KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 16 , Issue 1
Showing 1-31 articles out of 31 articles from the selected issue
  • Tohru Imanara, Nobuyuki Shishido, Tomohiko Kikkawa, Yoshiteru Yahiro, ...
    1990 Volume 16 Issue 1 Pages 1-8
    Published: January 10, 1990
    Released: February 19, 2010
    JOURNALS FREE ACCESS
    A dual-layer dynamic membrane was successfully developed and employed in dewatering aqueous gelatin solutions.
    The membrane was formed by flowing suspended solutions of alumina sol and colloidal silica on a porous ceramic tube. The silica layer was treated with buffer solution of pH 2 to 3, and was fixed by flowing either hot water or gelatin solution. This membrane rejected more than 90 % of polyethylene glycol, the molecular weight of which was about 1500.
    The optimum gelatin concentrating conditions were found to be : pressure, 2-3 MPa; mean flow velocity, 0.6-1.0 m/s; temperature, 60°C. Under these conditions this membrane was able to reject 99.5% of the gelatin with high water flux. Low-molecular weight components including inorganic salts in the feed were partly removed from the gelatin solution in this operation.
    Download PDF (1148K)
  • Tohru Imanara, Nobuyuki Shishido, Tomohiko Kikkawa, Tetsuya Hirota
    1990 Volume 16 Issue 1 Pages 9-15
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Characteristics of batch and continuous dynamic membrane dewatering processes were studied from a process designer's point of view. Gelatin concentration experiments on both botch and continuous processes were done with dual-layer dynamic membranes developed by the authors. The membrane itself was made from alumina sol and collodal silica.
    Process simulations were carried out, using basic data obtained from a singlemodule experiment. Calculated values of flux, rejection and pressure head loss showed good agreement with experimental results from a complex system composed of modules arranged in series.
    Download PDF (1155K)
  • Kenji Kawasaki, Akira Matsuda, Tetsuo Ide, Toshiro Murase
    1990 Volume 16 Issue 1 Pages 16-22
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Solid-Liquid Separation;Sedimentation;Freezing/Thawing;Activated Sludge;Settling Velocity;Floc DensityThe waste activated sludge produced at wastewater treatment plants is very difficult to filter, but its solid-liquid separation characteristics can be improved by freezing and thawing treatment. In this study the settling rates of three kinds of activated sludge suspensions (unfrozen, fast-frozen and slow-frozen sludges) was investigated and the settling rate of a representative single floc (V0) and the volume fraction of dry solid in a representative floc (Φkz) were estimated on the basis of Richardson and Zaki's equation. From the values of V0 and Φkz, it was found quantitatively that freezing and thawing sludges had better characteristics of gravitational settling and higher density of floc than unfrozen sludge. The solids concentration of the sediment of the slow frozen sludge was largest.
    Download PDF (1000K)
  • Masataka Mizutani, Masaki Minemoto, Masashi Hirao
    1990 Volume 16 Issue 1 Pages 23-30
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In the recovery plant for solvent containing cyclohexanone (hereafter called as “anone”), there is a great possibility of heating and further ignition of the activated carbon bed due to the higher reactivity of anone and the catalytic effect of the activated carbon. Some basic experiments were carried out and the possibility of ignition of activated carbon beds and the methods of preventing it were studied. It was found that ignition of activated carbon was caused by the heat of oxidation of anone to CO or CO2. Further, reaction rate constants and activation eneries of the reaction were obtained for several carbons. Effective methods of preventing ignition of activated carbon were conduded to be as follows.
    (1) Use of activated carbon of low catalytic effect having larger micropore volume, developed for anone recovery.
    (2) Sufficient desorption of anone from the carbon bed and replacement of the air in the adsorption bed with an inert gas such as nitrogen during plant shutdown.
    (3) AvoidaRce of temperature distribution and of distribution of residual anone in the adsorption bed.
    Download PDF (1176K)
  • Kunihisa Osasa, Masao Sambuichi, Hideo Nakakura, Tomomichi Nakamura
    1990 Volume 16 Issue 1 Pages 31-37
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Selective flocculation tests were conducted on ultrafine coals using heavy oil as flocculant for the purpose of making deashed coal-water slurry. In this technique, a coal-water slurry was conditioned with sodium tripolyphosphate as a dispersant. Carbonaceus matter was flocculated selectively and floated with microbubbles generated at high shear rate. Flocculated concentrate was washed with water to release the ash entrapped. In these studies the parameters of conditioning time were shear rate, dispersant dosage, oil dosage, washing condition and particle-size distribution of coal. The results showed that substantial reductions in final ash content required de-entrapment of ash from the flocculated concentrate by agitation. Under optimum conditions, clean coal products containing less than 1.5% ash were obtained for three kinds of bituminous coal at a coal recovery rate greater than 98%, by grinding to approximately 95wt%-30μm.
    Download PDF (3792K)
  • Yasuo Suzuki, Masanori Konno, Kunio Arai, Shozaburo Saito
    1990 Volume 16 Issue 1 Pages 38-45
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Urea adduct separation methods usually require several urea precipitation steps along with filtration, washing, and recovery of fractions enriched in polyunsaturated fatty acids. These complicated operations can be simplified by using supercriticalfluid as a solvent.
    In the present work a series of the formation and decomposition reactions of urea adduct were performed, using supercritical CO2 gas as solvent and their applicability to an industrial process was examined.
    Experimental results showed that urea adduct formation could not attain thermodynamic equilibrium and that final conversion of urea to the urea adduct was affected by several kinetic factors such as the existence of an activator like methanol and the amount of solid urea. Although an agitation vessel and a packed bed were employed as reactors, the conversion of adduct formation was almost independent of contacting method.
    Download PDF (1566K)
  • Toshiyuki Kobashi, Teruo Takahashi, Yoshiro Kitamura
    1990 Volume 16 Issue 1 Pages 46-50
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The heat transfer in a jacketed vessel with a newly developed perforated screw mixer was experimentally studied. This mixer was developed for efficient mixing of liquids in a wide range of viscosities. The heat transfer coefficient was measured under unsteady conditions. The coefficients for the perforated screw mixer were found to be equivalent with those for the helical screw with a draft tube. The heat transfer coefficient are correlated by an empirical equation in a range of Reynolds number from 10 to 2×105.
    Download PDF (726K)
  • Yoshitomo Hanakuma, Takashi Sasaki, Eiji Nakanishi
    1990 Volume 16 Issue 1 Pages 51-55
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The conventional PID method is said to be inadequate for the temperature control of batchwise polymerizations with rapid heat generation of reaction at temperatures somewhat higher than the initiation temperature of the reaction. Overshooting phenomena of reaction temperature can be practically avodied by a forced switching of heating to cooling at the so-called turning-point temperature, which is set according to past experience of operation. It is troublesome to determine the turning point by trial and error for every case where polymerization reactor conditions change dynamically or with time.
    We have developed a new iterative control system in which a hypothetical reference pattern to the above reactor's jacket temperature is determined automatically from the viewpoint of system similarity. The new system enables us to approximate batchwise polymerization reactor dynamics by the ARX model, using observed data at the first trial operation, and also to set a hypothetical reference pattern for the subsequent operation. The hypothtical reference pattern can be adjusted by iterative use of the error -modifying function.
    This new control system was applied to the batchwise exothermic reaction of PPS to confirm the design philosophy. It indicates that the new system is usable for the temperature control of large -scale polymerization reactors.
    Download PDF (743K)
  • Yoshinori Itaya, Kazuhito Miyoshi, Shu Maeda, Masanobu Hasatani
    1990 Volume 16 Issue 1 Pages 56-63
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The paper presents the experimental results of the formation of a flame in premixed methane/air formed on the surface of a porous ceramic plate. The plate surface was heated to high temperature by the flame, and then the high radiative heat flux from its surface could be emitted. Various apparent shapes of the flame according to the shape of the plate were also observed.
    The methane-air mixture passing through the porous ceramic plate was ignited on the upper side. From the temperature and the component concentration profiles measured under open-flame conditions, it was concluded that when the superficial velocity of the gas was lower than the combustion velocity of the premixed laminar flame, a reaction zone of combustion was formed at a position in the close vicinity of the surface where the gas velocity was balanced with the combustion velocity reduced by interactions between the gas and the solid surface. The surface temperature of the ceramic plate was higher than 900K equivalence ratios between 1.0 and 1.8. A peak surface temperature was observed at a certain heat load, and it was shown that smaller pore diameter, smaller thickness or higher effective thermal conductivity of the ceramic plate decreased the surface temperature. Flashback was not generated under the experimental conditions carried out.
    Download PDF (1520K)
  • Tsugio Tenda, Masaharu Takao, Satoru Komori, Yasuhiro Murakami
    1990 Volume 16 Issue 1 Pages 64-68
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Mixing time and final mixedness of particles in a horizontal gas-solid agitated vessel with paddle-blades on double parallel axes were investigated. Mixing times in the axial and tangential directions were well correlated with the Froude number and the clearance between blade tip and vessel bottom under equal or different particle-density conditions. Final mixedness was in good agreement with statistical prediction, suggesting that the particles are not segregated in the vessel. Further, the optimum operating condition and its scale-up expression were determined by defining the mixing energy as the product of mixing time and power consumption.
    Download PDF (754K)
  • Hideaki Asai, Satoru Kato, Kunio Nagahama
    1990 Volume 16 Issue 1 Pages 69-75
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Sorption-diffusion model was used to study permeation rates of water and ethanol using Nafion membrane.
    The ratio of bulk flow to permeation flux was quite large when the permeation flux of a key permeate was much lower than that of the other permeate, which means that bulk flows are not always negligible.
    Diffusion equations were expressed with the concentration gradient of the key permeate alone, and a concentration-dependent diffusion coefficient which includes a parameter was used. The one-parameter equation excellently correlated measured permeation rates.
    Download PDF (1020K)
  • Yoshinori Kutsuwa, Hisayoshi Matsuyama
    1990 Volume 16 Issue 1 Pages 76-82
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In the fault diagnosis of a batch process utilizing the pattern-recognition technique, the region of abnormal patterns corresponding to each causal event is defined by analyzing the accumulated operation data and the origin of failure currently faced is identified by matching the pattern observed in the process with the region. Modification of the region by the use of new data (learning) plays an important role in this method for fault diagnosis. Enlargement of the region makes it possible to prevent the wrong diagnosis, but causes the detection of plural candidates for the origin of failure. In the present paper, a definition of the region and a method for the learning are proposed to reduce the number of detected candidates by use of the degree of distinguishability from the abnormal patterns due to the different causal events. Experimental results confirmed that the repetition of learning can reduce not only the frequency of wrong diagnosis but also the number of candidates.
    Download PDF (1211K)
  • Masahiro Ohshima, Iori Hashimoto, Hiromu Ohno
    1990 Volume 16 Issue 1 Pages 83-91
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The stabilty of Model Predictive Control (MPC) for the SISO system is analyzed without restricting the function of MPC to one-step prediction. Some stability theorems are newly derived. They assure that a stable MPC system is easily realized simply by tuning a couple of control parameters even if large plant-model mismatch exists. A guideline for the tuning control parameters is also proposed.
    Download PDF (1563K)
  • Masahiro Nishio, Seiichiro Kaguei, Noriaki Wakao
    1990 Volume 16 Issue 1 Pages 92-98
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Nitrogen gas was introduced as a shot tracer into a column far below a bed of finely ground molecular sieve 5A particles fluidized with helium gas. Inlet and response nitrogen concentration-time curves measured respectively below and above the fluidized bed were found to have considerable noise. Using smoothed input and response curves obtained by eliminating the noise, values of gas mixing coefficient and adsorption equilibrium constant were estimated in the range up to the nearincipient fluidization stage.
    Download PDF (874K)
  • Masaki Minemoto, Naoyuki Kamishima, Shigekazu Hatano, Yoshihiro Kita, ...
    1990 Volume 16 Issue 1 Pages 99-107
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Within the closed system of a manned space station or other such environments, it is necessary to establish a life support system which removes CO2 produced by metabolism and produces O2. As a step in that direction, we have performed numerical simulations of CO2 adsorption and desorption based on the basic data such as adsorption equilibria and overall mass transfer coefficients.
    These data were previously determined with respect to a system of CO2 removal and concentration using solid amine.
    We then selected the optimum operating conditions by examining the influence of each parameter on CO2 recovery performance.
    The results indicate that the optimum operating conditions for recovery of CO2 produced by two persons are an adsorption column size of 0.24 m inner diameter and 0.20 m height and a desorption steam rate of 0.4kg·h-1, under a desorption pressure of 0.1 MPa.
    In addition, it has become clear that when the closed system of a manned space station is operated under such conditions, the specified performance can be sufficiently maintained even if adsorption gas temperature and humidity vary within the supposed conditions.
    Download PDF (1402K)
  • Yoshitaka Nishino, Toshio Sawa, Katsuya Ebara, Sankichi Takahashi, His ...
    1990 Volume 16 Issue 1 Pages 108-115
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The formation rates of NiFe2O4 which is the major product of reaction between nickel ion and corrosion products contained in the cooling water of boiling water reactors were studied according to a presented reaction model. Two kinds of amorphousiron (III) hydroxides and γ-FeOOH were used as simulated particles of corrosion products in the experiments. The amount of NiFe2O4 generated was measured in situ by a modified magnetic balance, utilizing its magnetic property. The presented model shows that diffusion of nickel ion into particles and dehydration of iron (M) hydroxide should occur simultaneously to form NiFe2O4. A mathematical formula of NiFe2O4conversion can be expressed as the product of the fraction permeated by nickel and the dehydration conversion calculated by Avrami's equation. The fraction permeated by nickel is calculated by a diffusion equation, assuming spherical particles. Based on the relationship of the diffusion coefficient of nickel ion to temperature, the apparent activation energy of γ-FeOOH is 1.24 × 105 J/mol, which is the highest of the three iron (III) hydroxides. The calculated values of NiFe2O3conversion by the presented model are in accord with variations of experimental values with time, and the model can estimate the final NiFe2O3 conversion within ± 10 % error.
    Download PDF (1204K)
  • Hiroshi Takahashi, Osamu Ohno, Takao Takeuchi
    1990 Volume 16 Issue 1 Pages 116-122
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The behaviour of gas in a solid-gas cross flow moving bed was studied by simulating the velocity distribution, streamline and distribution of static pressure by the finite element method. The flow channel of the gas expanded in the cross flow section of the moving bed where vertical descending particles contact the horizontal flowing gas. Part of the gas flowed out through top and bottom of the moving bed according to the pressure gradient when the top and bottom were not sealed. A method of predicting the amount of gas flowing through the bed was proposed. The analysis indicated that the vertical component of gas velocity at the gas-inlet-side upper corner of the cross flow section, uyc, was maximum. Theoretical characteristics of the gas streamline agreed with those estimated from the measured isobars of static pressure. As gas flow rate increased, a cavity was formed within the particles in contact with the wall (wired acreen) at the gas inlet. The study revealed that when the velocity uycincreased to the minimum fluidizing velocity of the particles bed, wall friction of particles disappeared locally and cavitation occurred.
    Download PDF (1321K)
  • Fumihide Shiraishi
    1990 Volume 16 Issue 1 Pages 123-129
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Expressions for apparent kinetic parameters V appm ane K appmobserved in immobilized enzyme reactions with diffusional and electrostatic effects are proposed on the basis of the equation of a tangent to the curve of a Sb/υ versus Sb plot. The validity of these expressions is shown by comparing the expression for K appm with two approximate expressions proposed by other workers for the reaction catalyzed by an enzyme immobilized on the external surface of a nonporous support. Calculation showed that the effect of substrate concentration on V appm and K appm is basically different for systems where an enzyme is immobilized on the external and pore surfaces respectively of supports.
    Download PDF (1168K)
  • Mitsuyuki Nakajima, Daisuke Hirota, Koichi Nakamura, Ryohei Yamazaki, ...
    1990 Volume 16 Issue 1 Pages 130-136
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The effect of internals on bubble behavior in a gas-solid fluidized bed with ringshaped baffles was examined experimentally by changing location, number and size of baffles as parameters.
    It was found that ring-shaped baffles in the vicinity of column wall, where there were very few bubbles, had a prominent effect on bubble behavior, flattened the radial distribution of bubbles and made the mean bubble size smaller.
    To elucidate the mechanism of this change in bubble behavior caused by the baffles, particle flow in a transparent semicylindrical fluidized bed was observed. It was confirmed that ring-shaped baffles changed the downflow of particles, which then influenced the bubble behavior.
    Download PDF (1233K)
  • Katsumi Honda, Yoshiki Kawasaki, Tsuyoshi Munakata
    1990 Volume 16 Issue 1 Pages 137-144
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In our previous work a theoretical analysis of the partial condenser for binary vapor mixture was proposed, based on the two-film theory.
    In the present work, experimental measurements of the separation performance of the wetted-wall type partial condenser were carried out in the laminar and turbulent vapor flow regime under counter- and co-current contacting conditions.
    The observed enrichment of the more volatile component in the vapor phase is affected by the manner of contact and the inlet vapor flow rate, and is rather different from the results of calculation of the differential condensation, i.e. Rayleigh correlation. The observed data agree well with the calculated values from the analysis in the previous work using the estimated local mass transfer coefficients. It is concluded that the liquid-phase mass transfer resistance is negligibly small compared with the vapor-phase value.
    Download PDF (1241K)
  • Yasutoshi Shimizu, Minoru Rokudai, Sachio Tohya, Eisuke Kayawake, Tets ...
    1990 Volume 16 Issue 1 Pages 145-151
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To investigate the influence of membrane properties on filtration flux for methanogenic waste, filtration examinations employing tubular alumina membranes having controlled membrane resistances Rm, pore sizes and surface charges were carried out.
    The filtration flux for methanogenic waste through Rm-controlled membranes showed the same value except for the 0.01 μm pore membrane, which had the maximum Rm in the examination. It was also found that the limiting flux value was not affected by filtration pressure. These findings were explained by the gel layer model.
    Membrane pore size and surface charge affected filtration flux. It was assumed that membrane properties affected hydraulic resistance Rp, which was attributed to adsorption and plugging of particles to membrane, to induce the reduction of filtration flux. This influence was explained by the gel layer model. Taking into account the fact thatRp was formed in the starting period of filtration, permeability of the membrane was restricted not only by Rm but also by Rp. Therefore, it can be assumed that flux diminished form the limiting flux value when (Rm+Rp) became bigger than the filtration resistance RL, which was calculated by the limiting flux value.
    Download PDF (2762K)
  • Haruo Yamazaki, Toshiro Murase, Masashi Iwata, Mompei Shirato
    1990 Volume 16 Issue 1 Pages 152-159
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A high flux rate of dynamic filtration is attained by producing, in a filter chamber, a liquid velocity high enough for sweeping a filter cake from the medium completely. Measurements were made of the tangential velocity distributions as sociated with a rotating ungrooved disk enclosed in a chamber without permeation. Also, the relationships between the flow of power-law liquid and the frictional resistance of the rotor were experimentally studied.
    The velocity distribution of the liquid in the axial gap between the rotor and the fixed plate was broken down into three regions : the core and two boundary layers. The increase in the velocity profile consequent to a change in the rotational speed of the rotor, the dimensions of the chamber and the physical properties of the liquid were evaluated in terms of the center-to-disk ratio K of tangential velocity. The K-value was empirically determined from calculations based on a newly defined operational factor, thus providing a method for estimating the velocity of the liquid and the torque of the rotor in the filter. It was demonstrated that liquid motion in the closed chamber occurs in any of three types of flow according to the operational factor.
    Download PDF (1156K)
  • Yukio Nakanishi, Masao Kobari
    1990 Volume 16 Issue 1 Pages 160-167
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The rates of adsorption of ethanol vapor (the principle flavoring constituent) on tobacco materials with various water contents were studied.
    The rates correlated well with those predicted by the internal diffusion control model. The effective diffusivities of ethanol were obtained by comparing the experimental values with the theoretical sorption curve. It was shown that the effective diffusivities at constant water content can be determined by the corrected diffusivity and the adsorption equilibrium relation. In addition, the possibility of a flavoring method dependent solely on adsorption was investigated. The results suggested that flavor can be distributed more homogeneously through tobacco by using this method rather than by spraying.
    Download PDF (1173K)
  • Makoto Tanaka, Fumitake Chisaka
    1990 Volume 16 Issue 1 Pages 168-173
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    An equation was derived for predicting the effective thermal conductivity of a discontinuous solid system in a wide range of void fraction. Comparison with the experimental data indicated that the equation is satisfactory for granular beds, stacked wire nets and stacked cloth.
    It was found that an equation which exchanged the solid and void thermal conductivity of the above-mentioned equation could describe the effective thermal conductivity of continuous solid systems.
    Download PDF (1000K)
  • Tohru Imanara, Nobuyuki Shishido, Tomohiko Kikkawa, Tetsuya Hirota, Te ...
    1990 Volume 16 Issue 1 Pages 174-177
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Practical methods of washing and removing the dynamic ultrafiltration membrane developed by the authors were experimentally studied. The membrane itself was of dual-layer type, made from alumina sol and colloidal silica. The material of the membrane support was porous ceramics made of sintered alumina and silica.
    The membrane, after its use in concentrating aqueous gelatin solutions, was successfully washed by passing hot water through it without appreciable deterioration in its separation ability. Then, by passing an aqueous hydroxide solution through it, the membrane layer was dissolved and removed from the support. However, because of a small amount of silica eluted from the ceramic support by the hot water and the alkaline solution, the mechanical strength of the support was lowered.
    Download PDF (720K)
  • Toshiro Miyahara, Mitsuhiro Asada, Teruo Takahashi
    1990 Volume 16 Issue 1 Pages 177-180
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Experiments were conducted to study the pressure drop, liquid holdup and stable operating range in a sieve-plate column with plates having large free areas under gas-liquid cross flow conditions. The studies indicate that such plates are applicable to the high gas velocity range because of the low pressure drop. Stable operating ranges for the plates are roughly estimated by the equation of those for countercurrent-flow conditions previously reported by the authors. The dynamic energy balance of the two-phase dispersion on a sieve plate gives a theoretical treatment for determining the total pressure drop. Empirical correlations for the aeration factor and liquid holdup, which are necessary to estimate the pressure drop, were obtained.
    Download PDF (618K)
  • Hiromitsu Kojima, Kazuhisa Minagawa, Hitoshi Masuda, Tohru Ichikawa
    1990 Volume 16 Issue 1 Pages 180-184
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The critical rotating speed for a solid suspension in a gas-sparged stirred vessel with propeller-type impeller was studied experimentally, with attention to the effect of the impeller diameter, the distance between impeller and vessel bottom, and the gas-sparging rate.
    An empirical equation for the critical rotating speed in the three-phase stirred vessel was obtained by using the model proposed by Baldi et al. for the solid-liquid system.
    Download PDF (777K)
  • Hiroshi Takeuchi, Katsuroku Takahashi, Makoto Nakano
    1990 Volume 16 Issue 1 Pages 184-187
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Measurements were made on interfacial tension between aqueous and n-heptane solutions under conditions of Ni (II) -and Co (II) -extraction by two organophosphorous esters : di (2 -ethylhexyl) phosphoric acid (DE) and 2-ethylhexyl phosphonic acid mono2 -ethylhexyl ester (ME). For the systems of Ni-DE and Ni-ME, the interfacial tension during the extraction, γ, fell with increasing metal loading in the organic phase, unlike the Co-ME system. In addition, the γ -values were smaller than interfacial tensions obtained under no-reaction condition, the difference between the two being large in the lower region of metal loading. On the other hand, no significant change in interfacial tension during back-extraction was observed for any of the systems. This suggests that the reactions for the back-extraction proceed at a fast rate in comparison with the forward extraction.
    Download PDF (693K)
  • Tsugio Tenda, Satoru Komori, Yasuhiro Murakami
    1990 Volume 16 Issue 1 Pages 187-189
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Power consumption in a horizontal gas-solid agitated vessel with paddle-blades on double parallel axes was investigated. Experiments were performed for cohesive particles. In this study, a dimensionless parameter defined as the cohesion force divided by the inertial force was introduced to correlate the power consumption. The results show that the dimensionless averaged power consumption is well correlated with the Froude number, the dimensionless height of charged particles and the dimensionless cohesion parameter. Further, it was found that the ratio of maximum torque to averaged torque is given by the same correlation as for cohesionless particles.
    Download PDF (414K)
  • Hideo Tsuruga, Hiroshi Imai, Kazuo Endoh
    1990 Volume 16 Issue 1 Pages 189-193
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Measurements were made on torque exerted by sinusoidaly oscillating blades in an oscillatory mixer in the range of amplitude from π / 12 to π radian. Obtained data were evaluated by fitting an equation that considers the inertial force exerted by the added mass of impellers and the resistance force of fluid. Drag coefficient and added mass coefficient were defined as the average of the coefficient of each term over one cycle of oscillation.
    The relation between drag coefficient and Reynolds number was similar to that for the power number of impellers in stationary mixing. The drag coefficients gradually decreased with increasing amplitude of oscillation and showed almost constant value over the range of amplitude greater than π/ 2.
    Maximum torque of the oscillatory mixer was well estimated by taking into account only the drag coefficient over the range of amplitude greater than π / 2.
    Download PDF (641K)
  • Kenji Hashimoto, Yoshihito Shirai, Mitsugu Morishita, Shuji Adachi
    1990 Volume 16 Issue 1 Pages 193-196
    Published: January 10, 1990
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A simulated moving-bed adsorber is constructed with several adsorption columns, which are usually arranged into four zones to carry out their inherent functions. Some models have been proposed to calculate the concentration profiles of adsorbates in the adsorber, but they are not always useful in designing adsorbers. A simplified method is proposed to determine the length of columns, their arrangement into four zones and the operating conditions of the adsorber, in the case where the adsorption isotherms of two components are linear and independent of each other.
    Download PDF (614K)
feedback
Top