KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 18 , Issue 6
Showing 1-31 articles out of 31 articles from the selected issue
  • Shiro Kaneko, Masaaki Shirai, Ken Toyokura
    1992 Volume 18 Issue 6 Pages 773-780
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Phosphorus removal rate of low phosphate ion concentration by crystallization was investigated using magnesia clinker seed crystals. A decreasing-rate equation of phosphate ion concentration was correlated with second order concerning phosphate ion concentration by a batch shaking method under conditions of constant pH and calcium ion concentration. The rate constant obtained by a batch shaking method was found to be 4.525.11×10-5m3/m2h (mol/m3) at pH=8.28.4 and [Ca] =1.25mol /m3. In addition, the rate constant including variations of solution pH and calciumion concentration was found to be 3.867.44×10-4m3/m2h (mol/m3) 2.5
    On the other hand, the rate constant obtained by a packed column method was found to be 4.835.72×10-5m3/m2h (mol/m3) under conditions of pH=8.39.0 and [Ca] =1.25mol/m3. This was nearly equal to that by the batch shaking method.
    Furthermore, the decreasing rate in a packed-column experiment using a synthetic feed solution and that in the pilot-scale experiment using secondary effluent were compared. There was highly close relationship between the packed-column experiment and the pilot-scale experiment.
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  • Noriyuki Yamada, Eiichi Abe, Hideharu Hirosue
    1992 Volume 18 Issue 6 Pages 781-789
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Segregation of particles resulting from difference in size has been observed in spray-dried products consisting of particles with a wide size distribution. As an application of this segregation phenomenon to encapsulation technology, spray-drying suspensions of two particles of two different sizes was carried out for the purpose of producing microcapsules having a shell made up of fine particles. Spray-drying suspensions of SiC-SiC mixtures with a size ranging from 1 to 10 μm provided microcapsules thoroughly covered with finer SiC particles under the conditions of a volume fraction of finer particles larger than 2/3 and a particle size ratio less than 0.2. When colloidal silica of nm order was used as a shell material 2 μm magnesium hydroxide carbonate of as a core material, microcapsules free from micropores of size more than 10 nm were obtained. The microcapsules showed sustained release behavior in an acidic solution of pH 2, which seemed to be induced by micropores in the shell formed after dissolution of the soda component.
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  • Tomoaki Miho, Naotake Katoh, Shigehiko Yamamoto
    1992 Volume 18 Issue 6 Pages 790-795
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Recently, chemical process operations are becoming more precise, making process control more difficult by conventional dynamics and control theories alone. The zone melting process considered in this work is a typical example of advanced chemical processes and requires highly precise operations. A precise temperature profile must be achieved and maintained against strong disturbances due to the movement of a sample tube or heaters and to interactions between heaters.
    To overcome this difficult problem, a new zone melting process is proposed in this paper. Without movement of either sample tube or heaters, realization of the desired time-varying temperature profile is attempted by manipulation of fixed heaters. The process dynamics are treated as a distributed-parameter system. Applying distributed parameter control to the zone melting process in a simulation, simulation verified that the process could be realized. Moreover, experimental results using an anthracene zone melting apparatus also showed good control performance.
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  • Ryôkichi Yamada, Shuntarô Koyama, Hiroshi Miyadera, Norio ...
    1992 Volume 18 Issue 6 Pages 796-803
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The pressure swing adsorption method was employed to concentrate oxygen in the air using zeolite adsorbent. Nitrogen adsorption behaviour was studied, using vacuum desorption and purge desorption. A part of the oxygen produced served as purge gas in the operation. The effects of operating factors related to the purge oxygen, such as desorption pressure, amount of purge gas, flow rate and temperature, were investigated to improve the efficiency of nitrogen desorption without oxygen leakage from the adsorption bed.
    The amount of desorbed nitrogen increased with reducing desorption pressure.
    The amount of purge oxygen increased with decreasing desorption pressure and temperature. A larger amount of nitrogen was found to desorb by the vacuum purge method, resulting in high-efficiency nitrogen desorption achieved in operating the adsorption regenerator.
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  • Hiroyo Matsumoto, Hikaru Kitamura, Toshihiro Kamata, Nobuyuki Nishikaw ...
    1992 Volume 18 Issue 6 Pages 804-812
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    We have conducted a series of basic experiments in CO2 removal from the flue gas of a thermal power plant by use of hollow-fiber gas-liquid contactors. The results indicated that microporous membranes are suitable for the CO2-MEA (monoethanolamine) system because the overall mass transfer coefficient K of the membrane is approximately 10 times that of composite membranes consisting of microporous membranes and homogeneous membrane. The value of K for the CO2-MEA system could be theoretically estimated by the theory of mass transfer with chemical reaction in the hollow-fiber contactor when there is no wetting of the microporous membrane. Due to the high hydrophobicity of teflon membrane, it is not subjected to wetting when used in the CO2-MEA system. This was confirmed by approximately 4000 hours of continuous treatment testing. The overall volumetric mass transfer coefficient Ka of the hollow-fiber contactor is more than five times larger than that of a conventional packed bed, which suggests that adoption of the present method has the advantage of making the absorber more compact.
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  • Shuzo Ohe, Toshiyuki Komori
    1992 Volume 18 Issue 6 Pages 813-818
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A vapor-liquid equilibrium (VLE) prediction expert system for designing a distillation process has been developed to select the optimum method of prediction and to link with a specialized program, using Al language ART. Al technology is effective for the development of such a complex system as the VLE prediction system, which requires much non-numerical and empirical knowledge that is difficult to process using conventional computer technology.
    The following knowledges were implemented in the present system : those
    (1) to determine each structural formula from the name of components in a mixture.
    (2) to classify the mixture from the formula, and
    (3) to select a prediction equation based on the classified mixture.
    The present system is especially useful for the engineer who has no special knowledge of VLE prediction. The system can generate VLE by merely inputting both a component's name and the operating pressure.
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  • Hajime Ino, Nobuyuki Imaishi, Mitsunori Hozawa, Katsuhiko Fujinawa
    1992 Volume 18 Issue 6 Pages 819-826
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The effect of type of electrode on the continuous demulsification of W/O emulsion under an A.C. electric field was investigated experimentally.
    Kerosene, NaCl aqueous solution, and Span 80 were used respectively as the oil phase, the internal aqueous phase and the surfactant. As the demulsifier, vertical acrylic cylindrical columns of 4.9 cm I.D. and 45 and 100 cm in height were used without stirring. As the conductive electrodes, copper electrodes, the tops of which are of disc-like, conical and spherical were used. As the nonconductive ones, disc-type electrodes made of glass and paintcoated metal were used. Effects of type of electrode and of the experimental conditions an the maximum demulsification rate in continuous operation, Vd [s-1], defined as the maximum possible emulsion flow rate per effective column volume, were examined. The effect of electrode shape on Vd was insignificant, although the disc-type ones showed the highest Vd.
    The following experimental equation was obtained.
    Vd=K·Cs-0.35·d3p·E0.75
    K=2.1×1010 [m-2.25·s-1·V-0.75]
    for the conductive copper electrode and
    K=1.6×1010 [m-2.25·s-1·V-0.75]
    for the nonconductive glass electrode.
    Here Cs is the volume fraction of surfactant in the oil phase [-], dp is the average drop diameter [m] and E is the apparent strength of the electric field [V·m-1]. Stable demulsification was always possible with the nonconductive electrodes. For the conductive metal electrodes, Vd was larger than that for the nonconductive ones.
    However, electric sparking occurred when the tip of the electrode top approached the W/O emulsion phase, and stable operation was not possible.
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  • Keisuke Fukui, Satoshi Syoya, Tatsuo Kanki
    1992 Volume 18 Issue 6 Pages 827-831
    Published: November 10, 1992
    Released: November 12, 2009
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    Both weak and strong unstably stratified turbulent flows are formed downstream over a flat plate heated at different temperatures in the spanwise direction. In such a mixed, unstably density-stratified turbulent flow the velocity and temperature were measured simultaneously to investigate the structures of the flow field and the turbulent heat transfer. Strong upward convection was observed in the strong unstably stratified region. As a result of the upward convection a vortex was formed in the weakly unstable region, causing a flow field of complex structure. The structure of heat transfer was investigated by profiles of mean temperature and turbulent heat flux obtained by measurement.
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  • Masaaki Yokota, Ken Toyokura
    1992 Volume 18 Issue 6 Pages 832-839
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    L-SCMC seed crystals were grown in a supersaturated solution of DL-SCMC with sodium chloride, and the generation rates of fine crystals in the supersaturated solution and adhering rates of fine crystals on the surface of seed crystals were measured. At 2.1×10-4kg·kg-1 of operational supersaturation, both the generation rates and adhering rates of fine crystals remained almost constant throughout the experimental period. At higher operational supersaturation (5.7×10-4, 8.9×10-4, and 16.7×10-4kg·kg-1), however, the adhering rates of fine crystals were almost constant for initial 6.5, 5.5, and 3.5 hours of growth time, and then became almost 0. Also, generation rates of fine crystals were constant for initial 5.5, 4.5, and 3.0 hours and increased after these periods. When the seed crystal surfaces were observed, it was found that substantially all the adhering fine crystals became buried into the seed crystals. The time when adhering fine crystals began to bury themselves closely agreed with the time until the adhering rates of fine crystals became 0.
    From these results, it was considered that fine crystals adhered to the surface of a seed crystal at a constant rate during the initial growth time; then these adhering fine crystals began to bury themselves into the seed, and the adhering rate and burying rate of fine crystals were balanced in these periods.
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  • Yasunobu Akiyama, Katsuyuki Nakano, Tsuneyuki Sato, Nobuyuki Imaishi
    1992 Volume 18 Issue 6 Pages 840-848
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    ZrO2 thin films were prepared from β-diketonate complexes on the inner tube wall of a horizontal tubular hot-wall CVD reactor. Experimental temperature, pressure, flow rate and oxygen concentration were in the range of 823K-973K, 0.4 kPa-24 kPa, 0-1500sccm and 0-50 mol%, respectively.
    The dependency of growth rate, color and crystal form of the deposited ZrO2 filmes on experimental conditions was studied experimentally.
    Numerical calculations of the governing equations, with the gas-phase reaction rate constant as an unknown parameter, were conducted to determine the gas-phase reaction rate constant, with which the theoretical growth rate distributions can be fitted to the experimental ones for all runs. The activation energy of the gas-phase reaction, using Zr (DPM) 4 as a source compound, was found to be 140kJ/mol. This simulation also indicated that the pressure drop has to be taken into account in a LPCVD calculation.
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  • Hiroshi Takahashi, Yoshihiko Honda
    1992 Volume 18 Issue 6 Pages 849-855
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Velocity and stress profiles related to particles in moving beds are estimated theoretically. based on a flow model that describes the stress-strain relationship of flowing bulk solids. This model takes account of the expansion in bulk volume of the particle bed during shearing deformation. The validity of the theory is examined by applying the model to a gas-solid crossflow moving bed and gravity flow of solids (without gas flow) through a vertical tube. Further, the theory is extended to predict the behaviour of solids with gas flow in a vertical tube. Predicted velocity and stress profiles depend on the mode of gas-solid contact, cocurrent or countercurrent. The frictional force of solids on a wall surface increases markedly in cocurrent flow, which induces considerable lag of particle velocity on the wall surface. The model parameter indicating the bulk volume expansion effect is a function of the particle velocity, and is almost unaffected by the flow rate of gas moving through the particle bed.
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  • Takao Suganuma, Naotake Katoh, Shigehiko Yamamoto
    1992 Volume 18 Issue 6 Pages 856-861
    Published: November 10, 1992
    Released: November 12, 2009
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    The main control problem of a batch process is how to overcome its highly nonlinear dynamics.
    In this work, sliding-mode control, which shows nonlinear control action, is applied to a strongly endothermic NH4-alum pyrolysis reactor. Both simulation and experiments are carried out for this process. Results by sliding-mode control compared with PID control are quite favorable and suggest the possibility of controlling Al2O3 product particle size and its distribution.
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  • Mansour Shirvani, Makoto Inagaki, Tadaaki Shimizu
    1992 Volume 18 Issue 6 Pages 862-866
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    This paper proposes a parallel combination model of the well-known transfer function G (s) =Kexp (-Ls) / (1+Ts) and shows its ability to approximate complex dynamic behaviour such as that of distributed parameter systems. First, the gain and phase of the transfer function were calculated and were shown to have resonance in its frequency response with appropriate parameters, which means that their slopes can be varied in a wide range. As a result, the function can approximate various dynamic behaviours well. Next, their asymptotic behaviours, which can represent the relation between the parameters of the function and help to estimate approximate values of the parameters, were shown. Fitting to frequency and indicial response data of heat exchangers which are common in chemical industries and the dynamic behaviours of which have been studied from theoretical and experimental points of view were done. Results of the fitting showed a good approximation, not only in frequency response but also in indicial response. This indicates that the transfer function model presented here can fit to various complex dynamic models.
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  • Jiro Suzuki, Masato Hosaka, Yoshitaka Kawasaki, Hironao Numoto, Atsush ...
    1992 Volume 18 Issue 6 Pages 867-874
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To check the completion of catalytic combustion, the catalytic reaction of a fuelrich mixture (rich enough to keep the catalyst temperature high) and lean intermediates formed upstream of a honeycomb substrate were studied. Using kerosene as a rich mixture and propane/air or CO/air mixture as lean intermediates, the effects of a platinum-group metal catalyst and weight loading of the metal on combustion completion were investigated.
    To be able to complete the combustion using the catalyst at the highest temperature possible, the catalyst's heat durability was also examined. The results are summarized as follows.
    1. Oxidation completion of the lean intermediates at lower temperature depends on both the kind of catalyst and the metal weight of boating.
    2. Combustion completion of rich mixture at higher temperature does not depend on the kind of catalyst, but it is affected by the metal weight loading. In this case, oxidation completion of the lean intermediates in the downstream region depends only on the weight of loading.
    3. Durability of the catalyst depends on both the kind of catalyst and weight of loading.
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  • Masayuki Sasaki, Takeshi Shimazu, Kozo Nakamura, Hiroyuki Kitahara, At ...
    1992 Volume 18 Issue 6 Pages 875-880
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Hydrodynamic behavior in a fermenter for brewing was studied experimentally. Using a conical fermenter of 1 m diameter and 3.5 m height. the CO2 germination rate, gas volume flux, and liquid flow rate were measured. To investigate the bubble behavior, the bubble size distribution, bubble rise velocity and gas holdup were measured, using a two-dimensional conical fermenter of 0.3 m width and 1.3 m heigt.
    Analysis of the data shows that the driving force of the recirculation is the radial gradient of density that results from the uneven distribution of CO2 bubbles. The circulating flow model explains the hydrodynamic behavior of the fermenter.
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  • Seiichi Deguchi, Hitoki Matsuda, Masanobu Hasatani, Kazushige Kato, Iw ...
    1992 Volume 18 Issue 6 Pages 881-886
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To clarify the fundamental burning characteristics of nitrocellulose/nitroglycerin double-base solid propellant, measurement of the burning rate, identification of the composition of exhaust gases and observation of the burning appearance were carried out under various conditions. The pyrolysis behavior of solid phase was investigated by thermogravimetry of the double-base solid propellant particles. The results were as follows.
    1) The combustion of the double-base solid propellant is imperfect in the range of low burning rate.
    2) The combustion characteristics of the double-base solid propellant gradually change to the theoretical ones with increase in burning rate.
    3) The burning rate is increased by inserting a thin aluminum sheet in the doublebase solid propellant.
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  • Toshikuni Yonemoto, Shigeyuki Takagi, Takeyuki Doi, Fumiko Uchida, Tei ...
    1992 Volume 18 Issue 6 Pages 887-893
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Fine particles of hydrated titanium dioxide were prepared by hydrolysis of titanium tetraethoxide in ethanol solution. Time courses of conversion to solid and size change of the solid particle were measured, and small-angle X-ray scattering measurements were conducted for the solutions from which solid particles were removed by filtration. The initial concentration of titanium tetraethoxide required to produce unagglomerated and monodispersed particles was determined. The effect of addition of a dispersant, hydroxypropylcellulose, on particle formation was also elucidated. Chronomal analysis was applied to clarify the kinetics and the mechanism of particle formation. The rate process was explained by the following kinetic model. 'Nuclei' that contain many titanium atoms are generated in the early stage and subsequently deposit on the surface of particles under the diffusion limited condition. The diameter of the 'nuclei' was calculated from analysis of the small-angle X-ray scattering data.
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  • Kazuyuki Suzuki, Morio Iriyama, Yoshiteru Nakamori
    1992 Volume 18 Issue 6 Pages 894-903
    Published: November 10, 1992
    Released: November 12, 2009
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    Rotary kiln sewage sludge incinerators play an important role in the sewage treatment system. However, a practical control system has not yet been developed because of the complexity of the process, including large disturbances of inputs and lack of accurate instruments for measuring state variables.
    In this paper, an interactive modeling method based on fuzzy set theory is applied to modeling and analyzing the dynamic performance of the process.
    In fuzzy modeling, the process dynamics are represented by a number of IF-THEN rules comprised of fuzzy variables in the premise (IF) part and an ARX model in the consequence (THEN) part. Each rule claims local characteristics of the process in each sub-space. By integrating these sub-models, we can predict the process performance more correctly.
    A fuzzy model was identified by using time-series data after various statistical examinations. The model's accuracy was evaluated by an error index and computer simulations, and the model was compared with a conventional time-series model. The results showed that the fuzzy model is superior in describing process performance. Fuzzy modeling is also expected to be an effective method for other ill-structured processes.
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  • Kunihisa Osasa, Hideo Nakakura, Satoshi Nitta
    1992 Volume 18 Issue 6 Pages 904-910
    Published: November 10, 1992
    Released: November 12, 2009
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    Deashing of ultrafine coal slurries by selective flocculation was examined experimentally by using anionic polyacrylamides (polymer) with different hydrophobicities. As a result, (1) the agitation condition giving the optimum separation was clarified in terms of floc formation; (2) the addition of dispersant and pH adjustment of slurries were necessary for dispersion between coal and ash particles ; (3) with increasing hydrophobicity of the polymer the coal recovery increased, but the optimum dosage region of the polymer to maximize ash reduction became narrower; (4) the amount of the polymer adsorbed, and therefore the coal recovery, increased with increasing rank of the coal; (5) ash reduction was improved by washing with water to release the ash particles entrapped in the sediment enriched with carbonaceous matter.
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  • Tatsuo Kanki, Susumu Harada, Ryuichi Sakamoto, Takao Matsumoto, Isamu ...
    1992 Volume 18 Issue 6 Pages 911-919
    Published: November 10, 1992
    Released: November 12, 2009
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    Flow of a rarefied gas in a rectangular groove faced with a moving plate is analyzed numerically, using a linearized Boltzmann equation focussing on the flow in the transition regime, and flow conductances at arbitrary Knudsen numbers, as well as the gas velocity fields, are made clear. Free molecule iteration and slip-continuum solutions are also given to investigate the asymptotic behaviors in the two limitting regimes and to check the validity of the numerical solution. Flow conductances, in the cases of Couette and of Poiseuille flows, are found to take greater values as the aspect ratio of the channel becomes larger. The Couette flow conductance is almost insensitive to the Knudsen number, though it shows a tendency to increse very slightly with Knudsen number when the aspect ratio is small and vice versa. The Poiseuille conductance increases with Kn at high Knudsen numbers, decreases at low Knudsen numbers, and has a minimum (the Knudsen minimum) at the transition regime. The present results will be applied to designing various types of gas lubrication systems and mechanical molecular pumps.
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  • Shinji Kambara, Takayuki Takarada, Nobuyoshi Nakagawa, Kunio Kato
    1992 Volume 18 Issue 6 Pages 920-927
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The effect of coal properties on nitrogen devolatilization in coal during the rapid pyrolysis of 20 coals from lignite to semianthracite has been investigated at 853K to 1488K. Almost all the nitrogen in coal (Fuel N) devolatilized as NH3, HCN and N2. Fuel N conversion or distribution of nitrogen compounds was strongly influenced by coal properties and pyrolysis temperature. The conversion of coal nitrogen roughly showed a tendency to increase with decreasing carbon content.
    NOxemission from various coals was investigated by using a coal combustor of laboratory scale. The relation between the behavior of coal nitrogen species during rapid pyrolysis and NOxformation during combustion was examined.
    A model incorporating devolatilization of the volatile nitrogen species was proposed to explain the influence of coal composition. On the basis of the proposed model a determining factor correlated with NOx conversion in a turbulent flow furnace was discovered.
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  • Masahiro Goto, Takahiko Kakoi, Muneharu Goto, Makoto Narisako, Fumiyuk ...
    1992 Volume 18 Issue 6 Pages 928-934
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Using newly synthesized surfactants, selective separation of copper and molybdenum with 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A) as a carrier was carried out, using liquid surfactantmembranes (LSMs). The influence of surfactants and carrier concentration in the liquid membrane as well as conditions of internal and external aqueous phases on the separation were investigated. The selection of stripping reagents is the key factor in the above system. It was clarified that effective separation of copper and molybdenum can be done by using mannitol as a stripping reagent of an internal aqueous phase. The surfactant also strongly affected the extraction rate and concentration of molybdenum into the internal phase, new cationic surfactant gave the best results in separation and concentration of molybdenum. The extraction behavior of molybdenum by LSMs could be explained by an interfacial reaction model between the carrier and cationic species of molybdenum, taking into account the break-up of the emulsion. It is very important to use stable emulsions for high concentration of molybdenum.
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  • Masami Furuuchi, Tomoo Honda, Hideo Harifuchi, Keishi Gotoh
    1992 Volume 18 Issue 6 Pages 935-941
    Published: November 10, 1992
    Released: November 12, 2009
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    The transverse bed motion of a binary mixture of spherical and non-spherical particles in a rotating horizontal cylinder was experimentally investigated in relation to the rotational speed N of the cylinder, the bed height and the mixture ratio of the particles. Particle segregation due to shape difference was also examined.
    At lower N, bed motions categorized as slipping and slumping occurred and were explained in terms of the angle of repose of the mixtures. At higher N. the cascading and cataracting motions occurred. They could not be explained by the angle of repose alone because of the shape segregation of particles. In the cascading and cataracting flow regions, alternating stripes of particle layers arose along the cylinder axis. The variation in the local mixture ratio became pronounced in the cataracting region.
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  • Yasuo Kousaka, Yoshiyuki Endo, Yasunobu Nishie
    1992 Volume 18 Issue 6 Pages 942-949
    Published: November 10, 1992
    Released: November 12, 2009
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    To make clear the mechanism of liquid bridge formation, profiles of a bridge formed by ideal pure water between two identical spherical particles were analyzed theoretically by applying the Kelvin equation for zero contact angle. It was found that the profiles of liquid bridges could be expressed as functions of surrounding humidity, properties of the liquid, particle diameter and other variables. It was also found that the neck diameter of a water bridge formed by the Kelvin effect was very small (less than 100 nm). Microscope observation of the profiles of water bridges formed between two convex glass lenses and two glass beads which were left in a thermohygrostat supported this analysis, and, at the same time, observation sug-gested that a very small amount of soluble impurity contained in the bridge might have a significant effect on bridge formation.
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  • Yoshiyuki Endo, Yasuo Kousaka, Yasunobu Nishie
    1992 Volume 18 Issue 6 Pages 950-955
    Published: November 10, 1992
    Released: November 12, 2009
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    The mechanism of liquid bridge formation between two identical spherical particles was theoretically and experimentally analyzed, taking the effect of liquid impurity into account. A modified Kelvin equation, in which the decrease in vapor pressure caused by soluble impurities (salts) contained in the liquid was taken into account, was applied to evaluate the formation and profiles of liquid bridges. It was found that a liquid bridge containing soluble salts could be more easily formed than one formed by pure water, and that the profiles were expressed as functions of the surrounding humidity and solute concentration. In the experiment, bridges formed by Na2SO4, CaCl2 and NaCl solution between two convex glass lenses which were left in a thermohygrostat were observed by a steromicroscope. The effects of humidity and solute concentration on liquid bridge formation could be well explained by the theoretical analysis. It is pointed out that soluble impurities contained in usual wet-powder processing operation have a significant effect on bridge formation between particles after they are dried out.
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  • Eiji Obata, Eishi Hachiro, Makoto Akiyoshi, Koji Ando
    1992 Volume 18 Issue 6 Pages 956-958
    Published: November 10, 1992
    Released: November 12, 2009
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    Glass beads and crushed glass particles of diameters ranging from 1.0 to 5.0 mm were fluidized with tap water. The bed was initially fluidized completely, and then the liquid velocity was gradually decreased to obtain a fixed bed. The relationships of relative particle diameter ratios with the relative heights of the sampling sections in the beds were obtained at 7 mm height intervals. With respect to binary systems of glass beads, good size classification was accomplished at the size ratio of 1.10. This size ratio is much smaller than the widely accepted critical size ratio of 1.30 for classification in liquid fluidization. For a multicomponent system of crushed glass, the continuous classification of various size ranges was observed.
    Inclination of the fluidized column had a great adverse effect of the size segregation.
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  • Shinkichi Yamaguchi, Kaichiro Wakabayashi, Fumihiro Sasai, Hiroyasu Ba ...
    1992 Volume 18 Issue 6 Pages 959-961
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    An experimental study of electroosinotic dewatering was carried out, using a kneaded clay bed. By investigating the experimental results, the following conclusions were obtained. (1) After a long time, a final moisture distribution is formed in the clay bed where the electric current flows but electroosinotic flow does not occur. (2) The gradient of the final moisture distribution curve increases with increasing voltage applied to the clay bed. (3) The minimum moisture content on the final moisture distribution curve can reach a lower value than either experimental data published in the literature or the critical moisture content for dewatering shrinkage of the clay bed.
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  • Kei Sunouchi, Kazuo Takeuchi
    1992 Volume 18 Issue 6 Pages 962-964
    Published: November 10, 1992
    Released: November 12, 2009
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    An extended particle growth rate equation was proposed. This equation is based on the most simplified solution of the collision and coalescence model and can be used both in the free molecular region and in the continuous region under changing conditions. In the free molecular region, transition region, and continuous region, the dependence orders of mean particle size on the product of initial concentration of monomer and growth time were found to be 2/5, 1/4, and 1/3 respectively.
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  • Tomohiro Kawai, Ryuichi Egashira, Junjiro Kawasaki
    1992 Volume 18 Issue 6 Pages 965-969
    Published: November 10, 1992
    Released: November 12, 2009
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    Axial dispersion coefficients and Peclet numbers for fixed beds of various fine particles were measured within the range of mean particle diameter from 4.8×10-5m to 1.7× 10-4m, and that of Reynolds number from 1.0× 10-2 to 2.0. From the experimental results, the effects of Reynolds number, particle diameter and particle size distribution on the Peclet number were investigated and a correlation was proposed. It was suggested from the results of simulation of the chromatogram for preparative HPLC that the Peclet number affected the shape of the chromatogram when the linear velocity of mobile phase was low and the adsorption coefficient was small.
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  • Yoshio Iwai, Tsuyoshi Tara, Toru Ishidao, Yasuhiko Arai
    1992 Volume 18 Issue 6 Pages 969-971
    Published: November 10, 1992
    Released: November 12, 2009
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    The solid molar volumes of naphthalene, biphenyl, 2, 3-xylenol, 2, 5 -xylenol, 2, 6 - xylenol, 3, 4-xylenol and 3, 5-xylenol were measured from 15 to 35°C, using a flotation method, and the results obtained were compared with the literature values.
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  • Toshiro Miyahara, Myung-Sup Lee
    1992 Volume 18 Issue 6 Pages 971-974
    Published: November 10, 1992
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Experiments were performed to understand the effect of trace ethanol on gas holdup, size of bubbles leaving a three-phase fluidized bed, the axial dispersion coefficient and the volumetric mass transfer coefficient. The addition of trace ethanol to water causes a small increase in gas holdup, whereas the size of bubbles leaving the three-phase fluidized bed decreases remarkably, including the wider size distribution. The axial dispersion coefficient obtained from experiments of oxygen absorption into the solution increases significantly with the addition of trace ethanol. This is also true of the volumetric mass transfer coefficient. It is possible that the increase in volumetric mass transfer coefficient could be due to the increase in gasliquid interface area, resulting in a reduction in size of the bubbles.
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