JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
Print ISSN : 0021-9592
Volume 36 , Issue 3
Showing 1-18 articles out of 18 articles from the selected issue
Thermodynamics, Physical Properties and Molecular Simulation
  • Takahiro Murakami, Noriyuki Kurita, Ichiro Naruse
    Type: Research Papers
    Subject area: Thermodynamics, Physical Properties and Molecular Simulation
    2003 Volume 36 Issue 3 Pages 225-230
    Published: 2003
    Released: November 15, 2003
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    Desulfurization performance of wasted seashells was found to be over twice as high as that of limestone, which was currently used as a desulfurizer in fluidized bed coal combustors. NaCl-doping into limestone was also found to be effective in improving the desulfurization efficiency. From X-ray diffraction (XRD) analyses of calcined seashell, limestone and NaCl-doped limestone, on the other hand, not only the calcined seashell but also the NaCl-doped limestone had strong peaks of CaO crystal, and those two materials also had high desulfurization activity. This improvement was hypothesized to be due to NaCl causing a change in the crystal structure of CaO. In order to elucidate the effect of NaCl addition on the CaO crystal structure in the incineration of CaCO3, the change of structures was simulated by means of molecular dynamics simulations of CaO. In the simulation one molecule of NaCl was exchanged into one molecule of CaO. A pair correlation functions and the distances between Ca and O atoms, which were obtained by the simulations, were compared with those from the crystal CaO.
    NaCl-doping affected the crystalization temperature of CaO. The crystallization temperature increased due to adding a little bit of NaCl. From the result of the pair correlation functions obtained in NaCl-doped CaO, the difference of the potential energy of NaCl from that of CaO seemed to contribute to the crystallization of the bulk of CaO. The simulation and experimental results obtained suggested that NaCl-doping contributed to crystallizing the CaO molecules.
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Transport Phenomena, Fluid Mechanics and Mixing
  • Shin-ichi Furukawa, Tomoshige Nitta
    Type: Research Papers
    Subject area: Transport Phenomena, Fluid Mechanics and Mixing
    2003 Volume 36 Issue 3 Pages 313-321
    Published: 2003
    Released: November 15, 2003
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    Molecular simulations have been performed on permeation and adsorption of n-butane in a ZSM-5 zeolite membrane. In all simulations, a flexible potential model is used for n-butane since the smallest size of the permeating molecule is almost the same as the pore size of the ZSM-5 crystal. Equilibrium densities of n-butane in the ZSM-5 membrane calculated from the MC method are in good agreement with experimental adsorption data, being represented by the Langmuir adsorption isotherm model. Permeability of n-butane calculated from the μVT-NEMD method has a maximum against temperature, which agrees qualitatively with the experimental results. It is noted that the whole pores in the membrane are filled with molecules at room temperature. As compared with the local values of the Fick and the Maxwell–Stefan diffusion coefficients (DF, DMS) and the self-diffusion coefficients in the permeate direction (Ds, x), we confirm that the DMS is almost independent of molecular loadings in the membrane, and that DF > DMS > Ds, x at high loadings. In addition, the three diffusion coefficients are almost identical at the zero loading. By providing a modification for the distribution coefficient (S) and diffusion coefficient (D) in the case of nonlinear isotherms, we have clearly demonstrated that the permeation at low temperatures is controlled by the diffusion process, where whole pores are filled with molecules, and then the controlling step changes to the adsorption process at higher temperature where the pores are characterized by medium loadings.
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  • Setsuro Hiraoka, Yutaka Tada, Yoshihito Kato, Yoshio Ukai, Jun Sasaki, ...
    Type: Short Communications
    Subject area: Transport Phenomena, Fluid Mechanics and Mixing
    2003 Volume 36 Issue 3 Pages 333-338
    Published: 2003
    Released: November 15, 2003
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    Power consumption in a baffled agitated vessel with pitched wire-gauze blade impeller is measured over a wide range of Reynolds number in turbulent flow region, where the power consumption decreases with decreasing the wire-gauze blade angle. The power consumption without aeration is well correlated with the baffled condition parameter (BW/D)nb0.8. The rotational speed to occur the gross circulation of gas NR increased with the decrease of a blade angle θ for the upflow condition. In the operating conditions of the gross circulation flow of the gas back into the impeller (N > NR) and the turbulent flow (Red > 200), the power consumption under aeration at the standard baffled condition Npg is correlated with the modified equation by the blade angle θ, which was reduced to the power correlation for the wire-gauze impeller (θ = π/2). In the range of the rotational speed of N > NR the power number under aeration is almost independent of the impeller position and the liquid flow direction through the impeller.
    The measured gas-liquid mass transfer volumetric coefficient for the pitched wire-gauze blade impeller kLa coincides well with the correlation of kLa for the wire-gauze impeller in lower viscosity liquid, whereas the former is smaller than the latter in higher viscosity liquid because of the lost of the wire-gauze blade effect.
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Catalysis, Kinetics and Reactor Design
  • Maw-Ling Wang, Tsuan-Hsuan Huang
    Type: Research Papers
    Subject area: Catalysis, Kinetics and Reactor Design
    2003 Volume 36 Issue 3 Pages 231-242
    Published: 2003
    Released: November 15, 2003
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    Epoxidation of dicyclopentadiene via phase transfer catalysis was successfully carried out in an acidic solution/organic solvent two-phase medium. The reaction is greatly enhanced in the presence of quaternary ammonium salt using hydrogen peroxide as the oxidizing agent, and sodium tungstate and phosphoric acid as the cocatalyst. Three products, which include epoxidation of two single-site double bonds and epoxidation of one two-sites double bonds, were obtained. The organic-phase reaction was found to be the rate-determining step. Thus, the organic-soluble methyltrioctylammonium chloride (Aliquat 336) was chosen as the phase transfer catalyst to enhance the reaction rate. The purpose of this work is to build up a rational reaction mechanism in which an active oxidation catalyst was synthesized from the reaction of hydrogen peroxide, sodium tungstate, phosphoric acid and quaternary ammonium salt. Based on the experimental data, a pseudo steady state hypothesis (PSSH) approach was considered for the variation of the concentration of the active oxidation catalyst during the reaction. The apparent rate constants of the organic-phase reactions were obtained. Factors which influenced the apparent rate constants were discussed in detail.
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  • Chu-Yuan Chen, Chun-I Lin, Hsi-Kuei Chen
    Type: Research Papers
    Subject area: Catalysis, Kinetics and Reactor Design
    2003 Volume 36 Issue 3 Pages 265-270
    Published: 2003
    Released: November 15, 2003
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    In the present study, adsorption of β-carotene from soy oil with acid-activated rice hull ashes was conducted under vacuum. Concentrations of β-carotene in the oils before and after adsorption were measured by a UV-vis spectrophotometer. The adsorption rate was found to be increased by increasing the ratio of activated rice hull ash/soy oil or bleaching temperature and by decreasing the particle size of activated rice hull ash. Furthermore, an adsorption rate expression has been determined.
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  • Tetsuo Take, Toshiaki Yachi, Masaru Tomura, Chikako Kiyohara, Toshiyuk ...
    Type: Research Papers
    Subject area: Catalysis, Kinetics and Reactor Design
    2003 Volume 36 Issue 3 Pages 271-276
    Published: 2003
    Released: November 15, 2003
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    We have developed Cu-Zn/Al2O3/Al-plate catalysts for the methanol steam-reforming reaction. They were prepared by supporting the catalyst metals (copper and zinc) on alumina layers of anodized aluminum surfaces with and without a pore widening treatment. Characterization and methanol steam-reforming tests showed that a BET surface area and roughness factor were considerably increased by the pore widening treatment. However, the treated catalyst supported less copper and zinc than the untreated one. Copper and zinc were highly dispersed to pores inside the treated catalyst, while they congregated and aggregated on the catalyst surfaces to form larger particles in the untreated one. The prepared plate catalysts had high catalytic activity for the methanol steam-reforming reaction, and they had much lower catalytic-activity deterioration rates than the commercial CuO-ZnO catalyst. The pore-widened plate showed a lower deterioration rate than the non-pore-widened one, in which only the supported amount of copper decreased after the steam-reforming test. Thus, the pore widening treatment can suppress catalyst deterioration.
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  • Kazuyoshi Doi, Takeshi Noda, the late Norio Arai, Tomohiko Tagawa, Shi ...
    Type: Short Communications
    Subject area: Catalysis, Kinetics and Reactor Design
    2003 Volume 36 Issue 3 Pages 322-327
    Published: 2003
    Released: November 15, 2003
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    As a major anesthetic, a mixture of nitrous oxide (N2O), oxygen (O2) and isoflurane (CF3CHClOF2H) is used in medical operating rooms. Catalytic decomposition of N2O over alumina-supported rhodium catalyst (Rh/Al2O3) has been investigated to clean the air contaminated with N2O in medical operating rooms. Although N2O decomposition activities over Rh/Al2O3 were significantly decreased by isoflurane, N2O was completely decomposed at higher temperature. The deactivation effect of isoflurane was investigated and a reaction rate equation was proposed.
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  • Takafumi Sato, Gaku Sekiguchi, Tadafumi Adschiri, Kunio Arai
    Type: Short Communications
    Subject area: Catalysis, Kinetics and Reactor Design
    2003 Volume 36 Issue 3 Pages 339-342
    Published: 2003
    Released: November 15, 2003
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    The reactivity of phenol under noncatalytic conditions with propionaldehyde, acetone, and propionic acid were determined in the presence of water at supercritical conditions and in the absence of water at 673 K. The reaction of phenol with propionaldehyde gave alkylphenols in supercritical water. The yield of the alkylphenol products and ratio of para isomers to ortho ones increased with increasing water density. Over the range of reaction conditions studied, acetone showed no reactivity with phenol regardless of whether water was present or not. The reaction of propionic acid with phenol yielded the corresponding ester in the absence of water.
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Materials and Devices
  • Yasuhiro Shiraishi, Takayuki Hirai, Isao Komasawa
    Type: Short Communications
    Subject area: Materials and Devices
    2003 Volume 36 Issue 3 Pages 343-347
    Published: 2003
    Released: November 15, 2003
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    S-Methylsulfonium salts, obtained by desulfurization of vacuum gas oil (VGO) and catalytic-cracked gasoline (CCG) based on alkylation and a subsequent precipitation process, were used as initiator for polymerization of epoxide (glycidyl phenyl ether: GPE). The initiation behavior and activity for the salts obtained from VGO and CCG were compared with those obtained from light oil. Both the salts from VGO and CCG showed almost no activity at room temperature but become active with an increase of temperature, thus indicating that the salts act as thermal latent initiator. The initiation activity for the salts from VGO was relatively low, but the salts from CCG showed significantly higher activity than the salts from light oil. Most of the salts, obtained from CCG, are derived from less nucleophilic thiophenes, and therefore unstable against thermal stimulation, thus giving the higher initiation activity.
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  • Eri Yamamoto, Jun Kobayashi, Keiko Kanamaru, Toshiaki Miura, Fujio Wat ...
    Type: Short Communications
    Subject area: Materials and Devices
    2003 Volume 36 Issue 3 Pages 348-352
    Published: 2003
    Released: November 15, 2003
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    A new hydrophilic method for achieving a high-performance adsorbent by impregnating silica into pores of activated carbon has been proposed. In the process, silica-gel was synthesized in the pores of activated carbon after inserting a sodium silicate solution into the pores. Three types of activated carbon were tested to produce hydrophilic activated carbon and to investigate the hydrophilicity by measuring the adsorption isotherms of water vapor and pore structure characteristics. The proposed method worked effectively for adding hydrophilicity to activated carbon, since all of adsorption isotherms of the material treated with this method shifted to a lower region of water vapor pressure than that of the raw material. The shift to a lower relative pressure of adsorption isotherm was maximum when the concentration of sodium silicate solution was 1 mass%.
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Separations
  • Chan Ho Lee, Jong Joo Ha, Byung-Hee Chun, Hyung Kee Yoon, Sung Hyun Ki ...
    Type: Research Papers
    Subject area: Separations
    2003 Volume 36 Issue 3 Pages 259-264
    Published: 2003
    Released: November 15, 2003
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    In an absorption refrigeration system, it is well known that water vapor absorption into lithium bromide (LiBr) aqueous solution is enhanced by the addition of surfactants. Marangoni convection plays a role but its mechanism has not clearly been understood yet. In the present study, a relation between heat and mass transfer and Marangoni convection was investigated using mathematical modeling and numerical simulation in a falling film type absorber. We used an advanced Marangoni convection model that is able to predict velocity, temperature and mass fraction distribution in a falling film type absorber. Firstly, the effect of Marangoni convection on heat and mass transfer in an absorber was examined. As a result, efficiency of heat and mass transfer was increased due to Marangoni convection. Secondly, analysis for the effects of different operating conditions on an onset of Marangoni convection was carried out. The Marangoni number for the onset of convection decreased as the initial temperature and initial water mass fraction of solution decreased.
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Particle Technology and Fluidization
  • Yoshihide Mawatari, Tomoaki Ikegami, Yuji Tatemoto, Katsuji Noda
    Type: Research Papers
    Subject area: Particle Technology and Fluidization
    2003 Volume 36 Issue 3 Pages 277-283
    Published: 2003
    Released: November 15, 2003
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    A model for estimating the agglomerate size of Geldart group C powder in a vibro-fluidized bed was proposed. The agglomerate size was estimated by using the experimental value of the lower limit of gas velocity for channel breakage, ucha, and the void fraction, εcha, at ucha. The force balance between cohesive force (van der Waals force) and separation force (gravity, vibration and shear force by a gas flow) was considered. The vibrational force was considered to act on the agglomerates to increase the effect of gravitational force. The calculated agglomerate size decreased with increasing vibration strength.
    The value of ucha decreased with increasing vibration strength for all tested group C powders in this study. The effects of particle properties such as particle diameter, density and material on ucha were discussed. It was found that a higher value of ucha was obtained when the cohesive force was large in the cohesive-separation force balance. This indicates the particle properties affect the cohesive–separation force balance.
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Process Systems Engineering
  • Hsiao-Ping Huang, Jyh-Cheng Jeng
    Type: Research Papers
    Subject area: Separations
    2003 Volume 36 Issue 3 Pages 284-296
    Published: 2003
    Released: November 15, 2003
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    The PID controllers of single loop systems are, in general, designed according to FOPDT or SOPDT models which represent the dynamics of open-loop processes. An identification system, which aims to identify such low order models for monitoring and autotuning of PID controllers, is presented. The identification is conducted by compensating the output of the relay feedback loop with a simple compensator laying outside the loop. The objective is to make the compensated output behave like the one from a process consisting of an integrator plus dead time. An on-line mechanism to adjust the compensator is presented, which will lead to the final apparent model. Meanwhile, the optimal performances of PID control associated with low order dynamics are tabulated. Based on the identified model, the performance of the system can thus be assessed. As the identification is implemented in parallel to a relay feedback loop, it is thus feasible for on-line use to monitor the performance of a PID controller in the system. From the control assessment, the control performance can be improved by an autotuning procedure.
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  • Masatoshi Yoshida, Shunichiro Ueno, Shigeru Matsumoto
    Type: Research Papers
    Subject area: Process Systems Engineering
    2003 Volume 36 Issue 3 Pages 297-306
    Published: 2003
    Released: November 15, 2003
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    A rigorous numerical model is developed to simulate the dynamic performance of a stacked molten carbonate fuel cell with commercially realistic dimensions. The model takes account of gas stream utilization due to electrochemical reaction, conductive heat transfer between cell hardware and gas streams, energy transfer accompanying mass addition to the bulk streams, and in-plane heat conduction through the cell hardware. The over-potential is calculated using the resistance as a function of temperature and composition of chemical species from literature. It is shown that for a step increase in the current load the output voltage falls at once to a considerable degree and then gradually recovers to the steady state level. The sluggishness of the response is mainly due to the slow dynamics of cell temperature. Therefore, control of cell temperature is necessary to stabilize the response of output voltage under varying current-load situations.
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Biochemical, Food and Medical Engineering
  • Tatsuo Maruyama, Sadafumi Noda, Noriho Kamiya, Masahiro Goto
    Type: Research Papers
    Subject area: Biochemical, Food and Medical Engineering
    2003 Volume 36 Issue 3 Pages 307-312
    Published: 2003
    Released: November 15, 2003
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    We have performed the ring-opening polymerization of lactones catalyzed by surfactant-coated lipases in organic solvents. A great improvement in the number-average molecular weight (Mn) of the produced polymer was observed compared to that of the lyophilized native lipase. The Mn vs monomer conversion profile suggests that the polymerization catalyzed by the surfactant-coated lipase is a step polymerization, whereas that catalyzed by lyophilized lipase powder is a chain polymerization. The effects of reaction temperature and the reaction solvent on the polymerization of lactones were also investigated.
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Safety, Environment and Energy
  • Ming-Chi Wei, Ming-Yen Wey, Chiou-Liang Lin
    Type: Research Papers
    Subject area: Safety, Environment and Energy
    2003 Volume 36 Issue 3 Pages 243-249
    Published: 2003
    Released: November 15, 2003
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    The main objective of this study is to investigate the competitive adsorption behavior of multiple components on sorbents (silica sand with limestone) at different operating conditions (temperature, additives of chloride, operating time). Moreover, the Toxicity Characteristic Leaching Process (TCLP) analyzed the leaching rates of metals from the spent sorbents.
    The results show that the adsorption capacities of Pb and Cd are better among those four metals on the sorbents. At 850°C, the adsorption of Pb and Cd can reach the adsorption saturation points. However, the adsorption amounts on the sorbents will increase as the operating temperature increases. X-ray powder diffract meter (XRD) analysis revealed the adsorption components on the sorbents had metal fusion formations. The TCLP tests show that the leaching rate of metals are significantly lower at 600°C, however, as the operating temperature increases (700°C and 850°C), the sorbents became more stable. At the same temperature, increasing the operating time on the incinerator shows a decreasing leaching rate on the sorbent. Adding PVC or NaCl will decrease the adsorption amounts of Pb and Cd, but increase the leaching rates of all metals on the sorbent. Competitive effects were analyzed by comparing single-component adsorption and multiple-component adsorption cases. The result shows that a multiple-component case has a better adsorption capacity than that of a single-component case.
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  • Wen-Jang Chen, Tson-Nan Chen
    Type: Research Papers
    Subject area: Safety, Environment and Energy
    2003 Volume 36 Issue 3 Pages 250-258
    Published: 2003
    Released: November 15, 2003
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    We have studied some post-electroflocculation wastewater sludge treatments using a jar-test method, by which the aluminium-containing sludge flocculates at the optimal polymer dosage under an optimized mixing condition, developing larger flocs with improved strength and then exhibiting increased settleability as well as ease of dewatering. Cationic polymer conditioner successfully decreased the final sediment volume and the capillary suction time about 70% and 50% for the conditioned sludge, respectively. The main driving force for the adsorption of cationic polymer flocculant onto the negatively charged sludge particles is the charge neutralization mechanism, as indicated by the lowering of zeta potential. The experimental results indicated that the minimum polymer dose required for the lowest capillary suction time, wherein maximum flocculation occurs under corresponding mixing conditions, gives a reasonable agreement with that at zero point of charge for optimal sludge conditioning. It was also pointed out that verification and control of mixing conditions in conditioning processes are very important for attaining an optimized sludge flocculation and subsequent maximum dewaterability enhancement.
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  • Koichi Yamada, Toshinori Kojima, Yukuo Abe, Masahiro Saito, Yasuyuki E ...
    Type: Short Communications
    Subject area: Process Systems Engineering
    2003 Volume 36 Issue 3 Pages 328-332
    Published: 2003
    Released: November 15, 2003
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    Afforestation is one of the most promising measures to mitigate global climate change because the expected carbon stock is estimated at as much as tens of tons per hectare or more. However, possible large-scale afforestation areas are limited to unused or ineffectively-used arid type lands. In the present study, a hardpan layer in Western Australia in an arid zone with no remarkable vegetation, a land type which is often found in the arid zones of the world, was blasted to produce holes and cracks for water penetration and root development. This study shows that hardpan blasting drastically accelerated root development and tree growth one or two years after planting. The blasting was done with additional CO2 emission of only one fortieth of the CO2 expected to be absorbed by trees after maturity.
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