KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 3 , Issue 3
Showing 1-16 articles out of 16 articles from the selected issue
  • Hiroki Nishizaki, Kazuo Endoh
    1977 Volume 3 Issue 3 Pages 219-223
    Published: May 10, 1977
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Thermal decomposition of polystyrene was studied in a batch fluidized bed of 35 mm ID under atmospheric pressure, at temperatures ranging from 380 to 550°C, with gas rate from 0.5 to 4.0 cm/sec, the gas containing oxygen up to 21.0 vol %.
    The overall reaction rate was found to obey the first-order equation. The distilling rate of liquid product proceeded comparatively to the rate of loss-weight. The result obtained was
    Rw=dw/dθ= (k0*+kα*·y0.8)w
    where Rw : reaction rate by loss of weight method dw/dy
    w : fractional weight
    k0*, ka* : coefficients of rate equation in the inert gas and the gas contained oxygen, respectively
    y : oxygen concentration
    θ : reaction time after the induction period
    When the y is about 18% and the temperature from 400 to 500°C the liquid product yield was maximum over 70 wt %.
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  • Kazuo Kondo, Fumiyuki Nakashio
    1977 Volume 3 Issue 3 Pages 224-230
    Published: May 10, 1977
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Benzene oxidation, which is a highly exothermic consecutive-parallel reaction, is carried out in a fixed bed catalytic reactor and the experimental results are simulated with a one-dimensional model.
    With low inlet temperatures and reactant concentrations, the temperature rise in the reactor is relatively small and the reactor behavior can be simulated well with a pseudo-homogeneous model. As the inlet temperatures and reactant concentrations increase the agreement between experimental and calculated results becomes unsatisfactory.
    A criterion which has been derived for evaluating the significance of interphase or intrapartide temperature temperature gradients for a single reaction is applied to the present case. It is found that the criteria can be used effectively for complex reactions.
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  • Tadashi Shirotsuka, Masao Sudoh, Hideo Nishiumi
    1977 Volume 3 Issue 3 Pages 231-235
    Published: May 10, 1977
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    To discuss the influence of optical density on a light-induced chain reaction with biradical termination, photooxidation experiments were carried out on the initial reaction rates with different reactant concentrations of n-butylaldehyde.
    Efficiency of active radical utilization obtained in the optically dense concentration contrasts with the value derived by the constant diffusion coefficient in constant mixing. The increase of reactant concentration produce a steeper profile of light intensity, and almost all of incident light is absorbed in the boundary layer of the vicinity of the incident wall. Then, the results are fairly well explained by the decrease of overall diffusion coefficient in the high optical density, considering of molecular diffusion in the boundary layer.
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  • Ikuo Nagashima, Noriaki Yamamoto, Toshitaka Fujikawa, Takehiko Furusaw ...
    1977 Volume 3 Issue 3 Pages 236-242
    Published: May 10, 1977
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Carbonization of non-caking coal (Taiheiyo in Hokkaido, mean particle size = 350 micron) was carried out in continuous laboratory scale fluidized bed. Yields and composition of produced char, tar and gas were investigated at various levels of both carbonization temperature (440°C880°C) and coal residence time.
    The maximum yield of tar was attained at ca. 600°C and the corresponding residence time of coal to complete carbonization was more than ten minutes.
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  • Norio Arai, Tatsuo Higashi, Masanobu Hasatani, Sachio Sugiyama
    1977 Volume 3 Issue 3 Pages 243-247
    Published: May 10, 1977
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The rate of thermal NOx formation was measured for a binary system of N2-O2 in an isothermal tubular reactor. The concentration ratios of nitrogen to oxygen were varied from zero to unity and the reaction temperatures, from 1, 550 to 1, 750 K. As result, the following over-all rate equation of NO formation was obtained.
    d [NO] /=7.07×1013exp (-127, 500/RT) [N2] [O2] 1/2
    It was seen that, in the temperature range of the present investigation, the values of rate constant of the proposed equation were so small as to be about 1/3 of those of Zeldovich equation.
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  • Toshiyuki Yokota, Toshihiko Iwano, Teiriki Tadaki
    1977 Volume 3 Issue 3 Pages 248-254
    Published: May 10, 1977
    Released: February 12, 2010
    JOURNALS FREE ACCESS
    To estimate the light absorption rate in a heterogeneous photochemical reactor, a new method based on the light path length distribution in the reactor was proposed. The locus of a ray of light traveling in the reactor was computed according to the rules of geometrical optics so that the probability distributions of the light path length and number of collision with dispersed phase could be obtained. The light absorption rate was derived theoretically from these distributions.
    The photoreduction of potassium ferrioxalate was performed in a rectangular reactor with cylindrical glass pipes, glass rods or metal rods plated with nickel as dispersed phase, which were settled vertically to the incident light so that rays of light scattered within a horizontal plane. The experimental results agreed well with the theoretical values predicted and supported the validity of the derived light absorption rate.
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  • Isamu Yabe, Daizo Kunii
    1977 Volume 3 Issue 3 Pages 255-260
    Published: May 10, 1977
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    The purpose of this study is to observe directly how the gas molecules diffusing from a gas bubble disperse in the liquid phase. The single bubble was formed at single nozzle and rising up through the column full of a quiescent liquid. The observation of dispersion phenomena around a bubble were mainly carried out in the region from the release point of the bubble to the point where the bubble velocity reaches the steady state. Some observation were also carried out in the steady state region.
    When the dispersion of gas molecules were visualized by using the iodine-starch reaction the dispersion phenomena was continuously photographed with a camera which is designed to move with single bubble. Consequently, it was confirmed that the dispersion pattern of the gas molecules around the bubble can be classified by two dimensionless parameters, namely Reynolds number Re=deUb/ν and the dimensionless time elapsed from the bubble release t*=tUb/de.
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  • Masao Yamazaki, Terukatsu Miyauchi
    1977 Volume 3 Issue 3 Pages 261-265
    Published: May 10, 1977
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    A technique of temperature detection in bubble and emulsion phases in fluid-bed is presented when the bed is subjected to a temperature gradient.
    Phase alternation is, so fast that a minute thermocouple (RTC) and some auxiliary circuits are required.
    The temperature difference between the two phases must be ably corrected by taking into account the time lag of RTC in each phase and by proper choice of the mean bubble diameter.
    A possible error of the temperature difference is estimated to be 10 % when the bubble size is estimated by 20% lower.
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  • Masao Yamazaki, Genji Jimbo, Tsuneo Matsumoto, Akira Mizutani, Shizuhi ...
    1977 Volume 3 Issue 3 Pages 266-271
    Published: May 10, 1977
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    An electronic system called “Hot-Wire Scope” has been developed for measurement of bubbles in a three-dimensional fluidized bed.
    The probe is an assembly of seven long nichrome fine wires that are evenly spaced by one centimeter span horizontally. Soldering a copper lead on the fine wires at every centimeter, the multi-channel hot-wires are formed.
    Neon lamps corresponding to each hot-wire through an electronic circuit, form a lamp matrix. When a bubble passes the hot-wires, lamps repeat lighting and the lamp matrix shows a horizontally sliced bubble pattern in a mosaic form.
    The horizontal bubble diameter is thus determined by cinematographing the pattern. A few examples are presented in this paper.
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  • Masao Yamazaki, Nobuaki Ito, Genji Jimbo
    1977 Volume 3 Issue 3 Pages 272-276
    Published: May 10, 1977
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    A multi-channel hot-wires system called “Hot-Wire Scope” is a device which can detect all bubbles of more than one centimeter diameter passing a horizontal plane at any height in fluidized beds.
    Observation by “Hot-Wire Scope” in a bed of FCC particles showed that the horizontal bubble diameter has a bi-modal distribution under a large bed height vs. bed diameter ratio (Ls/DT_??_10), and at low gas velocity and at lower bed height, the distribution of bubbles becomes a monomodal or a log-normal form.
    From cine-films and visual observation at the wall, the bed is seen to be composed of three regions, viz., a lower region where intensive particle movement is occurring, a middle region where bubble coalescence is progressing, and an upper region where bubble size distribution becomes a bi-modal form.
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  • Toru Imanara, Hikoji Inazumi, Yutaka Haruyama
    1977 Volume 3 Issue 3 Pages 277-282
    Published: May 10, 1977
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    A numerical solution was obtained for the basic nonlinear partial differential equations which represented the rates of simultaneous absorption of CO2 and H2S into aqueous sodium hydroxide solutions. In this situation, it was assumed that the reaction between dissolved CO2 and OH- ion was (1, 1) th order, and that the rates of any other reactions in the liquid phase were instantaneous.
    Experiments were carried out using wetted-wall columns for the system CO2-H2S-NaOH aq. sol. over the range of gas-liquid contact time 0.02-1.5 sec, partial pressure of CO2 0.02-0.9 atm and that of H2S 0.05-0.1 atm.
    The experimental values of absorption rates of CO2 and H2S were in good agreement with numerical solution in this work.
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  • Takeshi Kataoka, Tadaaki Nishiki, Koretsune Ueyama
    1977 Volume 3 Issue 3 Pages 283-288
    Published: May 10, 1977
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    Equilibria and rates of extraction of cadmium from the aqueous solutions of hydrochloric acid and sodium chloride were investigated in order to clarify the extraction mechanism of cadmium by amines of high molecular weight.
    Over a wide range of the concentration of cadmium, the extraction equilibria could be expressed by the equilibrium relationships considered the extraction reactions in which three extracted complexes, i.e., (RH) 2CdCl4, (RH) 2CdCl4·RHCl and (RHCl-RH) 2CdCl4 are produced.
    The extraction rates measured with a stirring cell with a flat liquid-liquid interface could be approximately expressed with a simple model, adopting the diffusivity of CdCl2 in the aqueous phase and that obtained by considering each extracted complex in the organic phase as an apparent diffusivity.
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  • Takashi Kamemoto, Mototake Yano, Yoshio Harano
    1977 Volume 3 Issue 3 Pages 289-295
    Published: May 10, 1977
    Released: October 21, 2009
    JOURNALS FREE ACCESS
    As the concentration of phenol was largely changed before and after adsorption, the liquid phase phenol adsorption on active carbon was measured in a stirred tank adsorption vessel at 3050°C.
    At the early stage of the adsorption, the adsorption rate on the external surface is so rapid with respect to other mass-transfer processes, that the initial adsorption rate is governed by the boundary film mass-transfer process between the bulk liquid and the external surface of the active carbon. The coefficient of the boundary film mass-transfer ks is proportional to the revolution speed of impeller N in term of Sh/Sc1/3.
    The later part of the adsorption was governed by intraparticle diffusion, and among the boundary film mass-transfer process and intraparticle diffusion process, since an intermediate mass-transfer region existed, then the starting point of intraparticle diffusion is not clearly determined. A convenient method is proposed for estimating the effective particle radius at the starting point of intraparticle diffusion region by using a shell model, and the starting point was determined from the Drydens nomograph using a modified fractional approach to equilibrium E', by trial and error method.
    The effective intraparticle diffusion coefficient De was obtained from such convenient method and shows that the later part of the adsorption was controlled by a diffusion resistance in a pore diffusion with radius of 3545Å.
    The tortuosity factor in the particle was calculated from the molecular diffusivity coefficient Dm and De, and it is of an order of 1012.
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  • Tokuro Mizushina, Ryuzo Ito, Sadaji Yamashita, Hiroshi Kamimura
    1977 Volume 3 Issue 3 Pages 296-302
    Published: May 10, 1977
    Released: October 21, 2009
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    Heat transfer during film condensation of superheated pure vapor flowing downward or upward in a vertical tube has been studied experimentally.
    The average heat transfer coefficients of vapor phase were measured in both cases with and without condensation. The heat transfer coefficients with condensing mass flux are predicted well by the film theory, and agreed with those for dry tube at the limit as mass flux approaches zero.
    The average heat transfer coefficients of condensate film were also measured. They show fairly good agreements with the theoretical equation for downward vapor flow and with that given by the authors for upward vapor flow, respectively. Considering the effect of superheating, the apparent latent heat of condensation is used in these calculations to allow treatment similar to the saturated vapor. It is theoretically predicted that considerable difference in Nusselt number of condensate film between the downward and upward vapor flow arises under the higher flow rate of vapor and the lower temperature of cooling wall. However it was practically impossible to show this difference due to the occurrence of flooding. Consequently, the Nusselt number showed no significant difference by the directions of vapor flow in our experimental range. The same result is also observed in the j-factor of vapor phase.
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  • Mompei Shirato, Toshiro Murase, Niichi Hayashi, Kohei Miki, Toshiharu ...
    1977 Volume 3 Issue 3 Pages 303-310
    Published: May 10, 1977
    Released: February 12, 2010
    JOURNALS FREE ACCESS
    In a screw press, also known as an expeller, solid-liquid mixtures are fed to a thick-walled barrel containing a rotating worm having a gradually decreasing channel-area, and expressed under an increasing pressure condition. The mechanism of continuous expression in a screw press is studied, and analytical methods for the continuous expression of semi-solid materials are shown.
    The screw expression processes of slurry materials consist of the two parts of filtration and consolidation, and the process of semi-solid materials can be analysed on the basis of the principles of a variable pressure-variable rate consolidation for a batch process. Under the conditions of known feed rates and expression pressure distributions in screw presses, the dehydration rate and the residence time for semisolid materials at steady states are calculated from the volumetric flow rate distribution (Qx-equation) and from the mass fraction of solids distribution (s-equation) in worm channel, respectively. It is shown that both of the mass fraction of solids in final cakes and of the residence time for screw expression of semi-solid materials are heavily dependent on the number of revolution of worm and the feed pressure. Reasonable coincidence between calculated results and experimental performances are obtained for the tapered type screw press, of which the height of the worm thread is a linear function of helical length of the channel.
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  • Takaitsu Iwata, Yuichi Sato, Mitsuhiro Nakamura, Yasuto Sakakibara, Yo ...
    1977 Volume 3 Issue 3 Pages 311-322
    Published: May 10, 1977
    Released: October 21, 2009
    JOURNALS FREE ACCESS
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