All issues
Volume 6 (1980)
- Issue 6 Pages 551-
- Issue 5 Pages 441-
- Issue 4 Pages 327-
- Issue 3 Pages 221-
- Issue 2 Pages 113-
- Issue 1 Pages 1-
Predecessor
Volume 6, Issue 6
Displaying 1-17 of 17 articles from this issue
- |<
- <
- 1
- >
- >|
-
Issei Fujiyoshi, Tai Sakurai1980 Volume 6 Issue 6 Pages 551-556
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSThe acid treatment of phase-separated glass was studied. The rate of porous layer formation was chemical reaction-controlling in the early stage. After the porous layer was slightly formed, it came to depend on both the dissolution reaction and the diffusion of acid. This reaction rate was proportional to the square root of acid concentration.
The increase of porous layer thickness was successfully explained by the pseudo steady-state diffusion approximation, and effective diffusion coefficient of acid was determined as follows.
Deff=5.71×10-4exp (-4, 530/RT) [cm2/sec]
It can be considered that Deff is influenced by two causes. They are (1) the filling in of pores by boric products and (2) the tortuosity of the porous layer. In this connection, the pore structure of porous glass at various leaching times was examined by nitrogen adsorption experiments.View full abstractDownload PDF (873K) -
Gong Hong Hong, Rhyohei Yamazaki, Takahiro Takahashi, Genji Jimbo1980 Volume 6 Issue 6 Pages 557-562
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSUsing two-dimensional and three-dimensional beds, the minimum fluidization velocity of various kinds of particles was measured at various temperatures. It was found that the mean voidage of bed at minimum fluidization (εmf) changed with increasing temperature. Taking into account the changes of gas viscosity and the mean voidage of bed at minimum fluidization with increasing temperature, the experimental results were consistent with the Kunii-Levenspiel equation for minimum fluidization velocity.
The increase of mean voidage of bed at minimum fluidization with temperature was affected by particle diameter and was related to the particle adhesion force. The particle adhesion forces, measured by the vibration and tensile strength method, increased with temperature.
An experimental equation which takes into account the gas viscosity and the mean voidage of bed at minimum fluidization is newly presented.View full abstractDownload PDF (907K) -
Teruo Takahashi, Toshiro Miyahara, Shigeo Senzai, Hiroshi Terakado1980 Volume 6 Issue 6 Pages 563-568
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSThe bubble formation in cocurrent, countercurrent and crosscurrent flow under the condition of constant gas flow rate is considered theoretically.
Relationships predicting the volume of bubbles generated are proposed. Under a variety of physical properties of liquid, the relationships are compared with measurements taken with three kinds of nozzles of 0.111, 0.169 and 0.303 cm diameter and stream velocities up to 40 cm/s, while the stream velocities in countercurrent flow were up to 15 cm/s. The proposed model for bubble formation in moving streams is in good agreement with measurements. The bubble volume formed in both cocurrent and crosscurrent flow decreases with increasing stream velocity while the bubble volume formed in countercurrent flow increases. The smallest bubble volume is obtained under crosscurrent flow. Empirical equations of the correction factors involved in the theoretical development for each of the three flows are given.View full abstractDownload PDF (2121K) -
Nobuetsu Yutani, Naoshi Ototake1980 Volume 6 Issue 6 Pages 570-578
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSBed expansion of the liquid-solids fluidized bed was analyzed by use of the concept of statistical mechanics.
Assuming that cells composed of a combination of both individual particles and local fluid are in stochastic motion, the particle velocity distribution function is given in the form of an exponential function. An experimental determination of the function was made from measurements of the bed-expansion curve.
As a result, the exponential distribution function P(Usi)dUsi is given as follows :
p (Usi) dUsi=1/Us-Uscexp (-Usi-Usc/Us-Usc) dUsi
where Usi is instantaneous particle velocity and Us is average particle velocity. Also, it is indicated that minimum average particle velocity Usc can be estimated by a single term of terminal velocity.View full abstractDownload PDF (1345K) -
Yasuo Kato, Tokihiro Kago, Kazumichi Uchida, Shigeharu Morooka1980 Volume 6 Issue 6 Pages 579-584
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSThe apparent overall heat transfer coefficient between column wall and bed for gas-liquid-solid systems was measured over a wide flow range from packed to fluidized bed, and the effects of column diameter (0.12 and 0.052 m), gas velocity, liquid velocity, height of heat-transfer section, properties of solid particles and liquid viscosity were studied.
When water was used as liquid phase in the tower of 0.12 m i.d., as liquid velocity increased at constant gas velocity, the heat transfer coefficient first increased, reached a maximum, then decreased to a minimum and again increased rapidly. In a higher range of liquid velocity, the bed showed stable three-phase fluidization. The rate of increase of heat transfer coefficient with respect to liquid velocity decreased gradually, and finally the heat transfer coefficient converged to a value of bubble column.
On the other hand, no maximum-minimum mode of the heat transfer coefficient was observed for the tower of 0.052 m i.d. under all present experimental conditions, or for the tower of 0.12 m i.d. using a viscous liquid of 3.6×10-2 Pa·s.View full abstractDownload PDF (888K) -
Nobuyuki Imaishi, Yasuo Suzuki, Mitsunori Hozawa, Katsuhiko Fujinawa1980 Volume 6 Issue 6 Pages 585-590
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSFundamental characteristics of interfacial turbulence in gas-liquid mass transfer were studied by desorbing six surface tension-lowering solutes from aqueous solution in a liquid jet column and a wetted wall column, and monitoring the liquid-phase mass transfer coefficient by simultaneous transfer of oxygen as a tracer component.
A general correlation of the enhancement factor R vs. the Marangoni number is obtained as R= (Ma/Mac) n. Where n is revealed to have a constant value of 0.4 ±0.1. A diagram is proposed to estimate the critical Marangoni number Mac.View full abstractDownload PDF (903K) -
Masashi Kuramae1980 Volume 6 Issue 6 Pages 591-596
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSThe phenomenon of unsaturated liquid flow in porous bodies as the granular bed is expressed by a network structure model of cubical packing and simulated by a computer. The mechanism of the unsaturated liquid flow and the apparent behavior of the coefficients used to describe the liquid flow phenomena were studied in general. It was found that this network structure model of the void of porous bodies could express the behavior of the moisture content dependency of the relative permeability and the moisture diffusion coefficient.View full abstractDownload PDF (899K) -
Masahiro Takahashi, Hiromu Ito, Hiroshi Takeuchi1980 Volume 6 Issue 6 Pages 597-601
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSThe rates of absorption of pure oxygen in alkaline aqueous solutions of hydroquinone and/ or p-quinone were measured at 298.15 K using a wetted wall column.
Experimental results were compared with the theory of gas absorption accompanied by an irreversible second-order chemical reaction. As a result, it was found that the second-order reaction rate constant is proportional to the square of hydroxyl ion concentration in the pH range of 9.6 to 10.75, being 12.1 m3/mol s at pH> 10.75.
In the case of alkaline hydroquinone solutions, the rate of O2-absorption becomes larger than the calculated values based on gas absorption with second-order reaction since p-quinone as the reaction product returns to the original hydroquinone according to the hydrolysis reaction. Also, the presence of hydrosulfite ion in the alkaline solutions containing quinone type compounds increases the absorption rate of oxygen.View full abstractDownload PDF (800K) -
Ken Toyokura, Akihide Sato, Makoto Uchiyama, Kenji Tawa1980 Volume 6 Issue 6 Pages 602-608
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSSecondary nucleation rates generated from fluidized seeds and their crystal growth rates were observed respectively in CuSO4 · 5H2O-H2O and MgSO4 · 7H2O-H2O systems. A fluidized bed crystallizer with sieved seeds was used as experimental apparatus, and the total number of secondary nuclei generated was observed by direct counting under a microscope.
Secondary nucleation rates and crystal growth rates are correlated as exponential function of supersaturation of solution, and the powers for secondary nucleation rates are 1.6 and 3.8 respectively in CuSO4 · 5H2O-H2O and MgSO4 · 7H2O-H2O systems. The power 1.6 in CuSO4 · 5H2O-H2O system is almost identical to that for crystal growth rate. On the other hand, in MgSO4 · 7H2O-H2O system the power 3.8 is different from that for crystal growth rate. The latter relation of powers is the same as in KA1 (SO4) 2·12H2O-H2O system previously studied.
The mechanisms of secondary nucleation in these three systems are discussed from the viewpoint of interfacial energy calculated by Nakai's Method.View full abstractDownload PDF (863K) -
Masao Kuroda, Akira Takei, Hiroshi Yukawa, Sachio Sugiyama1980 Volume 6 Issue 6 Pages 609-613
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSA study has been made to obtain basic information about the acid production and methane fermentation rates in mesophilic methane fermentation.
The rate of methane fermentation was measured by using acetic acid solution as a substrate, and the rate of acid production was measured by using livestock excreta as a substrate.Rate equations in each stage were obtained. When the pH of digestion liquor is held at pH = 78, no toxic effect of acid on methane fermentation is shown at an acetic acid concentration of 10, 000 ppm. The yield of gas was about 55%.View full abstractDownload PDF (741K) -
Yasuo Kato, Akira Ishimaru, Hidekazu Kadone, Shigeharu Morooka1980 Volume 6 Issue 6 Pages 614-620
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSAn experimental study was performed on gas holdup, bubble size, interfacial area, longitudinal dispersion coefficient of liquid and volumetric coefficient of mass transfer in a bubble column equipped with a simultaneous gas-liquid injection nozzle of 5.8 to 25 mm I. D. as a gas-liquid distributor.
The gas holdup increases with increasing gas and liquid flow rates. At the same flow rate, a smaller diameter nozzle gives a larger gas holdup. The volume-surface mean diameter of gas bubble decreases with increasing injected liquid velocity in the nozzle and increases a little with increasing gas velocity. An increase in liquid viscosity increases the gas holdup and reduces the mean bubble diameter. From the above, a new correlation equation of the interfacial area was obtained.
The longitudinal dispersion coefficient of liquid was measured as a function of gas velocity, liquid velocity and nozzle diameter.
The rate of oxygen absorption by aqueous sodium sulfite solution containing cupric ion as a catalyst and the rate of carbon dioxide absorption by deionized water were measured, and the volumetric coefficient of liquid-phase mass transfer was obtained. The liquid-phase mass transfer coefficient calculated from the interfacial area and the volumetric coefficient of liquid-phase mass transfer agreed well with previous experimental values in the literature.View full abstractDownload PDF (982K) -
Dependence of the degradation rate on type of degradation equipmentAtsushi Inaba, Hakuai Inoue1980 Volume 6 Issue 6 Pages 621-627
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSPolystyrene was degraded in three different types of apparatus at 31590°C.
The first-step degradation rate was measured by the quartz spring method in vacuum. This activation energy is 39.3 kcal/mol.
The degradation rate effected by the second degradation step was measured in a long tubular stirred vessel at atmospheric pressure. This rate is less than the first-step rate and its activation energy is 54.2 kcal/mol.
In the stirred vessel, which was the same type as industrial equipment, the first-step degradation rate was measured in vacuum and at high stirring speed. At atmospheric pressure and low-speed stirring, the rate effected by the second-step degradation was measured. Mass transfer of the degraded products is hardly affected by the difference in equipment type because the products are boiling in the polymer.
The degradation rate and products were considered to be closely related to the type of equipment and the operating conditions.View full abstractDownload PDF (921K) -
Ryuichi Aoki, Hiroshi Murata, Hiroshi Homma, Hideo Wada1980 Volume 6 Issue 6 Pages 628-634
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSExperimental study concerning plug-type pneumatic conveying of cohesive powder with spherical stoppers has been made using flour as material powder and table tennis balls as stoppers.
The experimental observations that friction stress τw, between plug and pipe wall decreased with decreasing plug length Hs and plug velocity Us led to experimental equations correlating H8, U8 and τw.
Stress ratio k, which characterizes the flow property of plug, is calculated based on theoretical consideration on the powder pressure in a moving bed and measured pressure difference across the plug.
From the data covering the whole range of possible steady flow, it is concluded that efficiency is highest where the plug length is as short as possible and the air speed is as close as possible to the critical conveying velocity.View full abstractDownload PDF (718K) -
Naoya Yoshioka, Yuji Yoshimura, Tsuyoshi Oishi1980 Volume 6 Issue 6 Pages 635-642
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSInitial filter coefficients, which express the collection efficiencies of non-spherical suspended particles in a clean deep-bed filter, could be estimated by trajectory calculations using volume equivalent diameter measured by Coulter Counter or Stokes' diameter as representative diameter of irregular kaolin particles. These calculated values were correlated with five dimensionless groups, i. e. modified adhesion group, modified gravity group, interception parameter, Kuwabara's flow model parameter and retardation group, and expressed exactly by graphical expressions under conditions where double-layer repulsion forces between suspended particles and filter media were negligible and the adhesion efficiency was 1.
However, these values could be estimated approximately by a semiempirical correlation equation under the usual filtration conditions.
The difference between trajectory calculations and experimental results could be explained to some extent with corrected trajectory calculations, obtained by taking into account the adhesive forces between suspended particles and filter media.View full abstractDownload PDF (1175K) -
Mompei Shirato, Toshiro Murase, Kunio Atsumi1980 Volume 6 Issue 6 Pages 643-650
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSThe filter press with membrane-compression mechanism has been employed in widely divergent fields of industry because of its high capability in deliquoring performance. In general, the operation can be divided into three stages of deliquoring processes, namely, the 1 st-step filtration period under relatively low filtration pressure, the 2nd-step filtration period and the consolidation period under high expression pressure.
For the given case of a fixed chamber thickness of the filter press, the optimum operating conditions for attaining maximum throughput are studied on the basis of filtration theory and the socalled Terzaghi consolidation theory (creep effects neglected). It is shown that the ratio of the filtration down-time θd to the expression time θeH defined in this paper has a great influence on the optimum operating conditions.
By using the experimental results of the two filtration curves and the expression results Ls vs. θeLs described in this paper, a graphical method for determining total deliquoring time θt, average feed rate of slurry Ls/ (θt+θd) and their optimum values is presented. The method is based upon experimental observations and theories, and may be applicable to industrial problems even when creep effects are appreciable.View full abstractDownload PDF (1028K) -
Katsuroku Takahashi, Fujio Ohtsubo, Hiroshi Takeuchi1980 Volume 6 Issue 6 Pages 651-656
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSDiameters of drops in an agitated vessel were measured for water drops dispersed in kerosene (W/O-emulsion) and W/O-emulsion drops dispersed in water ((W/O) /W-dispersion) in the presence of Span-80 as an emulsifying agent.
Drop size distributions for the W/O-emulsion were expressed by a logarithmic normal distribution. Sauter mean diameters for the W/O- and (W/O) /W-dispersions depend on the agitation speed, impeller diameter and emulsifying agent concentration. The concentration dependence corresponds to the variation of interfacial tension obtained under dynamic conditions. Water drops dispersed in oil scarcely coalesced when the emulsifying agent was added. As the result, the drop size distribution did not vary with the dispersed-phase holdup fraction, and the effect of Weber number on drop diameter was larger than that reported for system without emulsifying agent.View full abstractDownload PDF (2313K) -
Yuji Yoshimura, Kenichi Fukumura, Naoya Yoshioka, Shuji Sakohara, Haji ...1980 Volume 6 Issue 6 Pages 657-665
Published: November 10, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSDownload PDF (1426K)
- |<
- <
- 1
- >
- >|