical and irregularly shaped particles with size distribution.

    This report was originally printed in KAGAKU KOGAKU RONBUNSHU, 11(4), 438-443 (1985) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Chemical Engineers, Japan.
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  • Kanji Matsumoto, Akira Suganuma, Ryuichi Aoki
    1986 Volume 4 Pages 13-22
    Published: 1986
    Released: June 30, 2014
    JOURNALS FREE ACCESS
    The following results were experimentally obtained by analyzing the packing and stress conditions of CaCO3 (P-30) powder filled through a sieve into a shallow and a deep bin of low and high powder-bed height to bin diameter ratio, respectively: 1) The ratio of horizontal stress to vertical stress in the powder at the bin wall increased linearly with decreasing porosity in both cases. 2) The relationship between the logarithm of mean consolidation stress and the void ratio was linear in both cases. 3) In the shallow bin the vertical stresses in the radial direction were observed to be almost uniform. Hence the stress condition in the powder was well expressed by Janssen's equation, evaluated using the coefficient of wall friction measured by a direct shear tester. 4) The Mohr circles which represented the stress conditions of the powder at the bin wall were not tangent to the effective yield locus, but approximately tangent to the wall yield locus. 5) The static state of the powder in the deep bin could be roughly estimated by using the results obtained in the shallow bin.

    This report was originally printed in KAGAKU KOGAKU RONBUNSHU, 10(6), 667-674 (1984) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Chemical Engineers, Japan.
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  • Jusuke Hidaka, Yutaka Kirimoto, Shigeo Miwa, Kazutaka Makino
    1986 Volume 4 Pages 23-34
    Published: 1986
    Released: June 30, 2014
    JOURNALS FREE ACCESS
    The stress-strain relation in the deformation and flow of granular materials is generally discontinuous. The discontinuous behaviour is one of the fundamental properties of granular materials. The mechanism of discontinuous behaviour in the flow of granular materials is investigated by the penetration of a circular plate into a powder bed. The penetration characteristic curve (load-displacement curve) of a dense powder bed shows a step-wise curve. The load required to penetrate a circular plate into the powder bed is in satisfactory agreement with the values calculated from Meyerhof's equation. The plasticity pattern formed by the penetration of a plunger into the powder layer is observed by an X-ray radiograph. It is shown that discontinuous behaviour results in successive or periodical shear yields which occurred in the powder bed. The generating mechanism of intermittent or periodical shear yields is theoretically discussed, and the relationship between the periodicity of intermittent shear yields and the frictional property of the powder bed is experimentally confirmed. The static and dynamic angles of the internal friction of powders can be measured by the penetration test.

    This report was originally printed in J. Soc. Powder Technology, Japan, 22(7), 427-435 (1985) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Powder Technology, Japan.
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  • Keijiro Terashita, Kei Miyanami, Takanobu Konishi, Kazuo Furubayashi
    1986 Volume 4 Pages 35-45
    Published: 1986
    Released: June 30, 2014
    JOURNALS FREE ACCESS
    Flowability assessment of dry and wet fine coals has been attempted on the basis of their dynamic properties such as internal friction factor, shearing cohesiveness and tensile strength. The dynamic parameters have been determined by using a constant load direct shearing tester and a hanging-type split-cell cohesiveness tester. Several kinds of coals with different water contents have been used.
    The flowability of brown coal is highest with low values of the internal friction factor, shearing cohesiveness and tensile strength. The ranking of flowability is in order of bituminous coal and semi-bituminous coal. The flowability of anthracite is high. The flowability of fly ash is higher when compared to fine coals but it is easily influenced by a slight change in the water content.
    The flowability of wet fine coals can be better evaluated by the tensile strength and shearing cohesiveness rather than by the internal friction factor. The tensile strength of wet fine coals shows a maximum when a comixture of funicular and capillary zones is formed. The flowability of wet fine coals is controlled by water adsorbed onto the surface of coal particles.

    This report was originally printed in J. Soc. Materials Science, Japan, 33(372), 1130-1134 (1984) and 34(386), 1249-1254 (1985) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Materials Science, Japan.
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  • Hidehiro Kamiya, Jun-ichiro Tsubaki, Genji Jimbo
    1986 Volume 4 Pages 46-53
    Published: 1986
    Released: June 30, 2014
    JOURNALS FREE ACCESS
    To study more quantitatively the fatigue failure phenomenon of powder beds, which was earlier discovered and reported by a part of the authors, this study was an attempt to obtain the relation between repeated tensile stress and fatigue life, which is usually represented by S-N relation, in a wide range of the repeating number N. Experiments were carried out by using vibration to exert dynamic repeated tensile load on the powder bed, with a vertically vibrating cell and a horizontally splitting cell. The frequency of vibration used was in the region of 5–300 Hz, and Kanto loam powder (JIS-11), fused alumina powder and lactose powder were used as samples.
    The results obtained are analyzed statistically and quantitatively concerning the distribution of fatigue failure life.
    It is found that within the limited range of the number of repeated stress less than 106, the existence of a lower limit of tensile stress (endurance limit) where the powder bed fails is confirmed at a stress ratio of the order of 0.7. The distribution of fatigue life is expressed by a Weibull distribution, and then it is shown quantitatively that the distribution of fatigue life of the powder bed is wide compared with other kinds of material, and it is suggested that the S-N relation of the powder bed obtained previously can be divided into two ranges, a sloping part and a horizontal part.

    This report was originally printed in KAGAKU KOGAKU RONBUNSHU, 11(2), 186-192 (1985) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Chemical Engineers, Japan.
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  • Torajiro Honma, Masafumi Kuriyama, Yoshiteru Kanda, Masahiro Hasegawa
    1986 Volume 4 Pages 54-60
    Published: 1986
    Released: June 30, 2014
    JOURNALS FREE ACCESS
    Measurements of specific surface area of product were made on a new type of ball mill operated under centrifugal force. The results indicated that this type of mill was superior in grinding performance to the conventional ball mill operated under gravitational force and that the use of centrifugal force was effective in reducing the grinding time.
    An empirical equation was proposed for expressing the increase of specific surface area of product by the introduction of a non-dimensional parameter to evaluate the effect of centrifugal force. This equation was found to express well the grinding process under gravitational force as well as that under centrifugal force.

    This report was originally printed in KAGAKU KOGAKU RONBUNSHU, 11(3), 311-316 (1985) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Powder Technology, Japan.
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  • Eiichi Abe, Hideharu Hirosue, Hiroshi Kikuchi
    1986 Volume 4 Pages 61-72
    Published: 1986
    Released: June 30, 2014
    JOURNALS FREE ACCESS
    Coating seed particles of 53 to 210 µm with clayey particles was carried out by means of a tumbling fluidized bed in order to enlarge and reuse the clayey particles wasted in producing a carrier for driftless dust formulation. The influence of operating factors on the coating efficiency η and on the growth rate of seed particles was investigated. η varied depending upon thermal operating factors but was not influenced much by mechanical ones. It was found that η was related roughly to RW defined as the ratio of the feed rate of water fed as slurry droplets to the maximum theoretical evaporation rate of water in a coating chamber. η increased with RW. The relationship between η and RW varied with the additive ratio of binder PVA to clayey particles, Cb, and η became high with increasing Cb. The growth rate of seed particles was explained well by an equation derived on the basis of the mass balance of clayey particles in a coating chamber.

    This report was originally printed in J. Soc. Powder Technology, Japan, 22(5), 278-287 (1985) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Powder Technology, Japan.
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  • Ken Okazaki, Takashi Nishikawa, Kazutomo Ohtake
    1986 Volume 4 Pages 73-81
    Published: 1986
    Released: June 30, 2014
    JOURNALS FREE ACCESS
    Physicochemical properties of ash particles and their effects on the collection characteristics of electrostatic precipitator in the pulverized coal combustion system were investigated, focusing on enrichment processes of sulfur on the particle surface. An experimental system composed of one-dimensional laminar flow furnace, cyclone, bag-filter and electrostatic precipitator was used to derive the mutual relations among coal properties, combustion conditions and characteristics of ash particles collected in each device. The following conclusions were obtained.
    1) Chemical properties on the particle surface are affected not only by the shape and surface structure of particles but also by particle size, temperature history and coal properties.
    2) Soot particulates attached to the small ash particles enhances the enrichment of sulfur on them, and this effect depends on coal properties and combustion conditions.
    3) Collection characteristics of ash particles in the electrostatic precipitator largely depend on the enrichment behavior of sulfur in it for the case of high sulfur coal.

    This report was originally printed in KAGAKU KOGAKU RONBUNSHU, 10(6), 751-757 (1984) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Chemical Engineers, Japan.
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  • Noriyoshi Kaya, Tohei Yokoyama, Masafumi Arakawa, Naohiko Yazawa
    1986 Volume 4 Pages 82-88
    Published: 1986
    Released: June 30, 2014
    JOURNALS FREE ACCESS
    For the purpose of determination of particle size distribution in the submicron range, a new apparatus has been developed on a basis of the principle of the balancing machine.
    The change of balancing moment caused by the centrifugal sedimentation of the particles is detected with the sensors attached onto the rotor shaft and analyzed with personal computer, which gives particle size distributions according to the calculation proposed by one of the authors previously.
    One of the advantages of this method is that the measurement by this method do not depend on the physical properties such as optical extinction coefficient, electric conductivity and so forth. It is also possible to determine the size distribution of the particles in a suspension of much higher concentration by this method than other ones. Furthermore, it is not necessary for the settling time of the particle to reach the detecting zone because the analysis by this method monitors the unbalance caused from the settling particles positioned in the whole suspension.

    This report was originally printed in J. Soc. Powder Technology, Japan, 21(12), 768-773 (1984) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Powder Technology, Japan.
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  • Shigeru Matsumoto, Hiromi Harakawa, Mutsumi Suzuki, Shigemori Ohtani
    1986 Volume 4 Pages 89-97
    Published: 1986
    Released: June 30, 2014
    JOURNALS FREE ACCESS
    The control characteristics of the solid flow rate are investigated for a pilot scale pneumatic conveyer. The experimental system is a pressure-type vertical conveyer consisting of a 20 mm-I.D. and 5.6 m long transport line. Under a constant air flow rate, the solid flow rate was controlled by manipulating a vibrating feeder based on the feedback of the output signal from the hand-made impact flow-meter which was set downstream of the gas-solid separator. The control system was implemented on a personal computer. Since the output signals of the impact flow-meter contained significant amounts of random noise, the Kalman filter was applied as the observer. The controller was designed based on the discrete I-PD control formula. The formula is a kind of partial model matching method developed by Kitamori. Satisfactory control performance was achieved both as a regulator and as a servo-mechanism for the pilot plant.

    This report was originally printed in J. Soc. Powder Technology, Japan, 22(1), 3-10 (1985) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Powder Technology, Japan.
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