JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
Online ISSN : 1881-1299
Print ISSN : 0021-9592
Volume 41, Issue 5
Displaying 1-16 of 16 articles from this issue
Separation Engineering
  • Kyu Suk Hwang, Kwang Il Kim, Ju Yeong Lee, Young Han Kim
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 325-335
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    Though a cross pairing has previously been utilized in the control of a fully thermally coupled distillation column, the details of the experiment have not been examined yet. Investigated here is the employment and evaluation of a three-loop PI control with a cross pairing using a FTCDC as a control for a practical hexane process; how the pairing works is also investigated. HYSYS simulations of the process, with several different control configurations, are conducted to compare their control performances and to show that the proposed cross pairing gives a satisfactory specification control of three products in the distillation column.
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  • Wen-Haur Chang, Meng-Hui Li
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 336-343
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    Ternary diffusion coefficients of monoethanolamine (MEA) and triethanolamine (TEA) in aqueous solutions containing MEA and TEA using the Taylor dispersion technique have been measured for temperatures 303.2, 308.2, and 313.2 K. The systems studied were aqueous solutions containing total amine concentrations of 2.0 and 3.0 kmol·m–3, each having three different amine-molar ratios. The density and viscosity of the blended amine solutions were also measured. The mutual diffusion coefficients of aqueous MEA and aqueous TEA solutions were also reported. The main diffusion coefficients (D11 and D22) and the cross diffusion coefficients (D12 and D21) were reported as function of temperature and concentration of alkanolamines. The limiting conditions for the main diffusion coefficients and the cross diffusion coefficients were discussed at first, and a comparison between the ratios of the cross diffusion coefficients to the main diffusion coefficients for MEA and TEA was made. Finally, the dependence of the main diffusion coefficient Dik on the viscosity of solutions was investigated.
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  • Keisuke Fukui, Shingo Kouuchi, Yusuke Asakuma, Kouji Maeda
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 344-349
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    Ice was formed on a rotating cold cylinder, and the distribution of cations (i.e., K+, Na+, Mg2+ and Ca2+) between ice and water as a function of the operating variables of ice crystallization was discussed. Ice growth rate was controlled by the rotation speed and temperature of the cold cylinder. The shape of the ice formed on the rotating cold cylinder depended on the flow structure of Taylor vortices in the water solution. The effective distribution coefficients of the cations were extremely small compared with those in the fatty acid system. The effective distribution coefficients of the cations correlated well as a function of ice growth rate. According to the correlation model, pure ice can form if the ice growth rate is lower than the critical growth rate. The critical temperatures of the four cations showed no difference from each other, and increased with the supercooling temperature.
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  • Akihiko Ito, Masakuni Matsuoka
    Article type: Short Communication
    2008 Volume 41 Issue 5 Pages 350-353
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    Surfaces of L-Threonine (L-Thr) seed crystals placed in a supersaturated DL-Thr solution were observed under an optical microscope and an AFM to understand the effect of washing seed crystals with water on the purity drop during preferential crystallization. Similarly to a previous study, thin plate-like crystals of D-Thr were found to appear by the surface nucleation mechanism on the {210} faces of the seed crystals, when they had not been washed. For the case of washing, the {210} faces disappeared, and the {110} and {100} faces appeared in place of the {210} faces, and they grew to recover to form {210} faces. During the recovery, thin D-Thr crystals did not appear, but after the complete recovery were found to exist on the surface. From these observations, surface nucleation as the retardation mechanism of purity drop by the washing of seed crystals was proposed.
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Chemical Reaction Engineering
  • Aycan Gür, M. Emin Alkan
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 354-360
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    Boron minerals are crucial for our world. Colemanite, which is one of the most widely available boron minerals, has the chemical formula of Ca2·5B6O7·5H2O and a monoclinic crystal structure. The parameters selected for this study are particle size, reaction temperature, acid concentration, solid to liquid ratio and stirring speed. The dissolution rate of colemanite was found to increase with decreasing particle size and solid to liquid ratio, with increasing reaction temperature and acid concentration, while it was not affected by stirring speed. A model equation was constructed for the process. Employing graphical and statiscal methods, the dissolution rate, based on heterogeneous reaction model and evaluation of the experimental data and the mathematical model revealed that the dissolution process was found to be controlled by chemical reaction and the activation energy of this process was estimated to be 46.475 kJ mol–1. The mathematical model to represent the kinetics of this process can be expressed as: 1 – (1 – X)1/3 = 7.73 × 105 × (Rp)–0.2735 × (CA)0.1891 × (S/L)–0.2318 × e–5589.96/T × t.
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  • Masayuki Toyota, Takashi Aida
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 361-368
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    SO2 storage was performed on CuTa2O6 and its derivatives by repeating the cycle of oxidative sorption (SO2, 1000 ppm; O2, 3%) and reductive desorption (H2, 10%). Tantalum promoted the sorption of SO2 on CuTa2O6, and the synergetic oxidative sorption of copper and tantalum was investigated after several cycles. Observation of the specific surface areas of samples revealed that SO2 was absorbed also in the bulk of catalysts through synergetic oxidative sorption. XRD observation showed that the samples undergoing synergetic oxidative sorption were amorphous. Through observation of ammonia-TPD, it was found that the samples were comparable to super acid. Synergetic oxidative sorption was investigated on the physical mixture of copper oxide and tantalum oxide, as well as on the mixed oxides of CuO and MO (M = Nb, Cr, Ti and Zr).
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  • Baohua Liu, Teruoki Tago, Eri Fumoto, Jun-ichirou Hayashi, Takao Masud ...
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 369-373
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    To develop a method for converting paper sludge-derived tar to useful petroleum-related chemicals, the catalytic cracking of the tar over zirconia-supporting iron oxide catalysts (ZrO2/FeOX catalyst) in a steam atmosphere was examined. Useful aromatics such as toluene, ethylbenzene, and styrene are included in the tar at compositions of approximately 63% with the remaining 37% being unknown components. By applying the ZrO2/FeOX catalyst, the unknown components were effectively decomposed without decomposing the useful chemicals existing in the tar, and the concentrations of unknown components were decreased from 37 to 11%. Moreover, acetone and phenol were newly produced. The lattice oxygen of the FeOX was the active site for the catalytic decomposition of the unknown components in the tar, and the ZrO2 on FeOX had activity for decomposing H2O molecules, thereby yielding active oxygen species. The oxygen active species spilled over on the FeOX surface to regenerate the oxygen defects formed during the reaction. Accordingly, the catalytic activity and stability were due to the consumption and regeneration of the lattice oxygen.
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Process Systems Engineering and Safety
  • May Su Tun, Samavedham Lakshminarayanan, Genichi Emoto
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 374-383
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    The estimation of difficult and infrequently measured variables (composition, melt flow index, viscosity, etc.) using easily and frequently measured variables (temperatures, flow rates, pressure, etc.) is of industrial interest. From such multirate data (data available at different sampling rates), a mathematical model that relates the frequently measured variables to the infrequently measured variable is developed—this model is often referred to as the soft sensor. This work considers the development of soft sensors to predict the concentration of a hydrocarbon species R at the exit of a two-reactor train. Specifically, we examine the development of soft sensors (one for each reactor) using optimal window size and demonstrate the efficacy of multiple model based prediction.
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  • Seungjune Choi, Chang Jun Lee, Chonghun Han, En Sup Yoon
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 384-393
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    A new strategy for producing robust accident scenarios in quantitative risk assessment, which is performed in the process design or operation steps, is proposed. Worldwide chemical processes are in need of off-site risk assessment as well as the on-site risk management. Most governments over the world require industrial companies to submit proper emergency plans through the off-site risk assessment. However, there have been no systematic approaches or criteria for generating virtual accident scenarios reasonably, and it is very difficult to get the unified or coherent assessment results. To get over these shortcomings, this study proposes a strategy for analyzing process elements and then selecting and generating an accident scenario that simulates the worst accident most likely to happen, which should be given foremost consideration. The proposed scenario reasoning scheme consists of three types of knowledge base and four reasoning algorithms. The scenario reasoning structure consists of the following steps: macro decomposition, micro decomposition, equipment analysis, scenario selection, and the consequence analysis. In the macro decomposition, a process unit is selected through its function and the meteorological condition around the area. In the second step, the equipment behavior which consists of its property, flow rate, operating condition, safety devices, age, accident history and repaired history is analyzed using an equipment-screening algorithm, which is a sequential reasoning method. The analyzed process elements are ranked and risk grades are determined. According to the grades, risk assessment is performed. The result of the analysis enhances the reliability of the generated risk scenario and prevents the risks from being overestimated. The obtained result should be more helpful in the proper process design and emergency planning.
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  • Qing Guo, Masaru Noda, Hirokazu Nishitani
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 394-402
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    An objective function to determine the optimal operating conditions to produce polymers with a specified molecular weight distribution (MWD) in a continuous stirred tank reactor (CSTR) was formulated. Two polymerization cases were studied: free radical styrene polymerization and cationic isobutylvinylether polymerization. The optimization results of objective function J1 in view of finite weight fraction stopped near a curve that passes through a predefined optimal point instead of the target point for both cases. Objective function J2, based on two MWD parameters, was formulated to investigate the optimization result of J1. In the case of styrene polymerization, the optimization searches of J2 converged on the optimal point. On the other hand, in the case of isobutylvinylether polymerization, the optimal point cannot be obtained by minimizing J2. In this case, an additional constraint such as polymer concentration is needed to determine an optimal solution.
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  • Jun-Hyung Ryu, Soon-Ki Heo, In-Beum Lee, Jae Hak Jung
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 403-412
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    This paper presents a new methodology for simultaneous design and cyclic scheduling of multipurpose batch process. Two features in particular which were not explicitly addressed in the previous work are highlighted. First, the proposed design and scheduling model can address multiperiod operation. Second, production split ratio is determined in the model, while the previous research split the production ratio within a cycle according to convenience. In order to compute the solutions of the corresponding large scale MINLP problems, a decomposition methodology is presented by transforming the original MINLP problems into iterative MILP and NLP subproblems. Two numerical examples are presented to illustrate the applicability of the proposed methodology with comparison to the previous research.
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Biochemical, Food and Medical Engineering
  • Yoichi Kumada, Tomomi Kawasaki, Yoshinobu Sakan, Yasufumi Kikuchi, Shi ...
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 413-419
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    Effects of nucleotide sequences of polypeptide linkers on production of soluble single-chain Fv antibodies in E. coli were studied using scFv genes, in which genes of VH and VL domains were genetically linked with 4 types of linker genes with or without rare codons, namely genes of scFv (G4S)3, scFv (G4S)3R, scFv No. 10 and scFv No. 10NR. The transformants expressing scFvs having linkers with 3–4 rare codons (scFv (G4S)3R and scFv No. 10) could grow to higher cell concentrations under induction condition, while growth of the cells expressing scFvs having linkers without rare codon (scFv (G4S)3 and scFv No. 10NR) stopped after 3 h. Productivity levels of soluble scFv by cells expressing scFv (G4S)3R and scFv No. 10 were higher than those of scFv (G4S)3 and scFv No. 10NR. The specific productivity levels of inclusion bodies for scFv (G4S)3R and scFv No. 10 decreased in comparison with those for scFv (G4S)3 and scFv No. 10NR. This might show that decrease in the translation rate at the region coding polypeptide linkers with rare codons has a favorable effect for the subsequent folding process of scFv molecules. Furthermore, from a SPR analysis using an antigen-immobilized sensor chip, scFv (G4S)3R showed the same binding affinity as the original scFv (G4S)3. Thus, nucleotide sequences of polypeptide linkers are important to increase productivity of scFv expressed in soluble fraction. The nucleotide sequence of the flexible linker (G4S)3R used in this study may be useful for efficient production of various scFvs without loss of the binding affinity of target scFv.
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Micro and Nano Systems
  • Isao Kobayashi, Kunihiko Uemura, Mitsutoshi Nakajima
    Article type: Short Communication
    2008 Volume 41 Issue 5 Pages 420-426
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    The breakup phenomena of large oil-in-water (O/W) emulsion droplets in silicon microchannel (MC) array devices at low applied pressures were investigated by microscopic and high-speed observations. This study used two sizes of MC arrays, each of which consisted of uniformly sized MCs, slit-like terraces, and deeply etched wells. Monodisperse feed O/W emulsion droplets that had entered the MC arrays were broken up into fine droplets primarily by snap-off that occurs due to localized shear inside the MCs and by pinch-off due to interfacial tension effects inside the MCs or on the inlet side of a terrace. The average droplet size of the permeate O/W emulsions depended significantly on the MC size and exceeded the MC size by 1.2 to 1.4 times. Their coefficients of variation were 18% to 21%. The results obtained from preceding work were compared with the results for direct generation of O/W emulsion droplets using the same MC array device.
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Energy
  • Haibo Li, Lifeng Wang, Hideki Kawachi, Daisuke Saito, Makoto Sakurai, ...
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 427-432
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    CO2 adsorbent on anodic alumite for ethanol steam reforming was prepared by a dip-coating method. CO2 adsorption amount increased with the number of times the dip-coating was performed. The best results were obtained when the dip-coating was done more than 4 times, whereupon the adsorption amount increased drastically. Performance of the CO2 adsorbent at different temperatures was monitored and recorded. Also, cyclic adsorption–desorption on the selected sample was performed, the result of which shows that desorption at a lower temperature is preferred. The sample also exhibited excellent endurance.
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  • Akifumi Nakamura, Eiji Kiyonaga, Yukimasa Yamamura, Yoshihisa Shimizu, ...
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 433-440
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    Chicken manure feedstocks containing a suspended fine activated carbon catalyst were gasified by supercritical water gasification in an experimental pilot plant. A chicken manure feedstock of 2 wt% with 0.4 wt% of activated carbon was completely gasified, whereas the same feedstock without activated carbon was gasified with a carbon gasification efficiency of only 0.8. A feedstock of 10 wt% with 5 wt% of activated carbon was completely gasified. Our results indicate that suspended fine activated carbon is effective as a gasification catalyst. The data also confirm that use of a suspended activated carbon catalyst helps to prevent plugging in the gasification reactor.
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Environment
  • Yoshinori Saito, Hideto Sato, Yukio Sakabe
    Article type: Research Paper
    2008 Volume 41 Issue 5 Pages 441-446
    Published: May 20, 2008
    Released on J-STAGE: May 20, 2008
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    We investigated the use of Ba2TiO4 to remove CO2 from a flow gas at high temperatures. Experiments using a CO2/N2 gas and a vertical reaction tube showed that the CO2 concentration of the exit gas can be reduced to 1% or less at 500 to 800°C (and to even 0.1% or less at 600°C) when the space velocity (SV) of the flow is 2000 h–1. Also, the CO2 concentration changes for the gas mass flow at 700°C or lower. From the results of reaction rate analysis of Ba2TiO4 and CO2, at temperatures of 550°C and higher, the activation energy was 12.5 kJ/mol, indicating that this range is a diffusion-rate controlled area. The reaction rate had a linear correlation with the CO2 concentration from 500 to 800°C, and the estimated reaction degree was 0.96. These results indicate that Ba2TiO4 can effectively remove CO2 from exhaust gas at high temperatures.
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