KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 21 , Issue 3
Showing 1-36 articles out of 36 articles from the selected issue
  • Hideo Miki
    1995 Volume 21 Issue 3 Pages 403-410
    Published: May 10, 1995
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Computer simulation has been carned out for industrial crystallizers which crystallize and separate aluminum hydroxide from etching solution discharged from the alumite process. The numerical calculations of ΔC in crystallizer and etching tanks, and CV Dp50 and of the product crystals were accomplished by applying the population density function for product crystals and the material balance equations with aluminum in solutions from both the crystallizer and etching tanks. As a result, a good agreement between the calculated values and the measured data was confirmed.
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  • Hideo Miki, Yoshio Aoyama
    1995 Volume 21 Issue 3 Pages 411-416
    Published: May 10, 1995
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The crystallization of potassium halides has been carried out using cone-type fluidizing and mixing crystallizers operated as industrial crystallizers. Operational data obtained ove ten years were also analyzed. As a result, it became clear that there were limiting values in the degree of supersaturation for obtaining single crystals of good shape. The addition of habit modifiers resulted in an increase in the limiting degree of supersaturation and in the depression of agglomeration. The change of limiting degree of supersaturation and notable changes in the crystal habit also occurred upon pH control.
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  • Hideaki Kurokawa, Toshio Sawa, Kazuhiko Takino
    1995 Volume 21 Issue 3 Pages 417-423
    Published: May 10, 1995
    Released: November 12, 2009
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    To develop a new water purification system using a hydrophobic membrane, the membrane characteristics have been studied using basic equipment of 5l/h size. From results of the study, 100l/h size equipment was fabricated, and its characteristics were studied.
    The results are summarized as follows. The pore diameter of the PTFE membrane was optimized by waterproof pressure and mist separation characteristics, and a 0.1-0.2μm pore size membrane was selected for use in the system. Degassing by flash evaporation and oxidation by ultraviolet-rays were effective to decrease D.O. and T.O.C. to 1μg/l respectively. From these basic experiments, ultrapure water was able to be produced by the system. Water purity was characterized by a resistivity of over 18.2MΩ · cm, T.O.C. and D.O. of below 1.0μg/l and suspended particle of below 5units/ml. Finally, it was confirmed that the 100l/h size equipment could produce high purity water of similar purity to that of the small size equipment.
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  • Kazuo Kondo, Kazuyuki Harima, Kunio Shinohara, Yasushi Ohyama, Shigeo ...
    1995 Volume 21 Issue 3 Pages 424-429
    Published: May 10, 1995
    Released: November 12, 2009
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    The effect of additives on residual oxygen removal from A1N particles produced by surface corona discharge-CVD is discussed. A marked size growth and necking of particles were observed previously with carbothermal reduction without any additive.
    Ca, CaF2, and Y2O3 Additives were chosen and their effects on carbothermal reduction were tested, initially with commercially available Al2O3 particles. Several 100 nm diameter particles with uniform and independent shape were observed with Ca and Y2O3 additives. Particle sizes grew and coarse particles of a few gm in diameter were observed with additive of CaF2. The X-ray diffraction lines of Al2O3 disappear with Ca and CaF2, while the lines remain with Y2O3. Only the Ca additive was effective for preventing particle size growth and necking, and for accelerating the carbothermal reduction reaction.
    When Ca was added to the A1N particles, the X-ray diffraction lines of Al2O3 disappeared after heat treatment at 1673 K for 3 hrs, and reaction time was reduced to 1/7 of the reaction time without additive. Also, several 100 nm diameter particles with uniform and independent shape were produced. The CaO film coated over the A1N particle surfaces seemed to prevent necking of AlN particles.
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  • Keiichi Koga, Satoshi Hirabayashi, Kooji Kagara
    1995 Volume 21 Issue 3 Pages 430-436
    Published: May 10, 1995
    Released: November 12, 2009
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    For the development of a new crystallization method to steadily transform hydrate crystals of a thiazol acid, (Z) - [4- (2-aminothiazolyl)] -2-methoxyiminoethanoic acid, to the anhydrate form, it was confirmed that aqueous methanol solutions were the most suitable solvents for the transformation and various crystallization experiments were carried out using the solvents.
    Influences of composition of solvent, crystallization temperature, seed crystals and agitation speed on transformation rate were studied.
    On the basis of these results, a crystallization method to obtain the desired anhydrate crystals was established.
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  • Kooji Kagara, Kooji Machiya, Kiyoaki Takasuka, Nobutaka Kawai
    1995 Volume 21 Issue 3 Pages 437-443
    Published: May 10, 1995
    Released: November 12, 2009
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    In order to depress the solvent-mediated transformation of a tetralin compound, (+) -2, 2-dibutyl-5- (2-quinolylmethoxy) -1, 2, 3, 4-tetrahydro-1-naphthol, the influences of temperature, composition of solvent and rotational speed on transformation were investigated using a differential scanning calorimeter.
    Looking at the transformation process over elapsed time, the transformation from metastable A-form to B-form crystals showed S-curve behaviour after some waiting time. Through the analysis with a growth rate equation in the region of constant solution concentration, namely constant degree of supersaturation in the transformation process, a correlation of the overall transformation rate constant and the waiting time for the nucleation of B-form crystals under various crystallization conditions was determined.
    On the basis of these results, metastable A-form crystals free from stable B-from crystals were produced in a 500l crystallizer.
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  • Tetsuya Imai, Kennosuke Kuroda, Masaki Hirano, Toru Akano
    1995 Volume 21 Issue 3 Pages 444-450
    Published: May 10, 1995
    Released: November 12, 2009
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    Methanol synthesis by catalytic hydrogenation of carbon dioxide is one of the most promising processes for conversion of carbon dioxide to valuable chemicals. The activities and durabilities of CuO-ZnO-Al2O3 catalysts for methanol synthesis were investigated using a microreactor and a bench-scale test plant. It was found that catalysts containing 5 wt% Al2O3 showed better durability than a catalyst containing 8 wt% Al2O3. It was supposed that the high durability was due to the high dispersion and the sintering suppression of active sites by XRD, TEM and CO adsorption measurements. Test results obtained in the bench-scale test plant showed that the conversion of carbon dioxide to methanol was over 90% at a pressure of 8 MPa, a temperature of 512 K and a recycling ratio of 4 m3N/m3N by recycling unconverted reactant.
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  • Pingwei Zhang, Katsutoshi Inoue, Hiromi Tsuyama
    1995 Volume 21 Issue 3 Pages 451-456
    Published: May 10, 1995
    Released: November 12, 2009
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    The total dissolution in sulfuric acid of spent hydrodesulfurization catalysts results in an acidic solution containing a certain amount of rare metals like molybdenum, vanadium, cobalt and nickel as well as a large excess amount of aluminum. In the present work, the fundamental extraction characteristics of these metals from the sulfuric acid media with some typical commercial acidic organophosphorus compounds such as TR-83, PC-88A and CYANEX 272 have been investigated to develop an extraction process for the recovery of molybdenum and vanadium from the solution of the total dissolution. The experimental results demonstrated that CYANEX 272 was suitable for selectively separating and recovering molybdenum and vanadium over the other metals involved in the sulfate solutions at comparatively low pH. An elemental recovery processing route was proposed. Molybdenum was recovered by extracting with 40% CYANEX 272 in EXXSOL D80 from the sulfuric solution at pH 1.5, and by stripping with 6% NH4OH solution after the co-extracted iron and vanadium were scrubbed from the loaded solvent with a moderate concentration of H2SO4 solution. Vanadium in the scrub solution was further recovered by again extracting with the same extractant after the pH was adjusted to 1.5 with Ca (OH) 2 powder and by stripping with 6% NH4OH solution.
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  • Pingwei Zhang, Katsutoshi Inoue, Hiromi Tsuyama
    1995 Volume 21 Issue 3 Pages 457-464
    Published: May 10, 1995
    Released: November 12, 2009
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    The recovery of molybdenum and vanadium from sulfuric acid solution generated from the total dissolution of spent hydrodesulfurization catalysts by means of liquid liquid extraction with CYANEX 272 resulted in an aqueous raffinate solution with the composition of approximately (ppm) Co 1000, Ni 210, Al 12370 and pH 1.5.
    For the purpose of recovering nickel and cobalt from the solution, a systematic investigation was conducted on the synergistic extraction behaviors of the mixed extractants of LIX 63, an aliphatic alpha-hydroxyoxime extractant, in combination with a series of acidic organophosphorus reagents such as CYANEX 272, PC-88A, TR-83, D2EHPA and OPEHPA for cobalt, nickel and aluminum. It was elucidated that all of these mixtures exhibit an excellent synergistic effect for extraction of cobalt and nickel and that the lower the pKa of the acidic extractants, the greater the synergism. On the contrary, the extraction of aluminum is greatly suppressed by LIX 63. By using the mixtures, nickel and cobalt are effectively and selectively extracted from the sulfate solution at low pH leaving aluminum in the solution.
    In particular, the mixture of LIX 63 and CYANEX 272 appears to be the most feasible and economic from a process standpoint because of the substantial separation efficiency for cobalt and nickel over aluminum, the comparatively mild acidities necessary for stripping cobalt and nickel, and the negligible degradation of LIX 63.
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  • Yoshio Fuchigami, Toshiaki Inami
    1995 Volume 21 Issue 3 Pages 465-471
    Published: May 10, 1995
    Released: November 12, 2009
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    A simple and unique process for the continuous bulk polymerization of methyl methacrylate (MMA) by CSTR reactor was developed as a result of an investigation using a very short-life radical initiator. Advantages of the new process are as follows : (1) MMA conversion decreases with a rise in the reaction temperature. As a result, uncontrollable acceleration of the rate of reaction is avoided and MMA conversion is self-controlled and kept constant. (2) Initiator concentration in the reaction mixture is negligibly small compared with that of the feed stream (about 1/ 1000). This makes it possible for MMA conversion to be held constant during temporary shut-down of the continuous operation. As a result, not only material loss and energy loss but also troublesome operation for shut-down is avoided. (3) The half-life period of the initiator becomes shorter than the time for complete mixing, and consequently MMA conversion is changed by impeller speed. This leads to decrease in utilization efficiency of the initiator and compensates for acceleration of the rate of reaction by the gel-effect. As a result, MMA conversion can be controlled accurately by addition of AIBN solution using an automatic flow-rator.
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  • Manabu Yamaguchi, Yoshito Chikano, Tadashi Ise, Takashi Katayama
    1995 Volume 21 Issue 3 Pages 472-477
    Published: May 10, 1995
    Released: November 12, 2009
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    Characteristics of electrostatic dispersion and formation of charged uniformly-sized droplets for W/O and O/W type emulsions were investigated experimentally in the atmosphere. Both types of emulsion showed pseudo-plastic fluid behavior. A non-uniform electric field was formed by configuration of an earthed electrode of copper plate and a metal nozzle to which a positive DC voltage was applied. Feed rate of the emulsions in the experiments was in the range of single drop formation. Characteristics for formation frequency of charged uniformly-sized droplets changed significantly, depending on the physical properties of the emulsions.
    Empirical correlations for droplet size produced in the electric field were proposed for each type of emulsion used.
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  • Tomio Mimura, Shigeru Shimojyo, Taiichiro Suda, Masaki Iijima, Shigeak ...
    1995 Volume 21 Issue 3 Pages 478-485
    Published: May 10, 1995
    Released: November 12, 2009
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    The most important issue involved with the chemical absorption method for recovering carbon dioxide from a power plant's flue gas is to develop energy-efficient solvents. Laboratory screening tests on about 40 kinds of alkanolamine absorbents, along with absorption heat and corrosion tests, indicated sterically hindered amine (SHA) requires less energy for regeneration than coventional monoethanolamine (MEA). Bench-scale tests to examine SHA's CO2 absorption and stripping capability revealed the excellent characteristics of SHA.
    Subsequent performance tests with a pilot plant (gas quantity : 600 m3/h) showed that the thermal energy required for CO2 recovery by SHA was about 3000 kJ/kg-CO2-much lower than for conventional absorbents. There was little formation of decomposition products from SHA. Therefore, SHA was shown to have a longservice life.
    Furthermore, basic experiments showed the excellent to corrosive property of SHA. SHA's corrosion loss was only 1/20th of that of MEA without any corrosion inhibitor.
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  • Yasuhiro Imamura, Satoji Kobayashi, Hikoji Inazumi
    1995 Volume 21 Issue 3 Pages 486-494
    Published: May 10, 1995
    Released: November 12, 2009
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    The relationship between the behavior of gas-liquid flow and gas holdup, εG, and the principal operating factors were investigated experimentally in a horizontal liquid jet ejector emplayed as a gas-liquid contactor.
    The flow modes in the throat can be classified approximately into three regimes, which present different kinds of bubble formation and gas-liquid mixing. It was shown that a new flow parameter, based on a flow model proposed in this work, was more reasonable than that proposed by the previous works, and the correlation among εG and the principal operating factors was studied.
    The values of εG increased with an increase in gas flow rate, and on the contrary, decreased with an increase in liquid flow rate. It was confirmed that the values of εG increased with an increase in the volumetric fraction of gas flow rate, β, and took different values from β.
    The relationship between the values of εG and the operating conditions was investigated in the cases of single and multi nozzles. As a result, an empirical correlation by which the observed values of εG can be predicted within an error of ±20% was obtained.
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  • Izumi Hirasawa, Kenji Muraoka, Daisuke Katou, Ken Toyokura
    1995 Volume 21 Issue 3 Pages 495-501
    Published: May 10, 1995
    Released: November 12, 2009
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    In this study, lead sulfate particles were produced in a batch crystallizer, by feeding lead nitrate and sodium sulfate solutions (concentration : 0.025-0.4 mol/l) continuously to the vicinity of an agitator rotating at 400 rpm from individual feed pipes. The batch crystallizer contained a solution of Pb 10-2 mol/l, gelatin 5 wt% and acetic acid 3.48 mol/l. In the crystallization process, crystals were sampled over time to measure crystal size distribution based on number, and to observe the shape and surface condition of crystals. From the results of experiments, it was shown that the position, where the nucleation phenomenon was detected in the equipment, changed for a feed concentration 0.4-0.5 mol/l. This phenomenon was considered with respect to the supersaturation ratio in the equipment. Moreover, in the range of experimental conditions, where relatively monodispersed fine particles were produced, it was observed that crystals of unstable state were fromed in the beginning of the reaction, but after that they were transformed to a stable rhombic shape. The stable crystals were considered to grow while consuming all the reactant components in the equipment. Also, an experimental equation was presented showing that formation rate of nuclei to become product crystal was proportional to the fifth power of the feed supersaturation ratio.
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  • Yoko Hashi, Mamoru Senna
    1995 Volume 21 Issue 3 Pages 502-507
    Published: May 10, 1995
    Released: November 12, 2009
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    Grinding tests were carried out using a model agitation beads mill with a single disc. Four different discs were used to examine the effect of the motion of the grinding media in the axial direction. The median diameter of the ground products decreased with increasing movement of the grinding media in the axial direction under the same degree of filling of the grinding media and speed of rotation. Contamination in the product from the agitating element and grinding vessel increased with increasing energy input, irrespective of the shape of the agitating disc. Contamination from the grinding media increased with increase in the movement of grinding media in axial direction. The motion of grinding media in the axial direction is concluded to cause mutual collision and hence to increase abrasion of the grinding media.
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  • Masafumi Kuriyama, Minobu Ono, Eiji Harada, Hirotaka Konno
    1995 Volume 21 Issue 3 Pages 508-513
    Published: May 10, 1995
    Released: November 12, 2009
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    A new energy-balance model was developed for drop breakup in turbulent flow. This model theoretically derived a correlation for the maximum stable drop size. The correlation expressed the maximum stable drop size as a function of Reynolds number, Weber number, impeller size, dispersed phase-to-continuous phase viscosity ratio and density ratio. The validity of the correlation was examined by using both the experimental results obtained in this work and from the literature. The correlation was proven to be applicable over a wide range of dispersed-phase viscosities.
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  • Masafumi Kuriyama, Hideki Tokanai, Eiji Harada, Hirotaka Konno
    1995 Volume 21 Issue 3 Pages 514-520
    Published: May 10, 1995
    Released: November 12, 2009
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    An experimental study was performed to determine the natural-convection heat transfer characteristics of horizontal cylinders placed in a horizontal line in air.
    Local heat transfer coefficients were measured for three-and nine-cylinder arrays in various cylinder-spacing arrangements. As a result, it was found that there were no major differences in heat transfer coefficient among cylinders, other than for the array-edge cylinders. The mean value of all cylinders was clearly different from that of the array-edge clyinders.
    Based on a simple consideration for the effect of cylinder-spacing on heat transfer coefficient, correlation equations were proposed for each kind of heat transfer coefficient mentioned above. All the experimental heat transfer coefficients were expressed well by these equations.
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  • Yoshiaki Shimizu
    1995 Volume 21 Issue 3 Pages 521-530
    Published: May 10, 1995
    Released: November 12, 2009
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    Linear programs (LP) have been used popularly as practical optimization methods in many fields for many years. Due to the recent diversification of problem-solving, however, the problem must be formulated in a difficult and complicated manner. It is thus necessary to develop special methods that can solve large complex LP effectively as well as flexibly.
    A new approach for the simplex method, termed PAPA (pivot and probe algorithm), is considered promising for such situations. Since its effectiveness is confined to a special form of problem, we generalized it in this paper by applying a dual algorithm in the framework of the two-phase method for LP solution.
    In comparison with the revised simplex method, we examined numerically its efficiency by solving a variety of randomly generated test problems. Then, we paid special attention to application of the method in chemical processes. Thereupon, we pointed out the proposed method is especially effective where certain reference information is available to solve a family of problems repeatedly before arriving at a final result. This is why we propose calling the method “progressive linear programs” (PROLP).
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  • Chang Wang, Hiroshi Machida, Nobuyoshi Nakagawa, Takayuki Takarada, Ku ...
    1995 Volume 21 Issue 3 Pages 531-539
    Published: May 10, 1995
    Released: November 12, 2009
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    Catalytic pyrolysis of biomass materials was carried out by using a powder-particle fluidized bed (PPFB). Three kinds of wood-chips and a rice-shell were used in the experiment. Six kinds of catalyst particles were used as bed medium particles and the effect of catalyst upon pyrolysis products was investigated. A comparison was also made between the present results and those of the coal obtained previously by the authors. It was found that in the primary pyrolysis of wood-chips, the weight of the volatile matter was almost constant above a temperature of 700 K, and yields of light aromatic hydrocarbons, i.e, benzene, toluene, xylene and naphthalene (BTXN), increased with increasing pyrolysis temperature. BTXN yield of 3.1 wt% was obtained at a temperature of 1173 K. When wood-chip was pyrolyzed in a fluidized bed of CoMo-B particles under a hydrogen atmospaere, BTXN yield of 6.3wt%, (BTX : 5.3 wt%, daf, N : 0.8 wt%, daf) was obtained at 863 K. For all of the biomass materials, the ratio of yields of hydrocarbon gases to that of light aromatic hydrocarbons under the above conditions was almost 2.5, which is the same as that obtained from Yallourn coal and Taiheiyo coal.
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  • Chang Wang, Nobuyoshi Nakagawa, Kunio Kato
    1995 Volume 21 Issue 3 Pages 540-546
    Published: May 10, 1995
    Released: November 12, 2009
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    In a process of catalytic pyrolysis of woody chip by a powder-particle fluidized bed (PPFB), the effects of catalyst fluidized gases, pyrolysis temperature and catalyst static height on the yields of the pyrolysis products were investigated at ambient pressure. The optimum operating condition was found for obtaining a high yield of light aromatic hydrocarbon, such as benzene, toluene, xylene and naphthalene (BTXN). Under the optimum conditions of CoMo-B catalyst static height of 0.08 m and pyrolysis temperature of 863 K, BTXN yield was 6.3 wt%, (daf base). In the case of 50 vol% of highly active CoMo-A catalyst mixed with 50 vol% of low active alumina catalyst, the yield of BTXN was about 3.5 times larger than that in the case of activated alumina catalyst. As activity of NiMo-A catalyst is so high for the secondary reaction of the primary pyrolysis products, even at 723 K, most products of the pyrolysis were methane and the yield of methane was more than 45 wt%, dry base. If hydrogen content in the fluidized gas was higher than 50 vol%, the yield of BTXN was not affected by the hydrogen content. There is a possibility for using the pyrolysis-recovery gas or coke-oven gas as the fluidized gas for woody pyrolysis.
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  • Shuji Sakohara, Yasushi Tateishi, Masashi Asaeda
    1995 Volume 21 Issue 3 Pages 547-553
    Published: May 10, 1995
    Released: November 12, 2009
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    Effects of the pore size of a thin, porous ceramic (silica-alumina) membrane supporting acrylamide gel on the separation properties of water/ethanol mixtures were investigated. The usefulness of repeating polymerization of gel reported in a previous paper were also examined. The pore size of the thin ceramic membrane, which was prepared by the sol-gel technique on a cylindrical substrate, was controlled by changing the particle size of alumina sol and the coating times of sol. The pore size distribution was evaluated from the permeation properties of humid air. Separation experiments were carried out by the pervaporation method.
    Permeation properties of water/ethanol mixtures through acrylamide gel are largely dependent on the pore size of the ceramic membrane supporting the gel. This fact suggests that the pore size affects the thickness and shrinking properties of the gel polymerized in the pores. By repeating the polymerization of gel, the flu-x of ethanol decreased dramatically. The gel polymerized in the small pores, however, cannot block the permeation of ethanol sufficiently. On the other hand, the flux of water increased or decreased depending on the pore size of the ceramic membrane. There exists an appropriate pore size for which the promotion of water permeation occurs, as shown in the previous paper. From these results, it can be said that appropriate selection of the pore size is important for the improvement of selective permeation through this kind of composite membrane.
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  • Mitsuo Suzuki
    1995 Volume 21 Issue 3 Pages 554-564
    Published: May 10, 1995
    Released: November 12, 2009
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    Powder pressure distribution in funnel flow silos, including local peak pressure on the side wall, was discussed both theoretically and experimentally for quantitative prediction. Filling and discharge conditions were related to pressure distribution, with particular consideration of a flow channel formed within the material. The basic idea in this theory is as follows : i) Filling condition causes horizontal distribution in mechanical properties of the material. ii) Flow channel boundary is determined by slip lines in filling state and outlet position. In the calculation of pressure, material is divided into flow region and static region. A proper calculation method is thus applied to each region, and load interactions are incorporated. Experiments were conducted using a silo of nearly commercial size with two kinds of grains, which have different flow abilities, under various filling and discharge conditions. The distributions of physical properties were determined by material sampling and testing as well as by analysis of material stresses in the silo. Both location and magnitude of the peak pressure obtained by calculations agreed well with experimental results. Thus, the assumption in the flow channel and the method of calculation were found to be appropriate.
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  • Yoshifumi Tsuge, Kazushi Mori, Shigeyuki Tateno, Hisayoshi Matsuyama
    1995 Volume 21 Issue 3 Pages 565-572
    Published: May 10, 1995
    Released: November 12, 2009
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    Fault detection and diagnosis of a continuous process with input fluctuations such as load fluctuations can not be simply performed because of the difficulty of detecting the abnormality in the process, where normal values of state variables are uncertainly time-varying due to input fluctuations.
    In this study, normal values of output variables are estimated by the auto regressive exogenous model (ARX model). The measured value of an output variable is classified as 5-range signs (+, +?, 0, -?, -) by simultaneously performing two sequential probability ratio tests (SPRTs) based on the error residual between estimated and measured values : one test examines whether it is normal or higher than normal, the other examines whether it is normal or lower than normal. A combination of signs given to all the output variables is called a “pattern, ” which is considered to represent an abnormal situation occurring in the process. Then, the fault diagnosis algorithm based on signed directed graph can deduce the fault origin that causes the pattern. The effectiveness of this approach is demonstrated through experiments with a tank-pipeline system.
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  • Hiroaki Masuda, Shuji Matsusaka, Hironori Fujimoto
    1995 Volume 21 Issue 3 Pages 573-580
    Published: May 10, 1995
    Released: November 12, 2009
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    On-line measurement in gas-solids pipe flow was studied both theoretically and experimentally. The measurement is based on the amount of impact charge per unit time, namely, the current generated when particles are flowing through a pipe. In the new system, two detecting pipes made of different materials are installed in series, and the solution of the system-equations for the two generated currents brings about both the powder flow rate and the electric charge of particles simultaneously. The method is successfully applied in eliminating the initial charge effect which has often been pointed out. A characteristic value of electrification (particle charge per unit mass where effective contact-potential difference becomes zero) is an important factor in the computer treatment of the currents. The air velocity dependence of the characteristic value was experimentally clarified and the accuracy of the measurement was also evaluated. It was found that the accuracy became higher with increasing difference in the characteristic values between the two detecting pipes.
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  • Jusuke Hidaka, Junya Kano, Atsuko Shimosaka
    1995 Volume 21 Issue 3 Pages 581-587
    Published: May 10, 1995
    Released: November 12, 2009
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    Wall pressure and flow rate during discharge of granular materials from a bin-hopper system were measured to discuss the validity of a proposed mechanical model on granular flow in a bin-hopper system. The measured values agree well with the calculated ones based on the model. This shows that the model is applicable to the mechanical analysis of flowing granular materials in a bin-hopper system. The mechanical model is applicable to the estimation of flow rate of granular materials discharging through an orifice, and the dependence of the height of powder bed in a hopper and diameter of orifice on flow rate is discussed.
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  • Hiroyuki Kawasaki, Hisaya Tanaka
    1995 Volume 21 Issue 3 Pages 588-593
    Published: May 10, 1995
    Released: November 12, 2009
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    An experimental study was performed on gas holdup, φ, measured by varing gas flow rate, hole diameter and unaerated liquid height in a bubble column with a single hole orifice as a gas distributor.
    For single orifices, two different flow regions existed in the column : the spouting and calming sections. The former section was the lower region in the column and the flow heterogeneity for bubble dispersion existed there over the whole range of gas flow rates in this study. The latter was the upper region representing the common bubble flow regimes. Though the border between two sections was nearly two times the column diameter. The value of φin. the spouting section was negligible, compared with that in the calming section.
    Since the bubble rising velocity in the calming section was constant and independent of the operating conditions at low gas flow rate, this flow region was considered as the free rising one. Gas holdup in this section was correlated by a dimensionless equation with the flow parameter defined by the ratio of the reference velocity in the free to that in the circulated rising regions, respectively.
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  • Hideto Yoshida, Toshiyuki Fujioka, Keisuke Hashimoto, Keiichi Nagahash ...
    1995 Volume 21 Issue 3 Pages 594-602
    Published: May 10, 1995
    Released: November 12, 2009
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    Three-dimensional numerical simulation and experimental studies have been conducted on the fluid flow and particle movement in a cyclone classifier with blow-down. By use of the blow-down method, the downward velocity component near the conical wall becomes larger than the case without blow down. In the case of the blow-down method, the particles collected on the conical wall move to the dust box smoothly and 50% cut size decreases.
    It was also confirmed by the simulation that particles of small diameter enter the dust box first, but they eventualy exit the box in the case without blow-down. In the case of blow-down, particles of small diameter are aspirated into the blow-down tube and re-entrainment of particles from the dust box can be suppressed. From the experimental and theoretical studies, it was also found that the partial separation efficiency with small inertia tends to become constant in the case of the blow-down method.
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  • Katsutoshi Inoue, Naoto Ido, Kazuharu Yoshizuka, Keisuke Ohto
    1995 Volume 21 Issue 3 Pages 603-607
    Published: May 10, 1995
    Released: November 12, 2009
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    Equilibrium distribution in the solvent extraction of 12 kinds of rare earths from hydrochloric acid solutions with 2 kinds of commercial phosphorus-based acidic extractants, Cyanex 272 and TR-83, were investigated at 303 K using IP solvent, a commercial diluent of iso-paraffins, as a diluent in order to examine the separation factors between adjacent elements by these extractants. It was found that rare earths are extracted with these extractants according to the cation-exchange reaction releasing three hydrogen ions per unit metal ion as observed in the extraction with other acidic extractants. The plots of the apparent extraction equilibrium constants for each metal against atomic number exhibited the “tetrad effect” as reported in the extraction with PC-88A and D2EHPA. The separation factor between La and Ce by Cyanex 272 was much greater than other extractants. Those between Nd and Sm, and Gd and Dy were also great with this extractant. In the case of TR-83, it was great for Sm/Nd and Yb/Er.
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  • Junji Suzuki, Yoshio Yonei, Chiaki Yokoyama
    1995 Volume 21 Issue 3 Pages 608-613
    Published: May 10, 1995
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Gährs's data only exist for the solubility of nicotine in high pressure carbon dioxide. Moreover, Gährs's data show singular behavior. By using a high pressure cell which had glass windows, the phase behavior of a carbon dioxide-nicotine system was observed visually and the solubility of nicotine in high pressure carbon dioxide was measured at 313 K and 343 K. As a result, the solubility data obtained in this work were enhanced by increment of the density of carbon dioxide and differ from Gährs's data. These data were correlated with solubility parameters and the Soave-Redlich-Kwong equation of state. According to the correlation by solubility parameters, the solubility behavior of nicotine in carbon dioxide could be described easily with accuracy using the SRK equation. It became clear that the correlation with solubility parameters is one of the most practical methods.
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  • Yoshiaki Shimizu
    1995 Volume 21 Issue 3 Pages 614-617
    Published: May 10, 1995
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In chemical processes, we often take advantage of customizing daily problem-solving when a final solution will be obtained after solving a family of optimization problems repeatedly. In aid of the neural network, in this note we have engaged in improving and customizing the algorithm of progressive linear programs (PROLP) after introducing manifold criteria to estimate active constraints. Through a few numerical experiments, the effect of the approach has been examined.
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  • Kunihisa Osasa, Hiroshi Itemoto, Hiroyuki Tanaka
    1995 Volume 21 Issue 3 Pages 617-621
    Published: May 10, 1995
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A novel electroflotation method using bipolar sacrificial electrodes, which were comprised of alternating stationary and rotating disks was developed. The efficiency of turbidity removal reached a maximum value at acertain rotational speed of the electrodes, and then decreased gradually with increasing rotational speed, or remained approximately constant. The efficiency increased with increasing electric current and the number of electrode plates, and decreased with increasing flow rate of liquid. The separation process was based on the assumption that the removal of flocs was due to the flocculation-breakup process using the tanks-in-series model.
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  • Yoshihito Kato, Setsuro Hiraoka, Yutaka Tada, Seiji Shirai, Seung-Tae ...
    1995 Volume 21 Issue 3 Pages 621-624
    Published: May 10, 1995
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The mass transfer coefficient at the wall of a horizontally shaking vessel was measured with the constant potential method using 1N-KOH+0.2N-K4 Fe (CN) 6 +0.01N-K3Fe (CN) 6 aqueous solution.
    The average mass transfer coefficient depended strongly on a circulating frequency above the critical circulating frequency for mixing, compared to that below the critical frequency. In the higher circulating frequency range, the shaking vessel had almost the same performance as that for impeller mixing. In the lower circulating frequency range, the former had inferior performance to the latter.
    The local mass transfer coefficient showed a higher value at higher positions of the vessel wall from the bottom. The maximum local mass transfer coefficient was observed at the trough of the free surface wave.
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  • Toshiharu Sahashi, Susumu Nii, Katsuroku Takahashi, Hiroshi Takeuchi, ...
    1995 Volume 21 Issue 3 Pages 625-628
    Published: May 10, 1995
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A simple method for simultaneous removal of dust and SO2 from polluted gas was proposed by using sorbent-coated fabric filter. As a sorbent for SOx, commercially available GC-tron or Ca (OH) 2 was used. When the humidity of gas was high, both sorbents exhibited higher SO2 removal than dry gas. Especially for low SO2 concentration, SO2 removal by GC-tron was superior to that by Ca (OH) 2. When this method was applied to the treatment of flue gas from crude oil combustion, the dust was collected on the sorbent layer and SO2 was efficiently removed by a layer of 3 mm thickness.
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  • Masafumi Mochizuki, Noboru Takei, Tomonori Satoh, Kazumi Satoh, Takash ...
    1995 Volume 21 Issue 3 Pages 628-632
    Published: May 10, 1995
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Individual power required for the upper and lower impeller of a dual impeller in turbulent mixing vessels with nine types of dual impellers were measured. The following points were revealed.
    1) The power of disk turbines (D) in dual configuration is 0.7-0.9 times that of a single one, the power of downward pumping pitched turbines (Pd) was 0.6-1.9 times that of a single one, and the power of upward pumping pitched turbines (Pu) was 0.6-1.3 times that of a single one. These behaviors of power are closely related with flow transitions.
    2) In the range of impeller Spacing/Vessel diameter=1/6-1/4, for D (upper) -Pd (lower), Pu-D and Pu-Pd dual impellers, a downward pumping flow due to Pd becomes an upward flow, and an upward flow due to Pu becomes a downward flow.
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  • Kazumi Satoh, Norifumi Maeda, Noriyuki Ogawa
    1995 Volume 21 Issue 3 Pages 632-635
    Published: May 10, 1995
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The minimum power of impeller required for complete suspension of solid particles, based on Zwietering's criterion, was measured for single and twin impeller systems. The effects of the configuration of vessel and the number of impellers on the minimum required power were examined.
    The minimum required power per unit liquid volume Pfv for a single impeller system increased gradually as the length ratio of long side to short side A/B incresed over 1.5 Pfv for a twin impeller system remained nearly constant at a lower value than that of a single impeller system in the range of A/B=1.52.25.
    The Pfv of a pitched-blade turbine was below 1 / 2 of the value of a flat-blade disc turbine under the same conditions and was independent of the rotational direction of each impeller.
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  • Atsushi Toyoda, Tatsuo Kanki, Tsuyoshi Asano, Shigeru Momoda, Yoshimic ...
    1995 Volume 21 Issue 3 Pages 636-639
    Published: May 10, 1995
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In wastewater treatment by fluidized-bed bioreactor with polyurethane support particles, the influence of seed microbes on treatment characteristics has been investigated experimentally. In consequence, it was shown that the organic substrate concentration in the effluent and amounts of retained and suspended microbes show respective specific time-dependent variations in the day course from initial to steady stage, regardless of growth history of seed microbes. But these variation processes with unacclimated microbes were found to be retarded in direct proportion to day course when compared with processes with acclimated microbes. This was caused by the presence of an induction phase and related delay in the protozoa growth rate.
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