KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 19 , Issue 2
Showing 1-31 articles out of 31 articles from the selected issue
  • Takaaki Mizutani, Yasuhisa Nakamura, Akinori Uchida, Hitoki Matsuda, M ...
    1993 Volume 19 Issue 2 Pages 141-147
    Published: March 10, 1993
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To improve the performance of radiant-tube burners, which are widely used for indirect heating in industrial furnaces, we have devised a new radiant-tube burner that will improve the thermal efficiency and make the radiant tube surface temperature uniform by circulating the heat-resisting particles within the burner.
    In this study, we investigated the particle flow behavior in the burner tube and the operating condition of fluidization by using a three-dimensional visualized coldmodel apparatus.
    Our research we found the following points regarding development of the combustor :
    (1) The circulating fluidized flow and the range of circulating fluidized flow depend strongly on particle bed height and particle diameter.
    (2) The pressure in the combustion tube is approximately 12kPa and the pressure oscillation is around 3.5kPa for the state of circulating fluidization.
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  • Tamiya Kishimoto, Yusaku Nogami, Mitsuo Tanaka, Toshiro Miyahara, Yasu ...
    1993 Volume 19 Issue 2 Pages 148-154
    Published: March 10, 1993
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    An apparatus combining activated sludge reactors with a biofilm reactor was used for sequential removal of organic substrate, nitrogen and phosphorus from wastewater. The biofilm reactor was used for nitrification of ammonium. Activated sludge-adsorbed and-absorbed organic substrate from wastewater in the first aeration tank was for the sequential removal of nitrogen and phosphorus.
    In the batch operation, the highest removal rate of organic substrate was attained by activated sludge at four to five days aeration time after the addition of substrate, The iofilm nitrified ammonium in the case of COD values lower than 3.0×10-2kg/m3 in wastewater.
    In continuous operation of the apparatus, the removal efficiencies of organic substrate, inorganic nitrogen and inorganic phosphorus were about 93, 75 and 45% respectively. Since the COD value in the influent to the biofilm tank was lower than 1.0×10-2kg/m3, no effect of nitrification of ammonium occurred. The substrate adsorbed and absorbed by the activated sludge in the first aeration tank could be used for denitrification and phosphate removal in the case of COD values higher than 4.0×10-2kg/m3 in the influent to the first tank.
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  • Masaaki Sekino, Nobuya Fujiwara
    1993 Volume 19 Issue 2 Pages 155-161
    Published: March 10, 1993
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The optimum design for a double-element RO (Reverse Osmosis) module, which contains two RO elements in a cylindrical pressure vessel, was tried with module structure design, fluid stream design and analytical model simulation.
    Considering the feed flow velocity and the differential pressure between two elements, it was found that the expanding-contracting series flow type is most excellent among several double-element RO modules. This type of module also obeyed the scale-up effect.
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  • Chisato Marumo, Eiji Hayata, Niro Shiomi, Kenji Kojima, Fujio Watanabe ...
    1993 Volume 19 Issue 2 Pages 162-168
    Published: March 10, 1993
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Two kinds of granular molecular sieving carbon (MSC) which had different adsorption properties were prepared from polyvinyl alcohol (PVA) / phenolic resin. Air separation experiments were carried out by a pressure swing adsorption (PSA) method with these MSC, both at practical and at laboratory scale. From comparison of these experiment s, the following results were obtained.
    In pactical-scale experiments, maximum pressure of the adsorber during the adsorption process is lower for sample A, which has relatively large micropores compared to sample B, which has relatively small micropores. It was also found that high-purity nitrogen gas is obtained for sample A in a shorter adsorption period and for sample B in a longer adsorption period. This tendency can be explained from the results of laboratory-scale PSA experiments.
    The product gas flow per unit bed volume for a practical-scale PSA is estimated to be about 73 % of that for a laboratory-scale PSA at the same nitrogen purity.
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  • Zhe Shi Zhao, Hitoki Matsuda, Norio Arai, Masanobu Hasatani
    1993 Volume 19 Issue 2 Pages 169-174
    Published: March 10, 1993
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The gas-phase formation of NO, N2O and HCN through NH3 in gas systems with coexisting CH4 was investigated experimentally in a tubular-flow reactor.
    Experiments were conducted for NO/CH4/O2/Ar, NH3/CH4/O2/Ar and NH3/NO/ CH4/O2/Ar gas reaction systems at temperatures of 1143-1293K, with the initialconcentration of O2 and CH4 being lower than 3.0 vol %.
    It was found within the range of the present experimental conditions that : 1) The main product of the decomposition of NH3 was N2 in addition to NO, N2O and HCN, when the decomposition of CH4 was sufficient. 2) The concentrations of the produced NO, HCN and N2O depended on the ratio of the concentrations [O2] 0/ [CH4] 0 in the NH3/CH4/O2/Ar gas system. In the range of [O2] 0/ [CH4] 0 <1.0, the formation of HCN and of N2O were enhanced with an increase in the ratio of [O2] 0/ [CH4] 0, and formation of NO was inhibited. On the contrary, in the range of [O2] 0/ [CH4] 0>1.0, the changes in HCN, N2O and NO concentration show an opposite tendency to those observed in [O2] 0/ [CH4] 0 <1.0. 3) HCN of high concentration was formed by adding NO or NH3 to CH4 /O2 /Ar gas system.
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  • Itaru Tamura, Hirokazu Nishitani, Eiichi Kunugita
    1993 Volume 19 Issue 2 Pages 175-181
    Published: March 10, 1993
    Released: November 12, 2009
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    Traditional model predictive control with a process model represented by an impulse or a step response cannot be applied to integral processes, which are typical in chemical plants. In this paper a parametric input-output model was used to develop a model predictive control algorithm for the integral process. Two control algorithms with different prediction models were studied with respect to closed-loop properties. They make a difference in the robust stability of the control system in the case of under-estimated process gain.
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  • Fumihiro Koizumi, Hirokazu Nishitani, Shigeharu Toyoda, Eiichi Kunugit ...
    1993 Volume 19 Issue 2 Pages 182-189
    Published: March 10, 1993
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A new method to detect contour lines by the Marr-Hildreth filter was developed for the particle image. First, tuning of the filter parameter was studied to detect separate contour lines for a picture of two isolated particles. The correct contour lines can be obtained for both particles when the filter parameter σ is chosen so that the off-area radius of the filter is smaller than a certain value. This value is a linear function of the distance between the two particles, edge width and radius of the particle. second, the average value of the first derivative of the density on the contour line can be used for judging whether a particle image is in focus or not. These methods enable accurate detection of contour lines for the particle image in focus.
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  • Hideaki Kurokawa, Toshio Sawa, Tetsuo Yamaguchi, Kenji Mitani
    1993 Volume 19 Issue 2 Pages 190-197
    Published: March 10, 1993
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Based on a consideration of possible impurities in the feed for membrane distillation, experimental studies were performed to determine the concentration limit of nonvolatile substances and the permeate characteristics of volatile ones. The permeate experiments were done using Na2SO4 as nonvolatile matter and ethanol and ammonia as volatile components.
    The characteristics of volatile permeate were seen in which ammonia does not permeate to the cooling-water side by keeping pH less than 6. By considering concentration polarization as well as heat and mass balance, good simulations were made of the experiments.
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  • Eiji Suzuki, Kazunari Takahashi, Fusao Makishima, Haruhiko Morita
    1993 Volume 19 Issue 2 Pages 198-206
    Published: March 10, 1993
    Released: February 19, 2010
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    Dependence of antibody production rate per cell on hybridoma growth rate was experimentally examined for various -methods to regulate growth rate. Growthsuppression methods such as weak glutamine limitation or interleukin-6 supplementation, which are supposed not to disturb protein synthesis, enhanced antibody production two-to four-fold as the growth rate decreased from its maximum to one fifth there of. Increase of messenger RNA coded for antibody in each cell paralleled that of antibody production rate, while the growth was suppressed by the interleukin. These results are consistent with prediction by the model proposed by the authors. In cases of growth suppression via suppression of protein synthesis such as leucine limitation or actinomycin D supplementation, antibody production rate was not enhanced but decreased instead by growth suppression. These results were also predicted by the model. In conclusion, glutamine limitation is proposed as a feasible growth regulation method for enhancing antibody productivity. Especially, glutamine limitation in glucose-free medium is recommended for hybridomas which are viable with glutamine instead of glucose since lactate, a glucose metabolite, is thought to suppress antibody production.
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  • Satoshi Terada, Haruhiko Morita, Fusao Makishima, Eiji Suzuki, Hiroyuk ...
    1993 Volume 19 Issue 2 Pages 207-213
    Published: March 10, 1993
    Released: November 12, 2009
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    Hybridoma 2E3 cells produced two to three times as much antibody per cell in perfusion culture as did cells growing exponentially in batch culture. The proportion of γ1 mRNA to total RNA of the cells in perfusion culture was 1.7 times as much as that of the cells growing exponentially in batch culture. The growth rate of the cells in perfusion culture, determined by thymidine incorporation rate into DNA of the cells, was about one-third that of cells growing exponentially in batch culture. Cell cycle analysis using flow cytometry indicated that the cells which were growth-suppressed in the perfusion culture accumulated in G1 phase of the cell cycle. Concentrations of ammonium ion, glucose and lactate in the supernatant of the perfusion culture were almost equal to those of the late batch culture. Interleukin-6 enhanced the specific antibody production rate of the cell in perfusion culture.
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  • Junji Shibata, Masakazu Ohtomo, Mikiya Tanaka
    1993 Volume 19 Issue 2 Pages 214-219
    Published: March 10, 1993
    Released: November 12, 2009
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    Extraction behaviors of Ti (IV) and other metal ions, such as Fe (III), Fe (II), Cu, Zn, Mn, Mg and Al from sulphuric acid solutions were studied in order to separate Ti (IV) from aqueous solutions. The extractant used was tri-alkylphosphine oxide with the trade name Cyanex 923. Computer simulation for countercurrent multistage extraction and stripping was carried out by using mathematical models of extraction and stripping isotherms.
    Computer simulation was performed for the extraction step with countercurrent 2-4 extraction stages and phase ratios of A/O=0.66-1.33 and for the stripping step with countercurrent 6-10 stripping stages and phase ratios of 0.66-1.33. Extraction with four stages and a phase ratio of 0.8 gave 99.0 % total extraction, 21.6 g/dm3 of titanium concentration in the outlet organic phase and 0.207 g/dm3 of titanium in the outlet aqueous phase. Stripping with ten stages and a phase ratio of 1.0 exhibited 77.0 % total stripping, 15.4 g/dm3 of titanium in the outlet aqueous phase and 4.61 g/ dm3 of titanium in the outlet organic phase.
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  • Hidehiro Kamiya, Chiaki Nakayama, Genji Jimbo
    1993 Volume 19 Issue 2 Pages 220-229
    Published: March 10, 1993
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Fine Al2O3, MgO and SiO2 powders of various sizes were consolidated into a dense and uniform structure by high-pressure cold isostatic pressing. Although the average particle diameter was less than 21 nm, Al2O3, MgO and SiO2 powder compacts were densified to 60% of theoretical density by cold isostatic pressing at 1 GPa, because the open and strong aggregate structure was collapsed by the cold isostatic pressure. Pore size in these compacts decreased below primary particle size. Especially, in the case of MgO powders, the maximum relative density increased to 80 % and the ratio of pore size to primary particle size was less than 20 %. However, in the case of Al2O3 powders, whose size was more than 100 nm, increase in relative density and the decrease in pore size in the compacts slightly occurred with increase of isostatic pressure up to 1 GPa. In the case of particles larger than 100nm and high-hardness materials, high cold isostatic pressure was not effective in increasing the packing density.
    The mean vertical force and compressive stress at the contact point between particles in compacts and the maximum tensile stress in a particle during isostatic pressing were estimated by Rumpf's and Hertz's equation. Because these stresses were smaller than the hardness and tensile strength of Al2O3 or MgO materials, no viscous deformation or fracture of particle took place during compaction. The relations between the ratio of mode pore diameter to particle diameter and the relative density of Al2O3, MgO and SiO2 compacts agreed with those of spherical and monosized particle beds. The main mechanism of densification of compacts during isostatic pressing was the collapse of aggregation and rearrangement of particles.
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  • Masatoshi Yoshida, Hideto Itagaki, Shigeru Matsumoto, Hiroshi Sugiyama ...
    1993 Volume 19 Issue 2 Pages 230-237
    Published: March 10, 1993
    Released: November 12, 2009
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    An application of the neural net model is considered to solve the optimizing control problem for a fixed-bed reactor carrying out light-naphtha reforming, which exhibits complex, highly nonlinear dynamics because multiple reactions involving multiple species take place under catalyst deactivation during operation. A neural net consisting of three layers was trained by the back-propagation method using data sets generated by numerical simulation of a mathematical model. It was shown that the neural net model can predict the product stream compositions under a constant feed composition by using only the reactor-wall temperature and the initial profile of catalyst activity in the reactor as input data. It was also shown that optimizing control can be efficiently performed by use of a trained neural net model to keep the yield of the desired product constant.
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  • Yoshiro Kitamura, Qingfa Huang, Osamu Takemoto, Teruo Takahashi
    1993 Volume 19 Issue 2 Pages 238-244
    Published: March 10, 1993
    Released: November 12, 2009
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    The effect of surfactants on the superheating of a kerosene-water interface was experimentally investigated as a fundamental study of the microexplosion of emulsified fuels. As surfactants, Span 80 and NPEn were used. A three-layer sample was prepared in a glass capillary ; the bottom layer was kerosene, the middle layer was water and the upper layer was kerosene. The surfactants were dissolved in the upper kerosene layer and then adsorbed on the interface between the upper kerosene and the middle water layer. The samples were heated in an oil bath at a rate of 3K/min. Thirty to forty samples were used to determine the superheating temperature distribution. The superheating temperature decreases with increasing concentration of surfactant and approaches a constant distribution above a critical concentration. The superheating temperature also depends on the heating rate and the interfacial area of the kerosene-water interface. To explain such effects, we assumed that the surfactant adsorbed on the interface accelerates the nucleation rate. We suggest a modified nucleation rate that includes the surface coverage by a surfactant. The model predicts that the presence of surfactants reduces the superheating temperature and makes the distribution broader. The prediction from this model is in good agreement with the experimental data.
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  • Toshitaka Funazukuri, Kazuhiko Hori, Noriaki Wakao
    1993 Volume 19 Issue 2 Pages 245-250
    Published: March 10, 1993
    Released: November 12, 2009
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    Acacia chips cooked with water or aqueous alcohol solutions (methanol, ethanol, 1-propanol and 2-propanol, separately) were exploded. It was found that the strength indices (tear, burst, folding), breaking length, brightness and fiber length of pulps were improved and the Kappa numbers decreased when the chips were cooked with aqueous alcohol solutions. The physical characteristics of the pulp obtained with aqueous ethanol solution (30wt%) were almost the same as those with aqueous solutions (30wt%) of methanol, 1-propanol and 2-propanol. Also, pulps obtained with aqueous ethanol solution were found to be better bleached with H2O2 and NaOH than those treated with water only.
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  • Shuji Matsusaka, Masanobu Shimizu, Hiroaki Masuda
    1993 Volume 19 Issue 2 Pages 251-257
    Published: March 10, 1993
    Released: November 12, 2009
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    Formation of wall particle layers by simultaneous deposition and reentrainment was investigated for turbulent aerosol flows. Fine powder (mass median diameter=3 μm) was dispersed in an air flow and led into a circular glass tube. The process of particle layer formation was continuously observed and the mass of particles deposited on the wall was measured. Although the particle layers formed at low velocities uniformly covered the whole of the inside wall, they gradually changed into striped patterns at high velocities. It was found that the thickness of the particle layer decreases with increasing friction velocity of the flow, and is equal to the distance from the wall corresponding to a certain air velocity in a viscous sub-layer. The deposition patterns in their equilibrium states are determined only by the flow velocity, irrespective of the initial state. It was also found that the growth rate of particle layers has the maximum value for the variation of average aerosol velocity, because both the deposition flux and reentrainment flux increase with increasing velocity when it exceeds the critical reentrainment velocity.
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  • Kengo Tajima, Miki Niwa, Yuichi Murakami
    1993 Volume 19 Issue 2 Pages 258-264
    Published: March 10, 1993
    Released: November 12, 2009
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    A continuous-flow CVD (chemical vapor deposition) method by which a large amount of zeolite can be modified uniformly to control the pore-opening size is studied. In this study, Si (OCH3) 4 is deposited on Na-type and H-type mordenites, the pore-opening size narrowed by deposition is evaluated by competing cracking of octane isomers with different diameters, and the amount of coke residue formed by deposition is measured by thermal gravimetric measurement.
    On Na-type mordenite, silica can be deposited uniformly at higher temperatures such as 593 K. On H-type mordenite, however, silica can be deposited uniformly only at a lower temperature such as 343 K owing to the secondary reaction of the produced CH3OH. During heating of the bed after deposition, coke and H2O are produced from CH3OH and influence the apparent pore-opening size depending on the position of the bed. When the sample is treated with steam, however, the coke is removed and the structure of the deposited silica layer may be rearranged to widen the pore-opening size. Owing to these roles of steam treatment, the pore-opening size of H-type mordenite also can be narrowed uniformly along the bed.
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  • Masaaki Yokota, Ken Toyokura
    1993 Volume 19 Issue 2 Pages 265-271
    Published: March 10, 1993
    Released: November 12, 2009
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    S-carboxymethyl-L-cysteine (L-SCMC) seed crystals were grown in a NaCl-doped supersaturated solution of DL-SCMC, and the amount of D-SCMC fine crystals appearing on the surface of the seed crystals and also in the supersaturated solution were measured with the elapse of time. From these experimental results, D-SCMC was found to be incorporated on the L-SCMC crystals as follows. 1) In the initial stage of growth of the seed crystals, L-SCMC crystallized preferentially, and then fine crystals of D-SCMC were observed on the surface of the seed crystals after 0.75 to 6.0 hours of growth periods depending on the operational supersaturation. After about two hours of these periods, they began to appear in the supersaturated solution. 2) After 1), the weight of D-SCMC fine crystals on the seed surface WDS increased by the 4th power of growth periods and they almost agreed with the total weight of D-SCMC incorporated in the seed crystals WDC. 3) When the D-SCMC fine crystals were buried in the seed crystals, the rate of increase of WDS decreased, and WDS increased by the third power of the growth period of seed crystals.
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  • Hitoshi Funayama, Takuo Sugawara
    1993 Volume 19 Issue 2 Pages 272-278
    Published: March 10, 1993
    Released: November 12, 2009
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    The photocatalytic decomposition rate of chloroform in dilute aqueous solution was investigated in a suspension of titanium dioxide (anatase) to obtain fundamental information for the design of suspended-photocatalysts reactor.
    The absolute light intensity in a suspended titanium dioxide photoreactor was determined with a DPOF the mical actinometer system which detects dispersive as well as incident light. With increase of titanium dioxide concentration the light intensity rapidly increased first and gradually decreased later. The initial decomposition rate of chloroform was affected by the incident light intensity, the titanium dioxide concentration and the initial oxygen partial pressure, and was formulated by the following equation under the experimental conditions studied :
    (-γSO) =2.86 [PO2] /1+0.12 [PO2] √I1P·Cm
    where (-rSO) is initial reaction rate ; [PO2], partial pressure of oxygen; I1P, absolute light intensity in the reactor ; and Cm, titanium dioxide concentration.
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  • Hideto Matsuyama, Masaaki Teramoto
    1993 Volume 19 Issue 2 Pages 279-287
    Published: March 10, 1993
    Released: November 12, 2009
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    The performance of a membrane extraction module, was analyzed for the mutual separation of Er and Y in the presence of a water-soluble complexing agent (DTPA), and the effects of various conditions on the membrane areas of extraction and scrubbing sections were studied.
    It was confirmed that the required membrane areas decreased extremely by the addition of a complexing agent. There existed an optimum pH because pH influenced both complex formation equilibria in the aqueous phase and extraction ability. Moreover, selection of a porous support membrane with high permeability was found to be especially effective for improvement of membrane performance because the mass transfer through the porous support membrane was rate-determining in the scrubbing section. In the extraction section, the operating condition that the mass transfer with the dissociation of DTPA complex in the aqueous phase became the rate-determining step was desirable for obtaining high selectivity.
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  • Jun Fukai, Hisayuki Orita, Kazutaka Saruwatari, Osamu Miyatake
    1993 Volume 19 Issue 2 Pages 288-294
    Published: March 10, 1993
    Released: November 12, 2009
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    A method is developed to estimate the temperature dependency of a linear contraction of isotropic formed green carbon during the carbonization process. The linear contraction is given as functions of residue and true density, both of which are estimated from yields of gases released from filler and binder by devolatilization. The relation between true density and hydrogen content for the filler and binder is found to be same as that for coal and pre- heated coal. The relation is utilized to estimate the true density.
    Yields of released gases are measured at a constant heating rate of 1K/min to determine kinetic parameters, which are presented by the Arrhenius expression. Releases of H2, CO, CO2, CH4 and tar are considered. Linear contraction is estimated by using the kinetic parameters. The linear contractions which are estimated in the temperature range in which the porosity is kept constant agree well with the measured values for heating rates of 1 and 3K/min. The estimated values for another formed green carbon which has a different mixing ratio of filler and binder also agree with the measured ones in the same temperature range.
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  • Chouji Fukuhara, Akira Igarashi
    1993 Volume 19 Issue 2 Pages 295-302
    Published: March 10, 1993
    Released: November 12, 2009
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    Assuming a rectangular wall reactor which consists of alternating piles for a catalyst wall channel and a heat medium channel, the performance of reaction and heat transfer of a rectangular wall reactor for steam reforming and combustion of methane was simulated and compared with that of a fixed-bed reactor.
    In the case of steam reforming of methane, it was suggested that the rectangular wall reactor has excellent thermal conductivity between the heating area and the reacting area, and gives a uniform temperature distribution in the reactor. Further, the rectangular wall reactor showed activity nearly equal to that of the fixed-bed reactor, although the amount of catalyst in the rectangular wall reactor was less than that in the fixed-bed reactor. In the case of combustion of methane, it was inferred that use of the rectangular wall reactor results in stable reactor operation and long catalyst life.
    Finally, it was also demonstrated that the performance of the rectangular wall reactor would be powered up by laying a smaller channel.
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  • Hayatoshi Sayama, Youichi Tozawa, Kazuhiko Suzuki, Yukiyasu Shimada, K ...
    1993 Volume 19 Issue 2 Pages 303-310
    Published: March 10, 1993
    Released: November 12, 2009
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    This paper presents analytical expressions of the sensitivity coefficients for the total pressure and the feed liquid compositions in the multicomponent equilibrium flash process. The partial derivatives of temperature with respect to the total pressure are derived analytically by extending the implicit function theorem. The distillation calculation methods which chose the M-1 feed compositions as the independent variables and the one feed composition as the dependent variable defined d-sensitivity coefficients to satisfy the stoichiometric equations. This paper assumes that all the M feed compositions are independent and defines i-sensitivity coefficients, which violate the stoichiometric equations of the liquid compositions. d-sensitivity coefficients can be obtained from i-sensitivity coefficients and not vice versa. Numerical solutions are shown for both sensitivity coefficients.
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  • Zennosuke Tanaka, Hiroyuki Mitsuji, Teruo Takahashi
    1993 Volume 19 Issue 2 Pages 311-316
    Published: March 10, 1993
    Released: November 12, 2009
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    It is quite difficult to separate or concentrate an aimed particulate component in a multistage fluidized classification column in the case where differences of particle sizes or particle density are small.
    Introducing the concept of extractive distillation in fluidization, the effect of a third component for the elutriation in a binary system, that is, the particle equilibrium, is examined experimentally. Adding the third component to a binary mixture, the separation factor α was improved in a particle equilibrium. In the case of coarser particles for a third component, they work as a separation accelerant. On the contrary, finer particles work as a restrainer. Coarser third components, with particle sizes greater than twice that of other components, are ineffective as a separation accelerant. A particulate separation process similar to an extractive distillation can be developed.
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  • Kunihisa Osasa, Hideo Nakakura, Hiroyuki Tanaka
    1993 Volume 19 Issue 2 Pages 317-324
    Published: March 10, 1993
    Released: November 12, 2009
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    Batch separation tests on colloidal waste material such as disperse dye were conducted by electroflotation using aluminium sacrificial electrodes. The mechanism of the separation process was investigated and the experimental conditions were clarified to realize the maximum flotation rate. As a result, the dissolution rate of aluminium was found to be proportional to current density and larger than the rate calculated from Faraday's law. The separation process occurred in two stages. In the first, the sol concentration remained at the initial value and flocculation of the sol was due to surface charge neutralization of colloids by the released aluminium ion. The second stage formed the flotation process and the removal followed firstorder kinetics. The rate constant increased with increasing current density. Polarity conversion electrodes were used to enhance the dissolution rate of aluminium. The optimum conversion time was around 900s. Bipolar type electrodes were effective in keeping the applied potential at the appropriate value and making the flotation unit compact.
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  • Shiying Lin, Zibing Zhu, Mitsuho Hirato, Yoshihiko Ninomiya, Masayuki ...
    1993 Volume 19 Issue 2 Pages 325-332
    Published: March 10, 1993
    Released: November 12, 2009
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    During CO2 gasification in a high temperature range (1273K-1773K), characteristics of coal char pore structure were investigated by focusing on the effect on coal char reactivity and changes in the surface areas of pores of various sizes and in the reaction rates.
    With respect to the inner surface of unreacted coal char, the surface areas of micropore and mesopore decreased sharply with increasing carbonization temperature up to 1673K, although the surface area of macropore did not change much.
    During gasification, the average radius of micropore grew evidently, while the average radius of macropore did not change except for cases of high conversion. The pore structure change and the relation between S0 and (S/S0) max were described by a random pore model.
    The reaction rate showed a linear dependence on the micropore surface area over the whole temperature range.
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  • Hideki Higashiuchi, Yujiro Sakuragi, Masanori Nagatani, Yasuhiko Arai
    1993 Volume 19 Issue 2 Pages 333-337
    Published: March 10, 1993
    Released: February 19, 2010
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    To collect liquid-liquid equilibrium data for various types of quaternary systems having different numbers of immiscible binaries, this work reports experimental liquid-liquid equilibrium data for type 1 quaternary system isooctane (2, 2, 4-trimethylpentane) (1) -methanol (2) -benzene (3) -toluene (4) and type 2 quaternarysystem heptane (1) -methanol (2) -toluene (3) -octane (4) at 25°C. Solubility datafor the quaternary systems were obtained by using the cloud point method and experimental tie-line data were measured by gas chromatographic analysis of both phases. Further, the present tie-line data were correlated with good agreement using an improved Wilson equation previously proposed by the authors.
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  • Yushi Hirata, Keiko Fujioka, Takashi Okazaki, Yousuke Fujii, Ryuzo Ito ...
    1993 Volume 19 Issue 2 Pages 338-344
    Published: March 10, 1993
    Released: February 19, 2010
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    The apparent volume of a reaction bed and the real volume of solid substances have been measured at 303.2K for CaCl2/CH3NH2 gas-solid reaction which is used for driving a chemical heat pump. A sixfold expansion of the bed volume has been observed in the initial reaction (CaCl2→CaCl2·6CH3NH2), while its variation was reduced to half of the initial volume change in the repeated reaction (CaCl2.2CH3NH2↔CaCl2·6CH3NH2).The volume of CaCl2.1.6CH3NH2, CaCl2.2CH3NH2 or CaCl2.6CH3NH2 was obtained by subtracting the vacant volume in the reactor, which was measured by introducing nitrogen gas into it, from its total volume. The volume of the solid substances varies proportionally with the moles of methylamine reacted, and one mole of methylamine in the solid occupies a space equivalent to 95% of the molar volume of liquid methylamine. By analyzing the density data of hydrated and ammoniated salts, it has also been confirmed that the proportionality of the volume expansion depends upon the substance reacted with each salt.
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  • Tahei Tomida, Masahiro Kubo
    1993 Volume 19 Issue 2 Pages 345-347
    Published: March 10, 1993
    Released: November 12, 2009
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    Reflection behaviours of a light beam, which was applied to a dispersion of small bubbles (mean diameter, 0.19mm-1.17mm) in a rectangular cell, were simulated by the Monte Carlo method. The calculated values of both the intensity profiles of the transmitted light and the effective light pass length agreed well with the experimental ones. It was concluded that this method is useful in estimating the volumetric ratE of light absorption in small bubble dispersion systems.
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  • Issei Fujiyoshi
    1993 Volume 19 Issue 2 Pages 348-351
    Published: March 10, 1993
    Released: November 12, 2009
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    Experiment of simultaneous adsorption of nickel and cobalt on porous glass showed that di-ammine complexes of these metals were adsorbed by a ligand substitution and that the selectivity coefficient of these metals was 5.1 to 8.5 in the pH7.2 to 7.5 region. When porous glass was applied to separation of these metals by chromatography, the suitable concentration of ammonium chloride in eluent was 0.6 mol/l. With increasing concentration of ammonium chloride in conditioning solution, almost complete separation was accomplished, but a part of the cobalt component was oxidized to become insoluble. Supersonic irradiation of liquid phase was found to be effective for prevention of oxidation.
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  • 1993 Volume 19 Issue 2 Pages e1
    Published: 1993
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Download PDF (32K)
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