JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
Print ISSN : 0021-9592
Volume 18 , Issue 4
Showing 1-18 articles out of 18 articles from the selected issue
  • Kozo KOIDE, SEIJI YAMAZOE, SHIGEHIKO HARADA
    1985 Volume 18 Issue 4 Pages 287-292
    Published: August 20, 1985
    Released: April 19, 2006
    JOURNALS FREE ACCESS
    The effects of surfactants and antifoam agent on the gas holdup ε, the liquid-phase mass transfer coefficient kL and the volumetric liquid-phase mass transfer coefficient kLa in a bubble column were studied experimentally. An addition of surfactants such as n-alcohols to water increases e and decreases kL, and an addition of antifoam agent to water decreases ε, kL and kLa. However, the degree of reduction of kL value by an addition of surfactant to water is lower for bubble swarms in a bubble column than that for a single bubble in stagnant liquid. Based on these observations, the previous model for estimating kL of a single bubble in aqueous solutions of surface-active substance is modified so as to be applicable to the estimation of kL for bubble swarms in a bubble column.
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  • YASUO HATATE, YOUICHI KUROKAWA, HIROSHI HAMADA, ATSUSHI IKARI, FUMIYUK ...
    1985 Volume 18 Issue 4 Pages 293-302
    Published: August 20, 1985
    Released: April 19, 2006
    JOURNALS FREE ACCESS
    Styrene slurry polymerization in isooctane droplets suspended in water was carried out to clarify the characteristics. The following results were obtained: (1) revolution rate, existence of PVA and volume fraction of dispersion phase have no effect on the kinetics of the polymerization, and (2) the effect of initiator concentration on the kinetics in this polymerization is similar to that in common homopolymerization, while the effect of monomer concentration is different from that in homopolymerization. At low monomer concentrations in particular, the polymers produced have much higher molecular weight than those in homopolymerization.
    A two-phase separation model is proposed to describe the characteristics of the polymerization, and the kinetic equations are derived. The kinetic parameters were determined to show comparatively good agreement between calculated and observed relations of conversion and average molecular weight with reaction time.
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  • EIICHI KUNUGITA, IZUMI TSUBOI, YOSHINORI KUTSUWA, JOHN INGHAM
    1985 Volume 18 Issue 4 Pages 303-307
    Published: August 20, 1985
    Released: April 19, 2006
    JOURNALS FREE ACCESS
    A computer algorithm is proposed for the structure synthesis of liquid-liquid extraction processes employed for metal separation. The following simplified model is adopted. A process is composed of counter-current multistage mixer-settlers. The distribution ratios of the metals are independent of the composition of each phase, and the feed solvent employed for extraction and the water for stripping are each metal-free.
    A knowledge of the metal components to be separated, the solvents available and the distribution ratios of the metal species enables alternative feasible structures to be selected by use of a tree-type algprithm. For each alternative structure, the number of stages in each operation needed to separate the key component to a specified value may then be calculated with a computer programme in order to minimise the total number of stages in the process.
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  • YASUO KATO, SHIGEHARU MOROOKA, TOKIHIRO KAGO, TETSUYA SARUWATARI, SHOU ...
    1985 Volume 18 Issue 4 Pages 308-313
    Published: August 20, 1985
    Released: April 19, 2006
    JOURNALS FREE ACCESS
    The behavior of gas and solid particles was studied in a so-called three-phase fluidized bed of 12-cm diameter.
    The mean gas holdups in the dense and lean regions and the mean solid holdup in the dense region were correlated by experimental equations. The axial distribution of solid holdup in the lean region was analyzed by the sedimentation diffusion model. The mean settling velocity, vp, and the longitudinal dispersion coefficient of solid particles, Ep, were correlated with previous data for bubble columns with suspended solid particles, respectively, as follows.
    For Ug/v1<30:
    vp=vt{1+1.5(Ug/vt}0.3ψ2.5l
    For (dpvt/vl)=0.3-2.5:
    UgDT/Ep={13Fr/(1+8Fr0.85)}{1+0.009(dpvt/vl)Fr-0.8}
    For (dpvt/vl)=2.5-640:
    UgDT/Ep={13Fr/(1+8Fr0.85)}(1+0.023Fr-0.8)
    where DT = column diameter; dp = particle diameter; Fr=Ug/√dGT; g = acceleration of gravity; Ug = superficial gas velocity; vt = terminal velocity of solid particle; vl = kinematic viscosity of liquid or slurry; ψl = (volume fraction of liquid or slurry)/(l-volume fraction of gas).
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  • YASUO KATO, SHIGEHARU MOROOKA, MAKOTO KOYAMA, TOKIHIRO KAGO, SHOU-ZHI ...
    1985 Volume 18 Issue 4 Pages 313-318
    Published: August 20, 1985
    Released: April 19, 2006
    JOURNALS FREE ACCESS
    The longitudinal dispersion coefficient of liquid, E, , was measured in three-phase fluidized beds 12 and 19 cm in diameter. The data of Ef, were correlated by expanding the equation for liquid dispersion in the bubble column, and the following equations were obtained.
    Ug <9cm•s-1: UgDT/El = (1 + vl/Ul)0.40Bo0.225Pe(BC)
    Ug > 25 cm•s-1: UgDT/El = Pe(BC) In the range of Ug = 9-25 cm•s-1, El was approximated by connecting the above equations. The notations are:
    Pe(BC)=(ηlw)0.07[13(Ug/√gDT)/{1+6.5(Ug/√gDT)0.8}]
    Bo=gd2ppl/σ, DT = diameter of bed, dp = diameter of solid particles, g = acceleration due to gravity, Ug = superficial gas velocity, Ul = superficial liquid velocity, vt = terminal velocity of solid particle, ηl = viscosity of liquid, ηw = viscosity of water, Pl = liquid density and σ = surface tension.
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  • MITSUNORI HOZAWA, TAKAO TSUKADA, TOHRU KONDO, NOBUYUKI IMAISHI, KATSUH ...
    1985 Volume 18 Issue 4 Pages 318-325
    Published: August 20, 1985
    Released: April 19, 2006
    JOURNALS FREE ACCESS
    The combined effect of free and forced convections on mass transfer between two liquids was studied experimentally and theoretically.
    In the experiments, steady-state dissolution rates into flowing water of an aniline or furfural drop which was sandwiched between a capillary and a rod and had a nearly cylindrical surface were measured, and the continuousphase mass transfer coefficients were obtained. During an experimental run, the amount of the drop phase dissolved into water was supplied continuously through the capillary and the drop volume was kept constant.
    It was observed that the Sh values depend on the flow direction of water in the range of 5 < Re < 100 and that in the case of upward flow, Sh takes the minimum at some Re number.
    Numerical simulations of the phenomena were tried, using the finite element method, and the experimental results are explained qualitatively.
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  • MANABU YAMAGUCHI, TORU TAKAMATSU, FUMIYA YOSHIDA, TAKASHI KATAYAMA
    1985 Volume 18 Issue 4 Pages 325-330
    Published: August 20, 1985
    Released: April 19, 2006
    JOURNALS FREE ACCESS
    Mass transfer of iodine from single charged drops of aqueous iodine solution into a continuous phase of cyclohexane was measured during the overall process of formation, free fall and coalescence of the drops in a range of uniform electric field strength up to 2.4 kV/cm. The total amount of iodine transferred was separated into that during drop formation and that during the subsequent stages. Each mass transfer mechanism during the formation and the free fall of drops in the electric field was investigated with theoretical and empirical equations in the literature, which were obtained in the absence of an electric field.
    The mechanism of mass transfer during the formation of the charged drops in the presence of an electric field and that during free fall of the drops are the same as those obtained in the absence of an electric field. The enhancement of mass transfer obtained in the electric field is due to the increased effective interfacial area per volume of dispersed phase and to the increased moving velocity of the drops caused by applying the electric field.
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  • SHUJI SAKOHARA, HAJIME UNNO, TAKASHI AKEHATA
    1985 Volume 18 Issue 4 Pages 331-336
    Published: August 20, 1985
    Released: April 19, 2006
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    Turbidity removal from clay suspensions by use of organic polymeric flocculants was studied by relating the change in floe size, optical density through a flocculation tank and amount of flocculant adsorbed onto suspended particles. Turbidity removal is represented by taking two regimes into consideration, i.e., the earlier period, appearing just after flocculant injection, when the flocculant adsorption rate controls the process, and the later period when a limited number of floes named "mother floes" control the process. The turbidity removal rates in both regimes were evaluated easily from the modified optical density variation proposed in this work and represented by two different first-order processes with respect to the modified optical density. The rate constants in both regimes were related linearly to each other, and its proportional constant depended on the condition of agitation.
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  • HIROSHI YOSHIDA, TADASHI SHINKAWA, HIROSHI YUKAWA
    1985 Volume 18 Issue 4 Pages 337-342
    Published: August 20, 1985
    Released: April 19, 2006
    JOURNALS FREE ACCESS
    To analyze the electroosmotic dewatering process precisely, the variations of water content and electric potential distributions in the sludge are made clear. The distributions of water content and electric potential in gelatinous bentonite sludge with electroosmotic dewatering were studied experimentally under the conditions of both constant voltage and constant electric current. It is proved that the water content distribution is generally related to the electric potential distribution throughout the dewatering process. Electroosmotic dewatering under constant voltage is compared with that under constant electric current. Electroosmotic dewatering combined with vacuum dewatering is also discussed from the viewpoint of these distributions.
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  • KAZUHARU YOSHIZUKA, KAZUO KONDO, FUMIYUKI NAKASHIO
    1985 Volume 18 Issue 4 Pages 342-348
    Published: August 20, 1985
    Released: April 19, 2006
    JOURNALS FREE ACCESS
    A kinetic study concerning the stripping of copper chelate complex in toluene with hydrochloric acid was carried out at 303 K, using a stirred transfer cell and pure copper complex prepared from copper and synthesized N-8-quinolyl-p-dodecylbenzenesulfonamide.
    It was found that the mechanism of copper stripping could not be explained as simply a reverse process of the copper extraction by this extractant from acetate buffer media, due to the reaction between the extractant and hydrochloric acid and the low solubility of the ion pair complex formed by this reaction. Moreover, it was confirmed that the stripping rate was determined by the first step of the interfacial reaction between the copper complex and the acid, and by mass transfer of the copper complex.
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  • FUKUJI YAMASHITA
    1985 Volume 18 Issue 4 Pages 349-353
    Published: August 20, 1985
    Released: April 19, 2006
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    The effects of liquid depth, inclination angle of the column from vertically and baffle plates on gas holdup in bubble columns were determined, using three bubble columns.
    When liquid depth Hl was less than the critical liquid depth Hlc, gas holdup εg decreased with increasing Hl, but when Hl was larger than Hlc, εg was nearly constant.
    εg decreased with increasing column inclination angle, and the effect on εg was correlated.
    εg was independent of the cross-sectional shape of the column.
    Baffle plates set in bubble columns increased εg, and the effects of the area and number of baffle plates on εg were correlated.
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  • MASATO TANAKA, TAKASHI IZUMI
    1985 Volume 18 Issue 4 Pages 354-358
    Published: August 20, 1985
    Released: April 19, 2006
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    The stirred-tank reactor (DSTR) equipped with draft tube (DT) was applied to suspension polymerization of styrene. In the experiments the length of DT, the impeller height and the impeller speed were changed stepwise. The following points were found.
    1) Mean droplet diameter during the reaction and mean final particle size were not affected by impeller height.
    2) As DT became longer, droplet circulation time increased and droplet distribution became more uniform.
    3) As DT became longer, the size distribution and mean size of final particles became more uniform and larger, respectively.
    4) With increasing impeller speed, the particle size and uniformity decreased at first, became minimal around 5.8s-1 and then increased again.
    5) Particle size of polymer beads produced with DSTR was more uniform than that with the conventional fully baffled stirred tank (BSTR).
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  • KATSUMI NAKAGAWA
    1985 Volume 18 Issue 4 Pages 359-363
    Published: August 20, 1985
    Released: April 19, 2006
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    A theoretical equation for oscillation of chain bubbles was obtained by use of velocity potential. To examine theoretical considerations, experiments applying the pulse response method of sound and the floating bubble method were carried out. The numerical solutions were well in accord with the experimental results, and the validity of the theoretical considerations was demonstrated. The frequency of chain bubbles decreased with decreasing interbubble distance and with increasing number of bubbles in water.
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  • MASAO SUDOH, HISATSUGU KITAGUCHI, Kozo KOIDE
    1985 Volume 18 Issue 4 Pages 364-371
    Published: August 20, 1985
    Released: April 19, 2006
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    The relation between current density and overpotential for electroreduction of oxygen to hydrogen peroxide in the packed-bed electrode reactor was studied. Theoretical analyses were made on the basis of the two-dimensional two-phase model of the particulate electrode where the distribution of concentration of dissolved oxygen and the overpotential were considered. The kinetics of electrode reactions was determined with a rotating-disk electrode of graphite. The effective specific surface area available for electrode reaction in the packed-bed electrode was determined by analysing the transient current response to a potential step. The observed values of overpotential profile and the polarization curves of the packed-bed electrode agreed with the theoretical ones calculated by use of the kinetic and reactor properties.
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  • MOMPEI SHIRATO, TOSHIRO MURASE, EIJI IRITANI, SHUJI NAKATSUKA
    1985 Volume 18 Issue 4 Pages 372-376
    Published: August 20, 1985
    Released: April 19, 2006
    JOURNALS FREE ACCESS
    Dewatering of filter cakes can be accomplished by covering the cake surface with bentonite slurry at the end of filtration and applying compressed air. By this method, a skin layer of bentonite with high filtration resistance forms on the cake surface and acts as a mechanical piston which compresses the cake. Cake cracking is also rare compared with the case of non-Newtonian fluids shown in the previous paper.14) It is shown that the final equilibrium water content of compressed cakes is quite close to that obtained in mechanical expression. In the consolidation period, the reciprocal flow rate increases rapidly and the hydraulic pressure in the cake decreases enormously with consolidation time, resulting in a substantial decrease in porosity. Based upon the conventional expression theory of filter cake, a method has been developed for analyzing this operation on the assumption that the amount of permeated water from the bentonite slurry is negligible. The method can be used for evaluating the internal structures of compressed cake. Confirmation of favorable coincidence between theory and experiments is demonstrated.
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  • YASUHIKO NISHIMURA, Yosmo IWAI, YASUHIKO ARAI, MASANORI NAGATANI
    1985 Volume 18 Issue 4 Pages 377-381
    Published: August 20, 1985
    Released: April 19, 2006
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  • MASAHARU KOMIYAMA, ROBERT P. MERRILL
    1985 Volume 18 Issue 4 Pages 381-382
    Published: August 20, 1985
    Released: April 19, 2006
    JOURNALS FREE ACCESS
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  • KAZUHARU YOSHIZUKA, KAZUO KONDO, FUMIYUKI NAKASHIO
    1985 Volume 18 Issue 4 Pages 383-384
    Published: August 20, 1985
    Released: April 19, 2006
    JOURNALS FREE ACCESS
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