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Takashi Kato, Shigekatsu Mori, Iwao Muchi
1976 Volume 2 Issue 2 Pages
109-114
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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Many pressure-wave signals were superimposed on the main gas streams at an entrance plenum of a fluidized bed, and an isolated bubble was injected into the bed through a single nozzle. Pressure fluctuations of fluidized beds were examined by the use of transmission function methods.
A rising gas bubble causes complicated pressure waves in the bed. All components of transient pressure waveforms were detected with the aid of a piezo-elastic pressure transducer and an improved bridgecircuit instrument.
The results indicate that there exist three kinds of characteristic pressure waves in the bed and that these waves are closely related to the properties of solid particles and to operating conditions.
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Takashi Kato, Iwao Muchi
1976 Volume 2 Issue 2 Pages
115-120
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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To investigate the cause of the generation of bubbles at the bottom of a fluidized bed, the spontaneous oscillation of gas flow in the bed was studied theoretically.
Attention was focused on the characteristic that the relationship between the pressure drop caused by the bed and the flow rate of gas fed into the bed could be described by a curve approaching the level of saturation non-linearly. This characteristic has been taken into account in an equivalent circuit expressing the bed hydraulic behavior as well as the resistance to gas flowing through a distributor and working characteristics of blowers. A dynamic model has been developed further to predict the transient behavior of the fluidized bed system, and the stability of trajectory in the region around the singular point was investigated with the aid of the model.
Numerical results computed by the model show that the relation between pressure and gas flow rate can be expressed by a limit cycle and, in other words, that spontaneous oscillation takes place in the bed.
It may be concluded that the oscillatory motion of the bed definitely affects the formation of bubbles.
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Nobuetsu Yutani, Naoshi Ototake
1976 Volume 2 Issue 2 Pages
121-126
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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In this work, basic studies were carried out of the behavior of liquid-solid fluidized beds and, especially, stress was on laid on the effect of fluid velocity on the rate of solids entrainment from fluidized beds.
As an initial step in developing a more complete understanding of the mechanism of solid entrainment, the behavior of solid particles in beds is analyzed theoretically by means of the stochastic method on the bases of exponential probability function with fluid velocity.
On the results of experimental results and of theoretical considerations obtained in this work, a correlation between solids entrainment from the dense phase in beds and physical properties of particles is given, and experimental values are in satisfactory agreement with the calculated curve.
This approach is considered as an effective method for analysis of the motion of particles in fluidized beds.
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Ikuho Yamada, Setsuro Hiraoka, Masanori Inutsuka, Hideo Yoshizane, Kaz ...
1976 Volume 2 Issue 2 Pages
127-132
Published: February 10, 1976
Released on J-STAGE: February 12, 2010
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The thickness of liquid film and the transition of liquid film to ligament formation were measured by use of the optical method for three types of rotating conical surface.
a) For the thickness of liquid film δ, the relationship between the experimental value and the approximated theoretical solution has been summarized by i) ε≡δ
exp./δ
theo.=1 at
Re<15
ii) 1> ε>0.75 at 15 <
Re<50
iii) ε≅ 0.75 at
Re >50
where
Re is based on the volumetric flow rate.
b) For the transition of liquid film to ligament formation, the splitting position of liquid film observed by use of the stroboscope has been well-correlated by the equation
Q+We4/5Reω-1/2=0.237
where
Q+ denotes the dimensionless volumetric flow rate and
Reω is based on the angular velocity. Furthermore, no effect of the vertical angle on either a) and b) is observed in this work.
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Yasuo Hatate, Shoji Mori, Shigeru Okuma, Yasuo Kato
1976 Volume 2 Issue 2 Pages
133-137
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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Drop size was measured in gas- liquid- liquid system bubble columns, 6.6 cm and 12.2 cm in diameter, in which several kinds of organic liquids were used as dispersed phase. The sauter mean diameter of droplets in the bubble column,
dp [cm], is mainly dependent on column diameter,
DT [cm], superficial gas velocity,
uG [cm/sec], interfacial tension, σ [dyne/cm] and the mean concentration of droplets,
C [-]. However, in the range of
C >0.1,
dp is little affected by
C and can be correlated as the following equations.
In batch operation,
dp/
DT=15 (
uG2/
gDT) (
DTuG2ρ/σ)
-1.3where g [cm/sec
2] is gravitational acceleration.
In continuous operation,
dp= 2.8×10
-3·
uG-0.55 σ
1.3 (at
DT= 6.6cm)
dp= 1.2×10
-3·
uG-0.55 σ,
1.3 (at
uG-0.55 σ< 60 and
DT= 12. 2cm)
dp= 2.2×10
-5·
uG-1.1 σ
2.6 (atuG- 0.55σ >5 and
DT= 12.2cm)
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Constant gas flow condition
Teruo Takahashi, Toshiro Miyahara
1976 Volume 2 Issue 2 Pages
138-143
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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Much work has been done on the bubble volume formed at submerged single nozzles. Some of these studies concerned theoretical analysis under constant gas flow condition, that is, infinitesimal chamber volume. These results, however, agree with the experimental results only in a limited range of gas flow rate.
In the present work, it was observed experimentally that the constant gas flow condition was attained either by making the chamber number given by Tadaki
et al. less than unity or the nozzle length long enough to be compared with the nozzle diameter. Furthermore, when the two-stage model presented by Ramakrishnan
et al., was modified in the groups of surface tension and drag force, it was found that the theoretical results agree well with experimental values.
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Isamu Yabe, Daizo Kunii
1976 Volume 2 Issue 2 Pages
144-149
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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Both velocity distributions around a distorted spherical-cap bubble and pathlines separated from the edge of the bubble were measured by use of the flow-visualization method. A camera which moves simultaneously with the bubble motion being used, trajectories of fine tracer bubbles were photographed. The bubbles observed in our experiment were always accompanied by a fully developed toroidal vortex.
Experimental results were compared with velocity distributions calculated by use of conventional models, namely the potential flow model and the Parlange model. Significant discrepancies were shown in the vicinities of both the bubble's front and separated pathlines.
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Saburo Yashima, Fumio Saito, Tetsuro Mikuni
1976 Volume 2 Issue 2 Pages
150-153
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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Single spherical specimens made of 7 kinds of glassy materials and minerals having diameter of 2.0 cm were crushed under three environmental conditions of vacuum, air and water. A summary of experimental results is as follows : 1) sphere compressive strength, fracture energy, fracture surface energy and new surface produced decrease in the order, vacuum crushing, dry crushing, wet crushing; 2) the size of fractured products becomes coarser in the order, vacuum crushing, dry crushing, wet crushing; 3) assuming that fracture surface energy means crushing resistance, the crushing resistance decreases in the order, vacuum crushing, dry crushing, wet crushing.
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Yasuo Tamaki, Eiji Harada, Shiro Ito
1976 Volume 2 Issue 2 Pages
154-159
Published: February 10, 1976
Released on J-STAGE: February 12, 2010
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Effects of some geometric parameters on the interfacial area of horizontal shaft agitating gas-liquid contactor have been studied experimentally, and the relationship between the interfacial area and power dissipated is discussed.
Increment of the interfacial area, (α-α
0) is proportional to the width of impeller blade and to the number of turbines, where a is specific interfacial area and α
0 is specific interfacial area at rest.
Increment of the interfacial area may be expressed by
(α-α
0)
Di∝ Δ
Pv1.20 (
Fr <3× 10
-2)
(α-α
0)
Di∝ (
Pv·
We)
0.30 (
Fr > 3× 10
-2)
where
Di is impeller diameter, Δ
Pv is the power dissipated per unit volume of liquid which is due to the deformation of liquid surface,
Pv is power dissipated per unit volume of liquid and
We is Weber number.
Variations of the increment of interfacial area with these geometric factors are shown in figures, which should be useful for scaling-up of the contactor.
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Kazumi Sato, Ichiro Inoue
1976 Volume 2 Issue 2 Pages
160-164
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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Power consumption of a six flat-blade turbine in rectangular vessels with ratio of side lengths
A/B from 1.0 to 2.0 was measured for various locations of an impeller in the range of full turbulence.
Power numbers were in the range of 3.06.0 for an impeller one-third the length of the short side of the vessel.
In vessels of small
A/B, power numbers showed the minimum for the central location and increased gradually with distance from the central location.
In vessels of large
A/B, power numbers decreased for placing an impeller in a certain limited region apart from the center of the vessel. It was observed that this decrease of power number was closely related to the properties of the secondary circulation flow.
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Ryuzo Ito, Yushi Hirata, Toshio Shibata, Naofumi Akitomo
1976 Volume 2 Issue 2 Pages
165-170
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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Interfacial behavior has been studied experimentally in a wide range of operational conditions of circular air jets which impinge upon a liquid surface to mix the liquid and to promote mass transfer through the liquid surface.
A balance of the kinetic energy of the free jet and the potential energy of the liquid surface is applied to correlating maximum depth, diameter and shape of cavity with manipulating variables for the laminar impinging jet. But for the turbulent jet the energy balance is not applicable to the estimation of cavity diameter and shape except of maximum depth. The shape is approximated by part of a sine curve and the diameter is estimated from the momentum balance of impinging jet and displaced liquid. The critical jet momentum for splashing liquid has also been correlated experimentally with modified
We number (ρ
ggH2/σ
l).
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Kiyotaka Sakai
1976 Volume 2 Issue 2 Pages
171-175
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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New modified Karlovitz numbers
KM,
KM, from which the combustible flow rate at the blow-off limit was calculated, were obtained by eliminating the approximation in the
KM theory. Comparing these
KM,
KM with the experimental blow-off data of hydrocarbon flames,
KM of these new Karlovitz numbers was found to be of use. Assuming that the main chain carrier in the combustion reaction was O-atoms, blow-off limits of hydrogen flames were also calculated from this new modified Karlovitz number
KM.
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Hiroyasu Seko, Setsuji Tone, Tsutao Otake, Toshio Shibata
1976 Volume 2 Issue 2 Pages
176-181
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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The regeneration of coked silica-alumina catalyst was investigated and the characteristics of fluidized bed such as bubble sizes, velocities and frequency were measured at high temperature. From these results, the reactor performance is evaluated by considering the variations of bubble size and velocity in axial direction, and a simplified method to predict reactor performance is proposed for the purpose of design and optimization of fluidized bed. It was confirmed that the method is usable to predict reactor performance over a wide range of operating conditions.
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Takuya Honda, Atsushi Kanzawa
1976 Volume 2 Issue 2 Pages
182-187
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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Thermal equilibrium properties, e.g., viscosity, thermal conductivity and diffusion coefficient, of argon plasmas were calculated using simple and rigorous kinetic theories, and then a corrected simple kinetic theory was proposed. In this method, the properties are calculated by substituting the corrected collisional cross sections, which are evaluated by comparing the properties obtained by both theories, into the simple kinetic theory's equations.
It was found from these calculations that this method is not complicated and is in agreement with experimental values provided that atom-atom and atom-ion collisional cross sections are corrected. Furthermore, it was noticed from rigorous calculations that the ratio of ambipolar diffusion coefficient and ion diffusion coefficient is not two in the case of a high degree of ionization.
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Wataru Eguchi, Motonari Adachi, Ryuji Tsukada
1976 Volume 2 Issue 2 Pages
188-192
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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Overall partition equilibrium of carbon dioxide between air and aqueous sodium hydroxide solutions was measured at 1.01 atm and 298 K. The concentration of carbon dioxide in gas phase was between 1 and 0.01 mol %and the sodium concentration in liquid ranged from 0.2 to 0.01 mol/dm
3. The observed overall partition coefficients,
KD, lie closely on the extension of the data obtained by other investigators at higher carbon dioxide concentrations. It is found, however, that McCoy coefficients are not constant even when total sodium concentration in aqueous phase is constant, but they decrease gradually with decreasing concentration of carbon dioxide in gas phase.
The complicated dependency of partition equilibrium upon concentration is discussed by taking the elementary reactions into consideration. Further, the dissociate equilibrium constants of both sodium carbonate and bicarbonate are obtained from the observed overall partition coefficients.
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Hideto Sugie, Kazuyoshi Ono, Ikuho Yamada
1976 Volume 2 Issue 2 Pages
193-199
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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A method of calculating the critical locus curves of binary mixtures is proposed utilizing Sugie-Lu equation of state and the rigorous thermodynamic equations for the critical point of a binary mixture.
A completely analytical procedure with the aid of a digital computer was developed. The best values of binary interaction parameters arising from the combining rules used for the equation of state were obtained from experimental critical data by the direct-search optimization method of Williamson.
This method predicts critical pressures and temperatures quite precisely, and yields a much better prediction of critical volumes than that by methods of previous workers.
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Hisashi Miyashita, Kiyoshi Murokawa, Masuji Sugata
1976 Volume 2 Issue 2 Pages
200-204
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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The purpose of this paper is to study experimentally the improvement of heat transfer coefficients between fluid and wall surfaces by the use of turbulence promotors in the channel.
Glass rods of 3 mm, 5 mm, and 7 mm diameter were used as turbulence promotors, to cause an increase of turbulence in the bulk flow and the boundary layer. An alkaline solution was used as fluid.
Mass transfer coefficients were obtained by the use of an electrochemical reaction of the redox system, and heat transfer coefficients were obtained by means of the analogy between heat and mass transfer phenomena. The results with turbulence promotors were compared with those without them.
The increasing ratio of average and local transfer coefficients,
Nu/
Nuo and
Nux/
Nuxo, were correlated with the diameter and pitch of the promotor, Reynolds number and distance downstream from the promotor.
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Toshio Yasutomi, Sadaharu Yokota
1976 Volume 2 Issue 2 Pages
205-211
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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A model is proposed for the mechanism of heat transfer from the surface of a body fixed in a fluidized bed.
The emulsion phase is assumed to be a composite solid consisting of two layers. First layer contacts the surface and its void fraction is higher on account of wall effect, while its thickness approximately equals the radius of the fluidized particle. Second layer with the void fraction at minimum fluidization follows the first layer and its thickness is infinity. Equation for the heat transfer coefficient is drived on unsteady conduction from the surface at constant temperature to the solids. Correlation of the equation with some equations proposed previously is shown. The coefficients by these models are compared by use of the contact time calculated from the theoretical equation and heat transfer data in this work.
Under the same conditions as in heat transfer experiments, the frequency and ratio of contact time to total time of bubbles rising along the body were measured to estimate the contact time between the surface and an emulsion phase. In addition, the contact time calculated by solids circulation velocity in the bubbling-bed model is discussed.
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Yoshihiro Iida, Hiroshi Atsuura, Shigeru Mori, Akira Tanimoto, Masato ...
1976 Volume 2 Issue 2 Pages
212-216
Published: February 10, 1976
Released on J-STAGE: October 21, 2009
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1976 Volume 2 Issue 2 Pages
216a
Published: 1976
Released on J-STAGE: October 21, 2009
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1976 Volume 2 Issue 2 Pages
216b
Published: 1976
Released on J-STAGE: October 21, 2009
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1976 Volume 2 Issue 2 Pages
216c
Published: 1976
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1976 Volume 2 Issue 2 Pages
216d
Published: 1976
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