KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 17 , Issue 2
Showing 1-34 articles out of 34 articles from the selected issue
  • Eisuke Kayawake, Yoshihisa Narukami, Masatsugu Yamagata
    1991 Volume 17 Issue 2 Pages 225-231
    Published: March 10, 1991
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A membrane module enclosed in abio-Reactor was designed to complete a compact system that reduces the required permeability power.
    In this work, cross-flow filtration by suction of methane fermentation broth and by vertical flow in a tubular element of circulation broth were carried out with an externalpressure-type ceramic membrane. The effects of flow velocity, applied pressure and membrane washing were studied.
    Permeation flux was stabilized at3.82×10-6m3·m-2·s-1 (flow velocity : 0.4m·s-1), and it increased with increasing suction pressure from 760 to 360 torr.
    Membrane-washing methods were studied with regard to back-pressure washing and bio-gas circulation in order to maintain stable permeation flux. Permeation flux was increased byback-washing or fermentation gas circulation. High and stable permeation flux could be maintained by combined use of the two methods.
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  • Masashi Momonaga, Koji Kagara
    1991 Volume 17 Issue 2 Pages 232-237
    Published: March 10, 1991
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Since pyridyl alanine (PA) synthesized as an intermediate of medicine is racemic, the mixture requires optical separation.
    A novel method of optical separation comprising the formation of diastereoisomer salt by L-tartaric acid and preferential fractional crystallization was found, and the optical purity of L-PA crystals obtained was more than 96 %.
    Furthermore, it was clarified that the crystallization of D-PA, which is useless for medicine, is depressed by addition of NaOH to the crystallization solution. Finally, by using the Z-factor proposed by us as a key factor in crystallizer scale-up, the optimum design for industrial crystallization was developed.
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  • Hidefumi Toyohara, Yuji Kawamura
    1991 Volume 17 Issue 2 Pages 238-242
    Published: March 10, 1991
    Released: November 12, 2009
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    When binary particle mixtures were fluidized in a tapered bed, jetsam particles segregated to the bed bottom and formed core-type segregation within a certain range of gas velocities (i.e. the partially fluidizing region). The jetsam fraction in the core was larger than that in a conventional fluidized bed of uniform cross-sectional area, and at the bottom of the core an almost pure jetsam layer was observed.
    In this study, experiments in the continuous separation of binary particle mixtures were carried out by mean of continuous and constant feed of the mixtures on the bed surface and discharge from the surface and bottom of the core region of the bed.
    We found that selective and continuous discharges of jetsam particles from the bed bottom and flotsam particles from the bed surface were maintained under the condition of core-type segregation in the bed. It can be concluded that highly efficient continuous particle separation is possible when using a tapered fluidized bed.
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  • Shigeki Takishima, Hiromasa Matsumoto, Hirokatsu Masuoka, Yasunari Muk ...
    1991 Volume 17 Issue 2 Pages 243-252
    Published: March 10, 1991
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Experiments in binder removal from alumina green bodies were carried out, utilizing the supercritical fluid extraction technique to investigate optimum combinations of binder components and optimum operating conditions. Firstly, debindering from alumina samples molded with different waxes was carried out by using supercritical CO2. Paraffin wax having a melting point temperature of 320K was selected as the main binder component, since it showed the highest extraction yield. Secondly, debindering experiments were performed from samples for the JIS bending-strength test, which were molded with paraffin wax, stearic acid and one of several thermoplastic resins. It was found that damage to the debindered samples was closely related to species and amounts of the thermoplastic resins as well as the extraction yields of low-molecular weight binder components. In addition, polyethylene and polypropylene were found to be suitable as polymeric binder components. Moreover, when the debindered samples were sintered, the bending strength of the sintered products was as high as those of samples produced by the conventional methods.
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  • Susumu Yamada, Yasuhisa Nakamura, Tetsuo Watanabe, Hitoki Matsuda, Mas ...
    1991 Volume 17 Issue 2 Pages 253-259
    Published: March 10, 1991
    Released: November 12, 2009
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    A new double-tube radiant burner equipped with a fluidized bed in the outer exhaust gas tube was developed, in which the combustion gas released from the inner combustion tube was drawn off through the fluidized bed in the outer tube. The heat transfer mechanism of this burner across the burner tubes was studied and its heat transfer characteristics were investigated.
    It was found that not only a uniform temperature distribution along the outer tube but also heat transfer augmentation was obtained by the present burner with fluidized bed, ascompared to the conventional type without fluidized bed. It was found that a uniform temperature distribution along the outer tube was realized by the fluidized bed, owing to its uniform temperature distribution in the axial direction. It was also confirmed that the temperature distribution along the outer tube without fluidized bed was affected by the temperature distribution along the inner tube.
    These results showed that the fluidized bed equipped with a double-tube radiant burner contributed to the uniformity of temperature distribution along the outer tube and also to augmentation of heat transfer from the inner to the outer tube.
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  • Yasushi Tomisaka, Yasuo Tanaka, Eiji Nakanishi
    1991 Volume 17 Issue 2 Pages 260-266
    Published: March 10, 1991
    Released: November 12, 2009
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    A new internal heat-integrated distillation system with a heat pump that does not require any external heating and/or cooling is proposed together with a procedure to determine the operating pressure for the internal heat-integrated distillation system.
    This will give the pressure as a function of the number of stages, compositions at each stage of both columns, heat transfer areas and heat transfer coefficients of the distillation units.
    Simulation results prove that the proposed system has good performance in the low-temperature separation of air and can be applied to products of various specifications. Moreover, the simulation results show that the system has a characteristic behavior in that an increase in the heat duty of the condenser increases the purity of the distillate and decreases the purity of the residue. Such behavior is never found in usual distillation systems.
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  • Kenichi Yamaseki, Satoru Nakayasu, Kyoko Yamamoto, Hideo Kameyama
    1991 Volume 17 Issue 2 Pages 267-272
    Published: March 10, 1991
    Released: November 12, 2009
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    A porous alumina film was formed on the surface of an aluminum plate by anodic oxidation. The plate was then treated with a hot aqueous solution of chloroplatinic acid, thereby impregnating Pt on the alumina. Variations were made in the Pt impregnation conditions (such as Pt concentration, pH of the solution added, and ratio of the quantity of solution added to the surface area treated) in order to study the effects of these conditions on Pt concentration on the resultant catalyst. The catalytic activity during dehydrogenation of cyclohexane was measured.
    A catalyst was obtained with a Pt concentration of 1.89 g/m2 and a degree of dispersion of 0.42 which proved to be more active than three commercial Pt/alumina catalysts at 1 atm and 473 K when comparisons were made of reaction rate per unit volume of catalyst.
    This catalyst made possible the design of a compact endothermic reactor which also can serve as a heat exchanger. The catalyst is expected to exhibit high thermal conductivity and low pressure loss when installed in the reactor.
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  • Kyoko Yamamoto, Hideo Kameyama
    1991 Volume 17 Issue 2 Pages 273-280
    Published: March 10, 1991
    Released: November 12, 2009
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    A low-temperature-heat storage apparatus that stores the heat of water evaporation in the form of ice produced in a kind of organic polymer gel (WAPG) was proposed. An air conditioner with the above heat storage apparatus was also proposed (Fig. 5). The surface area of water can be spread by the use of WAPG in a thin sheet type. Part of the water contained in WAPG is vaporized at 0.2 to 0.6 kPa to change the remaining part of the water into ice. It was shown that the water vapor pressure above the polymer gel was the same as that above pure water. The heat stored in a liter of WAPG was around 222 kJ. From calculation, the coefficient of performance of heat storage (COPC) was 5 to 10, depending on the temperatures of vaporization and condensation (Fig.7). The coefficient of performance of the air conditioner (COPA) was calculated for various operating parameters such as COPC temperature and vapor pressure changes of the air-conditioned room, work of the blower and total energy loss. The proposed air conditioner can be operated at a COPA of 2 to 4 (Figs. 10, 11, 12).
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  • Yasuo Koseki, Sankichi Takahashi
    1991 Volume 17 Issue 2 Pages 281-287
    Published: March 10, 1991
    Released: November 12, 2009
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    To develop a high-solubility absorbent, a mechanism of solubility elevation was proposed and experimentally studied on the basis of the “co-hydration” phenomenon.
    The solute in an aqueous electrolyte solution is ionized and has many water molecules (hydration). Hydration has two regions, the structure-making region (SMR) and the structure-breaking region (SBR). Water vapor pressure depression relates to the hydration number of both regions, while solubility elevation relates to the hydration number of SMR. Solubility tends to increase when the hydration number of the ion, especially in the SMR, decreases.
    In the proposed solubility elevation mechanism, other ions are added to induce the “co-hydration” phenomenon, the hydration number in the SMR is decreased and the solubility is increased. This mechanism was examined experimentally using aqueous LiBr/CaCl2 solutions and the “co-hydration” phenomenon was confirmed by a compressibility depression seen in density measurements.
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  • Shigeaki Kasaoka, Eiji Sasaoka, Yoshiyuki Yokota
    1991 Volume 17 Issue 2 Pages 288-296
    Published: March 10, 1991
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To establish a catalytic process for the steam-reforming of methanol, various impregnated-supported and coprecipitated catalysts (supports : Al2O3 (γ, θ, α), CaO, CeO2, Cr2O3, La2O3, MgO, Nb2O5, SiO2, TiO2, Y2O3, ZnO, ZrO2) were prepared and the relationship between reaction conditions and catalytic reaction performance was investigated, together with an examination of the effect of impurities (ethanol, acetone, acetic acid) in methanol on the catalytic activity. Furthermore, the catalytic decomposition of methanol and the reaction of carbon dioxide and hydrogen formed (the reverse reaction of shift conversion) were studied.
    The experiments were carried out using a fixed-bed flow reactor under atmospheric pressure at 200° and 250°C. The inlet gases were mainly 10%CH3OH-10%H2O-N2, the total flow rate was 119 cm3N· min-1 per 1.0 ml of each catalyst with an average diameter of 1.0 mm, and the space velocity was 7.1× 103h-1.
    The main results obtained were as follows. (1) ZrO2 and α-Al2O3 were superior supports, giving good catalytic activity and selectivity, and the copper content was suitable at ca. 15 wt% for the impregnated-supported catalysts and ca. 70wt% for the coprecipitated catalysts. (2) The impurities in methanol caused a remarkable deactivation of catalysts above 10 ppm content, but were temporary poisons by the impurities, and in pure methanol the activities were completely recovered. (3) In ZrO2 and α-Al2O3 impregnated-supported copper catalysts, a by-product, carbon monoxide, was remarkably inhibited, and it was proved that this carbon monoxide was produced by the reaction of carbon dioxide and hydrogen formed.
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  • Shigeaki Kasaoka, Eiji Sasaoka, He De Hua
    1991 Volume 17 Issue 2 Pages 297-304
    Published: March 10, 1991
    Released: November 12, 2009
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    To establish a catalytic process for the cracking of methanol (CH3OH=CO+2H2), various supported platinum (such as rhodium, palladium, ruthenium) catalysts (supports : Al2O3 (γ, α), CaO, CeO2, Cr2O3, La2O3, MgO, Nb2O5, SiO2, TiO2 (anatase), Y2O3, ZnO, ZrO2) were prepared and the relationship between the reaction conditions and the catalytic activity-selectivity was investigated, together with the measurement of surface acidity by the temperature-programmed desorption method.
    The experiments were carried out using a fixed-bed flow reactor under atmospheric pressure, mainly at 300°C and 350°C. The inlet gas was mainly 10% CH3OH-N2, the total flow rate was 250 cm3 N · min-1 per ml of each catalyst with an average diameter of 1.0 mm, and the residence time was 0.24 s.
    The main results obtained were as follows. (1) Activity and selectivity were widely different according to kind of support, and CH3OCH3, CH4, CO2, H2O were more or less formed as by-products, in amounts that were larger at the acidic supports. (2) As side reactions, 2CH3 OH=CH3OCH3 +H2O, CH3OCH3 = CH4 + CO + H2, CO+ 3H2= CH4+ H2O and CO+H2O=CO2+H2 were considered. (3) Pt/MgO was the most suitable catalyst, giving good activity and selectivity to CO and H2 among the catalysts used in this study.
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  • Tohru Mitomo, Tomohiro Ohta, Hiroaki Sasaki, Kenichi Ohtsuka, Yasuhiro ...
    1991 Volume 17 Issue 2 Pages 305-312
    Published: March 10, 1991
    Released: November 12, 2009
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    Amorphous-carbon films were deposited by the RF plasma CVD method from hydrocarbon gases. Two types of properties were observed in respective films by changing pressure, flow rate and source gas species ; one film was hard with an amorphous structure, while the other was soft with a graphite-like structure. The highest deposition rate of hard film was 0.8 μm/h.
    The effect of the gaseous reactions on deposition rate and properties of films in the RF plasma were studied by using in-situ FT · IR and OES analyses. The results showed that the film properties were affected by the residence time of reactant gases. In particular, higher concentration of acetylene (≥ 2.3×1014 cm-3) was a cause of growth of soft, graphite-like films.
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  • Chao-Ran Deng, Yuzo Sanada, Tadatoshi Chiba
    1991 Volume 17 Issue 2 Pages 313-318
    Published: March 10, 1991
    Released: November 12, 2009
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    In an effort to estimate the rate of swelling of coal particles during liquefaction, measurements of volumetric swelling ratio were carried out using various kinds of solvents for 100-to 150-mesh Akabira coal particles which were heated up from room temperature to 723 K under 10.1 MPa hydrogen atmosphere or held at a constant temperature around 323 K. Observed changes of the swelling ratio with time were analyzed by an unreacted-core model for solvent diffusion through a swollen shell and relaxation reaction on the surface of the unswollen core of a particle. Results of analysis showed that the swelling rate depends on solvent properties and temperature and that fast swelling can be described as a relaxation reaction-controlling process while slow swelling is a diffusion or diffusion/relaxation reaction-controlling process. The apparent activation energy evaluated from the temperature dependency of the relaxation reaction rate constant was about 66kJ/mol, which corresponds well to the dissociation energy of hydrogen bonds. This confirms a conventional explanation that swelling proceeds through dissociation of hydrogen bonds in coal by solvent. Based on these results, the observed effects of solvent and heating rate on increase of the swelling ratio under liquefaction conditions were successfully simulated by the model.
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  • Jun Fukai, Osamu Miyatake
    1991 Volume 17 Issue 2 Pages 319-325
    Published: March 10, 1991
    Released: November 12, 2009
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    Laminar-flow heat transfer within two parallel plates to which baffles are attached in a staggered fashion is numerically analyzed. Both of the plates are assumed to be maintained at a constant temperature, while the baffles are respectively perfectly conductive and adiabatic. The computations are carried out for various geometric configurations and various values of Reynolds number, Re, and Prandtl number, Pr.
    Though the logarithmic mean heat transfer coefficient, Nu, generally increases with increase in the height of baffles, Re and Pr and with decrease of the distance between baffles, there are the following exceptions. 1. Nu approaches an asymptotic value at low values of Re for each configuration when the baffles are perfectly conductive. 2. Almost the same value of Nu is obtained for a given configuration even if the height of the baffles is different. 3. Nu increases with incriase of distance between baffles when the baffles are low in height and Pr is large.
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  • Akira Suzuki, Tadashi Nakamura, Shinji Itoh, Shin-ya Yokoyama
    1991 Volume 17 Issue 2 Pages 326-334
    Published: March 10, 1991
    Released: November 12, 2009
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    Steam distillation was studied as a means of oil separation from the reaction product of the direct thermochemical liquefaction of sewage sludge. The authors looked for any influence of liqufaction conditions on the distillable oil yield. It was found that the yield increased with increase in the liquefaction temperature. Holding time and catalyst loading had some bearing on the yield when considered in conjunction with the liquefaction temperature, but the kind of catalyst used for the liquefaction had little effect on the yield. Under the same liquefaction conditions, the distillable oil yield exponentially increased with rising distillation temperature. The distillable oils were similar to petroleum fuel oil in terms of heat value and viscosity.
    The reaction heat of the sewage sludge liquefaction was also observed by highpressure DTA (differential thermal analysis). The result of this DTA study revealed that the liquefaction of sewage sludge was an exothermic reaction with a peak at about 550 K.
    On the basis of foregoing data, the heat balance of the liquefaction process coupled with distillation was evaluated, and it was confirmed that the sewage sludge liquefaction process is a net energy producer.
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  • Ikuo Yonezu, Kenji Nasako, Shin Fujitani, Akio Furukawa, Takahiro Yone ...
    1991 Volume 17 Issue 2 Pages 335-340
    Published: March 10, 1991
    Released: November 12, 2009
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    The reaction heat for CaNi5-H2, LaNi5-H2 and Ca1-xLaxNi5-H2systems was measured by differential scanning calorimetry (DSC) under a high-pressure H2 atmosphere.
    The values of the reaction heat obtained from DSC were verified by calculation from van't Hoff plots and weight change values by therinogrametry, and they were correlated with the effective hydrogen content on pressure-composition isotherms.
    The reaction heat of hydrogenation and dehydrogenation increased with increasing effective hydrogen content.
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  • Ryoji Utsumi, Hiroshi Yamamoto, Masami Ichikawa
    1991 Volume 17 Issue 2 Pages 341-346
    Published: March 10, 1991
    Released: November 12, 2009
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    The pressure drop of fluid flow through a woven metal wire-cloth sieve has been the topic of several studies, since it is important for filters, rectifying apparatus and the like. But the data for an electroformed sieve have not been included in these studies. The purpose of this study is to obtain an experimental equation for the pressure drop coefficient of air flow through an electroformed sieve. Experiments were carried out by using eight kinds of sieves, having different aperture sizes in the range from 6.42 to 51.9gm, and by vanying the Reynolds number from 10-2 to 102. All results of these experiments have been correlated by a simple equation by which the pressure drop coefficient can be calculated from the Reynolds number based on sieve aperture. Also, it is shown that the equation of this study is better for the electroformed sieve than those in previous studies.
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  • Kiyoshi Idogawa, Takashi Fukuda, Hiroshi Nagaishi, Yosuke Maekawa, Tad ...
    1991 Volume 17 Issue 2 Pages 347-354
    Published: March 10, 1991
    Released: November 12, 2009
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    Axial and radial concentration distributions of solid particles were measured in a 39 cm-dia. bubble column with a simultaneous gas-liquid injection nozzle.
    Due to a spouted stream blow from the nozzle through the column, the solid concentration near the column wall was found to be higher than that around the center of the column. Axial distribution of solid particles at the center of the column was well described by an existing sedimentation-diffusion model, and an empirical correlation was deduced for the dispersion coefficient of solid particles. For a binary mixture of solid particles having different diameters and densities, no essential interaction between the solid components was detected, giving an equivalent coefficient for them.
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  • Takenari Takeshita, Kunio Atsumi, Mitsumasa Jinno, Genji Jimbo
    1991 Volume 17 Issue 2 Pages 355-361
    Published: March 10, 1991
    Released: November 12, 2009
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    The discharge rate of granular materials from a hopper equipped with a vertical pipe at the bottom decreased with increasing flow rate of air when the air was injected from the uppermost part of the pipe inlet. With decreasing particle diameter, the flow rate of air required to control the discharge rate of particle became smaller.
    The flow of particles from hopper to standpipe first contracted at the standpipe inlet and then expanded to fill the cross section of the pipe. The basic flow equations of granular materials and air, using an experimental equation that takes the contraction into account, gave estimates of the discharge rate of granular materials with an accuracy of ± 30 %. Calculated results of air pressure distribution along the standpipe agreed well with the experimental data.
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  • Tsuneyki Sato, Takenori Uasa, Nobuyuki Imaishi
    1991 Volume 17 Issue 2 Pages 362-370
    Published: March 10, 1991
    Released: November 12, 2009
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    Gas flow and mass transfer in a horizontal cold-wall CVD reactor are analyzed numerically using a two-dimensional model, in which homogeneous and interfacial reactions, thermal diffusion and temperature-dependent physical properties are taken into account.
    Criteria for the incipience of recirculating flow are expressed as Gr/Re>130 for Re<3 and Gr/Re>40 for Re>3. The film growth rate obtained by the simulation is in good agreemet with the experimental results of other investigators. Effects of the homogeneous and interfacial reactions on growth rates are discussed also based on the results of a simple model in which thermal diffusion and the temperature dependency of the physical properties are neglected.
    General aspects of the horizontal cold-wall CVD reactor can be obtained by the simulation models mentioned above.
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  • Masahiro Ohshima, Iori Hashimoto, Hiromu Ohno
    1991 Volume 17 Issue 2 Pages 371-379
    Published: March 10, 1991
    Released: November 12, 2009
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    The stability of multi-input multi-output model predictive control (MIMOMPC) systems is analyzed. Some new stability theorems for MPC systems with the capability of making long-range predictions are derived. These theorems ensure that a stable control system will be realized when either the reference trajectory or input weight coefficients are properly tuned, even if large model-plant mismatch exists.
    In the case of one-step prediction, the relationship between the tuning of the controller's parameters and the plant's loop interactions becomes apparent. Even for a plant for which only positive/negative sign of steady-state gain is known, a stable control system can easily be realized by one-step-prediction control.
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  • Hisashi Miyashita, Yasushi Kondo, Toshiyuki Hata, Tatsuo Nishimura
    1991 Volume 17 Issue 2 Pages 380-386
    Published: March 10, 1991
    Released: November 12, 2009
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    An experimental investigation was performed to study the mechanism of heat transfer enhancement due to placement of three kinds of turbulence promoters, each of different shape, in a rectangular duct. To check enhanced heat transfer, the enhancement ratio of local and average mass transfer coefficients were measured by an electrochemical method. Kinds of promoter, the pitch of the promoter, and the clearance between promoter and wall surface were varied in the experiments. In a performance evaluation of promoters, the triangular promoter (B-type) showed good enhancement at each clearance, and maximum evaluation value was shown at zero clearance.
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  • Mitsukuni Mizuno, Atsushi Fukaya, Genji Jimbo
    1991 Volume 17 Issue 2 Pages 387-394
    Published: March 10, 1991
    Released: November 12, 2009
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    Ultrafine particles have extremely large external surface area, strong adhesive and agglomeration forces, and a large bed voidage, exceeding 90%.
    Ultrafine particles were packed by means of tapping, centrifugal and compression methods, and the distributions of voidage in the resulting beds were measured by X-ray computed tomography (X-ray CT).
    The results of the measurements made clear the internal structure of the packed beds of ultrafine particles obtained by the above-mentioned methods as well as the characteristic distribution of voidage near theperiphery. It was also found that the packing characteristics depended on structural features of the constituent particles, such as chain-like structure and agglomerate structre.
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  • Yasushige Mori, Keishi Shimokawa, Hiroshi Katho, Masataka Tanigaki, Wa ...
    1991 Volume 17 Issue 2 Pages 395-401
    Published: March 10, 1991
    Released: November 12, 2009
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    This study deals with the recovery of chromium from.a waste water containing sulfuric acid by a batch-type liquid surfactant membrane, of which the organic phase is kerosene with 12 vol. % 2-ethylhexyl alcohol and 2 vol. % polyamine (Exxon Chem., ECA 4360J) without any extractant. A model for the chromium transport is proposed using experimental data in which the initial total chromium concentration is below 2 mol m-3. The extraction of chromium, the leakage of internal aqueous phase, the entrainment of the external aqueous phase, and the permeation of water were taken into account in this model, which satisfactorily simulated the effects of volumefraction of the emulsion and the sulfuric acid concentration in the external phase. The parameters of the proposed model were determined at various temperatures. This membrane system was also examined for the recovery of chromium (VI) from an actual waste water from chromium gilding, and it was found that chromium could successfully be transported from waste water containing various metal ions.
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  • Setsuji Tone, Masao Kawashima, Teruyoshi Morikawa, Toshiyuki Kita, Mas ...
    1991 Volume 17 Issue 2 Pages 402-409
    Published: March 10, 1991
    Released: November 12, 2009
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    Effective absorption coefficients were evaluated from the observed profile of light intensity in a square column with gas-liquid-solid dispersion containing TiO2 particles (in the range of mean diameter : 16.875.2 μm), and those were correlated as a first-order equation of specific surface areas of gas and solid.
    Quantum efficiencies were obtained from the measured photooxidation rate of NADH (reduced form of nicotinamide-adenine dinucleotide) in a small annular photoreactor and were expressed as a first-order equation of the specific surface area of TiO2.
    In an annular reactor (outer diameter= 10 cm, inner diameter = 4.6 cm and height = 1 m) with gas-liquid-solid dispersion, photooxidation of NADH was carried out and the observed NADH concentrations with reaction time agreed well with the values calculated from the model of light intensity profile using the effective absorption coefficient.
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  • Osamu Miyatake, Hiromi Omori, Hiroyuki Iwashita
    1991 Volume 17 Issue 2 Pages 410-416
    Published: March 10, 1991
    Released: November 12, 2009
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    Laminar heat transfer in combined forced -and natural -convective axial flow of fluid through closely packed triangular and square arrays of cylinders with a uniform wall temperature are investigated experimentally.
    Experiments are conducted for cooling a liquid (ethylene glycol) flowing vertically upward and vertically downward in heat transfer 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 results, semi-ampirical equations suitable for predicting the logarithmic-mean Nusselt number are derived for closelypacked cylinders with the pitch-to-diameter ratios of 1 to 1.1 and 1 to 1.2 for triangular and square arrays, respectively.
    In the case of laminar heat transfer in forced -convective axial fluid flow through a triangular array of cylinders with a uiform wall heat flux, the experimental results of the multipoint arithmetic-mean Nusselt number obtained by Kim et al. are found to be less in agreement with the authors' previous numerical results. The discrepancy between the two results is seen to be primarily due to the overestimation of the transitional Reynolds number.
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  • Michitaka Suzuki, Takatoshi Sakata, Syoji Nakamura, Mitsuaki Hirota, T ...
    1991 Volume 17 Issue 2 Pages 417-422
    Published: March 10, 1991
    Released: November 12, 2009
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    Particle packed beds with log-uniform or Andreasen (Gaudin-Schuhmann) size distribution were prepared by tapping a mixture of mono-sized glass beads or crushed glass particles. The pressure drop in the bed was measured using air and the effect of particle size distribution on the pressure drop was examined. From our experimental results the pressure drop of a packed bed with log-uniform size distribution increases with decreasing inclination of cumulative undersize distribution. For Andreasen size distribution, pressure drop increases with decreasing value of the Fuller constant, especially in the range of 0.3 to 10. The estimated values by combination of Ergun's equation with our proposed model equation for the void fraction of a multicomponent particle mixture were in fairly good agreement with experimental values in both distributions.
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  • Chiaki Igarashi
    1991 Volume 17 Issue 2 Pages 423-425
    Published: March 10, 1991
    Released: November 12, 2009
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    Research was carried out on the effects of adsorbed cationic charge on the moisture content of compressed cake under equilibrium conditions. There was almost no effect on the equilibrium moisture content of the compressed cake by the adsorbed cationic charge and it was considered that there was no qualitative change in the sludge particles by the adsorbed cationic charge. In the case of belt press dewatering, whereby both cationic and anionic polyelectrolytes were added, the decrease in moisture content following an increase in adsorbed cationic charge, was considered to be due to the increase in dewatering rate of the flocculated sludge.
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  • Kazuya Ijichi, Yasushi Nishiyama, Yasuhiko Tanaka, Yoshimitsu Uemura, ...
    1991 Volume 17 Issue 2 Pages 426-429
    Published: March 10, 1991
    Released: November 12, 2009
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    The solids holdup within the riser of a circulating fluidized bed (CFB) with twocomponent particles was measured. Iron powders and silica sand, which are of nearly the same diameter but different in density, were mixed and fluidized.
    A correlation was proposed to estimate the axial solids holdup within the riser by considering superficial gas velocity, solids circulation rate and initial concentration of iron powder.
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  • Chikao Oda, Hidekazu Nakamoto, Takatoshi Kinoshita, Morihisa Maruko
    1991 Volume 17 Issue 2 Pages 430-433
    Published: March 10, 1991
    Released: November 12, 2009
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    Flow and Mixing Characteristics have been investigated for the lattice-type twinshaft high-viscosity agitator, which is capable of mixing liquids of viscosity as high as several thousand Pa·s.
    It is found that the liquid hold-up during agitation increases as the ratio of Fr/ ReM increases, and the amount of liquid hold-up is given as a function of Fr/ ReM.
    The longitudinal equivalent number of stages for perfectly mixing tanks was found to be almost independent of viscosity in the region of 0.15 kPa·s and was determined to be proportional to (ReF/ ReM) 1/3.
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  • Masaya Matsumoto, Naotake Katoh, Shigehiko Yamamoto
    1991 Volume 17 Issue 2 Pages 433-437
    Published: March 10, 1991
    Released: November 12, 2009
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    Fuzzy control is adopted for an exothermic batch reactor for which operation is most difficult in chemical processes.
    Both simulation and experiments are carried out for a cellulose pyrolysis reactor. Results showed that a nonlinear control algorithm derived from fuzzy control theory is useful in the operation of a batch reactor and that a control parameter tuning rule similar to PID control is also needed for fuzzy control.
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  • Katsuya Ogawa, Taku Matsushita, Kazumori Funatsu
    1991 Volume 17 Issue 2 Pages 437-441
    Published: March 10, 1991
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    β-Carotene sample prepared by the previously reparted separation process from cultured carrot cells was found to be pure as a carotenoid pigment but to contain some other lipids. We then improved the separation process by omitting the saponification process and improving the adsorption chromatography and liquid-liquid extraction. This new process markedly reduced the operation time, and highly pure β-carotene sample which contained no other lipid was obtained while maintaining the previous β-carotene yield (5.14μg/g-dry cells)
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  • Zeng Wei-Ping, Hitoki Matsuda, Masanobu Hasatani
    1991 Volume 17 Issue 2 Pages 441-444
    Published: March 10, 1991
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    From the viewpoint of high-temperature energy transportation, a fundamental study of a chemical heat pipe which uses the SO2 /SO3 reversible thermochemical reaction is carried out in a closed system consisting of exothermic and endothermic reactors.
    For a relatively wide range of circulating gas flow rate, the gas composition, and initial temperature of the catalyst fixed bed, it is found that SO2 and SO3 of nearly equilibrium concentration could be circulated between the SO2-oxidation and the SO3-deoxidization reactors. Further, the possibility of continuous thermal energy transportation by use of this system was determined. The heat transportation characteristics of the system is made clear by the relationship between the heat flux released from the catalyst fixed bed and the molal velocity of SO2.
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  • Makoto Tanaka
    1991 Volume 17 Issue 2 Pages 445-447
    Published: March 10, 1991
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    An equation is derived for predicting the effective thermal conductivity of wetted granular beds. Comparison of the equation with experimental data indicates that it is satisfactory. Effects of the respective thermal conductivity values of solid, liquid and gas and of the liquid content on the effective thermal conductivity of wetted granular beds are shown by use of the proposed equation.
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