KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 23 , Issue 3
Showing 1-21 articles out of 21 articles from the selected issue
  • Satoshi Hirata, Masahito Taya, Setsuji Tone, Masao Hayashitani
    1997 Volume 23 Issue 3 Pages 331-341
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A bioreactor equipped with a sunlight-collection device has been developed, for the production of microalgal biomass using sunlight. The bioreactor comprised a mirror-type sunlight collection device to collect sunlight, quartz fibers for transmission of the light, illumination plates made of acrylic resin for irradiation to cells, and an airlift fermentor. This bioreactor facilitated the culture of microalgal cells in a closed system. The efficiency of light collection, including transmission and irradiation in the bioreactor, was achieved up to 30% on the basis of photosynthetically active radiation. Under photoautotrophic conditions, continuous culture of Chlorella cells was successfully carried out for 14 days with regulation of flow rate of fresh medium in response to the change in solar irradiance. The cell concentration in the bioreactor could be kept almost constant for the culture period. The average production rates of the cells per unit area of sunlight collection was 0.20×10-3 kg m-2h-1, and the efficiency of conversion from light energy to chemical energy of cells was 9.8% based on a photosynthetically active radiation.
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  • Masafumi Mochizuki, Noboru Takei, Tomonori Sato, Hiroki Tada, Kazumi S ...
    1997 Volume 23 Issue 3 Pages 342-347
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The power required for the upper impeller of a dual disk turbine was measured in a 0.30 m diameter aerated vessel. The gas flow rate passing through the upper impeller was estimated with the relation between power consumption and flow rate of sparged-gas. The following results were obtained.
    1) The measured power of upper impellers in the loading regime was correlated with an average absolute deviation of 4.5% by the expression (Pg/P0) U=1-kNA where (Pg/P0)U is aerated/unaerated power ratio required for an upper impeller, NA is gas flow number and coefficient k depends on the Froude number, vessel diameter dT, impeller diameter d, and impeller spacing. It was successfully correlated not only for dual turbines with combination of the same diameter, but also with combinations of different diameter.
    2) The ratio of gas flow rate passing through the upper impeller to lower impeller, Qg, U/Qg, L, in-creased with the diameter, spacing and rotation speed of the impeller. Qg, U/Qg, L were 1/4-1/3 for d/dT =1/3, 1/3-3/4 for d/dT= 5/12 and 1/2-4/5 for d/dT= 1/2.
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  • Tatsuji Shizawa, Gyou Mizuno
    1997 Volume 23 Issue 3 Pages 348-352
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    An on-line automatic analyzer system for an interfacial polymerization polycarbonate polycondensation reactor has been developed.This analyzer system has two analyzer units, which are respectively set up for two sections in polycarbonate plant, and moreover the analyzer controlling system atilizes DCS (Distrubuted Control System). One analyzer unit is applied for checking oligomer in the first polycondensation reactor and the other is applied for measuring the unreacted raw material in the second polycondensation reactor. These analyzer units take advantage of titrators, and these units include hydrolysis of oligomer, washing of the beaker and, electrode sensor, and are operated by fully automatically. Accuracy of the data obtained by the on-line automatic analyzers is equivalent to that of the conventional manual operation. The measured data are calculated by DCS to make the analyzer controlling system manipulate raw material control valves. This system contributes to the stability of quality control, operation, labor saving and improvement of safety of the plant.
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  • Hiroyuki Tsujimoto, Toyokazu Yokoyama, Isao Sekiguchi
    1997 Volume 23 Issue 3 Pages 353-362
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Aiming at stable automatic operation of a fluidized bed granulator, three factors namely, moisture content, fluidization activity and input thermal energy were selected as principal ones affecting the granule diameter. The techniques of in-line measurement of these factors and their feed-back control were examined.
    The amplitude level of the stress wave generated by the fluidized particles was measured and applied for estimating fluidization activity. The new attempt quantified well particle properties and fluidization condition change.
    A fuzzy control system was established by the use of the production rules, determined by considering the degree of influence of the three factors having a strong interaction on granule quality.
    The ideal pattern of moisture content change in stable fluidization condition, which produces granules having narrow size distributions, was successfully obtained by using the established system, for even difficult granulation conditions by usual control methods.
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  • Hideto Yoshida, Tetsuya Yamamoto, Kengo Okanishi, Hideki Morisaki, Tak ...
    1997 Volume 23 Issue 3 Pages 363-370
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Experimental studies were conducted on the classification of flyash particles by use of a modified cyclone with movable 50% cut size on a bench scale. The 50% cut size of cyclone changed from 1 to 10 μm by the change of apex cone height and blow-up flow rate.
    When the height of the apex cone was higher at a constant blow-up flow rate, the 50% cut size increased. The reason for this was due to the fact that a decrease in the effective cross-sectional area near the inlet of the dust box gave rise to the increased average upward fluid velocity.
    In the case of blow-down, two kinds of different-sized fine particles were obtained simultaneously. When the blow-down flow rate was 5%, collection efficiencies of 4 and 28% were obtained with mean particle diameters 2 and 6 μm respectively.
    When both the blow-down method and a movable guide plate at the cyclone inlet were used, particles of average diameter of 1.5 μm were collected. Although the cyclone diameter was 400 mm, elaborate classification of flyash particles was achievable.
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  • Fumiaki Yoshikawa, Norihisa Shiraishi, Kenji Hashimoto
    1997 Volume 23 Issue 3 Pages 371-377
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In order to use coke oven gas (COG) as a chemical feedstock and/or city gas, it is necessary to reduce or eliminate various impurities, especially sulfur compounds, found in COG. Catalysts active at around room temperature were explored as a means of removing a sulfur compound, carbonyl sulfide (COS), through catalytic hydrolysis at low temperatures. An alumina impregnated with potassium carbonate was found to show high catalytic activity. COS was hydrolyzed in the low temperature range of 10 and 80°C. The reaction rate was first order with respect to COS and zero order with respect to water. However, the rate decreased rapidly as the water vapor pressure increased in the region over approximately 1.5 kPa at 40°C because the hydrolysis reaction was inhibited by a large amount of water adsorbed on the catalyst. In COG containing large amounts of hydrocarbons and carbon dioxide, the developed catalyst exhibited high long-term activity for COS hydrolysis at between 40 and 50°C under atmospheric pressure.
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  • Kang Liu, Tadaaki Shimizu, Makoto Inagaki
    1997 Volume 23 Issue 3 Pages 378-383
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In this paper, in order to get better robustness not only good response characteristics, we applied the Internal Model Control (IMC) to the system which includes time delay, and by using the Integral Square Error (ISE) and the complementary sensitivity function as the response and robustness measures respectively, to design the IMC controller. Here we first opplied IMC and PID Control to the distributed constant system, and compared the results on response performance and robustness. Finally, for comparing the control results among the IMC, PI control and Smith predictor about response characteristics and robustness, we did the control experiments on the heat exchanger which includes time delay. Consequently, the response performance and robustness of the control system by using IMC are better than that of by using PI control and Smith predictor.
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  • Masahiro Ohshima, Hiroko Ikenoue, Sigeyuki Tomita, Masataka Tanigaki
    1997 Volume 23 Issue 3 Pages 384-390
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In the industrial polyolefin production processes, quality improvement has been attracting considerable attention. In most polymer production processes, blenders are installed downstream of the production line for damping out quality variation.
    It is an admission of the fact that the conventional way of reducing quality variation is unable to provide acceptable solution of satisfying the increasing demand from customers for the highest possible quality. Therefore, the cooperative blending operation is pursued optimally at the blender units.
    In this paper, an optimal blending operation is discussed. The optimal blending scheme is derived by solving a mixed integer linear programming problem (MILP). The scheme is tested on an industrial blender process of the polyethylene production plant. As a result, the optimal blending operation reduces the variances of the final product quality dramatically.
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  • Yoshitaka Sudo, Motoyuki Suzuki
    1997 Volume 23 Issue 3 Pages 391-396
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The present work is aimed at determining the effective surface diffusion coefficients, Ds, and adsorption equilibriums during adsorption of o-chlorobenzoic acid on activated carbon from aqueous solution and alcohol aqueous solution (Methanol, Ethanol and n-Propanol) by batch operation. The solubility of o-chlorobenzic acid into the alcohol aqueous solution changed about 100-fold as alcohol concentration rose from 0% to 100%. This aim of work is to formulate, by chemical potential theory, adsorption isotherms and Ds during adsorption from alcohol aqueous solution.
    As a result of this work, the investigated concentration range can be represented by Freundlich type isotherms. Ds depend on the amount of o-chlorobenzoic acid adsorbed and the solubility. The adsorption equilibriums and Ds can be formulated by chemical potential theory.
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  • Hironao Ogura, Shinji Fujimoto, Susumu Sato, Hiroyuki Kage, Yoshizo Ma ...
    1997 Volume 23 Issue 3 Pages 397-403
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In order to promote the low-temperature heat-generation of a Chemical Heat Pump unit using a CaO/H2O/Ca(OH)2 reaction, the design and experimental testing of the Chemical Heat Pump unit for practical use were carried out. In particular, from the viewpoint of heat and mass transfer effects, the effects of apparatus design and heatexchange condition on the low-temperature heat-generating characteristics were studied.
    The mass transfer of steam in the reactor was enhanced by spreading the steam way between the particle-tray and the reactor wall, and the heat-generation was promoted. It is also considered that high steam pressure due to the lower inlet of the reactor enhances the reaction and the heat generation. The temperature of the heatexchanging medium in the reactor was found to affect both the reactivity of CaO and the reaction-equilibrium pressure, and the balance of them decides the generated-temperature-level and the heat-generating rate.
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  • Guo-Qing Lu, Tetsuya Toyama, Hee-Joon Kim, Ichiro Naruse, Kazutomo Oht ...
    1997 Volume 23 Issue 3 Pages 404-412
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Characteristics of pyrolysis and combustion of biobriquettes were studied by using an electrically heated batch combustor. The influences of biomass content of the biobriquette on the combustion characteristics which were obtained by measuring the fuel consumption profile and the experimental results were analyzed by both volume and shrinking-core reaction models.
    The following conclusions were obtained (1) total volatile matter content in the biobriquette was directly proportional to its biomass content. Biomass in the biobriquette promotes ignitability and burning rate of low grade coal ; (2) combustion time history was divided into two stages, in which volatile matter mainly evolved and burned to lead fixed carbon combustion ; (3) in the former stage, the reaction rate constant and its order always remained linear related to biomass content ; (4) in the latter stage, the combustion behavior may be simulated by using the shrinking-core reaction model and the reaction was controlled by oxygen diffusion through both the gas boundary layer film and the ash layer almost evenly, and ash layer diffusion coefficients were also linear related to biomass content.
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  • Toshimasa Hirama, Hideo Hosoda, Osamu Nakanishi, Yukako Sawada, Yoshih ...
    1997 Volume 23 Issue 3 Pages 413-420
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A new combustion method, an Improved Three-Stage Combustion (ITS) system, has already been proposed for simultaneous control of NOx and N2O emissions in bubbling fluidized-bed coal combustion. This research aims to clarify optimum operating conditions experimentally and to simulate the reactions by a simple model based on one-dimensional gas flow.
    It has confirmed from experimental work using a bench-scale combustor that two important factors are existant in ITS operation, in addition to the maximum temperature in the freeboard of bubbling bed. The optimum value of the ratio of primary air to total air for coal (main fuel) combustion and that of the stoichiometric ratio of secondary air to secondary (additional) fuel were, respectively, 0.80.85 and approximately 0.7. If we maintain the above values and a maximum freeboard temperature of 925°C in ITS operations, it becomes possible to reduce N2O emission by 1/10 and NOx emission by 2/5 in comparison with those emission levels in single-stage combustion. Modeling work has also confirmed that, in ITS operations, the N2O and NOx reduction in the freeboard is brought about by gas-phase reactions under areducing atmosphere and high temperature, in addition to gas-solid and heterogeneous catalytic reactions for NOx, reduction on the surface of char particles.
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  • Manabu Kano, Shinji Hasebe, Iori Hashimoto, Hiromu Ohno
    1997 Volume 23 Issue 3 Pages 421-427
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In order to solve servo problems and regulator problems simultaneously for external signals in arbitrarily given function classes, such as step set-point changes and ramp disturbances, the conventional Model Predictive Control algorithm is extended by introducing a filter into the output prediction equation. The necessary and sufficient conditions for eliminating steady-state errors were derived for a stable process and a process with an integrator. The filter design problem resulted in the problem of solving Diophantine equations, the number of which is equivalent to the number of steps of the coincidence horizon. For an integrating process with ramp disturbances, a filter can be designed easily by taking advantage of characteristics of the process. Simulation results demonstrated successful functioning of the proposed control algorithm.
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  • Yasuo Hatate, Ryoko Aikoh, Kiyoshi Taniguchi, Yoshimitsu Uemura, Masan ...
    1997 Volume 23 Issue 3 Pages 428-432
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Equilibrium ratios of minute amounts of ethyl n-caproate, ethyl n-caprate, ethyl n-laurate, β-phenethyl alcohol and β-phenethyl acetate in ethanol aqueous solution were measured to obtain the following results.
    1. Constant equilibrium ratio was confirmed below the concentration of 10-2 mole fraction for each minute component in ethanol.
    2. It was obvious from the measurements of equilibrium ratios of each minute component in ethanol aqueous solution that equilibrium ratios of each minute component are independent of its concentrations below 800 ppm, and increase with decreasing ethanol concentration in the same manner as the other minute components in Shochu mash.
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  • Kouji Maeda, Yoshihisa Nomura, Keisuke Fukui, Shouji Hirota
    1997 Volume 23 Issue 3 Pages 433-436
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Crystallization of fatty acids for a lauric acid + myristic acid system from ethanol aqueous solutions, which extracted the fatty acids from their organic solutions, has been carried out. The mole fractions of lauric acid excluding solvent components in the aqueous solutions after the liquid-liquid extraction were a little higher than those in the organic solutions. As crystallizing of the fatty acids from the aqueous solutions proceeded, the crystals of the fatty acids floated on the surface of the aqueous solution, and the mole fractions of lauric acid in the crystals increased considerably from the mole fractions of lauric acid excluding solvent components in the aqueous phase. The effect of experimental conditions on the mole fraction of lauric acid in the crystals was shown.
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  • Shiro Takashima, Yasuhisa Honda, Jiro Katayama, Eiji Obata, Hiroshi Ta ...
    1997 Volume 23 Issue 3 Pages 437-439
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Mean heat transfer coefficient hs around a single, horizontal pipe settled in a fast circulating fluidized bed was measured under various fluidizing condition. The heat transfer coefficient could be correlated well with the solid fraction in gas-solid mixture flow, being a function of solid circulating rate, gas velocity and riser position. The value of hs increased as the solid circulating rate became high. However, it was found that there was a critical solid fraction, ranged from 0.01 to 0.02, over which the increasing ratio dropped to a smaller one. This phenomenon was considered to be due to a characteristic change of the particle behavior around pipe.
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  • Hideo Ono, Koji Takahashi
    1997 Volume 23 Issue 3 Pages 440-442
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A preparation method for micron scale spherical silica particles was investigated by combining the hydrosis and condensation of tetraethylorthosilicate (TEOS) in W/O emulsion. The aggregation took place when ammonia was used as catalyst. On the other hand, micron scale spherical silica particles could be obtained in the presence of water instead of ammonia.
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  • Kimihito Narukawa, Hidenori Goto, Yong Chen, Ryouhei Yamazaki, Shigeka ...
    1997 Volume 23 Issue 3 Pages 443-446
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To make clear the reason for high De-HCl efficiency in RDF fired fluidized bed combustion in spite of high combustion temperature, combustion tests of RDF were carried out in an electric furnace and the De-HCl characteristics versus calcium added to the RDF were investigated. The following results were obtained : (1) De-HCl efficiency was more than 85% for three samples which were each produced by different processes, and which had different amounts of calcium added. (2) De-HCl efficiency became higher at low heating temperature and it was about 95% at 600°C.
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  • Shinichi Hasegawa, Keisuke Fukui, Syouji Hirota
    1997 Volume 23 Issue 3 Pages 447-451
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Liquid ice is useful as a cold heat storage material. In this work, heat transfer experiments in U-bent pipes for continuous formation of liquid ice were carried out to make clear the effects of pipe diameter on heat transfer efficiency and mass fraction of ice. In the case of using a 15-mm pipe, the experimental results showed that the mass fraction of ice and the heat transfer efficiency had maximum values at a certain volume fraction of water and that the heat transfer efficiency of a 15-mm diameter U-bent pipe system was about twice as large as those of 12-mm and 10-mm diameter pipe systems. From photographs of flow visualization, it was found that these phenomena were caused by the difference of flow pattern in the downward and horizontal flow region of the U-bent pipes.
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  • Toshiro Murase, Abudu-Wayit Yosufu
    1997 Volume 23 Issue 3 Pages 452-454
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The high-flux dynamic microfiltration of an oil-in-water emulsion was studied under constant pressure by using a rotating cylinder type membrane filter with a suspending particle bed in the filter chamber. Using this dynamic filtration, much smaller hydraulic cake-resistance can be obtained than that encountered in conventional operation. It was quickly discovered that, due to the powerful sweeping force acting on the fouling cake-layer, the dynamic effects of the additional suspended solids yield remarkable improvements in the microfiltration flux of poorly filterable O/W systems.
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  • Ryoichi Nagata, Shinichiro Gondo, Masami Shiozawa, Yasuo Hatate
    1997 Volume 23 Issue 3 Pages 455-459
    Published: May 10, 1997
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Catalase, ascorbate oxidase, glucose oxidase and uricase immobilized on oxirane acrylic particles were packed into a column. Each sample of substrate solution of volume G and substrate concentration C was injected into the inlet flow of the fixed buffer solution flowing through the column at the rate v and temperature T, and the dissolved oxygen concentration in the outlet flow was analyzed by a dissolved oxygen sensor. Sensor output was integrated with respect to time to obtain S. In each sample, stoichiometric relations of S were formed approximately in under about S = 5.5 mv·min.
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