KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 11 , Issue 6
Showing 1-18 articles out of 18 articles from the selected issue
  • Norio Kimura, Masashi Iwata, Kazuyoshi Komatsu
    1985 Volume 11 Issue 6 Pages 621-627
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A capture mechanism of aerosol particles in fibrous mat filters with dust loads was studied, and a method for estimating the collection efficiency of the fibrous mat filter is presented by using an interception model.
    Aerosol particles accumulate on a fiber surface as a filtration process proceeds; this leads to a drastic increase in the collection efficiency of the filter. In this work, it was assumed that a layers of captured particles built up on the front of the fiber and interception by these captured particles was the predominant mechanism of the filtration process of the fibrous mat filter. To obtain the increment of a single fiber collection efficiency due to dust loads, an approximate equation was derived by using Happel's flow field around a cylinder. The correction factor, K, for the mean solidity of the layers of captured particles could be determined experimentally as a function of interception parameter, NR, and inlet dust load m0.
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  • Masahiro Takahashi, Hiroshi Takeuchi
    1985 Volume 11 Issue 6 Pages 628-633
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Studies were conducted on the equilibrium and reaction kinetics for the extraction of cadmium from aqueous chloride solutions by di (2-ethylhexyl) phosphoric acid (D2EHPA) in n-heptane, kerosene, toluene and m-xylene as diluents. Distribution ratios for the paraffinic hydrocarbon solvents are considerably higher than those for the aromatic ones; it was found that the extractable species is CdR2.3HR for n-heptane and CdR2.4HR for the aromatics. The equilibrium constants for the respective extraction reactions were also determined by taking into account the overall stability constants of cadmium chloride complex in aqueous solution.
    The extraction rates of cadmium by D2EHPA in n-heptane as the diluent were obtained using a stirred vessel with a plane interface. The initial extraction rate is proportional to the total concentrations of cadmium in the aqueous phase and of D2EHPA in the organic phase, and inversely proportional to hydrogen ion concentration. The reaction mechanism is also discussed.
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  • Yoshihiro Nakashima, Itiro Fujiwara, Totaro Goto
    1985 Volume 11 Issue 6 Pages 634-639
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The concept of a forced stratified thermal energy storage tank which has multiple compartments divided by insulating and permeable horizontal plates is proposed for energy conservation. Performance of this tank is evaluated by a relatively simple evaluation method and compared with the ideal perfect stratified thermal energy storage tank and perfect mixed thermal energy storage tank. It is suggested that the performance of the forced stratified thermal energy storage tank is high and nearly comparable with the perfect stratified thermal energy storage tank. It is also shown that energy loss with thermal energy accumulation by the forced stratified thermal energy storage tank having 8 compartments is about one-fifth that of the perfect mixed thermal energy storage tank.
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  • Takeichiro Takamatsu, Iori Hashimoto, Yoshihiro Hashimoto
    1985 Volume 11 Issue 6 Pages 640-646
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A new geometric approach is proposed to evaluate the interaction between two control loops. First, it is shown that manipulated variables of a distillation column can be classified into five groups and that the strength of interaction in various pairs of manipulated variables for dual composition control can be evaluated by using only five transfer vector loci. By applying this method, an effective control scheme is developed. The purity of the distillate is controlled by the ratio of liquid to vapor flow in the enriching section and the purity of the bottom product is controlled by the ratio of liquid to vapor flow in the stripping section. It is confirmed by conducting a simulation of the distillation that this control scheme gives good controlled response to set-point change. In addition, it can also be insensitive to a disturbance in the flow rate and can be realized without complicated calculations
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  • Tadaatsu Ido, Seiichi Yamaoka, Donghai Shen, Shigeo Goto
    1985 Volume 11 Issue 6 Pages 647-654
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The co-methanation of carbon monoxide and carbon dioxide was investigated in a stirred-slurry reactor containing nickel powder (catalyst) and silicone oil (inert solvent) at 250°C and atmospheric pressure.
    The respective rates of hydrogenation of carbon monoxide and carbon dioxide were measured to obtain the kinetics of co-methanation. In the stirred-slurry reactor, the resistances due to mass transfer from liquid to solid and intraparticle diffusion were negligible but the resistance of mass transfer from gas to liquid could not be neglected. The expressions of intrinsic reaction rates were the same as those in the packed-bed reactor without inert solvent. The hydrogenation of carbon dioxide was inhibited by the presence of carbon monoxide from the point where the concentration exceeds 1.23×10-3 mol/m3. The degree of inhibition was strongly dependent on the concentration of hydrogen.
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  • Hiroshi Yukawa, Akihiro Suda, Teruhiko Hoshino
    1985 Volume 11 Issue 6 Pages 655-661
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Recently, clarification of the rheological characteristics of gelatinous materials has become important since they are closely related to the fields of ultrafiltration, expression, immobilization of enzymes or bacteria, gel permeation chromatography and the like. In these fields, gelatinous materials are generally applied by compressive stress. Therefore, in the present work, the rheological behavior of gelatin gel under compressive stress was investigated. The two-element Voigt model is usable in this case. The elastic modulus and the viscosity were calculated by the model and the effects on them of compressive stress, gelatin concentration, temperature and pH were experimentally investigated.
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  • Yoshinori Itaya, Norio Arai, Masanobu Hasatani
    1985 Volume 11 Issue 6 Pages 662-667
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The effects of suspension concentration, depth of layer and boundary optical condition on the rate and efficiency of radiative energy collection of a volume heat-trap type solar collector in which a FPSS is used as a heat vehicle and storage medium were studied experimentally and theoretically. Experiments were conducted for the stagnant layer of a graphite-diethylphthalate suspension, heated stepwise by a Xe-lamp from the upper side.
    The theoretically calculated results were in satisfactory agreement with the experimental data, and it was shown that the efficiency of radiative energy collection in this type of solar collector could surpass easily that in the surface heat-trap collector. In addition, peak efficiency was observed at a certain suspension concentration, and the optical thickness at the peak was almost constant regardless of the depth of the suspension layer.
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  • Masato Tanaka, Takashi Izumi, Hiroyoshi Yoshimura
    1985 Volume 11 Issue 6 Pages 668-673
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Impeller speeds at which gas enfoldment from the free liquid surface and stationary dispersion of enfolded bubbles began were measured by changing various factors such as the shape of the impeller, the number of baffles, the impeller location, the liquid depth, the tank diameter and surface tension and by installing a draft tube.
    For all impellers investigated (six-bladed disc turbine, four-bladed pitched fan turbine, three-bladed propeller), the installation of baffles and the increase of their number raised the impeller speed for gas enfoldment. For the condition of four baffles, the following expression was obtained :
    Nre2di/g=A (σ/σ0) 3.6 (di/DT) -3.6 (hL/DT) c (hL-hi/hL) d
    where the values of A, c and d depended on the shape of the impeller.
    For impellers other than the disc turbine, installing the draft tube and lengthening it raised the impeller speed for gas enfoldment.
    Moreover, simultaneous installation of baffles and draft tube was found to raise the impeller speed for gas enfoldment for all impellers.
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  • Fumiaki Takeuchi, Takeshi Kano, Satoshi Yamada, Sigenori Fukuda, Kiyos ...
    1985 Volume 11 Issue 6 Pages 674-679
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Dispersion phenomena of coal dust and methods to prevent dispersion were studied in a wind tunnel.
    The critical friction velocity had its minimum value when the particle diameter of coal dust was around 180 μm. At wind speeds between 10 and 15 m/s, the dispersing quantity of coal dust had its maximum value when the particle diameter of coal dust was between 200 and 600 μm.
    The dispersion quantity of less dispersable fine powder increased when it was mixed with more dispersable powder or when coarse grain was located on the surface of the powder bed, and the quantity had its maximum value at a certain ratio of the mixture.
    The addition of water to coal dust was effective for preventing dispersion, especially at low wind speed and short elapsed time after its addition. Non-dispersion chemicals completely prevented dispersion. Fundamental data to determine the desirable amount and concentration of the chemicals for practical use were obtained.
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  • Mompei Shirato, Haruo Yamazaki, Toshiro Murase, Masashi Iwata
    1985 Volume 11 Issue 6 Pages 680-686
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In dynamic filtration, also known as thin-cake staged filtration, final solid content in discharged cake is kept constant through the power required to rotate the disk in the filter chamber. Torque on a grooved disk enclosed in a cylindrical chamber without permeation or throughflow was measured to analyze operational factors affecting the power. Effects of groove and chamber dimension on induced liquid flow and frictional resistance of rotating disk were studied.
    Groove effects on the torque were evaluated in terms of a newly defined factor, taking into account the number and width of grooves. Chamber dimension effects were represented by means of the factors for both axial and radial clearance.
    Correlations of torque coefficient as a function of the operational factors are proposed for turbulent flow. The relative core velocity of liquid flow is also correlated for estimating velocity profile in the chamber. It is shown that the power and the induced flow are strongly dependent on the groove, the radial tip clearance and the rotational speed of the disk.
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  • Syoichi Morohashi, Nobuichi Ooi, Isamu Matsubara, Saburo Yashima
    1985 Volume 11 Issue 6 Pages 687-695
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    An experimental study of the temperature rise in brittle materials was carried out by use of a rotating friction mill devised to produce submicron powders by the mutual friction grinding of two specimens of the same brittle materials. Limestone, marble and talc were used as samples. The temperature rise in a cylindrical specimen at the stated working speed and load was measured by a thermocouple method. As a result of analysis by two-dimensional steady-state conduction, it was found that the temperature rise in the cylindrical specimen was proportional to the friction work. This was in accord with the experimental results. Because of this fact, the working speed and load could be explained to be in equivalent relation for the temperature rise. Also, investigation of the temperature rise distribution of the cylindrical specimen showed that it became maximum on the central axis and decreased in the radial direction. Furthermore, presuming the temperature rise on the real contact surface it was apparent that extremely high surface temperature might be developed even under moderate conditions of working speed and load. This temperature rise in brittle materials was closely related to comminution efficiency and the occurrence of mechanochemical phenomena.
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  • Ichiro Funada, Kazuhiko Asahara, Yasuo Hirose
    1985 Volume 11 Issue 6 Pages 696-701
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    From the industrial point of view, it is important to determine the optimum feed location of the upper column in order to produce high-purity oxygen product in an air separation process.
    In this work, first the optimum feed stage was defined as the feed location at which maximum product oxygen purity is realized at the bottom of the upper column under all given stages.
    Secondly, by using the nonideal multicomponent theoretical stage calculation method, this optimum theoretical feed stage was simulated for some design factors such as required Air/O2, that is, air rate, product oxygen rate for the double rectification column, theoretical stage numbers and the oxygen purity of product at the upper column, and then these relations were simulated and were plotted on a graph.
    If two design factors are given on the graph, the one remaining design factor and optimum theoretical feed stage number are determined by using the graph. Therefore, in this work, an industrially useful design method for optimum feed location at the upper column is proposed for high-purity oxygen product in an air separation process.
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  • Nobuyuki Fujisawa, Hiroyuki Shirai
    1985 Volume 11 Issue 6 Pages 702-707
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Centrifugal instability for the occurrence of Taylor-Görtler vortices was investigated theoretically for turbulent boundary layers with polymer additives. A neutral stability diagram for critical Görtler parameters was obtained in relation to some parameters dependent on the type of polymer and its concentration.
    The results indicate that the critical Görtler parameter decreases with increasing elongational viscosity and with increasing drag reduction by the Toms phenomenon. The critical Görtler parameter is also significantly affected by the Reynolds number, and turbulent boundary layers become more unstable for the occurrence of Taylor-Görtler vortices as the Reynolds number increases.
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  • Toshio Kawaguchi, Gunji Hira, Toshihisa Wakasugi, Takeji Tatsumi
    1985 Volume 11 Issue 6 Pages 708-714
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A crude acetylene produced by partial combustion of natural gas and containing 1 % of heavy acetylene compounds such as methyl acetylene as impurities was purified by a large moving-bed adsorber for the purpose of vinyl acetate synthesis. Through adsorption by a moving bed of crushed active carbon, the impurities were reduced to as low as 0.1-0.3 %.
    Experiments were performed with three adsorbers of different sizes (100, 320 and 1000 mm in diameter) to obtain data on mass transfer as well as to make clear the effect on designing and operating a moving-bed adsorber. Finally, an industrial plant 2.2 m in diameter, 17.5 m in height and having a 38 m3 bed volume was constructed.
    Through experiments with equipment of different sizes, the following results were obtained. The moving velocity of the carbon particles showed a considerable distribution in the radial direction and the value of HETP became larger with increasing bed diameter.
    In spite of these disadvantages, the operation of the industrial adsorber showed good performance, resulting in high-grade purification of the gas, low by-products formation and low deactivation rate of the catalyst in vinyl acetate synthesis.
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  • Toshiro Murase, Hideo Nakakura, Hidetoshi Mori, Mompei Shirato
    1985 Volume 11 Issue 6 Pages 715-720
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A method was studied for determining the final equilibrium moisture content of a granular bed under air-blow drainage. The bed was visualized as a collection of capillary tubes of various radii. The residual saturation profile in the bed is evaluated from calculation based on the capillary pressure curve, by assuming that the capillary drain height of a tube is proportional to the difference between air pressure and capillary suction pressure of the tube.
    A simplified equation for average residual saturation is derived in terms of a factor Zav. determined from the residual saturation profile. It is shown that the final moisture content under air-blow drainage can be easily predicted in ways similar to those for centrifugal drainage.
    The experimental results for packed beds of glass beads, Soma sand and calcium carbonate agree well with the theoretical predictions, under conditions where modified capillary number J·Ncap. ranges from 1.1 to 4.6.
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  • Naotsugu Ito, Toshikatsu Hakuta, Hiroshi Yoshitome, Teiriki Tadaki
    1985 Volume 11 Issue 6 Pages 721-728
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A reaction progress mechanism in a rotary drum reactor of the solid particles accompanying an endothermic reaction was analyzed. Model equations were derived and solved by the finite difference technique by considering the changes of the rotating orbitals of the particles and their reaction hysteresis, which were caused by the cascading movement of particles occurring every circulation.
    Batch dehydration experiments of Mg (IO3) 2 ·4H2O particles, chosen as a model reaction, were carried out by use of a rotary drum reactor, and changes with time of conversion and temperature of the cascading zone were measured simultaneously. Further, measurements of each conversion of the particles collected in the course of the reaction were performed in order to examine the conversion distribution, which was related to the flow pattern of the circulating particles in the reactor.
    It was found from the comparison between the calculation and observation results that the circulation movements of the particles was close to piston-flow. The experimentally obtained conversion and temperature changes closely agreed with the curves predicted by solving the model equations.
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  • Manabu Yamaguchi, Atsushi Kobayashi, Kohzi Ohbori, Takashi Katayama
    1985 Volume 11 Issue 6 Pages 729-734
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Flow equipment for phase separation of water-in-oil emulsion by D.C. electric field was developed. The effects of various factors on the separation were examined experimentally by the system of Kerosene-Span 80 (surfactant) -NaCl aqueous solution.
    High separation efficiency and stable continuous-phase separation of the raw liquids (30-50 vol % water-in-oil emulsion) were obtained satisfactorily when the flow rate of the liquids supplied into the electric field was low. It was also confirmed experimentally that the demulsified oil phase is available repeatedly.
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  • Toshinori Kojima, Satoshi Yamashita, Takehiko Furusawa, Yoshiyuki Band ...
    1985 Volume 11 Issue 6 Pages 735-742
    Published: November 10, 1985
    Released: November 12, 2009
    JOURNALS FREE ACCESS
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