KAGAKU KOGAKU RONBUNSHU

Catalysis, Kinetics and Reactor Design

Design of an Algal Bioreactor and Control of the Gas-Liquid Interface Shape under Microgravity

Yuichi Ohira, Yoshikazu Kuga, Kiyoshi Idogawa, Takashi Fukuda, Koji An ...

Article type: Keynote Paper
Subject area: Catalysis, Kinetics and Reactor Design
2002 Volume 28 Issue 4 Pages 369-378
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.369

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Studies on methods of controlling air-liquid interface shape and bubble behavior were reviewed to clarify the designing problems involved in creating an algal bioreactor for use in a microgravity environment. In this work, the effects of vessel size, vessel rotating speed, liquid properties, vessel aspect ratio and the volume ratio of water/vessel on the formation of an air-liquid hollow profile were experimentally investigated to find conditions suitable for algal cultivation. The effects of a centrifugal acceleration and bubble diameter on the bubble breakage time in a low centrifugal force field were clarified by microgravity experiments. Experiments were performed using the energy of aeration to control the air-liquid interface shape and the formation of an air-water dispersion system under microgravity.

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Characteristics of Regeneration and H2S Removal During Desulfurization -Regeneration Cycles Using Honeycomb Type Iron Oxide Sorbent in Simulated Hot Coal Gas

Hiromi Shirai, Makoto Kobayashi, Makoto Nunokawa

Article type: Technical Research Paper
Subject area: Catalysis, Kinetics and Reactor Design
2002 Volume 28 Issue 4 Pages 379-385
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.379

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Honeycomb type iron oxide sorbent, which removes H2S and COS in hot coal gas, has been developed. The sorbent must be regenerable. In this paper, the regeneration characteristics and the characteristics of H2S removal during desulfurization-regeneration cycles are evaluated.
The sorbent was regenerated using 1.5% O₂ containing gas and it was found that over 570 K, more than 60% of sulfur absorbed during desulfurization is removed. Nevertheless it was also found that over 570 K, if SO₂ is introduced with the regeneration gas, it is absorbed by regenerated Fe₂O₂. This result indicates that the regeneration process should be stop as soon as possible when regeneration reaction ends.
The residual sulfur in the sorbent after regeneration was decomposed and SO₂ was released during desulfurization. In order to prevent S02 release, a reduction process, in which the residual sulfur is decomposed by coal gas at more than 630 K, is needed. In desulfurization regeneration cycles test with reduction process, it was found that our sorbent has a beneficial effect in the sense that desulfurization performance became stable at more than 5 cycles.

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Solubility of Carbon Monoxide in Liquid Methyl Formate

Hiroshi Kuma, Qiusheng Liu, Kenji Nakamura, Fumio Takemura, Akira Yabe ...

Article type: Chemical Engineering Data
Subject area: Catalysis, Kinetics and Reactor Design
2002 Volume 28 Issue 4 Pages 468-472
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.468

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Decomposition and synthesis reactions of methyl formate are potentially useful for recover of the waste heat from factories and for air conditioning of residential areas. In this study, solubility of carbon monoxide in liquid methyl formate was measured to get fundamental data for designing a chemical heat pump system. The solubility of carbon monoxide in liquid methyl formate was measured for pressures between 0.5 MPa and 2.2 MPa and temperatures between 303 K and 373 K. Empirical correlations for the solubility were derived by the method of least squares for the temperature and pressure terms. The results of the solubility measurement, demonstrated that the ratio of fugacity to mole fraction of carbon monoxide increases with the increase of temperature. Furthermore two empirical formulas of solubility characteristics were obtained as functions of the temperature and the total pressure or the partial pressure under vapor-liquid equilibrium conditions.

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Effect of Mixing Method in Flow-Type Supercritical Water Oxidation Reactor on Glucose Oxidation Characteristics

Masahiro Shishido, Keisuke Okubo

Article type: Note
Subject area: Catalysis, Kinetics and Reactor Design
2002 Volume 28 Issue 4 Pages 490-492
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.490

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For supercritical water oxidation of glucose in a continuous flow reactor, the relation between mixing methods of two solutions (supercritical water +O₂, glucose solution) in the reactor and the profile of oxidation products was examined experimentally. Several types of mixing section with different sizes and modes of mixing were made with a commercially-available stainless-tee. For each mixing section, the profiles of gaseous products obtained from glucose oxidation were measured. These experiments revealed the following: 1) the yields of H₂ and CO were slightly influenced by the relative position of the outlets of two feeder lines and the orientation of the feeder lines relative to gravity, 2) the volume of the mixing section had no effect on the profiles of the products.

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Materials and Devices

Development of Thermal Heat Storage Material Utilizing Fatty Acids as Solid-Liquid Phase Change Materials

Tsutomu Matsui, Masahiro Yoshida, Yoshimitsu Uemura, Yasuo Hatate, His ...

Article type: Fundamental Research Paper
Subject area: Materials and Devices
2002 Volume 28 Issue 4 Pages 451-455
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.451

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We have developed low-temperature thermal energy storage material using fatty acids. The fatty acids, capric and lauric acids, were used as solid-liquid phase change materials (PCMs) at temperatures between 0 and 7°C. The thermodynamic properries of PCMs were investigated in detail by utilizing a differential scanning calorimeter (DSC). We found that the solid-liquid phase change temperature was freely controllable by adjusting the mixture of the two-component system (capric and lauric acids).
Furthermore, we researched the additive effect of unsaturated fatty acids (oleic acid, ricinoleic acid, or linoleic acid), anionic and nonionic surfactants (sodium di (2-ethylhexyl) sulfosuccinate, S1–4, T1–4), and surfactants derived from a Paty acid (sodium oleate or sodium laurate) . In particular, the addition of 20 wt% sodium oleate was effective to suppress the supercooling temperature and control the solid-liquid phase change temperature between 0 and 7° C. No physicochemical degradation of the capric and lauric acids with 20 wt% sodium oleate was found in the 50 recucling tests bymeans of the DSC analusis

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Separations

New Reflux Policy for Batch Distillation

Tetsuo Fujii

Article type: Technical Research Paper
Subject area: Separations
2002 Volume 28 Issue 4 Pages 386-390
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.386

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A new reflux policy for optimal operation was derived by examining theoretically the optimal operating conditions for batch distillation. The policy involves keeping the instantaneous minimum theoretical stages (using Fenske's equation) constant by controlling the reflux ratio, and it provides a reasonable operating method to maintain distillation column efficiency throughout the operation.
A method for calculation of reflux ratio was derived for the new reflux policy using the McCabeThiele calculation method for a no-holdup model.
The theoretical new reflux policy was compared with the optimal reflux policy in the literature, which is solved by using economical data, and found to correlate well in terms of optimal batch time. The new policy is simple and allows the optimal reflux ratio to be determined easily for given separation conditions.

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Electrically Aided Continuous Demulsification of Water-in-Oil Emulsion

Atsushi Kobayashi, Shinji Adachi, Manabu Yamaguchi

Article type: Fundamental Research Paper
Subject area: Separations
2002 Volume 28 Issue 4 Pages 404-408
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.404

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Characteristics of electrical demulsification of water-in-oil emulsions were studied experimentally by using a flow-type column separator equipped with perforate plate-electrodes at the top and the bottom of the column. The system of kerosene-span 80 (surfactant) and NaCl aqueous solution was used as W/O emulsion. The effects of pulsed DC and AC voltages applied on the demulsification rate of the emulsions were investigated, and the changes in droplet size distribution and dispersed phase holdup in the emulsion phase demulsifying under applied electric fields were examined by in-situ observation as a basis for understanding the demulsification behavior. Also the effect of the applied voltage on residual water content in the demulsified oil phase was examined. The results are expected to be practically useful as design and operational principles for the separator.

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High-Performance Harvesting of Cultured Chlorella with Bubble Flotation

Keiko Yamaberi, Kunihiro Yasui, Hiroshi Sawaki, Yushi Hirata

Article type: Fundamental Research Paper
Subject area: Separations
2002 Volume 28 Issue 4 Pages 461-467
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.461

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Flotation harvesting of cultured Chlorella was investigated by examining the surface charge of microalgae and the foaming ability of culture solution. With decreasing pH of the culture solution, microalgae Chlorella were more effectively recovered, probably due to the decrease in electrostatic repulsion between gas bubbles and microalgal cells. The cell concentration in the solution decreased exponentially with time, and the separation rate constant increased with the decrease in bubble diameter and the increase in gas holdup. The amount of recovered microalgae increased with the gas flow rate, and it was shown that nearly perfect recovery was attainable by adjusting the operational conditions. The microalgae were concentrated in the froth layer formed above the surface of the liquid column, and the layer became more deeper and stable with decreasing solution pH. The cell concentration in the recovered solution increased with the depth of the froth layer, and it was possible to achieve high enrichment of 20 to 40 times the cell concentration of the culture solution. Capillary electrophoresis of metabolites produced from the microalgae showed that the charge of metabolites approached zero with decreasing solution pH. This suggests that the metabolites contribute to the decrease in electrostatic repulsion and the stability of the froth layer.

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Development of Continuous Freeze Concentration Equipment

Masahiro Teduka, Juzo Matsuda, Eiji Obata, Hiroshi Matsuda, Yoshikatu ...

Article type: Note
Subject area: Separations
2002 Volume 28 Issue 4 Pages 473-477
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.473

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We have proposed a new method of continuous freeze concentration and performed tests of the equipment assembled. The equipment consists mainly of an ice making part, which continuously produces ice flakes on a rotating cooling drum, and a continuous centrifuge separating part. Tests were conducted under the following conditions: cooling drum temperature, −11-−24°C; rotation period of the drum, 98–610s; and residence time of ice flakes in the centrifuge, 15–600 s. Diluted seawater (Cl⁻ concentration of 0.62–0.67 wt%) was used as a sample. The following results were obtained. The Cl⁻ concentrations of the separated liquor and the separated ice were 1.6–3.9 wt% and 0.27–0.55 wt%, respectively. The residual liquor ratio of the separated ice was 0.10–0.20.

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Profiles of Moisture and Polymer Content in Porous Material Wetted with Aqueous Polymer Solution upon Convective Drying

Hironobu Imakoma, Yukihiro Hashimoto, Katsuyuki Kubota, Masamichi Yosh ...

Article type: Note
Subject area: Separations
2002 Volume 28 Issue 4 Pages 478-480
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.478

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Convective dryingof a glass particle layer wetted with aqueous polyvinylalcohol (PVA) solution was examined. Profiles of moisture and PVA content in the layer during drying and the drying rate were measured for different initial solution contents. With a low initial content, a receding drying front was observed in the same way as in the layer wetted with water, and there was no PVA movement. With a high initial content, the receding front was not observed in the low content region, and much PVA moved toward the drying surface in the early period of drying and stayed there after. The PVA disturbed the drying and there was no constant rate period.

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Effect of Spray Column Height on Liquid Membrane Separation of Hydrocarbon

Junjiro Kawasaki, Satoru Kato, Akihiro Kamei, Ryuichi Egashira, Hisash ...

Article type: Note
Subject area: Separations
2002 Volume 28 Issue 4 Pages 485-487
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.485

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The permeation of a binary model mixture though an O/W/O emulsion liquid membrane was studied experimentally. Considerable axial mixing and coalescence of the emulsion drops were observed near the distributor, which atomized the emulsion, as reported previously. The diameters of the emulsion drops in the middle to bottom section of the column increased, that is, the average specific interfacial area between the emulsion and solvent decreased with column height. The overall volumetric permeation coefficients of the permeates, therefore, fell with column height. There was no substantial effect of the height on the separation factor.

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Control of Polymer Content Profile within Dried Porous Material Wetted with Aqueous Polymer Solution

Hironobu Imakoma, Tatsuhiro Nakazawa, Katsuyuki Kubota, Masamichi Yosh ...

Article type: Note
Subject area: Separations
2002 Volume 28 Issue 4 Pages 488-489
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.488

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In the conductive-convective drying of a glass particle layer wetted with aqueous polyvinylalcohol (PVA) solution, it is known that PVA content in the dried layer is higher near both the drying surface and the conductive plane. A series of experiments with a range of air temperatures at the drying surface and constant air temperature at the conductive plane showed that lower air temperature at the drying surface caused higher PVA content near the conductive plane and lower drying rate. With a low initial PVA solution content, however, a uniform profile of PVA content was observed.

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Particle Technology and Fluidization

Application of Particle

Wall Collision to Parallel-Flow-Type Classification

Jiangbo Chen, Toshihiko Shakouchi

Article type: Fundamental Research Paper
Subject area: Particle Technology and Fluidization
2002 Volume 28 Issue 4 Pages 417-423
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.417

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The present research aimed to improve the performance of a parallel-flow-type classifier by employing particle-wall collision, which is referred to here as impact effect. The numerical methods employed include a k-ε two-equation turbulent model for the gas phase, the random simulation technique and the two-way method for coupling the interaction between the gas and solid phases. The partial classification efficiency from numerical analysis was tested experimental by. They data showed the same trends as the numerical analysis though some discrepancy was found. The main reason for this discrepancy was suggested to be the underevaluation of slip velocity between particle and gas in the numerical analysis. A modification factor of classifier free time coefficient was suggested as a mens to correct this underevaluation and bring about agreement with the experimental results. The method of adding a small impact body at main nozzle was shown by numerical and experimental results to enhance the impact effect and improve the performance of the classifier.

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Analysis of Particle Flow in an Internally Circulating Fluidized Bed Having Several Chambers

Seiichiro Toyoda, Yuki Iwadate, Tatsuya Hasegawa, Daisaku Fukuoka, Kim ...

Article type: Fundamental Research Paper
Subject area: Particle Technology and Fluidization
2002 Volume 28 Issue 4 Pages 424-434
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.424

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Particle flow was analyzed, in an internally circulating fluidized bed having several chambers, in which solid circulation rate was controlled by changing gas velocity supplied to each chamber. Solid circulation rate in a 4 MWth test plant for an internally circulating fluidized bed gasifier (ICFG) was predicted fairly well from experimental data for 1/1 scale ratio cold model. The solid circulation rate in an internally circulating fluidized bed is affected by the particle plunge by splash, the restricted resistance at the opening and the bed viscosity around the opening. Based on the pressure balance around an opening, a mathematical model to predict solid mass flow rate was developed. The model developed in this paper was well validated by the observed values of ICFG hot model test data.

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Process System Engineering

Simple Optimal Regulator for Temperature Control of a CSTR

Jun Morimoto, Yoshinobu Shikanai, Daisuke Obara, Yoshiyuki Yamashita, ...

Article type: Fundamental Research Paper
Subject area: Process System Engineering
2002 Volume 28 Issue 4 Pages 391-395
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.391

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A nonlinear-optimal regulator with simple calculation is proposed for temperature control of a CSTR. The method is based on the expansion of a regulator for a single-variable affine system to a two-variable system, and it is smoothly combined with bang-bang control. The proposed method does not require matrix calculation or solution search, and it can be implemented in a relatively traditional computer.
In experiments with a simulated-reactor system, this method showed excellent performance for set-point change, disturbance and tracking for optimal trajectory.

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Biochemical, Food and Medical Engineering

Characterization of Stimuli-Induced Membrane Fusion of Liposomes

Matundu Menayame Félix, Toshinori Shimanouchi, Hirosh Umakoshi, ...

Article type: Note
Subject area: Biochemical, Food and Medical Engineering
2002 Volume 28 Issue 4 Pages 481-484
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.481

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The phenomena of aggregation and fusion of liposome membranes under the stimuli conditions (heat and pH) were shown to be triggered by the conformational change of the stimuli-responsive polymers and proteins. It is found that the percentage of liposome fusion and the liposome size under the specific stimuli condition were well corresponding with the capacity factor obtained from the peak shift of the elution profile on the immobilized liposome chromatography.

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Safty, Enviroment and Energy

Conversion of NaCl to HCl in the Presence of SO₂/O₂/H₂O under Conditions Simulating Municipal Solid Waste Incinerator

Shoji Ozawa, Keisuke Ito, Hitoki Matsuda

Article type: Fundamental Research Paper
Subject area: Safty, Enviroment and Energy
2002 Volume 28 Issue 4 Pages 396-403
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.396

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The formation of HCl by sulfation of NaCl under municipal waste combustion conditions was studied experimentally. NaCl sulfation was carried out with a packed bed of NaCl reagent in the temperature range 623–1123 K.
The amount of HCl formed from NaCl was found to increase with the increment of the concentrations of SO₂, O₂ and H₂O. However, the depemdence of HCl formation rate on the SO₂, and H₂O concentrations differed at temperatures above and below 923K. It was assumed that sulfation of NaCl proceeded by different reaction mechanisms in each temperature range. The existence of different reaction mechanisms at dofferent temperatures is responsible for the partial melting of NaCl solid at temperatures over 920 K. The equation of reaction rate of NaCl sulfation in the temperature range 623–1123 K was formulated as follows,
-dX/dt=4.31×10^-4×exp(-23.0/RT) × (1-X)^2/3×P_SO₂^0.3×P_O2⁰⁶×P_H₂O^0.2 (<923K)
-dX/dt=7.91×exp(-144.4/RT) × (1-X)^2/3×P_S0₂^1.4×P_O₂^0.7×P_H₂O^0.8 (≧923K)

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Simulation of Solid-State Sintering Behavior of Two Spherical Particles with Formation of Eutectic Composition

Atsuko Shimosaka, Yasushi Ueda, Yoshiyuki Shirakawa, Jusuke Hidaka

Article type: Fundamental Research Paper
Subject area: Safty, Enviroment and Energy
2002 Volume 28 Issue 4 Pages 409-416
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.409

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A method was proposed for simulation of the solid-state sintering behavior of two spherical particles with different chemical composition, namely, Ag and Cu particles, and the formation of interparticle neck composed of an eutectic composition. For sintering of Ag and Cu particles, a eutectic point exists in the two-composition system, and the sintering behavior depends on the sintering conditions. For a sintering temperature near the eutectic point, the sintering progresses with the formation of a neck between two particles, and for lower temperature, the sintering progresses without the neck.
For the sintering without formation of the neck, the simulation method employed the rate of mass transport derived by evaluating the surface and grain boundary energies of the system (model I ). For the sintering with formation of the neck, a hybrid simulation method was employed in which model I was switched to a model for solid solution type according to the volume of grain growth (model II ) . The validity of the proposed simulation method was confirmed by the agreement of the simulated values with the experimental ones. Consequently, by analyzing the effect of sintering conditions on shrinkage and grain growth, it was possible to determine the best sintering conditions. It was also possible to evaluate the ratio of composition in the solid solubility neck.

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Numerical Analysis and Optimization of the Mass Transport and Generation Phenomena for Single Cell-Scale Solid Oxide Fuel Cells

Hitoshi Miyamoto, Masatoshi Hattori, Masaki Minemoto

Article type: Fundamental Research Paper
Subject area: Safty, Enviroment and Energy
2002 Volume 28 Issue 4 Pages 435-442
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.435

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This work provides a numerical analysis method for on a scale of several tens to a hundred micrometers Solid Oxide Fuel Cells phenomena. The analysis depends on the assumption that the effective electrode reaction area is restricted to the three-phase boundary where mass fluxes and electric current are concentrated and cause polarization. Concentration profiles were obtained analytically and used for calculating polarization and voltage-current curves. Optimum calculations for cathode structure showed that the composite particle diameter electrode gives better SOFC performance.

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Numerical Analysis of Planar Solid Oxide Fuel Cells by Two-Dimensional Approximation

Hitoshi Miyamoto, Masatoshi Hattori, Masaki Minemoto

Article type: Fundamental Research Paper
Subject area: Safty, Enviroment and Energy
2002 Volume 28 Issue 4 Pages 443-450
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.443

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An integrated performance analysis of solid oxide fuel cells (SOFC) in a non-uniform flow field was investigated. The main feature of the analysis is the combination of the two-dimensional flow, mass and energy balance equations together with micro-modeling based on the electrochemical reactions, such as internal methane reforming. The model allows SOFC performance to be predicted more precisely than by assuming a uniform flow field. The calculated values agreed with the test results with discrepancies of less than 15% for the current-voltage characteristic and less than 10% for the gas concentration. Results showed a remarkable difference in temperature and concentration profiles between the internal reforming condition and the hydrogen fuel condition. The most suitable cathode gas supply techniques are also discussed.

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Large-Scale Desert Afforestaion and its Effect of Precipitaion Increase in Australia

Dayin Li, Hiroshi Komiyama

Article type: Fundamental Research Paper
Subject area: Safty, Enviroment and Energy
2002 Volume 28 Issue 4 Pages 456-460
Published: July 20, 2002
Released on J-STAGE: May 30, 2009

DOIhttps://doi.org/10.1252/kakoronbunshu.28.456

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The impact of desert afforestation on weather modification in western Australia was studied focusing on precipitation increase. A three-dimensional spectral mesoscale model was used to simulate limited-area weather modification by changing surface conditions including surface wetness, roughness, and albedo. Using global analysis data sets as the initial and boundary conditions, comparative simulations were made for original and modified surface conditions in the region of 500× 500 km under typical conditions of clear days and rainy days in four seasons.
The results show that precipitation is enhanced by the surface modification in all the cases studied. On rainy days in summer, in particular, precipitation increase amounted to more than double the evaporation increase, through a mechanism by which strong solar radiation evaporates water from the afforested area to cause a wet upstream, which stimulates the low pressure coming from outside. The mechanism of precipitation increase as indicated in this study provides an efficient watering policy to save the precious water resource in arid land.

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