KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 16 , Issue 6
Showing 1-26 articles out of 26 articles from the selected issue
  • Yasuo Suzuki, Masanori Konno, Yukiko Sato, Ikuro Shishido
    1990 Volume 16 Issue 6 Pages 1133-1137
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To produce a sardine powder for gelatinous product (such as KAMABOKO), a new continuous dehydrating machine with avoiding protein denaturation is developed by applying mechanical and electroosmotic dehydration methods.
    Final water content is only 60% by the conventional mechanical method, but is reduced to less than the 40% in only 1518 minuites by applying the mechanical method together with an electroosmotic method.
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  • Eiichi Kojima, Yelian Miao, Shigeru Yoshizaki
    1990 Volume 16 Issue 6 Pages 1138-1145
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Four kinds of wood materials were pyrolyzed in a fluidized bed under nitrogen gas atmosphere in the temperature range of 350-550°C. The catalytic effect of inorganic components on the pyrolysis was investigated, and the method of washing treatment of the wood materials for increasing the yield of levoglucosan from the pyrolysis was studied.
    Experimental results indicated that the removal of most inorganic components by dilute acid washing could improve the yield of levoglucosan by 6-9%. In addition, the yields of pyrolysis products were found to be exponential functions of the ash content. Also, the catalytic activity of K and Na was larger than that of Ca and Mg in the secondary pyrolysis of tar and levoglucosan.
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  • Eiichi Kojima, Yelian Miao, Shigeru Yoshizaki
    1990 Volume 16 Issue 6 Pages 1146-1152
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Cellulose particles of 4.3-14.3 mm diameter were pyrolyzed in a fluidized bed under nitrogen gas atmosphere in the temperature range of 320-550°C. Under these conditions, the pyrolysis rates and kinetic models were investigated. The pyrolysis rates, the distributions of temperature and fractional conversion in a single particle were analyzed, using simultaneous equations involving heat and mass transfer, cellulose pyrolysis reaction, and heat of reaction.
    Experimental results indicated that the pyrolysis of particles smaller than 7.5 mm followed the homogeneous model below 400°C. The endothermic heat of cellulose pyrolysis was determined to be 3× 105 J/kg. Theoretical and experimental values of the pyrolysis rates of a single particle showed good agreement in the reaction-controlling range, but poor agreement in the diffusion-controlling range since the effect of volatile matter diffusion in the particle became large enough to slow down the pyrolysis rates.
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  • Takeo Komuro, Norio Arashi, Akira Okada, Tsukasa Nishimura
    1990 Volume 16 Issue 6 Pages 1153-1161
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In this report, the dynamic characteristics of a moving-bed adsorber for a dry desulfurizer utilizing coal ash adsorbent produced from coal ash, slaked lime and gypsum, were numerically analyzed.
    The simulator for the dynamic characteristics comprises an adsorption rate equation of sulfur dioxide with the above adsorbent and a mass balance equation.
    The validity of the simulation was confirmed by actual operation results obtained a twin-tower moving-bed adsorber for a dry desulfurizer utilizing coal ash, with an exhaust gas treatment capacity of 50, 000 Nm3/h.
    The results showed that by the control method of constant molar ratio of Ca/S, which might be a measure of the adsorbent supply to the moving-bed adsorber meeting the daily load of a boiler in the range of full load to one-quarter, load the prescribed desulfurizing performance and the rate of slaked lime utilization can be maintained stably.
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  • Eiichi Kunugita, Sang-Rok Lee
    1990 Volume 16 Issue 6 Pages 1162-1166
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Start-up operation of an acylation reaction is very hazardous because the reactor temperature rises sharply before reaching a desired steady state.
    A region of the state space (a safe operating region) in which all trajectories lead to the desired steady state for acylation in an adiabatic continuous stirred-tank reactor is determined, and a method for determining the safe start-up procedure is proposed in which reactor temperature does not rise to the boiling point of reaction mixture before approaching a high-temperature steady state during the start-up operation.
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  • Jong-Hwa Kim, Eiichi Kunugita, Isao Komasawa
    1990 Volume 16 Issue 6 Pages 1167-1172
    Published: November 10, 1990
    Released: November 12, 2009
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    The extraction and separation of alkaline earth metals such as magnesium, calcium, strontium and barium was studied, employing a commercial β-diketone extractant, LIX 51 (α-perfluoroalkanoyl-m-dodecylacetophenone) and a neutral oxygen-donor extractant, TOPO (tri-n-octylphosphine oxide). LIX51 can extract magnesium from neutral and alkaline aqueous solutions. The mean composition of the extracted species is MgR2 (RH) 0.5.RH and R denote, respectively, the extractant and its anion.
    The extraction performance of the combination of LIX51 and TOPO is much enhanced, and this combination can thus extract metals from acidic aqueous solution. The extracted species is MgR 2 (TOPO) 2. The extractibility of this combination increases with the radius or eletronegativity of the ions and thus the order is Mg >Ca >Sr >Ba. The extractibility for barium is still higher than for lithium, the most extractable alkali metal. The separation of the alkaline earth metals is quite feasible by this extraction process.
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  • Daiqing Zhao, Takeshi Sakai, Masayoshi Sadakata, Masayuki Sato
    1990 Volume 16 Issue 6 Pages 1173-1179
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Internal-mixing twin-fluid atomizers are used as burners particularly for combustion of heavy fuel oils, coal-water slurry fuels and sludges. However, design standards for these atomizers have not yet been established. The present paper describes an experimental study of the turbulent characteristics of the air jets issuing from the outlet port of the internal-mixing atomizer. Measurements were conducted by means of a laser doppler velocimeter to clarify the atomization mechanisms as the first step.
    For comparison, the jet characteristics of a circular-tube nozzle were also measured. It was found that the internal-mixing nozzle has remarkably different characteristics from those of circular-tube nozzle. The jets which issued immediately after the nozzle port had higher turbulent intensity and larger integral scale than those of the circular-tube jets and showed a self-preserving nature while moving downstream. Due to these phenomena, it is considered that turbulence may be amplified by recirculation flow caused by a confined jet within the mixing chamber.
    The high-intensity turbulence in the region near the nozzle had high Reynolds stress, resulting in momentum transport which could be considered to contribute to liquid atomization and flame stabilization.
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  • Zhe Shi Zhao, Norio Arai, Masanobu Hasatani
    1990 Volume 16 Issue 6 Pages 1180-1186
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The gas-phase formation of NO, NO2 and N22O via NH3 in a mixture of NH3, H22, CO, O2 and Ar was investigated experimentally in a tubular-flow reactor.
    Experiments were conducted for NH3/O2/Ar, NH3/H2/O2/Ar, NH3/CO/O2/Ar and NH3/H2/CO/O2/Ar gas reaction systems at temperatures of 11501243K, the initial concentration of O2 being lower than 3.0 vol. %.
    It was found within the range of the present experimental conditions that : 1) the main product of the decay of NH3 was N2 in addition to the products NO, NO2 and N2O; 2) the decay rate of NH3 was enhanced by coexisting H2 and CO and the rates of formation of NO and N2O were inhibited by coexisting H2 more than by coexisting CO ; 3) the concentrations of NO and N2O were related to the concentration ratios of [H2+CO]0/[O2]0 and [H2]0/[CO+O2]0 respectively ; and 4) the concentration of NO2 was considerably low.
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  • Tooru Ishikawa, Tamotsu Kamiya
    1990 Volume 16 Issue 6 Pages 1187-1194
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Experiments were carried out in a 120 mm × 30 mm rectangular duct with 10 mm-high blocks.
    The dimensionless values of the increasing rate of heat transfer due to recirculating flow per loss of mechanical energy at Re= 44, 500 and Re= 24, 400 were 2 and 20 respectively and varied proportionally to -3.0 power of the average velocity.
    With respect to block shapes, the values decreased in the order of round block, triangular block, square block, and dam, and the recirculating flow behind the round block had the lowest value for loss of mechanical energy.
    The promoting effect of heat transfer developed from the rear face of the block to a position about 45 times the block height, and the average heat transfer coefficient was about 1.5 times that of the flow without block.
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  • Atsushi Inaba, Yuji Shindo, Hiroshi Komiyama
    1990 Volume 16 Issue 6 Pages 1195-1202
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The material balance of carbon at steady state in the ocean was analyzed by use of a box diffusion model, in which the fixation of carbon by the plant biota and the transportation of carbon by the up-flow of water were taken into account. The distributions of the concentration of dissolved inorganic carbon and organic carbon measured in the northern Pacific Ocean were simulated by this analysis, in which the diffusion coefficient in the deep sea Ez=2200m2/y, the velocity of the up-flow of water Uv =2.44 m/y and the sedimentation velocity of CaCO3 and organic aggregate Usp = 9. 32 m/y were assumed. The difference between the rates of fixation of inorganic carbon and decomposition of organic carbon was calculated to be 1.10 mol/m2/y. If this rate is applicable to the ocean surface of the earth, 4.8 Gton of carbon is fixed at the surface and transported to the deep sea per year. By this analysis, the important role of the plant biota in the ocean's carbon cycle was shown quantitatively.
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  • Hideaki Kurokawa, Yasuo Koseki, Akira Yamada, Katsuya Ebara, Sankichi ...
    1990 Volume 16 Issue 6 Pages 1203-1209
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The heat and mass balance of membrane distillation using PTFE porous membrane were studied using 3.4wt% NaCl solution as feed liquid. Parameters such as temperature and flow rate of feed and cooling water were varied and heat and mass transfer characteristics were studied by measuring the permeate rate and the temperature difference between feed and cooling water.
    The results are summarized as follows. In the membrane distillation system, heat and mass transfer mechanisms changed when the gap was below 5 mm or over 10 mm. For a gap below 5 mm, heat transfer was controlled by thermal conduction and mass transfer was controlled by diffusion. For a gap over 10 mm, the heat and mass transfer were controlled by free convection. These transfer rates were expressed using thermal conduction, diffusion and free convection equations. Numerical studies were performed and good correlations were confirmed between numerical and experimental results.
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  • Kiyoshi Idogawa, Takashi Fukuda, Hiroshi Nagaishi, Yosuke Maekawa, Tad ...
    1990 Volume 16 Issue 6 Pages 1210-1216
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Gas holdup, bubble rising velocity and bubble size were measured by an opticalfiber probe near a nozzle in a bubble column with simultaneous gas-liquid injection.
    A jet-like spouting stream was formed near the nozzle, and the height of the jet was not affected by the diameter of the nozzle. Bubbles were formed at the side wall and the top of the jet, and they dispersed radially with increasing axial position. When the axial position was greater than 88 cm from the nozzle, the radial distribution of gas holdup became uniform regardless of axial position.
    The radial dispersion and the bubble diameter depended on the nozzle diameter, and the effects of simultaneous gas-liquid injection on the bubble formation were similar to those of an increase of pressure.
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  • Toshiro Miyahara, Myung-Sup Lee, Teruo Takahashi
    1990 Volume 16 Issue 6 Pages 1217-1223
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Experiments were conducted to investigate the mass transfer characteristics in a three-phase fluidized bed under conditions of gas-liquid upward flow in a column of 6.5cm inside dimeter and 157cm height. The particles employed were five kinds of low-density and small-size particles : nylon-6 particles with diameter of 6.32 and 9.52mm, polystyrene particles of 3.1 mm, activated carbon particles of 650μm and glass beads of 550μm.
    The three-phase fluidized beds showed two distinct regimes, i.e., the complete three-phase fluidization regime and the partial suspension regime in which some particles exist in the freeboard region, depending on gas and liquid velocities.
    The liquid-phase volumetric mass transfer coefficient, kLa, was calculated using the axial dispersion model together with the axial oxygen concentration profile.
    It was found that kLa increases with increasing gas velocities. This trend is almost the same as that in conventional three-phase fluidized beds and bubble columns, whereas the absolute values of kLa in the case of low-density particles are always larger than those for bubble columns. The behavior of kLa values is correlated as a function of gas holdup and the modified particle Reynolds number based on the density difference between particles and fluids.
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  • Takahiro Suzuki, Kazuhisa Ohtaguchi, Kozo Koide
    1990 Volume 16 Issue 6 Pages 1224-1233
    Published: November 10, 1990
    Released: November 12, 2009
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    The quantitative relationship between chemical structure and the flash point is not well known. In this paper, a principal component analysis of a set of data including flash points and ten other physicochemical properties of 50 organic compounds is performed to determine the number of significant structural factors affecting the flash point. Only two structural factors were found to be sufficient to reproduce the flash point data. The first factor is identified as the bulk or size parameter of a molecule and is related to its connectivity index. The second factor, while making a relatively small contribution to the flash point, is related to the specific polar characteristics of functional groups in a molecule. A significant correlation is found between the second factor and Fujita's inorganicity value. Analyses of this work lead to a predictive equation for the flash point using only the chemical structure of a molecule of interest. The robustness and utility of this method were examined by predicting the flash points of 164 compounds not included in the original data set.
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  • Masaaki Teramoto, Noriyuki Ito, Hiroyo Matsumoto
    1990 Volume 16 Issue 6 Pages 1234-1240
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To remove and concentrate dilute CO2 selectively, a series of experiments on the simultaneous permeation of CO2, O2 and N2 was performed using flowing liquid membrane in which gases permeate a liquid membrane solution which flows in a thin channel between two hydrophobic microporous membranes.
    Separation factors of CO2 relative to O2 and N2 were high, about 24 and 48 respectively, even when water was used as a membrane liquid. These results were explained by the physical solution-diffusion model in which permeability is dependent on the Henry constant and diffusivity. The separation factor was remarkably increased when potassium carbonste/bicarbonate was used as the carrier of CO2. The permeability of CO2 and pH of the membrane solution at steady state were simulated by a facilitated transport mechanism. Addition of diethanolamine was very effective in enhancing the permeability of CO2, and the separation factor αCO2, O2 was increased up to 380.
    By evacuating the strip side of the permeation cell, CO2 in N2 was concentrated from 0.98% to 42%, as expected from the very high separation factor.
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  • Kenji Kawasaki, Akira Matsuda, Toshiro Murase
    1990 Volume 16 Issue 6 Pages 1241-1246
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The expression characteristics and the final moisture content of unfrozen and frozen excess activated sludges produced at a municipal wastewater treatment plant were evaluated from constant-pressure expession experiments at 2062950 kPa. The modified consolidation coefficient Cg and creep constant η were approximately constant over these experimental pressures, but both values were increased 2025 % by the freezing and thawing process. Consequently, it is concluded that the freezing and thawing process increases the rate of both primary and secondary consolidation. The values of η of unfrozen and frozen activated sludges were nearly equal to those for typical inorganic sludge, but the values of Cg were 1/1000 of those of typical inorganic sludge. Regardless of expression pressure or the freezing and thawing process, the yalues of B, which is the ratio of secondary consolidation to the total consolidation, were about 0.9, which was much larger than those of inorganic sludge. Therefore, the rate of secondary consolidation is a controlling factor in the consolidation of excess activated sludge. The wet-basis moisture content of final cake of frozen excess activated sludge were 0.1 lower than those of unfrozen sludge. Thus, it is suggested that even the cake obtained under low pressure (200kPa) may burn without auxiliary fuel.
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  • Yoshio Iwai, Kohachi Kohashi, Hideyuki Eya, Koji Honda, Yasuhiko Arai
    1990 Volume 16 Issue 6 Pages 1247-1251
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The solubilities of oxygen in pure water and in aqueous solutions containing NaCl, (NH4) 2SO4 or sucrose were determined at 25°C by using a saturation method. Those in the aqueous solutions NaCl+(NH4)2SO4. NaCl+sucrose and (NH4) 2SO4+sucrose, which are key components of fermentation media, were also measured.
    The results obtained were correlated by the equation of Sechenov. Oxygen solubilities in aqueous solutions containing a single salt or sucrose were well represented by modified salting-out parameters of ammonium ion and sucrose. Those in aqueous solutions containing mixed components could be predicted by using the salting-out parameters of single salt and sucrose based on the linear relationship proposed by Danckwerts.
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  • Kazunari Ohgaki, Hiroshi Kobayashi, Takashi Katayama
    1990 Volume 16 Issue 6 Pages 1252-1255
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Rapid measurement of particle size ranging from 0.1 pm to 12 μm was studied by using a Poiseuille flow through a capillary tube. The experimental data were examined in terms of the so-called “tubular pinch” effect. The radial stationary position of fine particles was correlated with the Reynolds number regardless of fluid or kind of particle. An unstable region where the chromatographic peaks disappear or fluctuate was observed when the fluid Reynolds number decreases to a certain minimum level.
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  • Terumi Inagaki, Katsuo Komori
    1990 Volume 16 Issue 6 Pages 1256-1258
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In this study, heat transfer of natural convection around two vertically arranged horizontal cylinders was investigated experimentally. Heat transfer coefficients were measured in a wide variety of values of ratio H/D. The results showed that the heat transfer rates around two vertically arranged horizontal cylinders for 1<H/D<4 became larger than those for a single cylinder. However, a reduction of heat transfer for H/D<1 was observed.
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  • Eitaro Kumazawa, Kazuo Ido, Mario Okazaki
    1990 Volume 16 Issue 6 Pages 1259-1262
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Maltodextrin solutions involving minute amounts of acetone are dried by vacuum drying and by freeze drying. The higher the initial solids content of the feed, the higher is the retention of acetone in both methods.
    With the increase of initial solids content in freeze drying, freezing points of feed are lowered so that true freeze-drying is attained by using liquid nitrogen. (Above 50% T.S., feed is not frozen even at 233K.)
    As for quality, product made by freeze-drying is the most superior, followed by vacuum drying and practical spray-drying in turn.
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  • Masaru Hongo, Mitsuhisa Kusunoki, Kenji Mishima, Yasuhiko Arai
    1990 Volume 16 Issue 6 Pages 1263-1265
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Vapor pressures of binary solutions composed of an alcohol (methanol, ethanol, allyl alcohol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 1-pentanol, or 2-pentanol) and calcium chloride were measured at 298.15K using an apparatus based on a flow method coupled with gas chromatography. Measurements were carried out up to concentrated regions near the saturation concentration of calcium chloride. The error of measurement is estimated to be less than 2%. Further, the activities of alcohol were obtained from the vapor pressure data.
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  • Tsuneo Nakada
    1990 Volume 16 Issue 6 Pages 1266-1269
    Published: November 10, 1990
    Released: November 12, 2009
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    Six substances were used as the dispersed phase and photographs of drop formation were continuously taken by video camera so that their effective surface area could be measured.
    It was found that the ratio of effective surface area to nozzle area has the following relation to Bond number and relative time :
    A/AN=6.1 (NBO)-0.72 (Tf) 0.8
    0.015<NBO<0.9
    0.2<Tf<10
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  • Akira Ito, Toru Iizuka, Michihiro Fujii, Osami Tozawa
    1990 Volume 16 Issue 6 Pages 1269-1273
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Removal of chlorinated hydrocarbon solvents (chloroform, trichloroethylene and tetrachloroethylene) dissolved in water was studied experimentally by the pervaporation method using a module of composite silicone rubber hollow fibers. This membrane separation was able to remove roughly 80% of solvent in water at a concentration lower than 1 mg/l. The results were compared with a model based on the observed permeation rates of pure vapors.
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  • Masahiro Hasegawa, Torajiro Honma, Yoshiteru Kanda
    1990 Volume 16 Issue 6 Pages 1273-1276
    Published: November 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Vibration milling of four kinds of materials of different grindability was carried out using rod and ball media with the same volume and weight. Specific surface area was measured and the grinding rate was investigated. As a result, it was found that grinding with the rod medium was more effective than that with the ball medium for brittle materials with higher Hardgrove Index.
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  • Toshiro Miyahara, Myung-Sup Lee, Teruo Takahashi
    1990 Volume 16 Issue 6 Pages 1276-1279
    Published: November 10, 1990
    Released: February 19, 2010
    JOURNALS FREE ACCESS
    Three-phase fluidized systems comprising air/water/glass beads (diameter, 550μm), activated carbon particles (650 μm), polystyrene particles (3.1 mm) and Nylon-6particles (6.32 and 9.52 mm) were operated under gas-liquid cocurrent upflow conditions in a column of 6.5 cm inside diameter and 157 cm height.
    Experiments were conducted to investigate the axial dispersion coefficient using the axial dispersion model together with axial oxygen concentration profiles obtained from oxygen absorption experiments.
    As a result, the behavior of the axial dispersion coefficient in three-phase fluidized beds containing small or low-density particles is different from that in conventional three-phase fluidized beds containing heavy particles such as glass beads, silica, sand or various metal particles. The axial dispersion coefficient is an increasing function of liquid velocity but a decreasing function of gas velocity.
    Empirical correlations of the axial dispersion coefficient based on the correlation proposed by Kim et al. were obtained.
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  • Yoshimi Seida, Yoshio Nakano
    1990 Volume 16 Issue 6 Pages 1279-1282
    Published: November 10, 1990
    Released: November 12, 2009
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    The mechanism of shrinkage and dehydration of ionic hydrogels packed in an electric cell were investigated on the basis of the distribution of pH around the gel, the Na+ ion concentration within the gels packed in the cell and the dehydration rate.
    It was found that shrinkage and dehydration of the ionic gels take place through the following processes : (1) generation of H+ and OH- ions by electrolysis ; (2) ion-exchange between H+ ions generated on the anode and Na+ ions dissociated originally within the gels ; (3) accumulation of Na+ ions near the cathode by electrophoresis ; and (4) increasein ionic strength near the cathode caused by process (3). Therefore, the shrinkage and dehydration of ionic gels depend on the generation of H+ ions by electrolysis and electrophoresis of Na+ ions.
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