KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 5 , Issue 4
Showing 1-17 articles out of 17 articles from the selected issue
  • Takeichiro Takamatsu, Kenji Kawachi, Fuminao Watanabe
    1979 Volume 5 Issue 4 Pages 327-334
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    In this paper a method for designing a decoupled controlled system with regulators to maintain constant terminal compositions in a binary distillation column is proposed. In particular, it is found that good decoupling control can be obtained by this proposed method even if the system parameters that affect decoupling control should change. In this method the remaining freedom of pole assignment is used to make the control system insensitive to parameter changes and the values of the determinable poles are selected to be smaller than the dominant poles.
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  • Masunori Sugimoto, Kenichi Yamamoto
    1979 Volume 5 Issue 4 Pages 335-340
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    To investigate the axial mixing and segregation of a binary solid mixture in a horizontal rotating conical vessel, concentration profiles of the mixture along the axis of the vessel were observed by using alumina sphere/silica sand mixture under various initial loading conditions and speeds of rotation ranging from 10 to 30 rpm, below the critical speed ratio =0.35.
    Three patterns of axial mixing and segregation of a binary solid mixture in a rotating conical vessel were obtained. These patterns were given by the relationships between the initial and final arrangements of the mixture along the axis of the vessel. Mixing and segregation could be estimated by Rose's equations with a modification of demixing potential on the basis of the axial arrangements of the mixture at a state of equilibrium. The demixing potential φ could be represented by concentration profiles of the mixture along the axis of the vessel. It was found that scale of segregation and axial arrangement of mixture as a segregation profile could be determined by measuring CA-profile in a vessel.
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  • Fumikazu Ikazaki, Shigeki Toyama, Kazutaka Makino, Koichi Iinoya
    1979 Volume 5 Issue 4 Pages 341-347
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Adhesion force of a dust layer in an electric field similar to that in an electrostatic precipitator is theoretically and experimentally studied.
    Talc and calcium carbonate are used as the test powder. Electric adhesion force of the dust layer is measured by an improved tensile test device. The electric adhesion force increases almost linearly with increase of applied electric field and also depends significantly on the void ratio of the dust layer, though it increases quadratically with field strength in the case of a homogeneous pure dielectric.
    McLean's model of the adhesion force in an electric field is improved by use of the void fraction. The modified model is found to be in good agreement with the experimental results.
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  • Kenichi Ushiki, Hideo Kato, Shigeo Takahashi, Koichi Iinoya
    1979 Volume 5 Issue 4 Pages 348-355
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    This paper presents a study of the performance of louver-type mist separators of which the blades are set on the slant to air flow. Particle collection efficiencies and pressure losses of two kinds of blade type, i.e. flat and V-shape blades are experimentally obtained under the conditions of 0% and 10% blow-down flow.
    1) The collection efficiency of droplets is much higher than that of solid particles. For example, the solid particle collection efficiency is 80%, and the efficiency of droplets is nearly 100%, when the inertial parameter value equals 1 with 10% blow-down flow.
    2) Without blow-down flow, collection efficiency of a V-shape blade is much higher than that of a flat blade. For example, the former is about twice the latter, when the latter is 40%, even though pressure loss of the V-shape blade is only three-fourths that of the flat blade.
    3) There is little difference in efficiency between V-shape and flat blades under the condition of 10% blow-down flow as in the case of solid particles. Partial collection efficiency of the flat blade with 10% blow-down is much higher than that without blow-down. On the contrary, blow-down flow rate has no effect on the partial collection efficiency of the V-shape blade.
    Partial collection efficiencies are estimated by numerical calculation of particle trajectory on the assumption of potential flow model outside the experimentally obtained wake. This is effective in predicting the 50% collection droplet size. The theoretical curve does not completely fit the experimental one, but a modified calculation with turbulent mixing effect is in good agreement with experimental values.
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  • Katsunori Okaya, Akira Suganuma, Daizo Kunii
    1979 Volume 5 Issue 4 Pages 356-360
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The influence of the dispersion level of fine powder on the efficiency of classification was studied using a cyclone air classifier and several dispersing orifices. Agglomerated fine powder was dispersed by a high-speed air stream through an orifice, and the dispersed particles were classified by a cyclone air classifier. The range of orifice diameter was 630 mmΦ and that of air velocity was 10230 m/sec.
    By using a dispersing orifice before the classifier, the yield of fine particles was increased. The higher the air velocity, the higher was the yield. It was concluded that the high-speed air stream through an orifice disperses agglomerated particles and improves the classification efficiency.
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  • Hideki Tsuge, Shin-ichi Hibino
    1979 Volume 5 Issue 4 Pages 361-365
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The effect of column diameter on the volume of bubble formed from a submerged single orifice in the presence of pressure fluctuations in the gas chamber is investigated experimentally and it is found that the wall effect on bubble volume depends on gas chamber volume. By considering the inertia of liquid caused by the upward movement of liquid, the two-stage model of bubble formation accompanied by pressure fluctuations in the gas chamber proposed by the authors is extended to the model of bubble formation with wall effect. The calculated bubble volume by this extended model coincide qualitatively well with the experimental results.
    It is clarified that the smaller the column diameter, the more markedly is bubble volume influenced by liquid height.
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  • Tsutao Otake, Setsuji Tone, Ryoichi Kuboi, Yasuo Takahashi, Katsumi Na ...
    1979 Volume 5 Issue 4 Pages 366-373
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    An experimental study was performed on the flow regimes for gas-liquid flow in a throat, dispersed bubble size and gas hold-up for the bubble column employing an ejector as a gas distributor. The flow regimes in the throat are classified into four regions (slug flow, annular flow, bubble flow and jet flow) and the flow regime map is presented by plotting the ratio of gas to liquid flow rate, G/L against the Froude number based on the liquid velocity through the throat uLT, Fr (=uLT2/gDT). Dependencies of bubble size distribution, gas hold-up, εG, and volume surface mean bubble diameter, dBυs, on Fr and G/L markedly change near the critical Froude number Frc. In the slug and annular flow regions, Fr≤Frc, bubble size distribution is broad and its standard deviation increases with increasing G/L and εG nearly equals the gas hold-up in the bubble column at the same gas flow rate, εG0. In the bubble and jet flow regions, Fr> Frc, small bubbles of 14 mm in diameter are uniformly dispersed in the column, and εG increases and dBvs decreases with increasing Fr and/or decreasing ratio of nozzle-to-throat diameter, DN/DT. The mean bubble diameter and the gas hold-up for each region classified above are correlated with Fr, G/L and DN/DT.
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  • Yoshitaro Yamamoto, Katsumi Nakagawa
    1979 Volume 5 Issue 4 Pages 374-379
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The natural frequency of a bubble for the measurement of bubble size in liquids was studied experimentally. The bubble began to pulsate at the moment of release at the end of the terminal nozzle or orifice. The sound wave was caught by hydrophone and its natural frequency was obtained. After the sound wave was already damped out, the natural frequency of the rising bubble in liquid was measured with the response for a sinusoidal impulse by a speaker. The measurements were carried out over the bubble size range 0.16 to 1.56 cm and over 3 octaves frequency range. Experimental relations between the natural frequency and the bubble equivalent diameter satisfied the Minnaert equation in our experimental range. It was shown especially that the impulse method was effective for determining the equivalent diameter of a bubble rising in liquid.
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  • Masayuki Sato, Masao Kuroda, Takeshi Sakai
    1979 Volume 5 Issue 4 Pages 380-384
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    An experimental investigation of the formation of gas bubbles issuing from a single orifice in distilled water is carried out under high potential applied between the nozzle and the earth ring.
    From observation of the states of bubble formation with increasing potentials, the disintegration pattern of bubbles is classified into five regions. Region (I, II) : At a lower potential and larger nozzle diameter and gas flow rate, a single bubble is produced periodically, and bubble size decreases with increasing potential to the extent of about 2/3 of the diameter at zero potential. (III) : With increasing potential, bubbles are dispersed in a cone shape. (IV) : Many small bubbles of about 0.5 mm diameter are produced as if they are spouting from the nozzle tip with decreasing nozzle diameter and gas flow rate. (V) : When suitable conditions are satisfied, very small bubble crowds are obtained i.e. cloudy bubbles having a nearly uniform diameter of about 85μm.
    It is suggested that the bubble sizes can be controlled over a wide range by application of high potentials between the nozzle and the earth ring.
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  • Harumi Matsuzaki, Osamu Kuroda, Sankichi Takahashi
    1979 Volume 5 Issue 4 Pages 385-390
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The authors have developed a new type electrodialyzer with gas-liquid mixture flowing along the surface of the ion-exchange membrane.
    In this paper, the effect of bubble turbulence on concentration polarization is studied.
    Experiments were carried out in 3 different cases, using an electrodialyzer with sheet flow, liquid flow with spacer, and gas-liquid mixture flows.
    The results are analysed using the equation of electric resistance between electrodes. It is clarified that bubble turbulence is effective in decreasing concentration polarization. For example, limiting current density, ic, under the effect of bubble turbulence is twice as much as in the case of so-called sheet flow type. And the optimum operating condition of the new electrodialyzer is obtained. Also the relation between ic and diffusion layer thickness obtained by the equation agreed with the data in the literature.
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  • Kenzo Takahashi, Hideaki Kusakawa, Osamu Tanaka
    1979 Volume 5 Issue 4 Pages 391-396
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Equations were proposed for estimation of average tortuosity factor, radius of capillary and number of capillaries of porous fiber materials by using a bundle model of tortuous capillaries.
    Average tortuosity factor, radius of capillary and number of capillaries of papers and membrane filters were estimated with proposed equations.
    Furthermore, in the case of polymer-impregnated papers, an equation was proposed for estimation of vapor permeability coefficient by introducing effective number of capillaries, and observed water vapor permeability coefficients through polymer-impregnated papers were compared with estimated values.
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  • Isamu Tanaka, Toshifumi Ishikura, Akira Uchiyama, Hisashi Shinohara
    1979 Volume 5 Issue 4 Pages 397-403
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The conditions for stable fluidization of continuously operated, multi-stage fluidized beds were studied.
    The performance in each stage of the multi-stage fluidized bed was found to be not markedly different from that of a single-stage fluidized bed in the region of stable fluidization.
    An empirical dimensionless equation for the relations among the geometry of the perforated plate, the properties of fluidized particles and the operating conditions is proposed for this region.
    It was found that the particles were discharged intermittently from a hole in the distributor, that the mass and frequency of discharge were inversely proportional to the superficial gas velocity, and that the former was proportional to the hold-up of particles within the bed.
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  • Kunio Kato, Kiyomi Amada
    1979 Volume 5 Issue 4 Pages 404-409
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The reaction characteristics (conversion of reactant gas and yield of intermediate product) of simultaneous successive first-order reactions are analyzed by the two-phase model introduced in a previous paper for the case where these reactions take place in a packed fluidized-bed reactor under several operating conditions.
    These reaction characteristics are influenced by the reaction rate constants of each reaction, the ratio of each reaction rate constant, fraction of catalyst in the bubble phase and the ratio of superficial gas velocity to minimum fluidized gas velocity.
    The following results are obtained. When the reaction rate constants of each reaction decrease and when the fraction of catalyst in the bubble phase and the ratio of superficial gas velocity to minimum fluidized gas velocity increase under constant average residence time of reactant gas, conversion of reactant gas and yield of intermediate product increase and are almost the same as those for an ideal plug flow reactor.
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  • Yukimichi Okamoto, Masabumi Nishikawa, Kenji Hashimoto
    1979 Volume 5 Issue 4 Pages 410-415
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Local dissipation rates were calculated in a corrected way from the data of turbulence energy spectrum measurements to obtain dissipation rate distributions.
    For both baffled and unbaffled agitation, dissipation rates showed a wide variation in the vessel space up to several tenfold, with a space-mean value nearly equal to the power input per unit mass. Under geometrically similar conditions of the vessels, these rates tended to change proportionally to the power per mass so that the distribution pattern should be kept unchanged.
    The effects of dissipation rate distributions on liquid-liquid and solid-liquid agitation were examined quantitatively. The influence of impeller dimensions on droplet size and solid-liquid mass transfer shown in the literature was explicable based on the change of distribution.
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  • Shuji Sakohara, Hajime Unno, Takashi Akehata
    1979 Volume 5 Issue 4 Pages 416-420
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The relationship between flocculant dosage required to obtain the desired turbidity removal and the mean molecular weight of polymeric flocculant was studied experimentally. Kaolin and nonionic polyacrylamide were used for suspension and flocculant, respectively. Flocculants with various mean molecular weights were prepared mechanochemically, i.e. through vigorous cutting of polymer chains by a bladed mixer.
    It was found that the effective dosage region, defined as the range of flocculant dosage over which residual turbidity less than a specified value could be obtained, increased with increase of mean molecular weight, reached a maximum and then decreased. This result suggests that clarification will be achieved by use of a flocculant whose effective dosage region is the maximum, because in most actual operations the fluctuations in concentration or composition of suspended materials are quite usual. For the selection of a polymeric flocculant the effect of mean molecular weight of the flocculant on turbidity removal should be evaluated in terms of the effective dosage region.
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  • Katsuji Noda, Takamitsu Yoshida, Kiyoharu Ishida
    1979 Volume 5 Issue 4 Pages 421-423
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The solubilities of sulfur are measured in propane n-butane n-pentane ethyl alcohol and n-butyl alcohol in the temperature range -2040°C. The composition of sulfur is determined by weighing a saturated solution and the solid sulfur after the evaporation of the solvent. The solubilities of a homologous series over the temperature range -20 80 °C are well correlated by using the activity coefficient equation combining the Wilson equation with the regular solution equation. This equation may be useful for the estimation of solubilities in n-paraffins and alcohols.
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  • Kenichi Ushiki, Hiroyuki Sawada, Koichi Iinoya, Shigekatsu Mori, Mitsu ...
    1979 Volume 5 Issue 4 Pages 424-435
    Published: July 10, 1979
    Released: October 21, 2009
    JOURNALS FREE ACCESS
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