JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
Print ISSN : 0021-9592
Volume 41 , Issue 3
Showing 1-11 articles out of 11 articles from the selected issue
Transport Phenomena and Fluid Engineering
  • Hiroshi Suzuki, Kenji Kubo, Katsutoshi Shoji, Yoshiyuki Komoda, Hiromo ...
    Type: Research Paper
    2008 Volume 41 Issue 3 Pages 139-144
    Published: March 20, 2008
    Released: March 20, 2008
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    Three-dimensional numerical computations have been performed in order to investigate the mixing mechanism of a multi-holed (composed of two pairs of 4- and 5-hole elements) static mixer for Newtonian fluid. The hole Reynolds number based on the size of straight part of the hole and the mean velocity in a hole of the 5-hole element, Rea, was changed in three steps from 5.25 to 52.7, while the hole size of the straight part of the hole, the pipe diameter and fluid viscosity and density were fixed at 5 mm, 18 mm, and 0.0978 Pa·s and 1304 kg·m–3, respectively, which were the same as in the previous experiments. From the results, it was found that twin vortices are formed in a hole of the 5-hole element as observed experimentally in the previous study. These twin vortices cause the twist motion in a hole and intensify the mixing process of the static mixer. It was also found that the vorticity of the twin vortices linearly increases with the hole Reynolds number. Thus, the increase of the hole Reynolds number causes high mixing characteristics as pointed out in the previous study.
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  • Katsumi Shiobara, Setsuro Hiraoka, Yoshihito Kato, Shuichi Iwata, Yuta ...
    Type: Research Paper
    2008 Volume 41 Issue 3 Pages 145-154
    Published: March 20, 2008
    Released: March 20, 2008
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    The heat transfer coefficient at side wall of a fully turbulent agitated vessel h was estimated from the universal expression of the tangential velocity at boundary layer edge, and it was shown that the estimated value of the heat transfer coefficient coincided well with the experimental one. Besides this, from the relation of the power consumption per unit volume Pv to the average shear stress at side wall of an agitated vessel τw, it was derived that the variable (h/ρcpvθ)Pr2/3 containing the heat transfer coefficient h was proportional to the characteristic turbulent velocity (Pvν/ρ)1/4, where the value of the proportional constant {(f3ReG)1/4/1.48m} calculated from the universal expression of the tangential velocity at side wall of an agitated vessel was almost constant at 1.5 for wide ranges of both impeller similarity parameter X and generalized Reynolds number ReG. The value 1.5 was nearly equal to 0.13 the proportional constant of the correlation proposed by Calderbank and MooYoung. From the discussion of the local value of momentum flux at vessel wall, it was shown that the heat transfer coefficient at baffled agitated vessel was correlated with the same correlation form as that at non-baffled agitated vessel, though the proportional constant was slightly smaller than that for a non-baffled vessel.
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  • Shin-ichi Kondo, Nobuhiro Yamada, Koji Takahashi
    Type: Research Paper
    2008 Volume 41 Issue 3 Pages 155-160
    Published: March 20, 2008
    Released: March 20, 2008
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    In the present study, we investigated the influences of diameter and impeller position on drawing from the liquid surface and on the dispersion of solid particles lighter than liquid in a vessel stirred by dual impellers. We defined the just drawdown condition as the state in which there are no floating lighter-than-liquid particles on the liquid surface at the just suspension speed for heavier-than-liquid particles. The best type of upper stage impeller, which drew floating particles on liquid surface into the liquid efficiently, was found to be the pitched paddle pumping up and the best impeller-diameter-to-vessel-diameter ratio was 0.5. In addition, the optimal position of the upper side impeller to minimize the just drawdown speed was located at 0.85 of the total liquid level from the bottom of the vessel. We examined the influence of the clearance of dual impellers on the distribution of solid particles in the vessel. The obtained results indicated that the best type of lower stage impeller is the pitched paddle pumping down and the impeller-diameter-to-vessel-diameter ratio is 0.5. The standard deviation of the dispersion of solid particles was found to be lowest when the clearance of the dual impellers to vessel diameter ratio was 0.83.
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Particle Engineering
  • Mohammad Asif
    Type: Short Communication
    2008 Volume 41 Issue 3 Pages 161-164
    Published: March 20, 2008
    Released: March 20, 2008
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    The main obstacle in the prediction of the minimum fluidization velocity is probably a reasonable estimate of the bed void fraction at the incipient fluidization condition. An attempt is made here to predict the bed void fraction for the limiting cases of the laminar flow as well as the turbulent flow using well-established correlations, namely the Ergun equation for the pressure drop in packed beds and the Richardson and Zaki correlation. The bed void fractions are found to be 0.415 for the laminar flow and 0.396 for the turbulent flow.
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Separation Engineering
  • Hassan Pahlavanzadeh, Arsalan Farahnak
    Type: Research Paper
    2008 Volume 41 Issue 3 Pages 165-173
    Published: March 20, 2008
    Released: March 20, 2008
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    In separation of acidic gasses from natural gas, synthesis gas and refinery gasses chemical solvents such as MEA, DEA, MDEA and DIPA, or physical solvents such as selexol, rectizole, propylene carbonate are used. All of those solvents have imperfect functions, each having own specific advantages and disadvantages. DGA solvent regarding the effective factors for the economy of gas refinery units seem to act better than the above mentioned solvents. Simulation of an absorption column of CO2 with 40% DGA solvent has never been performed before. The available softwares are either not capable of simulating the absorption column with the DGA solvent in weight percentage of 40% (such as Aspen Hysys® and ProII simulators) or even if it is capable of, the information related to i.e. pH, ionic strength, the rate of reaction, and the heat released in the trays are not taken into accounted (such as Design II, Chemcad, Aspen Plus® simulators). While knowing parameters such as the concentration of ions and pH in removing process passages and operation conditions such as the extremity of absorption and corrosion, are important. In this research the simulation of CO2 absorption with 40% DGA solvent has been done. In addition to the temperature, pressure, concentration and mole fraction of the elements (ions and molecules), quantities of pH, ionic strength, rate of reaction and the heat released from the reaction in all of the trays are considered. Mole loading of a solute gas, CO2, in DGA solvent using the experimental results performed at various temperatures under atmospheric pressure and using the published data under the condition of different pressures were used in the simulation of a carbon dioxide absorption column. In his simulation the Kent–Eisenberg model for the liquid phase and the equation of the state of Peng–Robinson for the gas phase were utilized. The results of this work are in good agreement with design and operational data.
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  • Akihiko Ito, Masakuni Matsuoka
    Type: Research Paper
    2008 Volume 41 Issue 3 Pages 174-181
    Published: March 20, 2008
    Released: March 20, 2008
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    In order to understand the effect of initial supersaturation on the mechanism of purity drop during preferential crystallization, two sets of experiments were carried out with a threonine-water system. One set was the observation of the {210} faces of L-Thr seed crystals placed in solutions at various supersaturation levels of D-Thr, and the other was preferential crystallization on the basis of the observation results. From the observation, needle-like D-Thr crystals, which nucleated in the bulk solution, were observed in supersaturated DL-Thr solutions at supersaturation of D-Thr (σD) below 0.19, while thin plate-like D-Thr crystals were found to appear on the {210} faces when σD was above 0.21. During preferential crystallization for the solution of initial supersaturation of σi = 0.16, needle-like crystals nucleated in the bulk solution were observed and the bulk nucleation of D-Thr was the mechanism of the purity drop. On the contrary, when the initial supersaturation σi was 0.21, thin plate-like D-Thr crystals were found to appear by surface nucleation. The surface nucleation of D-Thr was the mechanism of the purity drop. On the basis of observations and preferential crystallization, the mechanisms of the purity drop were concluded to be dependent on the σi in solutions.
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Thermal Engineering
  • Akinori Goto, Yoshio Morozumi, Hideto Hagiya, Hideyuki Aoki, Takatoshi ...
    Type: Research Paper
    2008 Volume 41 Issue 3 Pages 182-193
    Published: March 20, 2008
    Released: March 20, 2008
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    In the present study, waste plastic injection in blast furnace processes is investigated numerically. A mathematical model developed in this study describes turbulent flows, heat and mass transfer, chemical reactions in gas, particle and coke-bed phases, and particle trajectories. In the simulation, pulverized particles of coal or plastics are injected into a blowpipe with a nitrogen gas stream, and are then supplied to the raceway region in the coke particle bed. The difference in the gasification behaviors between coal and plastic particles are discussed. The effects of the diameter of plastic particles on the gasification behavior are also investigated. Coal particles are rapidly gasified in the blowpipe because of their small size. In contrast, the gasification of plastic particles rarely occurs in the blowpipe, even if small plastic particles are injected. In addition, the flows of plastic particles are biased in the blowpipe, and consequently the reaction zone of gasification is narrow. In the raceway of the coke bed, the pulverized coal particles exit the raceway due to their small diameter, and are then discharged from the coke bed without sufficient gasification. On the other hand, the plastic particles circulate in the raceway until the diameters thereof decrease below a critical diameter. As a result, since the gasification reaction progresses during the circulation, the combustion efficiency of plastic particles remains high even though the initial diameter of the plastic particles is large.
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Chemical Reaction Engineering
  • Joao Manzi, Ed Carrazzoni
    Type: Research Paper
    2008 Volume 41 Issue 3 Pages 194-199
    Published: March 20, 2008
    Released: March 20, 2008
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    Determination of optimal operating conditions of chemical processes is difficult. Minimization of entropy generation is a simpler option for standard, either numerical or analytical, optimization techniques. This paper illustrates how entropy generation minimization can simplify the analysis and optimization of the operation of a CSTR. A typical irreversible, exothermic, first order chemical reaction taken from the literature has been considered. For this system, the entropy generation rate has been derived based on mass, energy and entropy balances. Using analytical derivatives it was found that entropy generation can be minimized if the inlet stream temperature is the same as the operating temperature of the reactor. Additionally, it was easy to draw from the analysis the operating temperature that achieved maximum conversion. Finally, the procedure proposed was compared with an indirect entropy minimization method, and shown to be simpler and clearer.
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Biochemical, Food and Medical Engineering
  • Noriko Yoshimoto, Yuko Nishijima, Parvin Akbarzadehlaleh, Sachie Fujii ...
    Type: Research Paper
    2008 Volume 41 Issue 3 Pages 200-205
    Published: March 20, 2008
    Released: March 20, 2008
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    As a method for surveying efficient separation conditions for the mobile phase, a 96-well micro-plate based monolithic ion-exchange chromatography system was developed. Discontinuous flow was accomplished by a vacuum manifold. Linear salt gradient elution experiments were carried out with this system and the elution curves were compared with those for monolithic disk column IEC. The normalized gradient slope–the peak salt concentration data for the micro-plate system agreed with those for the monolithic disk column IEC. This system is useful as the liquid volume needed for the experiment is highly reduced, and large amounts of data are obtained quickly.
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  • Shigeyuki Nomura, Chiaki Kaga, Ryuji Kato, Mina Okochi, Hiroyuki Honda
    Type: Short Communication
    2008 Volume 41 Issue 3 Pages 206-209
    Published: March 20, 2008
    Released: March 20, 2008
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    Laminin (LN)-5 is an epithelial specific adhesion component and a main ligand for keratinocyte. It regulates various cellular functions, including cell adhesion, spreading, and motility. The human LN-5 α3 chain globular (LG) 2 and 3 domains interact with integrin α3β1 selectively. Using peptide array-based interaction assay, screening of cell-adhesive peptide was performed with 6-mer peptide library of LG-2 and -3 domains. Eight peptides with high cell-adhesive effects were found, and the activity of DWKLVR (LN1143–1148) and GLRLLI (LN1239–1244) peptides showed about 2.5-fold increase compared to no peptide. From the adhesion inhibition assay, NFEGCI (LN1271–1276) and NQLLQD (LN1333–1338) peptides were seen to interact with integrin α3β1.
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Energy
  • Seiichi Inoue, Seiji Uno, Tomoaki Minowa
    Type: Short Communication
    2008 Volume 41 Issue 3 Pages 210-215
    Published: March 20, 2008
    Released: March 20, 2008
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    Cellulose was treated at 423–623 K under hydrothermal conditions without a catalyst to produce charcoal. The charcoal generated under hydrothermal conditions was mainly analyzed by FT-IR in order to investigate changes in its chemical structures occurring during the carbonization process. Increasing reaction temperatures decreased charcoal yield, increased its carbon-to-oxygen ratio, and promoted cellulose carbonization. Furthermore, increasing reaction temperature during hydrothermal treatment of cellulose weakened FT-IR peaks from –OH and –CH groups, showing that dehydrogenation and deoxygenation had occurred. These studies confirmed that hydrothermal conditions promoted carbonization of cellulose.
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