KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 17 , Issue 4
Showing 1-30 articles out of 30 articles from the selected issue
  • Eiji Izumoto, Susumu Kyotani, Toshimitsu Nakashima, Hideki Fukuda, Eij ...
    1991 Volume 17 Issue 4 Pages 701-708
    Published: July 10, 1991
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A glyceride composition control method for an enzymatic continuous interesterification process of oil and fat using a microaquaous bioreactor was investigated. First, a continuous process model was derived by considering the deactivation of lipase based on the modified glyceride-enzyme complex model. It was found from simulation studies that there existed an optimal water content producing the maximum amount of triglyceride. Secondly, to suppress formation of diglyceride and to maintain constant composition of triglyceride, a simultaneous feedback control system for water content and triglyceride composition was proposed. Results of both simulation and experimental studies with the feedback controllers have proved that the system adequately controls the interesterification.
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  • Masaharu Takao, Hiromi Otsuka, Satoru Komori, Yasuhiro Murakami, Takan ...
    1991 Volume 17 Issue 4 Pages 709-715
    Published: July 10, 1991
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To operate a two-roll mill continuously in batch processing, a system which can regulate automatically the clearance between the two rolls is proposed. The system consists mainly of a dial gauge, a photointerrupter, an A/D converter, a microcomputer, a control module, a driver, a pulse-motor and a toothed wheel. The dial gauge is set on the outer surface of the rolls. The photointerrupter connected to the gauge detects the variation in clearance and the output signal is provided to the microcomuter through the A/D converter. The performance program calculates the difference in clearance between the measured and the expected values and sends an input signal to the control module. It transmits a pulse signal for motion command to the driver, which in turn makes the pulse-motor rotate. Finally, the clearance is slightly regulated by the action of the toothed wheel attached to the axes of the pulse-motor and roll handle. We also carried out experiments in the dispersion of fly-ash particles to confirm the dispersion philosophy of the proposed control system. The results show that the system can operate satisfactorily as expected.
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  • Shigeki Takishima, Hiromasa Matsumoto, Hironobu Nagasaki, Hirokatsu Ma ...
    1991 Volume 17 Issue 4 Pages 716-724
    Published: July 10, 1991
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Experiments in the extraction of low-molecular weight binder components from alumina green bodies were carried out, using supercritical CO2. Activated carbon was placed together with the alumina green bodies in an extraction cell. High debindering rates were obtained without flowing supercritical CO2 through the cell since binder concentrations in the supercritical fluid phase were maintained at small values due to the adsorption of extracted binders on the activated carbon. When the green bodies and the activated carbon were placed at adequate positions in the cell, natural convection of supercritical CO2 promoted the reduction of binder concentration in the supercritical fluid phase. Effective diffusion coefficients of the binder components in the green body were obtained by the correlation of experimentally obtained extraction yields using Fick's diffusion equation.
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  • Yoichiro Shimizu, Eiji Nakanishi
    1991 Volume 17 Issue 4 Pages 725-731
    Published: July 10, 1991
    Released: November 12, 2009
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    Choice of plant model order was investigated in applying an adaptive control system (ACS) to a real process from the viewpoint of control performance and the stability of zeros of the plant. It was confirmed that the conventional guidelines for plant model order, based on the step response of the plant, may not always lead to satisfactory results. We proposed an adaptive algorithm which does not update controller parameters if ACS identifies the plant as a nonminimum phase system, and also studied the problem of the conventional guidelines. Simulation results with the algorithm proposed above as performed on CSTF showed that conventional ACS, which identifies the plant as a nonminimum phase system if plant model order is determined on the basis of the conventional guidelines, goes unstably.
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  • Shigeaki Kasaoka, Eiji Sasaoka, Yösuke Okazaki, Makoto Hanaya
    1991 Volume 17 Issue 4 Pages 732-739
    Published: July 10, 1991
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To establish a catalytic process for the methanation of CO or CO2 with H2, Ru catalysts supported on ZrO2, TiO2, Al2O3 (θ) and SiO2 were prepared, and the relationship between the reaction condition and the catalytic reaction performance was investigated, especially from as to the effects of remaining chlorine in catalysts and dechlorination based on raw salt of Ru (RuCl3·4H2 O), with the temperature swing reaction (TSR), the temperature-programmed reaction (TPR) method and at a constant temperature. Experiments were carried out using a flow fixed-bed reactor under an atmospheric pressure at mainly 120°-350°C. The inlet gases were 10%CO-30%H2-N2 and 10%CO2-40%H2-N2, the total flow rate was 250 cm3N· min-1 per 0.5ml of each catalyst with average diameter of 1.0 mm, and the space velocity was 3.0× 104h-1.
    The main results obtained were as follows. 1) The remaining chlorine after reduction of catalysts with H2 was removed as HCl, the order of the amount being ZrO2>SiO2>Al2O3 (θ) >TiO2, and that after washing with warm water (85°C) being SiO2>ZrO2>Al2O3 (θ) >TiO2.2) The effect of remaining chlorine on the catalytic activity was much larger for CO2-methanation than for CO-methanation. 3) The remaining chlorine suppressed the formation of carbonaceous species on the catalyst surface and decreased the catalytic activity. 4) Ru/ZrO2 dechlorinated with warm waterwashing (85°C) was the most active among the catalysts used in this study.
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  • Shigeyuki Tomita, Hisaaki Yamaba, Eiji O'shima
    1991 Volume 17 Issue 4 Pages 740-749
    Published: July 10, 1991
    Released: November 12, 2009
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    A new concept called 'adaptive scheduling system' was proposed for managing a multipurpose chemical batch plant, where various uncertainties tend to occur. In the work presented here, the structure of the problem was first explored by introducing new concepts such as 'task' and 'subtask', and by defining a data structure based on the Object-Oriented Approach. The restrictions at various scheduling stages were explored and classified as well. Next, experiments for extracting heuristic rules which can be exploited for generating an acceptable schedule were carried out with a preparatory computer-based system. Then an Object-Oriented version of the Batch Plant Operating System (o BPOS) was developed by embedding these rules in the preparatory system. This system prepares for the user a flexible man-machine interface : he can backtrack to an arbitrary step of rolling scheduling since the computational enviromnent at each step of scheduling is stored in each individual instance of Scheduler-Class.
    The effectiveness of the paradigm of the adaptive scheduling system was also confirmed by applying the system to a model plant.
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  • Masashi Kuramae
    1991 Volume 17 Issue 4 Pages 750-757
    Published: July 10, 1991
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    This paper deals with the frequency response characteristics of dynamic heat transfer models of a heat pipe, which has been proposed in a previous paper. Transfer functions of the models are derived and calculated frequency response characteristics are represented by a Bode diagram. The relationships among the model and the effect of the model parameters on the frequency response characteristics are considered. For a typical heat pipe, where conditions of the cooling section have been each water circulation, natural convection and forced convection of air, frequency response characteristics are experimentally obtained by accommodation analysis using M sequence signal. Results obtained are compared with those predicted by each model, and it is found that for natural air cooling of small Bi, experimental values are approximated fairly well by the lumped model. For water cooling of larger Bi the lumped model is not appropriate, but a model that takes the radial thermal resistance, into account, snch as the stairs model, is recommended.
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  • Akimasa Yuuki, Takaaki Kawahara, Yasuji Matsui, Kunihide Tachibana
    1991 Volume 17 Issue 4 Pages 758-767
    Published: July 10, 1991
    Released: November 12, 2009
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    To study the film precursors of amorphous Si : H film in SiH4 Plasma-enhanced CVD, infrared absorption and trench coverage uniformity of the film, along with gas composition in the chamber and optical emission intensity of the plasma, were measured at various values of rf power.
    It was observed that Si-H2 bond in the film increases and film thickness uniformity in the trench becomes poorer with increasing rf power. The influences of rf power was significant at high-rf power, where SiH4 concentration decreases to half its initial value. Degradation of trench coverage at high rf power is considered to be due to precursors whose sticking probability is near unity.
    These observations suggest a model in which heavy silane radicals of large sticking probability deposits at high rf power. Furthermore, it was shown by use of kinetic simulation that the deposition rate of heavy radicals is sufficient to explain these experimental results.
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  • Kohei Ogawa, Shiro Yoshikawa, Yoshinori Seo
    1991 Volume 17 Issue 4 Pages 768-774
    Published: July 10, 1991
    Released: November 12, 2009
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    Lower-frequency sound was applied to a liquid flow in a rectangular pipe and the effects of the sound on the promotion of mixing and the mixing mechanism were investigated experimentally. It was found that the micro scale based on concentration fluctuations and the intensity of concentration fluctuations of the tracer became smaller and the mixedness increased when the sound was applied. The same usefulness of applied sound for the promotion of liquid mixing in a circular pipe was confirmed and the possibility of developing an in-line liquid mixer using sound was shown. It was confirmed that the micro scale based on concentration fluctuations, intensity of concentration fluctuations and mixedness were closely connected with one another and that mixing progressed as these indices kept their mutual relations. Additionally, it was found that the change of mixedness with time could be estimated by using the energy spectrum distribution of velocity fluctuations, and that the initial rate of mixing was in proportion to the volume of the space micro scale eddy based on velocity fluctuations.
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  • Hiroyuki Yoshino, Hiroshi Sato, Hiroshi Nogami, Takatoshi Miura
    1991 Volume 17 Issue 4 Pages 775-780
    Published: July 10, 1991
    Released: November 12, 2009
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    The behavior of the fracture mechanics parameter is studied by the estimated thermal stress distribution of the coke fissure in the initial stage of carbonization where the incremental theory is applied, and the CTOD (Crack Tip Opening Displacement) is evaluated as the parameter. The predicted CTOD is in good agreement with the experimental results, in which the CTOD increased with the heating rate. Furthermore, a sharp increase in CTOD is predicted near the transition point from the first maximum point of contraction coefficient of coke to the second maximum point, at which point the fissure on the coke surface would be produced. The predicted stress intensity factor derived from the thermal stress distribution near the fissure also increases with the heating rate and its behavior follows the experimental results.
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  • Yoshiro Inoue, Ryuzo Ito
    1991 Volume 17 Issue 4 Pages 781-788
    Published: July 10, 1991
    Released: November 12, 2009
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    The dynamic behavior of a cystal particle moving in Bénard convection was in vestigated theoretically with a simplified model that simulates the state of a crystal particle in crystallizers.
    While the crystal particle circulates along the flow stream and passes through the supersaturated and the unsaturated regions alternately, both its size and its orbit change gradually. The motion of a crystal particle can be treated as a dynamical system in phase space whose coordinates consist of the particle diameter and the orbit diameter. The effects of system conditions such as the Rayleigh number, temperature and concentration on the behaviour of the crystal particle were examined in this phase space.
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  • Yoshiro Inoue, Nobuhisa Ohta, Masashi Kawase, Ryuzo Ito
    1991 Volume 17 Issue 4 Pages 789-795
    Published: July 10, 1991
    Released: November 12, 2009
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    Two methods are proposed to calculate the size distribution function of crystal particles, which are moving in a roll cellular Bénard convection field, on the basis of a theoretical model describing their motion.
    In the first method, the behavior of crystal particles in real space is transformed into the motion in dynamical system in a phase space, and then the progress of the particle size distribution function is derived by use of continum approximation. In the second method, the motions of crystal particles within a given range of orbit are treated as a group but the motions of individual particles are not analysed.
    The particle size distribution calculated by the two methods agreed with each other. The former method gives more accurate results in less computing time, but the latter method would be superior to the former when applied to more complex systems.
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  • Takayuki Takarada, Fukuji Ebihara, Hideaki Matsushima, Kunio Kato
    1991 Volume 17 Issue 4 Pages 796-801
    Published: July 10, 1991
    Released: November 12, 2009
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    Diamond synthesis was carried out on a Si wafer surface by microwave plasmaenhanced chemical vapor deposition. A 5mm×5mm Si wafer was treated by the collision of particles. The Si wafer was immersed in a bed where relatively large particles were fluidized by fluidizing gas. The treated Si wafer was used for the deposition of diamond. The particle deposition density of diamond was enormously enhanced by the fluidized-bed treatment. The effectiveness of the treatment on the particle deposition density was affected by the kind of fluidizing particle, particle diameter, fluidizing gas velocity and the position of the Si wafer in the fluidized bed. In situ fluidized-bed treatment was also very effective for the nucleation of diamond. By using a Si wafer treated by the particles where both the kinetic energy and the number of collisions were controlled, the kinetic energy for the nucleation of diamond was determined.
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  • Terumi Inagaki, Katsuo Komori
    1991 Volume 17 Issue 4 Pages 802-809
    Published: July 10, 1991
    Released: November 12, 2009
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    In this study, two-equation models for velocity and temperature fields are applied to an aiding flow of combined forced and natural convection in a uniformly heated vertical pipe and then predicted results were compared with experimental results.
    The numerical calculations are in generally satisfactory agreement with the experimental data. The reduction of heat transfer in the combined convection regime is also found numerically, and this region corresponded to the region of 1.0×10-5<Grd/ (Red2.7 Pr0.5) <1.0×10-3. This reduction in heat transfer is thought to be caused mainly by turbulence suppression.
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  • Yoshitaka Togari, Satoru Yonezu, Akihiko Yoneya, Yoshihiro Hashimoto
    1991 Volume 17 Issue 4 Pages 810-815
    Published: July 10, 1991
    Released: November 12, 2009
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    Fault diagnosis utilizing signed directed graphs is based on the analysis of fault spread patterns. Where an operator copes with an abnormal variable (e.g. too-high pressure), the cause-effect graph, which expresses the spread pattern of the fault, is cut at the variable and a new cause-effect graph is generated by the manipulation. Therefore, fault diagnosis systems utilizing single-layer signed directed graphs cannot deal with such dynamics. Fault diagnosis methods using multilayers graphs can deal with them, but they require up to hundreds of times more memory capacity than the algorithms using single-layer graphs. In this paper, a three-layer digraph is proposed to diagnose the single cause for the state shifts. This method can cope with the above situation and does not require much memory capacity.
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  • Tomoaki Minowa, Shin-ya Yokoyama, Tomoko Ogi, Yutaka Dote
    1991 Volume 17 Issue 4 Pages 816-822
    Published: July 10, 1991
    Released: November 12, 2009
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    Steam explosion was applied to liquefaction of bark (Japanese red pine) to increase the oil yield. When the bark was liquefied using an autoclave, the oil yield was as low as 23% because condensation or repolymerization of reactive fragments was promoted due to the slow cooling. However, the oil yield in liquefaction by steam explosion (300°C, 10MPa) reached 33%. This can be caused by the rapid cooling in steam explosion, which retards condensation or repolymerization leading to the formation of char. The heating value (30 MJ/kg) of oil was almost the same as that obtained by the autoclave experiment.
    The oil yield in steam explosion depended on catalyst loading, reaction temperature and holding time. It was decreased by addition of catalyst ; that is, no catalyst is needed for steam explosion. With respect to reaction temperature, the yield increased with the rise in temperature from 200 to 300°C. Liquefaction was completed within 5-10 minutes, and prolonged holding time tended to decrease the oil yield.
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  • Hideharu Yagi, Masato Yamaji, Tsuyoshi Yamamoto
    1991 Volume 17 Issue 4 Pages 823-827
    Published: July 10, 1991
    Released: November 12, 2009
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    With K-alum, secondary nucleation at a constant supercooling temperature and batch crystallization at a constant cooling rate were carried out under agitation by aeration. An increase in aeration rate and in supercooling accelerated the secondary nucleation and decreased the size of crystals produced by the batch crystallization. With an increase in number of seed crystals the secondary nucleation at a constant temperature was depressed at a low degree of supercooling, but the secondary nucleation at a constant cooling rate was promoted, resulting in a decrease in size of crystals produced by the batch crystallization. The aeration is applicable to agitation in a crystallizer, because the crystal size is controlled to some extent by changes in the operating conditions.
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  • Zhe Shi Zhao, Hitoki Matsuda, Norio Arai, Masanobu Hasatani
    1991 Volume 17 Issue 4 Pages 828-836
    Published: July 10, 1991
    Released: November 12, 2009
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    The gas-phase formation of NO, N2O and N2 through NH3 in a mixture of NH3, H2, O2 and Ar was analysed theoretically and the results were compared with experimental data obtained in a tubular-flow reactor.
    Theoretical calculations were carried out on the basis of 56 elementary reactions involving 18 chemical species, and comparisons with the experimentals were made in the temperature range of 950 to 1350 K and for a composition of reactant gases at the inlet of : [NH3] =1000 ppm, [H2] =0-5.0%, [O2] =0-3.0%.
    It was revealed within the range of the present experimental conditions that : 1) the experimental trends were confirmed to be in close agreement with the calculated results for the proposed reaction model; 2) the selectivity N2O was high at low reaction temperatures and low H2/O2 ratios in the gas phase, and decreased with increasing H2/O2 ratios and reaction temperatures ; and 3) it is difficult to inhibit the formation rates of NO and N2O simultaneously by controlling reaction temperature.
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  • Hidehiro Kamiya, Genji Jimbo
    1991 Volume 17 Issue 4 Pages 837-845
    Published: July 10, 1991
    Released: November 12, 2009
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    Dense and uniform packing of ultra-fine powders, the primary particle size of which ranges from 1 nm to 0.1 μm, is very difficult because of strong and sparse aggregation. In this paper, the aggregating process of ultra-fine powder is examined by Brownian dynamic methods, and the effects of interaction between the primary particles and the initial concentration on aggregate shape and size is analyzed quantitatively by Fractal dimension and Weibull's distribution function. Furthermore, the packing of aggregates, which are of various shapes and are composed of different numbers of particles, is investigated by computer simulation. The effect of the geometrical characteristics and size distribution of aggregate on the porosity and distribution of micropore diameter in a packed bed is analyzed. If many aggregates consist of hundreds of particles, the porosity is more than 94%. The porous structure is composed by bridging among several aggregates. The large spaces in ultra-fine powder composed by bridging are confirmed experimentally by mercury porosimetry. The effect of shape and size distribution of aggregates on packed bed structure is remarkable in the case of weak aggregated powder, which means that the number of constituent particles is below 10.
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  • Izumi Taniguchi, Satoshi Tanazawa, Hitoshi Kosuge, Koichi Asano
    1991 Volume 17 Issue 4 Pages 846-853
    Published: July 10, 1991
    Released: November 12, 2009
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    Experimental studies of the recovery of vapor by water spray were carried out for wide ranges of the mass flow rates of vapor, air and liquid. Measurements were made of local number fluxes of drops, local drop size distribution, local mass flow rate of liquid, and vapor and drop temperatures.
    The number flux of drops averaged by cross section of spray column showed a constant value with distance from the tip of the nozzle. Condensation of vapor in the water spray practically ended in the vicinity of the atomizing nozzle exit.
    The behavior of vapor recovery by water spray was well explained by a simulation technique with due consideration to the high mass flux effect for a single evaporating drop. The possibility of a vapor recovery system with multistage spray column was also discussed.
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  • Tamotsu Hanzawa, Xiang Jun Huang, Noboru Sakai
    1991 Volume 17 Issue 4 Pages 854-860
    Published: July 10, 1991
    Released: November 12, 2009
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    Streamline and temperature distributions and the heat transfer coefficient with natural convection for various fluids were investigated for a cylindrical flat enclosure heated from the bottom. By visualization of the flow pattern with a tracer, the fundamental equations of flow and heat transfer were derived and solved numerically. The streamline and temperature distributions in the enclosure and the heat transfer coefficient on the heated wall were calculated with air, water and olive oil. The range of Rayleigh number was 5.3×103-6.5×107 that of Prandtl number 0.7-200 and the aspect ratio (radius divided by height of cylinder) was 0.864-8.64. The experimental temperature distributions and the heat transfer coefficient were in close agreement with the calculated values.
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  • Tadaatsu Ido, Kazunobu Umemura, Shigeo Goto
    1991 Volume 17 Issue 4 Pages 861-866
    Published: July 10, 1991
    Released: November 12, 2009
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    Catalytic activities of p-toluenesulfonic acid, its homologs and eutectic mixtures of these compounds in both solid and molten states were investigated. The acid strengths of these compounds in the molten state, determined by indicators such as anthraquinone, were stronger than those in the solid state. The reaction rates of isomerization of butene in molten catalyst were also faster than those in solid catalyst. It was found from the reaction paths of isomerization that the porous polymer was superior to active carbon as support to maintain the molten state of the catalyst. The catalyst in molten state was not poisoned by water. Furthermore, the hydration of propylene was effectively catalyzed by molten p-toluenesulfonic acid on porous polymer.
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  • Hiroshi Tsuchiya, Keiji Miyazaki, Yuzou Iwanaga, Makoto Wakai
    1991 Volume 17 Issue 4 Pages 867-872
    Published: July 10, 1991
    Released: November 12, 2009
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    Solvolysis pulping, named for the method of extracting lignin from wood chips using a mixture of cresol and water for separating the pulp was studied as an organosolv pulping system. Because no selectivity of delignification relative to carbohydrate degradation reaction has been observed in this system, the yield of pulp and the characteristics of the paper, especially with reference to tear factor, are lower than those of kraft pulping the generally used pulping method in Japan. Acidity of aqueous cresol solution promotes the degradation of carbohydrate and acetic acid decomposed from acetylglucronoxylan during the delignification reaction, accelerating the degradation of carbohydrate. In this study, amines were added to reduce the formation of acetic acid. As a result, certain amines were recognized as additives leading to alteration of the rates of delignification and carbohydrate degradation. The optimum reaction conditions to suppress carbohydrate degradation were confirmed, using primary and tertiary amine.
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  • Katsumi Nakao, Kimitoshi Fukunaga, Yoshimasa Yasuda, Keiji Furumoto, S ...
    1991 Volume 17 Issue 4 Pages 873-881
    Published: July 10, 1991
    Released: November 12, 2009
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    The determination of gas-liquid and liquid-solid oxygen transfer coefficients, kLa and kS, from measurement of the steady-state dissolved oxygen concentration, CO, S, was examined by using oxidation of glucose with air catalyzed by glucose oxidase, GO. Free GO and immobilized GO gel beads were employed respectively for determination of kLa and kS. The contactors used were a small-scale aerated stirred cell and a bubble column with draft tube. The kinetic parameters for free GO were almost identical to those in the literature. The difference in the values of kLa between the enzymatic and physical methods was found to be attributable to foaming in the enzyme reaction medium. The determination of kLa could be applied to the cultivation broths. On the other hand, the rate equation for the immobilized GO gel beads was described in the same form as in the case of the free enzyme except that the utilization efficiency of GO loaded for immobilization, α, was introduced into the equation. The kLa values in the presence of gel beads were practically equal to those for the gas-liquid system. The values of kS calculated from CO, S, kLa, α, the kinetic parameters and the GO gel. beads loading agreed satisfactorily with those obtained in physical dissolution.
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  • Katsumi Nakao, Kimitoshi Fukunaga, Yoshimasa Yasuda, Yutaka Tejima, Ma ...
    1991 Volume 17 Issue 4 Pages 882-889
    Published: July 10, 1991
    Released: November 12, 2009
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    Reactor design and operation were explored for increased utilization of cellulase as well as for enhanced conversion and rate of saccharification of cellulose. The highest possible concentrations of cedar, pine and oak wood particles were hydrolyzed by a relatively low concentration of cellulase. The time courses in a batch stirred cell were well simulated with an apparent Michaelis-Menten rate equation.
    The results obtained in a single packed-column reactor showed that cellulase diffused into and adsorbed at the inner surface of substrate particles was susceptible to deactivation and that the denatured enzyme was reactivated on its desorption.
    A ball mill reactor and a dual packed-column in which buffer solution alone was fed alternately into the column for saccharification and the column for enzyme recovery were employed in order to hydrolyze cellulose particles with simultaneous renewal of particle surface and thus reactivation of denatured enzyme at the inner surface.
    The saccharification in the ball mill reactor proceeded in two stages, the kinetic parameters for which were almost identical. The ball mill reactor was superior to the dual packed-column reactor with respect to cellulase utilization, productivity, reducing sugar concentration and ease of operation.
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  • Atsushi Ikari, Yasuo Hatate, Kazuhiko Hosoda, Yuichi Kawabata
    1991 Volume 17 Issue 4 Pages 890-894
    Published: July 10, 1991
    Released: November 12, 2009
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    Vapor-liquid equilibria of hexane-acetic acid system and hexane-ethanol system containing a minute amount of water were measured at atmospheric pressure by use of an Othmer-type still in a dry box. It was shown that the equilibrium ratio curve and the activity coefficient curve of the trace component (water) display an unusual and specific shape in each system.
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  • Eiichi Osawa
    1991 Volume 17 Issue 4 Pages 895-897
    Published: July 10, 1991
    Released: November 12, 2009
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    A new group contribution method analogous to UNIFAC was investigated. Volume and surface parameters used in this method were obtained by considering the solid structure of molecules and group parameters as being a linear function of temperature. This method represents different activity coefficients for systems consisting of isomers.
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  • Takayuki Takarada, Keiji Mishima, Kouichi Inaba, Kunio Kato
    1991 Volume 17 Issue 4 Pages 898-901
    Published: July 10, 1991
    Released: November 12, 2009
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    Mass transfer in a vertical multiwafer stacked-in-tube CVD reactor was analyzed by simple fluid-flow models, and the applicable range of the models was determined. Carbon plate was burnt under the condition of relatively low burning rate in the CVD reactor. The local burning rate of the carbon plate was analyzed by a one-dimensional diffusion model in the wafer part and a cell-in-series model based upon the wafer distance in the annular part or cell-in-series model in the space between the wafers. The applicable range of the simple model was specified by a dimensionless modulus,
    J (=rwk/HD)
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  • Jun Fukai, Osamu Miyatake
    1991 Volume 17 Issue 4 Pages 901-904
    Published: July 10, 1991
    Released: November 12, 2009
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    A numerical analysis is performed to calculate pressure drop for laminar flow within two parallel plates with a series of staggered baffles, and heat transfer augmentation of the channel is evaluated by applying the authors' previous numerical result of heat transfer. The results are presented in ranges of both Reynolds numbers and Prandtl numbers from 1 to 102 for nine geometric configurations. It is found that a channel with low height baffle becomes a useful heat exchanger for fluids having high Prandtl number values.
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  • Tatsuo Kanki, Takaaki Yoshida
    1991 Volume 17 Issue 4 Pages 904-908
    Published: July 10, 1991
    Released: November 12, 2009
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    The flow field of a gas around a spherical particle moving slowly toward a plane plate is analyzed by taking the surface slip of the gas into account, and the stream lines around the particle at some given distances from the plate are illustrated. Frictional forces at arbitrary distances from the plate in the region of Knudsen numbers less than unity are calculated, and dependencies of the frictional force on particle-plate separation distance and on the Knudsen number are made clear. The frictional force increases sharply at any Knudsen number in that region as the particle approaches the plate.
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