KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 20 , Issue 4
Showing 1-22 articles out of 22 articles from the selected issue
  • Shigekatsu Mori, Noboru Iwasaki, Tomoaki Sawa, Mitsumasa Mitsunaka, Ta ...
    1994 Volume 20 Issue 4 Pages 463-467
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Coal fly ash discharged from pulverised coal-fired power stations can be utilized in cement. However, unburned carbon content in fly ash significantly affects the quality of fly ash cement, and JIS (Japan Industrial Standard) sets the upper limit of unburned carbon content in fly ash at 5%. To utilize more fly ash of higher carbon content than 5% as fly ash cement, a new reforming process of two-stage fluidized beds is developed. Fly ash is classified by particle size and by difference of density in this process, and unburned carbon is removed. Reformed fly ash containing less than 5 % unburned carbon is continuously obtained, and its yield is higher than 60% of the raw fly ash.
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  • Tadao Nakashima, Masataka Shimizu
    1994 Volume 20 Issue 4 Pages 468-474
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Various concentrations of O/W emulsions ranging from 0.2 to 50 voll were prepared from a kerosene/ water/surfactant system. Crossflow filtration of the emulsions was carried out by using a uniformly controlled pore glass membrane to clarify the effect of oil concentration on filtration parameters such as flux, rejection of oil and filtration resistance. Permeation flux gradually decreased with increasing oil concentration in accordance with concentration polarization on a membrane surface in a range of dilute concentration less than 5 vol % emulsions. At more than 5% oil concentration, however, much less flux was observed than that expected from the polarization.
    This fact was explained as the result of considerable decrease in gel scour effect due to the decrease in Reynolds number in the higher range of oil concentration in bulk emulsion.
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  • Yuko Sahashi, Hirotoshi Ishizuka, Ken Hibino
    1994 Volume 20 Issue 4 Pages 475-481
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Glucoamylase was immobilized on a capillary membrane of UF by the glutaraldehyde cross- linkage method. The membrane has an asymmetric structure and contains a great number of amino groups in porous areas. Liquefied starch of DE 13 was used as substrate and forced by applying pressure to permeate through the membrane. The obtained permeate once again permeated through the immobilized membrane. However, polymers in the liquefied starch were rejected by the membrane, and the glucose content in permeate was not more than 94%.
    Permeability of the polymers through the membrane was improved by making the skin layer of membrane porous and using liquefied starch of DE 20. Glucose content in permeate increased by using glucoamylase co-immobilized with pullulanase. The glucose formation rate increased and the glucose content reached 97%. The hydrolysis ratio of polymers in the substrate was higher when using glucoamylase with pullulanase than that when using only glucoamylase. Even if pullulanase was added to substrate of nearly 90% glucose content, glucose formation proceeded smoothly.
    It was found that continuous saccharification of liquified starch was possible by use of glucoamylase immobilized on a porous membrane in the first stage of reaction and that co-immobilized with pullulanase in the final stage.
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  • Koji Kuramoto, Kazuhiro Koizumi, Ichiro Naruse, Kazutomo Ohtake
    1994 Volume 20 Issue 4 Pages 482-488
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Formation/destruction characteristics of nitrous oxide (N2O) in bubbling fluidized-bed coal combustion, especially in char combustion, were experimentally studied, using a fixed-bed reactor in which char particles were packed in a single layer. In the combustion experiment, such combustion parameters as bed temperature, supplied oxygen concentration and char type were varied. The change of gas species concentration and compositions in the burning char were analyzed during the char combustion process.
    In the initial stage of char combustion, NO was produced rapidly, but N2O concentration increased slowly. This result is caused by N2O destruction due to H radical, which is produced from the oxidation of CO. In the latter half of combustion, however, N2O concentration increased faster since the formation rate of H radical decreased. The N2O concentration increased with decreasing bed temperature and with increasing supplied O2 concentration. This tendency is similar to that in the volatile combustion. From chemical and physical analyses of the burning char particles, the evolution behavior of N-component is influenced by the difference in surface and internal structures (network or balloon type) during the char combustion.
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  • Toshinobu Banjou, Kenichiro Sakamoto, Koichiro Tsutahara, Toru Yamaguc ...
    1994 Volume 20 Issue 4 Pages 489-496
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Based on the deposition mechanism and fine particle behavior, single wafer-type atmospheric pressure chemical vapor deposition (APCVD) equipment has been developed for boro-phospo-silicate glass (BPSG) deposition on 8-inch Si wafers.
    The gas composition near the wafer and the step coverage characteristic suggest that the deposition rate of the BPSG film is controlled by the SiH4 diffusion rate. Therefore, the uniformity of the source-gas injection velocity from the gas head as the holder temperature. is the key to achieving good film-thickness uniformity.
    Furthermore, it has been found that the behavior of fine particles produced in the reaction chamber is significantly affected by thermal migration, so particle deposition on the exhaust side wall was prevented by wall heating.
    The APCVD equipment can deposit 10, 000 Å BPSG film for more than 1000 wafers without chamber cleaning, while keeping film thickness uniformity within ± 3 %.
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  • Toshiro Miyahara, Mitsuaki Hirokawa, Mikio Ueda, Kan Yoshida
    1994 Volume 20 Issue 4 Pages 497-503
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Ozone absorption in water was investigated by blowing air containing ozone into a bubble column, where pH and water temperature were adjusted in advance. Dissolved ozone concentration in water reached a steady-state value in a short time. Dissolved ozone concentration at steady state was found to be a function of pH, ozone concentration in the air and temperature regardless of superficial gas velocity under the conditions investigated. The concentration increased with decreasing pH and temperature and with increasing ozone concentration in the air. The autodecomposition of ozone in water was satisfactorily represented by 1.5 th-order kinetics with respect to ozone. Empirical equations are proposed for the specific rate constant and Henry's constant, using the correlation of volumetric mass transfer coefficient in bubble columns by Akita et al. A mass balance equation for ozone absorption in water is solved by means of the Runge-Kutta-Gill method using the results mentioned above. As a result, the time course of dissolved ozone concentration can be well estimated.
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  • Wei-Ping Zeng, Hitoki Matsuda, Masanobu Hasatani
    1994 Volume 20 Issue 4 Pages 504-512
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The heat-exchange characteristics accompanied by exothermic reaction at the heat-demand end of a chemical heat pipe system using a SO2/SO3 reversible ther-mochemical reaction was examined in a lab-scale unit. Under the experimental conditions employed it was found that the conversion by SO2-oxidation reached almost equilibrium value and the heat-exchange medium (air) was well heated by the heat of reaction. The effects of reactant gas composition, mass flow rate of reactant gas and heat exchange medium on the reaction and the heat exchange characteristics were studied. Furthermore, a comparison between experimental and calculated results obtained by using a two-dimensional mathematical model, in which the reaction and heat transfer was considered simultaneously, was performed.
    It was found that the heat exchange characteristics obtained from experiments can be explained by the calculated results. Under adiabatic conditions, the temperature difference between the outlet and the inlet of the heat exchange medium increased with increase of the mass flow rate of SO2 and decrease of the mass flow rate of the heat exchange medium, while the efficiency of the heat exchange process decreased with increase of the mass flow rate of SO2 and decrease of the mass flow rate of the heat exchange medium.
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  • Masashi Kuramae, Mutsumi Suzuki
    1994 Volume 20 Issue 4 Pages 513-520
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    It is suggested that a two-component heat pipe utilizing the Marangoni effect caused by the concentration difference can be used without wicks, even in a microgravity environment. Microgravity experiments were carried out by using a large-scale dropping tower, and the behaviour of the working liquid in heat pipes in a microgravity environment was observed. It was shown that the working liquid condensed in the condenser section was returned to the heating section by the Marangoni effect, especially when the ethanol concentration was dilute. In such a case, the condensed liquid is rich in volatile component, and therefore the surface tension difference between the two sections becomes large. Furthermore, a simple mathematical model of liquid flow in heat pipes was developed, and the conditions for realizing a two-component heat pipe utilizing the Marangoni effect was derived.
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  • Fumihiro Koizumi, Shigeharu Toyoda, Eiichi Kunugita, Hirokazu Nishitan ...
    1994 Volume 20 Issue 4 Pages 521-528
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A new method was developed to identify each particle image of convex shape from an overlapped image of some particles. First, a contour line is divided into maximal arcs, and an appropriate number points on the arcs are chosen. Then these points (knots) and two auxiliary points for restoration are connected by a closed curve so that the square criterion of k-curvature is minimum. This approach can be applied not only to nonspherical images but also to contour lines which are not closed.
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  • Seiichi Deguchi, Hitoki Matsuda, Masanobu Hasatani, Noriyuki Kobayashi
    1994 Volume 20 Issue 4 Pages 529-534
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    This study is a trial of producing fine particles of metal-metal oxide semiconductors using a spray pyrolysis technique. Fine particles of multiple components were prepared by the spray pyrolysis method (SPM) from various multiple metal-salt solutions. SPM experiments were carried out under inert (N2) or reduction (N2/H2) atmospheres. The geometric characteristics and components of the fine particles produced were examined by SEM, XRD and EDS analysis. The effects of reactor atmosphere on the characteristics of the fine particles produced by SPM were studied. Under our experimental conditions, the atmosphere in the SPM-reactor had no influence on the size distribution or the shape of the fine particles. However, it was found that components of the fine particles produced could be modified by changing the reactor atmosphere. Moreover, it was recognized that the SPM, in which the reactor atmosphere was controlled, could be applied to the production of fine particles of metal-metal oxide semiconductors.
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  • Osamu Miyatake, Hiromi Omori, Yuji Kurishiro
    1994 Volume 20 Issue 4 Pages 535-541
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Laminar combined-convective heat transfer in axial flow of fluid through closely-packed triangular and square arrays of cylinders with a uniform wall temperature are investigated experimentally for the case where the direction of the buoyancy force is parallel to the mean flow direction.
    Experiments are conducted with water, 80 wt% ethylene glycol in water, and pure ethylene glycol as working fluids flowing downward in cooling ducts of the same cross-sections formed by both arrays of contacting cylinders, and the boundary condition of uniform temperature at the cylinder wall is substantially achieved.
    By comparing the experimental results with the authors' previous numerical analysis, which had been performed on the assumption of constant fluid properties, semiempirical equations suitable for predicting the logarithmic-mean Nusselt number and an empirical equation for the transitional Reynolds number are derived for both closely-packed arrays of cylinders.
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  • Yoshiyuki Endo, Yasuo Kousaka, Hidenori Onitsuka
    1994 Volume 20 Issue 4 Pages 542-548
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Water bridges formed among particles in industrial processes often contain soluble impurities such as salts. When such bridges are exposed to dry air, water in the bridges will vaporize and the salts crystalizes to form solid bridges.
    Solid bridges between two glass spheres were formed from NaCl, KCl, KNO3 and Na2SO4 solution by controlling humidity, and their tensile strength was measured. It was found from these experiments that 1) the adhesion force of a solid salt bridge which was uniformly formed in the gap between two spheres was one to two orders of magnitude larger than that of a water bridge without crystallization; 2) the average adhesion force of solid bridges was proportional to the 1/2 power of the product of salt volume and particle radius; and 3) the adhesion force of bridges of NaCl and KCl was influenced by the surrounding humidity, which was below their deliquescent points, because they adsorbed water until complete recrystallization took place.
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  • Koji Nanbara, Eiji Nakanishi
    1994 Volume 20 Issue 4 Pages 549-555
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Some chemical processes such as pH regulation by acid and/or base reagent additions are manipulated by promoting and/or repressing inputs. Using an optimization method such as linear programing may provide a basic solution of the system control problem. However, this approach is not practical for real-time control because of the large amount of computing time. When the promoting and repressing inputs are on a parity with each other in the sense that a negative quantity of input can be replaced always by a positive quantity of the other input in the mathematical model of the system, favorable control can be attained by accomodation of two parallel feedback controllers which are designed separately for two single-input single-output systems with a disturbance of each other's input. The control design method proposed in this paper can be easily extended to adaptive control by adding a suitable on-line model identifier. The usefulness of this adaptive control is investigated experimentally for pH regulation in a laboratory apparatus.
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  • Hidehiro Kamiya, Genji Jimbo, Makio Naito, Jun-Ichiro Tsubaki
    1994 Volume 20 Issue 4 Pages 556-563
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To investigate the process of creep failure phenomena in fine powder beds, the change in the tensile failure strength and the displacement of powder beds during the creep failure process was analyzed. The increasing displacement is divided into three sections (I, II, III). The increasing rate of displacement slows in the first stage (section I), almost constant in section II, and rapidly increases and falls in section III. By using the experimental equation to relate the creep failure life to the increasing rate of displacement in section II, the change in tensile strength of powder beds can be estimated during the creep failure process. No decrease in tensile strength is observed during the first stage (section I). However, in the second and third stages (section II and III), the strength decreased remarkably with increasing creep time. The increasing displacement can be fitted by a Voigt model in the region of section I, in which the tensile strength is almost constant. According to the elastic/viscous parameters of a Voigt model decrease in relation to the decrease in fracture strength of powder beds, the complex increase of displacement in the region of sections II and III can be quantitatively estimated. The deformation resistance of powder beds was quantitatively related to the fracture strength.
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  • Kunihisa Osasa, Hiroshi Itemoto, Yukio Fujii
    1994 Volume 20 Issue 4 Pages 564-567
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A novel electroflotation method using rotary, annular-type sacrificial electrodes was developed to study the efficiency of O/W emulsion removal. It was found that the oil removal efficiency increased with increasing electric current density and the average residence time of the liquid. The efficiency reached a constant value at a high rotational speed of the inner cylinder. This was because loose flocs were broken up in the range of high rotational speed by turbulence in the intercylinder gap. Modeling of the separation process was based on the assumption that the removal of oil was due to the flocculation-breakup process between oil droplets and microbubbles.
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  • Kohei Ogawa, Shiro Yoshikawa, Hirohisa Ogawa
    1994 Volume 20 Issue 4 Pages 567-570
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The relation between the friction factor and the Reynolds number of pulp-suspension flow in a circular pipe was investigated by using the similarity law of energy dissipation. The relation obtained between modified friction factor and modified Reynolds number is the same relation as that of a Newtonian fluid. Making use of this relation it is possible to calculate the pressure drops of pulp-suspension if apparent viscosity, supplementary coefficient, fiber concentration and pipe inner diameter are known.
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  • Weiqing Ye, Eiji Obata, Koji Ando
    1994 Volume 20 Issue 4 Pages 570-574
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    This study dealt with the extraction of chromium in an acetic acid solution with liquid surfactant membranes in which the carrier was a small quantity of tri-n-octylamine, TOA, and three surfactants, Span80, Polyamine-E and Polyamine-L, were used. The chromium concentrations in the external, organic and internal phases, and the swelling of the W/O emulson, were measured. Further, the chromium molar ratios changes with time in the external, organic and internal phases were calculated.
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  • Masaaki Sekino
    1994 Volume 20 Issue 4 Pages 574-579
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The analytical model for a hollow-fiber reverse osmosis module reported previously was applied to commercial seawater desalination plants, to be verified by measured plant performance data.
    Membrane permeability constants were obtained from seawater desalination labo-tests with several hundred hollow fiber membranes. The permeability constants of Toyobo's hollow fiber membrane for seawater were nearly equal to those of sodium chloride solution.
    The osmotic pressures of seawater were estimated by a modified Miyake equation. Calculated results by the analytical model with the above parameters showed to be in good agreement with seawater desalination plant performance data.
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  • Toshitaka Funazukuri, Takumi Mochizuki, Tsuneo Arai, Noriaki Wakao
    1994 Volume 20 Issue 4 Pages 579-582
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Polyvinyl chloride (PVC) pellets were subjected to dechlorination in a batch reactor with, separately, water and aqueous solutions respectively of tetrahydrofuran, cyclohexanone and methanol. In the temperature range of 230-280°C, dechlorination rate constants were obtained under the assumption of first-order kinetics with respect to the chlorine content in the solid sample. The rate constant for dechlorination with water (1ml) + THE (1ml) was found to be nearly three times that with water, although they have almost the same activation energy, 205kJ/mol.
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  • Issei Fujiyoshi
    1994 Volume 20 Issue 4 Pages 582-585
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Experiments in adsorption of nickel-ethylenediamine complex ions on granular porous glass showed that bis-complex ion was adsorbed selectively and that two silanol groups were exchanged by one nickel ion. At molarity ratios of ethylenediammine to nickel higher than two, the distribution constant was 0.0113m3/kg. Below a molarity ratio of two, the adsorption characteristic followed the law of mass action, and the apparent adsorption equilibrium constant was 9.13× 10-17kg0.5·m3/mol0.5.
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  • Mutsumi Suzuki
    1994 Volume 20 Issue 4 Pages 586-589
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The shape of the liquid bridge between two spheres was approximated by a circular meridian curve. Errors in capillary pressure and volume of the liquid bridge were found to be under a few percent.
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  • Yoshihito Watabe, Michio Yanadori
    1994 Volume 20 Issue 4 Pages 589-593
    Published: July 15, 1994
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    We designed and tested a fundamental adsorption refrigeration apparatus in which the adsorbent is silica gel and the refrigerant is water or ethanol for the purpose of producing cold energy at less than 0 °C.
    We found that (1) there is silica gel that reduces the temperature in the evaporator to-25 °C in the case of ethanol and to 0 °C with water, and (2) the minimum evaporator temperature depends on the initial adsorbent-refrigerant mass ratio.
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