KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 19, Issue 6
Displaying 1-43 of 43 articles from this issue
  • Hironao Ogura, Michito Kanamori, Hitoki Matsuda, Masanobu Hasatani
    1993 Volume 19 Issue 6 Pages 941-946
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    In this paper, the generation of low-temperature heat for cooling and refrigeration by a chemical heat pump using CaO/H2O/Ca (OH) 2 reaction is proposed. The temperature level of the heat and the heat-generation rate were investigated experimentally.
    It was found that low-temperature level heat around 273K was generated by use of the proposed chemical heat pump unit. The heat-generation was improved by heat and mass transfer augmentation in the reactant bed, and the temperature level of the heat was lowered. It was also recognized that the evaporation and mass transfer at low pressure should be enhanced in order to improve the heat-generation.
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  • Noriyuki Yamada, Eiichi Abe, Hideharu Hirosue
    1993 Volume 19 Issue 6 Pages 947-955
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    Microcapsules with a shell of colloidal silica of nm order and a core of magnesium hydroxide carbonate and SiC having a size of a few microns were prepared by spray-drying suspensions of these materials. The influences of the methods of dispersing the suspensions and the volume fraction of magnesium hydroxide in the core materials on the release profiles of microcapsules were investigated. It was found that the release rate increased as the volume fraction of magnesium hydroxide carbonate increased, and that dispersion by an ultrasonic homogenizer resulted in a smaller release rate compared to the use of a turbine mixer. The release profiles of the microcapsules proved to be expressed by a diffusion model. The effective diffusion coefficients became large with increasing volume fraction of magnesium hydroxide carbonate, resulting from the increase of pore volume in the shell of microcapsules. The difference in effective diffusion coefficient, resulting from the various dispersing methods used, was not attributed to the shell structure of the microcapsules.
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  • Takahiro Oshita, Tsutomu Higo, Shigeru Kosugi, Naoki Inumaru
    1993 Volume 19 Issue 6 Pages 956-962
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Research was conducted on an internally circulating fluidized-bed boiler as to formation of internal circulation and control of overall heat transfer coefficient. The boiler features a fluidized bed divided into a main combustion cell and heat exchange cells located on both sides of the combustion cell and separated by inclined partition walls. Silica sand was used to form a revolving flow in the main combustion cell and a circulation between the main combustion cell and heat exchange cells as the fluidized-bed material. It was found experimentally that adequate circulation of the fluidized-bed material between the main combustion cell and the heat exchange cell, which was needed to recover the required quantity of heat from the immersed heating surface, is obtained when the stable fluidized-bed height exceeds the height of the inclined partition walls and when the volume of fluidizing air supplied to either side of the main combustion cell exceeds a certain limit. It was also found that the descending rate of the moving bed in the heat exchange cell can be controlled by changing the amount of circulating air supplied from the lower part of the heat-exchange cell. Measurement of overall heat transfer coefficient values verified that this coefficient varies almost linearly with the change in fluidization velocity in the heat exchange cell in the range of U/Umf = 0 to 2. Thus a flexible load control method to control the internally circulating fluidized-bed boiler is established.
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  • Takashi Hibiki, Manabu Yamaguchi, Takashi Katayama
    1993 Volume 19 Issue 6 Pages 963-970
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    Equations predicting breakup length were proposed for laminar liquid jets in electric fields formea by such configulations as an electrified flat electrode arranged in parallel above an earthed flat electrode, an electrified liquid jet in the center of an earthed cylindrical electrode, and an electrified nozzle arranged vertically above an earthed flat electrode. It was found from observation of the jet breakup that the jet radius. Since the mechanisms of jet breakup in electric fields are the same as those in the gravitational field, the model for jet breakup in the gravitational field was applied to that in the electric fields. The growth rate of the wave, the initial amplitude of the wave and the interfacial velocity are necessary for predicting the breakup length of the jets. The equations for the growth rate of the predicting the breakup length of the jets. The equations for the growth rate of the wave were given in the previous papers, and the terms on the initial amplitude of the wave and the interfacial velocity were empirically correlated by the ratio of the electric pressure to the interfacial pressure. Experiments were performed for several systems, that is, water-air and xylene-air for liquid-gas systems and water-hexane, water-cyclohexane and water-silicone oil for liquid-liquid systems. Good agreement (±20%) was obtained between the measured breakup lengths of jets and the calculatedones.
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  • Yushi Hirofuji, Yukihito Sasaki, Yoichi Nagase
    1993 Volume 19 Issue 6 Pages 971-977
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    Sensitivity of the electrode in detecting the concentration mass of strong electrolyte solution was analysed numerically for the case of a single mass in an electric field between a large spherical or ring electrode and a concentric micro-spherical electrode. The response curve is spike shaped (large mass) or mountain shaped with a gentle slope (small mass) when a mass grazes a micro-electrode.
    The more a mass covers and passes concentrically through the micro-electrode, the more the slope and peak of the response curve are sharpened and the peak is flattened. The peak value, IM, is not only a nonlinear function of the mass concentration, but also a function of mass size. The real concentration of mass is larger than that estimated from assuming IM lineally proportional to the concentration.
    On the contrary, beyond the middle stage of turbulent mixing, where there are many of relatively large mass in high level of background concentration between electrodes, the peak value IM, though small, is approaching to direct proportionality to the concentration. Therefore, the reliability of electrical measurement of the concentration fluctuation is good in the final stage of mixing.
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  • Shigeo Goto, Tomohiko Tagawa, Tateo Oomiya
    1993 Volume 19 Issue 6 Pages 978-983
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    PSA (pressure swing adsorption) was applied to the regeneration of adsorbent in simultaneous operations of reaction and separation. Dehydrogenation of cyclohexane was used as the model reaction. The hydrogenstorage alloy (CaNi5) was suitable to the adsorbent. The reaction rate was of 0.8 th order with respect to cyclohexane concentration. The reaction temperatures were 150 and 190°C. Conversion in the reactor with hydrogen storage alloy greatly exceeded equilibrium and then turned gradually to equilibrium. The alloy could be regenerated by helium purge. High conversions were obtained by periodic operations of reaction and purge. The yields of product in one cycle were increased by increasing the weight of alloy.
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  • Tadao Nakashima, Masataka Shimizu
    1993 Volume 19 Issue 6 Pages 984-990
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    Although high-pressure homogenizers and ultrasonic homogenizers are commonly used in the commercial production of various emulsions, it is rare to obtain monodispersed emulsion or conveniently control particle size according to each practical target. The authors recently found a novel emulsification which might be able to solve this problems by application of porous glass membrane as liquid disperser. Present experiments were carried out from the standpoint of basic investigation in order to clarify relations between pore characteristics of membrane and emulsion particles obtained thereby.
    Porous glass membrane from phase separation was superior to other porous membranes such as porous ceramic as disperser. The following conditions were always necessary for preparation of monodispersed emulsion. (1) The porous membrane must have a narrow pore size distribution. (2) The membrane should never be wetted with dispersion liquid phase.
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  • Tadao Nakashima, Masataka Shimizu, Masato Kukizaki
    1993 Volume 19 Issue 6 Pages 991-997
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    The effect of surfactant on production of monodispersed O/W emulsion in membrane emulsification by controlled pore glass membrane was examined, with the following results. Although an appropriate amount of surfactant in the continuous water phase is indispensable, successful emulsification can be carried out with much less surfactnt than is used with conventional methods. Adding surfactant has the effect of decreasing the critical permeation pressure and spreading out the pressure range under which monodispersions may be prepared in steady state. However, when the polar group in a surfactant molecule has a charge opposite to that of the porous glass membrane surface, adsorption of surfactant on the membrane occurs and the membrane apparently becomes hydrophobic. Thus the emulsion obtained was considerably polydispersed.
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  • Toshihide Sakurai, Manabu Okamoto, Haruhiko Miyazaki, Katsumi Nakao
    1993 Volume 19 Issue 6 Pages 998-1005
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    The coprecipitates, precursors of fine zinc ferrite crystals, were prepared by continuously mixing an aqueous solution containing ferric and zinc nitrates with a sodium hydroxide aqueous solution. The coprecipitates were aged and calcined to from zinc ferrite crystals ZnFe2O4. Effects of various preparation conditions on the morphology of the crystals and on their capacity to desulfurize a simulated coal gas were examined.
    Although the coprecipitates formed were regarded as amorphous fine particles, they were converted perfectly to ZnFe2O4 crystals by calcination above 773 K. The size of zinc ferrite crystals decreased with increase in the molar ratio of sodium hydroxide to nitrates, R. At lower values of R, the optimal coprecipitation and aging temperatures appeared at which their size was minimum. The optimal preparation condition was determined as follows. R was 1.5, both coprecipitation and aging temperatures were 323K and the calcination temperature was 973K.
    Sulfur capacity of the sorbent molded from the present zinc ferrite crystals decreased with decrease in the surface area below 15 m2/ g. The properties of the sorbent prepared with sufficiently fine zinc ferrite crystals were as follows. The surface area was greater than 20 m2/g, the average pore diameter was 10-40nm and the sorbent showed good desulfurization performance in the range of 673-873K.
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  • Kouichi Miura, Jun'ichi Hayashi, Takuya Dohmoto, Kenji Hashimoto
    1993 Volume 19 Issue 6 Pages 1006-1014
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Molecular sieving carbons (MSCs) were produced by simply carbonizing a mixture of coal-phenolformaldehyde (PF) resin which was modified by organic substances such as coal pitches, anthracene, dihydroanthracene and acenaphthylene. By changing the carbonization temperature as well as the mixing ratio of coal, PF-resin, and organic substances we could prepare MSCs with sharp pore distributions around 0.37 to 0.44 nm in pore diameter. The possibility of using the MSCs for separation of gaseous mixtures of (1) C3 H8-C3 H6, (2) 1-C4 H8-i-C4H8, and (3) CO2-CH4 was examined from the viewpoint of adsorption isotherm and adsorption rate. We could successfully prepare MSCs that separate each gas mixture by the difference in adsorption amounts. We could also prepare MSC whose intraparticle diffusivity for CO2 is 40 times larger than that for CH4. The separation efficiencies of the MSCs for the above gas mixtures were well correlated with the size and shape of the gas molecules to be separated and the average size and the dispersion of pore distribution curves of the MSCs.
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  • Tomohide Watanabe, Hitoki Matsuda, Masanobu Hasatani
    1993 Volume 19 Issue 6 Pages 1015-1022
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Desulfulization reactivity of dolomite fully calcined in a temperature range of 9731473K was studied with thermogravimetric analysis (TGA) at 9731473K. The reactivities of calcined calcite, dolomite and magnesite were compared. The effect of the components of CaO and MgO in dolomite on the sulfurization of calcined dolomite was studied on the basis of the reactivities of calcined calcite and magnesite for sulfurization.
    The reactivity of fully calcined dolomite for sulfurization was decreased with an increase in the calcination temperature and had a maximum sulfurization temperature of about 1373K. In the temperature range where both MgO and CaO could react with SO2 from a viewpoint of thermodynamical equilibrium, the component of MgO in dolomite as well as that of CaO reacted with SO2. Sulfur dioxide, however, might react selectively with the component of CaO in dolomite under chemical reaction control at the beginning of the reaction because CaO had a much higher reactivity for sulfurization than MgO. In the temperature range where CaO could only react with SO2 from thermodynamical equilibrium, the sulfation reaction of the component of CaO in dolomite almost attained 100% since SO2 could pass through intraparticle pores which were not plugged by the presence of unreacted MgO.
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  • Kyoko Yamamoto, Takehiro Sano, Kyu Murata, Hideo Kameyama, Ken Hongo
    1993 Volume 19 Issue 6 Pages 1023-1030
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    The proposed ice storage system uses several kinds of hydrogel as heat supports. The vaporization heat of water from highly water-containing gel is stored as the heat of freezing of the remaining water. The first key to the realization of this system is development of a vacuum compressor with large evacuation rate for water vapor at low pressure and with high efficiency. It is also important to evaporate water at high temperature, as near the freezing point as possible, to produce ice with high efficiency.
    A 1-liter cylindrical Dewar vessel made of stainless steel was used as a heat container and diaphragm pumps were used for evacuation. Four types of polymer gel materials and two kinds of ice nucleation active substances (INS), AgI and ice nucleation active protein (INAP) produced by an ice nucleation active bacterium (INB : Xantmonas campestris), were used in the experiments.
    For practical use, the evaporation rate of water is described as proportional to the vapor pressure of water at the temperature of the gel.
    Both kinds of INS were effettive in raising the break-point of supercooling from -58°C (without INS) to -1-3°C (with INS). INAP is recommended for use in this system as a harmless, reproducible organic INS.
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  • Akiko Kage, Erica Arao, Ko Higashitani
    1993 Volume 19 Issue 6 Pages 1031-1037
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    The dependence of the ζ-potential of PSL particles in alcohol-water solutions on the dielectric permittivity and electrolyte concentration was investigated. The following features were clarified. 1) When no electrolytes are dosed, the ζ-potential of PSL particles in alcohol-water solutions does not depend on the dielectric permittivity : it is ind pendent of the kind and concentration of alcohols. 2) In the case of solutions of a monovalent electrolyte and a divalent electrolyte with a high dielectric permittivity, the variation of ζ-potential with dielectric permittivity and electrolyte concentration may be explained by the theory of electrical double layer. 3) In the case of solutions of a trivalent electrolyte with a low dielectric permittivity, the variation of ζ-potential with electrolyte concentration is caused mainly by the specific adsorption of ions. 4) In the case of solutions of a divalent electrolyte with a low dielectric permittivity and a trivalent electrolyte wite a high permittivity, the ζ-potential varies in an intermediate way between the above extreme cases.
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  • Osamu Miyatake, Takayuki Hashimoto, Yoshimasa Ando
    1993 Volume 19 Issue 6 Pages 1038-1043
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    A numerical analysis was carried out to determine the effect of the size of a spherical nucleus, that is, the effect of the initial bubble radius, on bubble growth rate in a uniformly superheated liquid.
    Numerical solutions obtained by means of a finite difference method are illustrated for an example of a growing bubble in superheated water with bulk temperatures, T, of 4080°C, superheats, ΔTs, of 520K and initial-to-critical bubble radiusratios, γ, of 1.0150, covering the inertia-controlled and heat-transfer controlled regimes.
    For cases of practical importance γ≥2, the restraining effect of interfacial surface tension on the bubble growth rate is found to be negligible, and a dimensionless equation for predicting the bubble growth rate in a superheated pure liquid is formulated from the numerical solutions.
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  • Yasuyuki Urata, Tomoshige Nitta
    1993 Volume 19 Issue 6 Pages 1044-1052
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    Supercritical fluids of carbon dioxide or ethylene, with tetrahydrofuran (THF) added in a stepwise manner, are used as eluents in a column-elution fractionation method to separate styrene-maleic anhydride coplymers. The column pressure is kept at 20 MPa for all experiments. The SC-C2H4/THF eluent is found to be superior to SC-CO2/THF eluent for molecular weight fractionation since the solubility of oligomers in SC-C2H4/THF eluent decreases in the order of molecular weight. Sharper fractionation is obtained at 90°C than at 50°C. The condition of equilibrium desorption at the column outlet was investigated by using a model of mass transfer from the stationary phase; the partition coefficients K's between supercritical fluid and polymer-gel are determined. The experimental K's are correlated in terms of the separation factor σ. The elution fractions of each oligomer, calculated from the mass-transfer model by evaluating the overall mass-transfer coefficients from the diffusivity in the supercritical fluids, agree with experimental elution fractions, which will help in determining the optimum condition for oligomers separation.
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  • Haruo Yamazaki, Toshiro Murase, Masashi Iwata, Mompei Shirato
    1993 Volume 19 Issue 6 Pages 1053-1059
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    The critical tractive condition in dynamic filtration, in which a particulate bed under permeation is swept away by the intensive liquid shear of crossflow, was studied using a rotating ungrooved and grooved disk. Equations were proposed for analysing groove effects on liquid shear, in consideration of three-dimensional flow near the bed. The critical tractive velocity of the rotating disk was determined on the basis of the force balance for a particle in the uppermost layer of the bed. Predicted results using an empirical exposure factor were in satisfactory agreement with experimental data for packed beds of glass beads with particle diamter of 0.151.05mm. It was also shown that grooving decreases the critical rotation of the disk quite appreciably and is beneficial for sweeping the granular bed.
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  • Tadaatsu Ido, Tetsuya Yoshida, Shigeo Goto
    1993 Volume 19 Issue 6 Pages 1060-1066
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    Vapor-phase aldol condensation and isomerization of butene were studied by use of a eutectic mixture of NaOH-KOH (m.p. 170°C) as the catalyst at 200°C and atmospheric pressure. The activity and stability of the catalyst varied remarkably with supports (activated carbon, alumina, titania, magnesia, silica-alumina) and supporting methods (impregnation method, physical mixing of catalyst with support). Three kinds of decay of catalytic activity were observed. When the catalyst impregnated on activated carbon was used, rates of both reactions decreased with time. In the case of alumina as the support, the rate of isomerization did not decrease with time but the rate of aldol condensation decreased. The rate of aldol condensation did not decrease with time when the catalyst was supported in the vicinity of the surface of activated carbon and silica-alumina. Basic OH- ions, which were formed by melting of the catalyst, were supposed as active species of catalyst for aldol condensation. The surface of these supports with catalyst was observed using a scanning electron microscope, and the interaction between catalyst and supports was investigated.
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  • Tadaatsu Ido, Toru Mizuta, Shigeo Goto
    1993 Volume 19 Issue 6 Pages 1067-1073
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    Vapor-phase reaction of methanol with isobutylene to produce MTBE (methyl tert-butyl ether) was carried out by use of molten benzenesulfonic acid (in.p. 45°C) as the catalyst at 60120°C under atmospheric pressure. The reaction rate varied remarkably with temperature and partial pressure of methanol due to the dissolution of methanol in the catalyst. The amount of methanol dissolved in the catalyst under the reaction conditions was measured and the variation of acid strength of the catalyst with the dissolution of methanol was investigated by using anthraquinone and benzalacetophenone as indicators. The reaction rates were corrected by considering these variations of acid strength of the catalyst. The dependences of temperature and partial pressure of methanol on these reaction rates were in good agreement with those of the ion exchange resin. Furthermore, it was found that the formation of by-product (diisobutylene) was depressed by dissolving methanol in the catalyst. The state of catalyst on the support was observed with a scanning electron microscope.
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  • Masafumi Kuriyama, Xiangyi Li, Eiji Harada, Hirotaka Konno
    1993 Volume 19 Issue 6 Pages 1074-1080
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    An experimental study was made of steady-state natural convection heat transfer to air from two horizontal cylinders arranged in a vertical line. Variation of heat transfer coefficients of both cylinders with cylinder spacing and surface temperature is presented, and it is shown that the heat transfer around the upper cylinder was strongly affected by the buoyant plume induced by the lower cylinder. Flow patterns and temperature profiles around the two-cylinder arrays are also presented, and interactions between the convections around each cylinder are discussed. On the basis of these experimental results, a simple model is proposed to evaluate the effects of the interaction on the heat transfer coefficient of the upper cylinder. The behavior of the experimental heat transfer coefficient is elucidated well by this model.
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  • Masaaki Yokota, Ken Toyokura
    1993 Volume 19 Issue 6 Pages 1081-1088
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    Surfaces of single crystals of s-carboxymethyl-L-crysteine (L-SCMC) grown in NaCl-doped supersaturated solution of DL-SCMC were observed. The generation rates of D-and L-fine crystals on the surface of the parent crystals (L-seed) were proportional to the 2.7 th and 1st power of operational supersaturation, respectively, . but were independent of the superficial velocity of the solution. Generation of D-fine crystals in the supersaturated solution began to be observed about 2 hours after D-fine crystals began to be observed on the surface of L-seed. From these experimental results, the generation of D-fine crystals is thought to be attributable to a heterogeneous nucleation mechaism. The D-fine crystals in the solution are thought to be born by the removal of the fine crystals on the L-seed. The generation rates of D-fine crystals and the induction time were also correlated with a classical heterogeneous nucleation rate equation. L-fine crystals were observed throughout the experimental in the supersaturated solution, but it was not found that whether heterogeneous nucleation or sticking of the fine crystals influenced the generation of L-fine crystals.
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  • Gensho Miyako, Kaoru Onoe
    1993 Volume 19 Issue 6 Pages 1089-1095
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    A numerical method for the calculation of equilibrium composition in multicomponent aqueous solutions has been developed. With this method the independent components are parted from the total equilibrium components in the system and the equilibrium relations of the dependent components are experessed by the independent components only. Combining the equilibrium relations with the mass and charge balance equations, the fundamental equations for calculating the equilibrium composition are reduced to the number of independent components. These non-linear simultaneous equations can be solved easily by the Newton-Raphson technique.
    The H-Na-Cl-PO4 aqueous system was chosen as an example. The calculated values of the pH and electric conductivity of the aqueous solutions are compared with the experimental values.
    The features of this method can be expressed as follows. 1) The method is applicable to a wide range of multicomponent aqueous systems. 2) Concentrations of all components at equilibrium can be easily obtained. 3) Physical properties, such as ionic strength and electric conductivity, can be calculated effectively.
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  • Crystal size and filtration behavior
    Koji Maeda, Hidetaka Noritomi, Satoru Kato, Kunio Nagahama
    1993 Volume 19 Issue 6 Pages 1096-1104
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    Batch crystallization of binary eutectic organic mixtures using liqufied gas as a solvent was carried out. Mean diameter of crystals in a crystallizer and mole ratio of liquid adhering to crystals in wet solid on the filter were determined. Propane or chlorodifluoromethane (HCFC22) was added as a liquefied gas solvent to binary eutectic mixtures : benzene+cyclohexane, p-xylene+m-xylene and p-xylene +o-xylene. Mean diameter of crystals increased with increase in moles of liquefied gas added. It ranges from 100 to 230 μm for benzene, 100 to 120 μm for cyclohexane and 400 to 600 μm for p-xylene. The diameter was represented by an exponentially decreasing curve with concentration ratio. Purity of wet solid increased with increasing moles of liquefied gas added. Ratio of adhering liquid to crystals was found to be well correlated with capillary number, which is calculated from density, surface tension of mother liquor and mean diameter of crystals.
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  • Gao Bai Zhan, Shin-ichi Nakao
    1993 Volume 19 Issue 6 Pages 1105-1112
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    Rejection ability of an ultrafiltration membrane is expressed as molecular weight cutoff (MWCO). However, in practical applications the observed MWCO is different from the nominal value and rejections of different molecules having the same molecular weight are also different. The reason seems to be the rejection mechanism of an ultrafiltration membrane, that is, the sieve effect based on molecular size and not molecular weight. In this study, Stokes radii of protein, dextran and PEG were measured by the GPC molecular-weight calibration curve and ultracentrifuge method, and the relationship between molecular weight and size was determined. Dextran, PEG, PVP and proteins were ultrafiltered by three types of membranes. It was obvious that molecules having the same molecular weight had different molecular sizes, and that rejection of an ultrafiltration membrane was determined by molecular size, not by molecular weight, if there was no molecule-membrane interaction. Therefore, the rejection property of an ultrafiltration membrane must be analyzed by the sieve effect by using molecular size, not molecular weight.
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  • Hiroshi Ohi, Takashi Nishikawa, Mototake Yano
    1993 Volume 19 Issue 6 Pages 1113-1119
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    When NiO/SiO2 particle is produced by simultaneous oxidation of NiCl2 and SiCl4 with air, the conversion of NiCl2 to nickel oxide is low, and NiCl2 remains in the NiO/SiO2 specimen.
    Water vapor was added as a promoter of the oxidation to diminish the NiCl2 in the particles produced. The reaction scheme with water addition was examined thermodynamically and it was revealed that the reaction proceeded by scheme 2. It was also found by inspection of temperature-programmed reduction (TPR) spectra that the addition of water enhanced the interaction between NiO and SiO2.
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  • Fumihiro Koizumi, Hirokazu Nishitani, Eiichi Kunugita, Norihide Komats ...
    1993 Volume 19 Issue 6 Pages 1120-1127
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    A method was developed to detect and measure transparent spherical particles concentrated in the picture. First, candidates of the contour lines of the particles are determined by a Marr-Hildreth filter. Then, real contour lines are recognized by evaluating the first derivative on every contour line. The inscribed-circle method was improved to recognize each particle from the overlapped particle image. An example for transparent polymer particles showed that the ratio of erroneous detection is less than 5 percent. This method can be applied to on-line measurement.
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  • Yoshiyuki Endo, Yasuo Kousaka, Mayumi Ishii
    1993 Volume 19 Issue 6 Pages 1128-1135
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    The profiles of liquid bridges formed between two spherical particles of different sizes, including a spherical particle and a flat plate, where the bridges are in equilibrium with surrounding humidities have been theoretically analyzed for contact angles of liquid to particle of 060°. The adhesion force arising from liquid bridges is also analyzed on the basis of the Laplace equation. The results were similar to those obtained by our previous theory for two identical spheres, in which the profiles were expressed as a function of surrounding humidities and solute concentrations in the liquid. The neck radius of a bridge formed by pure water was very small (about 0.15100nm), whereas that formed by liquid containing soluble impurities was large and controlling in most actual cases.
    The adhesion force theoretically related to bridge profiles was verified by tensile strength tests of water bridges formed between glass spheres of different sizes and between a glass sphere and a slide glass.
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  • Yoshiyuki Endo, Yasuo Kousaka
    1993 Volume 19 Issue 6 Pages 1136-1142
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    The stable separation distance between two spherical particles adhering by a liquid bridge is theoretically analyzed. The result shows that, as the separation between the two particles becomes smaller, the adhesion force increases and at the same time the surface free energy of the liquid bridge decreases. As a result, the two particles come into contact unless external forces are exerted.
    The relation between separation distance and adhesion force was observed using a pair of two glass spheres or two convex lenses where water bridges are formed. The result was found to be in good agreement with the theoretical analysis. Another observation supported the analysis, where two dry glass spheres separately hung to keep a certain horizontal separation between them came into contact when a bridge was formed by a drop of water between the spheres.
    The fact that the bulk volume of a powder bed decreases with increase of moisture content also supports the present analysis.
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  • Kazuya Ijichi, Yoshimitsu Uemura, Yasuhiko Tanaka, Yasuo Hatate
    1993 Volume 19 Issue 6 Pages 1143-1148
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
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    The effect of fine particles on minimum fluidization velocity and bubble size at high temperatures was investigated, using ceramic beads with bimodal particle size distributions. Minimum fluidization velocity was determined by the pressure-drop method and bubble size was measured by the VTR method.
    Minimum fluidization velocities were found to decrease with increasing fine particle content in the fluidizing particles and with rising temperature as predicted. Also, bubble size decreased with increasing fine particle content.
    No effect of temperature on bubble size was observed in the fluidized bed using ceramic beads.
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  • Setsuji Tone, Masahito Taya, Susumu Kato, Yasuhiko Horie, Yoshihiro As ...
    1993 Volume 19 Issue 6 Pages 1149-1156
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    For the photochemical sterilization of thermoduric bacterial spores (Bacillus stearothermophilus), light-irradiation experiments were conducted with a square bubble-column photoreactor (4cm in width×4cm in depth×25cm in height) containing slurried TiO2 semiconductor particles (mean diameter : 21nm). Under the operational condition that TiO2 particles and dissolved oxygen coexisted in reaction mixture, the spores were effectively sterilized. In the present study, a maximal rate of spore sterilization was obtained under conditions of average light intensity in the reactor of 6. 0×105J·m-3, TiO2 concentration of 5×10-2kg·m-3 and dissolved oxygen concentration of 7.7×10-3kg·m-3.
    Considering that oxidative radicals formed from dissolved oxygen via TiO2 photocatalysis cause the spores' death, the knetics of spore sterilization was analyzed on the basis of a second-order rate equation with respect to spore and oxidative radical concentrations, and a single-hit multitarget model. As a result, the elapse of spore sterilization could be expressed successfully and linear correlation was observed between determined rate constants of spore sterilization and average light intensity in the reactor.
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  • Toshitaka Funazukuri, Yuushi Fukuda, Norihiro Nishimoto, Noriaki Wakao
    1993 Volume 19 Issue 6 Pages 1157-1164
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Binary diffusion coefficients (D12) of some organic compounds were measured in n-hexane at 303.2K333.2K and 16.0 MPa, and in n-dodecane and cyclohexane, separately, at 313.2 K and 16.0 MPa by the Taylor-Aris tracer response technique. As compared with the correlations based on the Stokes-Einstein equation, the following freevolume equation :
    D12/√T1 (v-1.358 v0)
    was found to represent well the measured D12, where D12 is the binary diffusion coefficient, T is temperature, α is constant, ν is solvent molar volume and v0=Nσ3/√2; N is Avogadro's number ; σ is effective hard-sphere diameter. The values of α1 were almost proportional to Vb-0.6 for all the solvents.
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  • Fujio Watanabe, Jun Kozuka, Mikio Kumita, Masanobu Hasatani
    1993 Volume 19 Issue 6 Pages 1165-1170
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    The adsorption equilibria of water and ethanol vapour on three kinds of silica gels (SG) and active carbons (AC) with different pore size distributions were measured in the temperature region of 303 to 383K at reduced pressure of less than 0.1MPa. 1) The adsorption equilibrium curves of both adsorbates on SGs correspond to those expected from their pore size distributions. Those for SGs with mono-and di-modal micropores had the shape of one-and two-step increases respectively. The amount of ethanol adsorbed for super-AC is more than six times that for conventional ACs. 2) Heat of adsorption of water vapour on SGs is larger in the case of SG with smaller micropore. 3) Three combinations of adsorbent/adsorbate, i.e. SG and AC with malsler micropore/water vapour and super-AC/ethanol, can be applied to the adsorption heat pump.
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  • Kenji Mishima, Seishi Morii, Shigeyuki Nagayasu, Hideyuki Eya, Masanor ...
    1993 Volume 19 Issue 6 Pages 1171-1178
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    The liquid-liquid equilibria of the aqueous two-phase systems consisting of polyethylene glycol (Mw=7, 500) (1) -dipotassium hydrogenphosphate (2) -water (3), polyethylene glycol (1) -ammonium sulfate (2) -water (3) and polyethylene glycol (1) -dextran (Mw=515, 000, Mn =195, 300) (2) -water (3) were measured at 25°C. The partition coefficients of 15 benzene derivatives in these aqueous two-phase systems were also determined at 25°C.
    Further, the osmotic virial equation was used to correlate the liquid-liquid equilibria of the aqueous two-phase systems and the partition coefficients of 15 benzene derivatives. An estimation of the partition coefficients was attempted by using molecular connectivity indices.
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  • For treatment of Dialysis Wastewater
    Atsushi Toyoda, Tatsuo Kanki, Tsuyoshi Asano, Mitsumasa Murakami, Yosh ...
    1993 Volume 19 Issue 6 Pages 1179-1183
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    In dialysis wastewater treatment by a fluidized-bed bioreactor using polyurethane cubes as support particles, substrate consumption and microbial growth processes were investigated, focussing on the earlier stage of the process. Retained microbes were found to initiate growth inside the particles after sticking from water phase and to form biofilms after experiencing decay and falling-off. The mass increases very quickly and reaches a steady value in an unexpectedly short time. Following the growth of retained microbes, the mass of suspended microbes also reaches a steady value relatively quickly, recovering from a minimum caused by entrapment by the support particles. These prosesses were shown to be explained well by mass balance equations with the Monod kinetic equation by introducing new terms for sticking and falling-off processes. Rate coefficients are determined for various influent conditions.
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  • Sung-Sik Lee, Bong-Gun Kang, Jong-Hwa Kim
    1993 Volume 19 Issue 6 Pages 1184-1186
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    This study investigated the analytical data of metal components and leaching properties of petroleum fly ash from a U thermal power plant.
    Metal components in the crude oil differed according to the place of production, where it was concentrated as metal oxide type in fly ash containing V, Ni and so on. Valuable metal components of fly ash were treated as a second resource.
    From this point of view, our study carried out leaching, with hydrochloric acid and sulfuric acid of different concentrations in series being used as leachant. Leaching solution obtained a solid-liquid ratio of 1 : 5 at room temperature. Even though dilute acids and water were used as leachant, high concentration of various metal ions could be leached from fly ashes. The 'concentration of V and Ni in leaching solution was 40, 000 ppm, and Ga content was 8, 000 ppm.
    These basic data will be useful for any process for recovery and separation of rare metals in waste.
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  • Atsushi Ikari
    1993 Volume 19 Issue 6 Pages 1187-1189
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Distillation experiments with a hexane-ethanol azeotropic mixture containing a minute amount of water were performed with an Oldershow-type column. The reflux ratio was fixed at about eight and the distillate was returned to the still.
    From the ratios of the mole fraction of water in the distillate to that in the bottoms, the Murphree vapor efficiencies of water were determined. They ranged from 0.078 to 0.134 and were not influenced by the vapor rate.
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  • Toshifumi Ishikura
    1993 Volume 19 Issue 6 Pages 1189-1192
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Experiments were carried out in a half-column of a spout-fluid bed, incorporating the central flow in addition to the auxiliary side flow. A binary particle mixture containing coarse and fine glass beads was investigated.
    Six different flow patterns-such as spouting with aeration (SA) and spout-fluidization (SF) -were identified and mapped as regimes depending on the relative values of the central and the auxiliary air flow rates. Also, compared with the regime map for coarse particles only, it was recognized that a binary-particle mixture made the amount of gas flow to form SA or SF region small, but the operation range for SA or SF became narrow and the size segregation in the direction of radius appeared.
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  • Effects of repeating polymerization of gel on water flux
    Shuji Sakohara, Yasushi Tateishi, Masashi Asaeda
    1993 Volume 19 Issue 6 Pages 1192-1195
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Separation properties of water/ethanol mixtures by acrylamide gel polymerized repeatedly in the pores of silica-alumina thin membrane were examined. By repeating the polymerization of gel, the flux of ethanol decreases monotonously, while the permeation of water is promoted as the flux of ethanol becomes sufficiently small. As a result, extremely high separation performance can be obtained. The increment of water flux is closely related to the swelling degree of the gel in water, and an optimum gel composition for the promotion of water permeation exists.
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  • Muneharu Goto, Masahiro Goto, Fumiyuki Nakashio, Chiaki Hatanaka, Tosh ...
    1993 Volume 19 Issue 6 Pages 1195-1198
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Surfactant-coated lipase was prepared with a newly synthesized surfactant. The synthesis reaction of glycerides was investigated using the lipase and substrates of glycerol and oleic acid. The activity of the enzyme, which is significantly higher than that of native enzyme, depends strongly on the water content, and the optimal water content is about 3040 mol%. The main product of this enzyme reaction was monoolein under the present experimental conditions.
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  • Mitsuo Kamiwano, Meguru Kaminoyama, Kazuyoshi Arai, Masaru Seki
    1993 Volume 19 Issue 6 Pages 1198-1202
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    We developed multi-points and a real-time measuring method of measuring local slurry concentration using transmitted light-system mode in a solid-liquid agitated vessel by applying a real-time digital signal processing system which we produced for trial. By this method it is possible to measure local slurry concentration in the agitated vessel in an extremely short time interval. We defined a coefficient of local concentration variation and an average coefficient of local concentration variation in the vessel, using the measured concentration data, and proposed a method of indicating particle dispersion state in the solid-liquid agitated vessel.
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  • Takahiro Kawakatsu, Shin-ichi Nakao, Shoji Kimura
    1993 Volume 19 Issue 6 Pages 1202-1206
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Random packing phenomena of equal sized spheres (of micron or submicron size) were simulated assuming a quasi-three-dimensional packing structure based on rhombohedral tetragonal ordination. In the simulation, the probability of particle movement through a packed layer was determined with simple rules in accordance with the contact pattern of particles. The calculated average void fraction was 0.37, a value which agreed with that of random close packing and many previous experimental results with equal spheres.
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  • Haruo Yamazaki, Toshiro Murase, Masashi Iwata, Mompei Shirato
    1993 Volume 19 Issue 6 Pages 1206-1209
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    To analyze the flow pattern in the filter chamber of a dynamic filter with a rotating disk, the velocity of Newtonian liquid flow without permeation was measured by use of a fiber-optic laser velocimeter. The effects of the rotational speed of the disk and chamber dimensions on the flow pattern can be evaluated in terms of the ratio K of the tangential velocities of the core and the rotating disk. New empirical equations for K-value are presented and successfully correlate our data compared with the former equations.
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  • Akihiro Matsuura, Hajime Nakamura, Setsuro Hiraoka, Yutaka Tada, Yoshi ...
    1993 Volume 19 Issue 6 Pages 1209-1212
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Gas-liquid two-phase turbulent flow along a vertical flat plate immersed in bubble flow was numerically simulated using the SIMPLER method. Prandtl's mixing length theory was applied to estimate eddy viscosity. The predicted turbulent velocity profiles were in good agreement with the measurements in a bubble flow near the vertical plate, compared with the calculated laminar velocity profiles.
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  • Activation of magnesium oxide hydration
    Yukitaka Kato, Norimichi Yamashita, Yoshio Yoshizawa
    1993 Volume 19 Issue 6 Pages 1213-1216
    Published: November 10, 1993
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    A chemical heat pump using the reaction system of magnesium oxide/water was studied as a thermal storage system by kinetic analysis. This heat pump has been rarely studied because of the low activity of MgO hydration. Therefore, an experimental analysis for activation of MgO hydration was carried out. The result shows that the activity of MgO dehydrated at low temperature (below 623K) is several times higher than that of commercial MgO. The possibility was shown that the reaction system of MgO/H2O is applicable, and the working range of such chemical heat pumps was shown.
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