KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 12, Issue 4
Displaying 1-15 of 15 articles from this issue
  • Masanori Aoki, Tetsuro Goto, Toshiro Nishiwaki, Koichi Yamanaka, Isao ...
    1986 Volume 12 Issue 4 Pages 375-381
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    A new type of bath for use in separating settling and floating solid matter from liquid has been developed.
    In its operation, a liquid containing solid matter flows in a tangential direction into the round bath and the liquid freed of solid matter flows out of the outlet port located on the lateral wall. Liquid containing a high concentration of floating solid flows out of the overflow pipe located at the bath center, while liquid containing a high concentration of settling solid flows out of the drain port in the bottom of the bath.
    Experiments show that the separation and discharge functions of the new separation bath are better than those of the swirl concentrator. It was confirmed that the efficiency of separation was primarily determined by the nondimensional parameter hc'/h0. The approximate equations of separation efficiency were obtained.
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  • Shunya Ikumi, Haruhiko Mori, Hiroaki Masuda
    1986 Volume 12 Issue 4 Pages 382-387
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Aerosol particles flowing in a circular duct deposit on the inside wall and form a loosely packed particle bed. These particle beds have been investigated for both unipolarly charged and uncharged aerosol particles, with particular attention to surface profile and internal structure. It was found that the surface roughness of the particle bed increased with the mass of particles deposited per unit area (dust load). The roughness was greater for unipolarly charged particles than for uncharged particles. Scanning electron micrographs revealed that the particle bed was formed by aggregates, and was packed more loosely for charged particles than for uncharged particles. Packing fractions of these particle beds increased with increasing dust loads and gradually approached their respective maximum values. Differences in the structure of the particle beds were qualitatively explained by a simple computer simulation where the electrical polarization of charged particles was taken into consideration.
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  • Kenji Shimizu, Noriaki Kubota
    1986 Volume 12 Issue 4 Pages 388-392
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    The behaviour of steps on the (111) face of growing barium nitrate crystals were observed, using a reflection-type Nomalsky differential microscope. Several growth spirals always existed on the surface. Some of them originated form points on the surface to which small crystallites accidentally adhered from the solution. The velocity of the steps changed according to their mutual interference, the addition of impurity (Na+) and the existence of microscopic roughness on the surface. There were small crystal fragments adhering to the mechanically damaged surface of the crystal. These fragments were covered by new layers. In addition, macrosteps were easily formed on the damaged surface, and overhang of the steps and inclusion of mother solution were successively formed.
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  • Norio Arai, Yoshihiko Ninomiya, Yoshikazu Nakai, Masanobu Hasatani
    1986 Volume 12 Issue 4 Pages 393-400
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    The gas-phase formation of Volatile NO and N2 through NH3 in a mixture of NH3, H2, O2 and Ar (balance gas) was investigated both experimentally and theoretically in a tubular-flow reactor. The experiments were conducted in the temperature range of 970 to 1400 K and in an oxygen concentration lower than 2000 ppm. The experimental results obtained were compared with numerically calculated results of the reaction model based on elementary reaction kinetics, taking the heating process of the reactant gas into consideration.
    It was revealed within the range of the present experimental conditions that 1) the main product of the decay of NH3 is N2, while NO formation is relatively scant, and 2) the formation rate of N2 from NH3 is enhanced by the coexistence of H2 and O2.
    These experimental trends were confirmed to be in close agreement with the calculated results of the proposed reaction model.
    Finally, a main reaction route for the formation of NO and N2 was simplified.
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  • Yoshiyuki Yamashita, Shigeru Matsumoto, Mutsumi Suzuki
    1986 Volume 12 Issue 4 Pages 401-407
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    To analyze the characteristics of one-dimensional unsteady heat conduction in laminated materials, the relationship between temperature and heat flux is analytically derived in the s-domain as a function of the number of laminated layers. The error due to the homogeneous approximation with some apparent thermal properties is evaluated.
    These results are closely concerned with the method of unsteady measurement of thermal diffusivity Based on the results, consideration is given on the problems which arise in its application to laminated materials.
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  • Masaharu Yamada, Kohtaro Kuramitsu, Kazutaka Makino
    1986 Volume 12 Issue 4 Pages 408-413
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    The powder yield model presented by the authors can be applied to the estimation method for the yield locus of powders as its basic framework. However, an effective search method for the parameters in the model has not yet been sufficiently developed. Hence, from this standpoint, the basic properties of parameters in the model are systematically discussed in this paper. As a result, the following conclusions are obtained.
    1) The number of parameters to be searched is reduced to three (m, s and d) from four (m, n, s and d).
    2) The analytical solutions of the uniaxial compressive and tensile properties are obtained. These solutions make possible a quick and precise search method for the parameters (m, s and d).
    3) The parameter m depends on the stress ratio η. The parameters s and d depend on both the stress ratios κ and λ.
    4) The applicability of the search method for the parameters is experimentally checked.
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  • Yasuhide Nishi
    1986 Volume 12 Issue 4 Pages 414-419
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    ΔP-u relation, minimum fluidization velocity (umf), bed voidage at minimum fluidization point (εmf), bed expansion and pressure drop of bed were examined experimentally in a fluidized bed under oscillation. Effects of the oscillation were clarified by varying periodic time of oscillation, maximum inclination angle from vertical axis, length from a fulcrum to a distributor and bed width. Diagrams of ΔP vs. u were classified into several types by oscillating conditions and bed width. Violent oscillation reduced umf and εmf. By inclining or oscillating the bed, bed expansion was suppressed, and variation in bed height or pressure drop of bed was increased. Inclination or oscillation of the bed gave rise to channelling and slugging in the bed.
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  • Akira Yasunishi, Miki Fukuma, Katsuhiko Muroyama
    1986 Volume 12 Issue 4 Pages 420-426
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Volumetric liquid-phase mass transfer coefficient, kla, and axial variations of gas, liquid and solid holdups were measured in a slurry bubble column of 15 cm diameter and 1.05 or 1.55 m height containing concentrated solids supported by a concurrent upflow of a gas and a liquid. Gas and liquid media were air and water or air and aqueous glycerol solution. Slurry particles were glass beads with mean diameter of 0.16 and 0.23 mm and a density of 2500 kg/m3.
    In beds of high solid content, the measured axial variations of solid holdup indicated that :
    (1) At low gas velocity two slurry layers were formed in the column. The lower layer was the dense region with high uniform concentration of solids and the upper layer was the lean region where solid concentration decreased steeply with axial distance.
    (2) At large gas velocity the solid concentration in the column decreased continuously with axial distance as a result of sedimentation and diffusion of solids.
    On the other hand, gas holdup was fairly uniform from the bottom to the top of the column.
    The value of kla increased with gas velocity and decreased with solid concentration. kla values obtained in this work were empirically correlated by the following equation with a term of apparent viscosity of slurry.
    kla=3.09×10-7 {(1-φs/0.60) /μl} 1.50 Ug
    where, φss/ (1-εg) [-], kla [s-1], μl [Pa·s] and Ug [cm/s]. This correlation covers the range of variables, 0.8≤Ug≤8.0, 0.001≤μl≤0.002 and 0≤φs≤0.4.
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  • Atsushi Morihara, Syuntaro Koyama, Syunsuke Nogita
    1986 Volume 12 Issue 4 Pages 427-432
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Room-temperature data on particle residence time in a swirling flow, entrained bed gasifier were obtained by use of a tracer response technique. Orifice plates (constriction) of various diameters were installed at the exit to the gasifier. Particle-laden air was injected through two sets of four burners, spaced at 90° intervals around the bed circumference at two locations along the bed axis. The radial and tangential components of injection velocity, as well as the axial location of the upper set of burners closest to the exit, were varied.
    It was determined that particle residence times increased as the constriction diameter, or rotational circle diameter of the low burners (determined by the direction of injection), decreased. Increasing the height of the upper set of burners also increased particle residence times. This change can be related to variations in the tangential gas velocity profiles in the gasifier.
    Particle trajectories were affected principally by the centrifugal acceleration associated with the tangential injection configuration. This factor is incorporated into a dimensionless empirical expression for residence time :
    T=0.122×Z0.501
    where T is the ratio of particle residence time in swirling flow to the residence time in plug flow and Z is the ratio of the centrifugal acceleration to the gravitational acceleration.
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  • Yoshinori Kutsuwa, Hirokazu Nishitani, Eiichi Kunugita
    1986 Volume 12 Issue 4 Pages 433-439
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    The flexibility of a process system represented by the mixed integer linear programming (MILP) model was studied. First, the existence of an operation such that system specifications can be satisfied when the uncertain parameters in the model vary over the specified range is discussed. An algorithm to examine containment of the range of tolerance required by the designer within that of system inherent tolerance is developed. Second, the degree of flexibility which represents how much variation of the uncertain parameters the system can tolerate is discussed. The magnitude of flexibility can be determined by repeating the feasibility test algorithm. As an illustration, the flexibility of the heat exchanger network represented by the MILP model is analyzed.
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  • Yoshinori Kutsuwa, Hirokazu Nishitani, Eiichi Kunugita
    1986 Volume 12 Issue 4 Pages 440-446
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    During the operation of a process system, not only manipulated variables but also the operating pattern is adjusted for the uncertainties in the system. Then, the flexibility of the system is represented by a union of the tolerance regions for all operating patterns. In the present work, an iterative procedure to design the process system with fixed tolerance was developed for such systems. The two-stage approach is composed of the optimal design by mixed integer linear programming and the feasibility test of the design for the range of tolerance required by the designer. When the design does not have enough flexibility, the range of system inherent tolerance is enlarged by a design revision strategy. As an illustration, design problems of a steam and power system with fixed tolerance were studied under uncertainties in the demand and plant parameters.
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  • Yoshio Komazaki, Seijirau Suda
    1986 Volume 12 Issue 4 Pages 447-452
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    The hydriding and dehydriding kinetics of the RNi4.8Al0.2-hydride which has the AB5 type of hexagonal structure were studied.
    Pressure difference between the equilibrium and the system pressures was found to be more influential on the kinetics of hydriding materials than the hydrogen content in metal hydrides. Among several RNi4.8Al0.2-hydrides, LmNi4.8Al0.2-hydride with high La, Nd, and Pr contents showed higher rates of hydriding and dehydriding reactions than MmNi4.8Al0.2-hydride with lean contents of those elements. Through comparisons of kinetic properties of MmNi5-xAlx hydrides, it was found that partial substitution of Ni element with Al improved their kinetics considerably. N-values defined as the modified rate constants were evaluated as functions of temperature and pressure for each hydriding material.
    In each isobaric N-value vs. temperature plot a peak was observed corresponding to the conditions where the hydriding reaction proceeds at the highest rate.
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  • Katsuyasu Sugawara, Yasushi Takai, Takuo Sugawara, Hiroyasu Ohashi
    1986 Volume 12 Issue 4 Pages 453-458
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Sorption equilibria, apparent diffusivities and activation energies of diffusion were measured for four acids (hydrochloric acid, sulfuric acid, oxalic acid and phosphoric acid) in the anion-exchange membrane SELEMION-AMV. The sorption-equilibrium data were simulated on the basis of the Donnan theory with the ratio of activity coefficient of chloride ion insolution to that in membrane for hydrochloric acid, and the selectivity coefficients KHSO4SO4, KHC2O4C2O4 and KH2PO4HPO4 for polybasic acids, as parameters. The differential diffusivities of acids were determined in membrane as a function of hydrogen concentration in the membrane based on the sorption-equilibrium data and the apparent diffusivities.
    The results indicate that the anion-exchange membrane uptakes HSO4-and HC2O4-selectively and that the differential diffusivity of each acid becomes large with increasing hydrogen concentration in the membrane. The activation energy for polybasic acid tended to increase with increasing concentration in the strip solution, and was independent of the concentration in the feed solution.
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  • Examination based on impulse response method
    Kohei Ogawa, Chiaki Kuroda, Ichiro Inoue
    1986 Volume 12 Issue 4 Pages 459-464
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
    Effects of impeller style (paddle, turbine and pitched-blade turbine types) on the capacity of an agitated vessel with aeration are examined by injecting tracer gas impulsively. Though the paddle-type impeller gives the highest value of final average concentration and also the highest value of mixing rate of gas absorbed, the pitched-blade turbine-type impeller is expected to be the most appropriate one when ease of estimation of the relationship between operational condition and mixing phenomena is also considered. Additionally, it is made clear that each impeller style produces a characteristic inhomogeneity of concentration of gas absorbed in the vessel at even the high-mixedness stage, and it is presumed that the inhomogeneity will affect significantly the capacity of an agitated vessel with aeration in some cases.
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  • Mikio Kawagoe, Tsutao Otake, Yasuo Noda, Yosuke Kawashima, Satoru Iuch ...
    1986 Volume 12 Issue 4 Pages 465-497
    Published: July 10, 1986
    Released on J-STAGE: November 12, 2009
    JOURNAL FREE ACCESS
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