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Volume 41, Issue 10
Displaying 1-12 of 12 articles from this issue
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Transport Phenomena and Fluid Engineering
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Ryuta Misumi, Makoto Tsukada, Kazuhiko Nishi, Meguru KaminoyamaArticle type: Research Paper
2008 Volume 41 Issue 10 Pages 939-946
Published: October 20, 2008
Released on J-STAGE: October 20, 2008
JOURNAL RESTRICTED ACCESSAn investigation of the power input required to suspend a high concentration of solid particles was carried out in a draft-tube stirred vessel. The relation between the “just complete suspension” rotational speed of an impeller and the power consumption was measured under various important operating conditions. It was found that the power consumption at just complete suspension was minimized when the ratio of the inner cross-sectional area of the draft tube to the outer cross-sectional area of the annulus was 0.6 when the discharge flow was in the down direction. In this case, the just complete suspension of a glass bead slurry of 600 μm particles at 40 vol% was achieved with low power consumption.View full abstractDownload PDF (2418K) -
Yasumasa Ito, Satoru KomoriArticle type: Research Paper
2008 Volume 41 Issue 10 Pages 947-952
Published: October 20, 2008
Released on J-STAGE: October 20, 2008
JOURNAL RESTRICTED ACCESSGas absorption experiments across the gas–liquid interface in a capillary tube were carried out to investigate the mass transfer efficiency in a micro channel. The test channel used was a glass capillary tube having a diameter of 0.5 mm and a length of 30 mm or 200 mm. Carbon dioxide (CO2) and distilled water were supplied into the capillary tube. The flow rates were varied widely to form various types of flow patterns. The CO2 absorption rate was measured by a total organic carbon meter. The results show that the gas absorption rate increases remarkably with the superficial gas velocity. The volumetric mass transfer coefficient, kLa, and the superficial gas velocity generally have a linear relationship, regardless of the superficial liquid velocity. The change of flow pattern does not drastically affect the kLa profile. The values of kLa in a micro-tube are generally larger than those measured by conventional gas absorption equipment.View full abstractDownload PDF (1771K) -
Zongyuan Xiao, Reginald B. H. Tan, Weibin ChenArticle type: Research Paper
2008 Volume 41 Issue 10 Pages 953-960
Published: October 20, 2008
Released on J-STAGE: October 20, 2008
JOURNAL RESTRICTED ACCESSBubble formation with chemical reaction and mass transfer at a submerged orifice is analyzed theoretically. The phenomena of both hydrodynamics and mass transfer with chemical reaction are modeled successfully by the combination of the interfacial element approach and the penetration theory. Instantaneous bubble shapes, bubble volume and bubble growth rate simulated by the new model are in a good agreement with experimental data. Instantaneous liquid phase mass transfer coefficient, mass transfer rate from bubble surface, and gas–liquid contacting area are also predicted.View full abstractDownload PDF (766K)
Separation Engineering
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Hsun-He Fang, Rome-Ming WuArticle type: Research Paper
2008 Volume 41 Issue 10 Pages 961-966
Published: October 20, 2008
Released on J-STAGE: October 20, 2008
JOURNAL RESTRICTED ACCESSHydrodynamic shear force is a major factor that affects the formation of cake. The filtration rate increases with the cross-flow velocity under a wide range of conditions. In this work, a simple cross-flow filtration system was simulated using a multiphase flow model and studied experimentally. The shear force distribution on membrane surface along flow direction was calculated directly. This technique of shear force analysis on the membrane surface is a useful tool for investigating how to reduce the fouling rate on the membrane and improve the efficiency of cross-flow microfiltration.View full abstractDownload PDF (2506K)
Chemical Reaction Engineering
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Bidhan Chandra Bag, Makireddi Sai, Krishnamurthy Sekhar, Chiranjib Bha ...Article type: Research Paper
2008 Volume 41 Issue 10 Pages 967-972
Published: October 20, 2008
Released on J-STAGE: October 20, 2008
JOURNAL RESTRICTED ACCESSThe reaction kinetics of formation of N,N′-Dichlorobis-(2,4,6-trichlorophenyl)-urea (CC2) from bis(2,4,6-trichlorophenyl)urea (HCC) by N-chlorination using hypochlorous acid as chlorinating agent has been studied at various temperatures in a batch reactor. Experiments were carried out at different stoichiometric reactant ratios. Analysis of the experimental data by Integral method indicated that the reaction follows a second order kinetics. The effect of temperature on the reaction rate has been determined using Arrhenius equation. The graphical analysis yields an activation energy, Ea = 39.7456 kJ mol–1 and the frequency factor, ko = 1.49554 × 106 L mol–1 min–1. The kinetic data obtained by this study will be of immense help to design engineers for designing a plant of industrial capacity.View full abstractDownload PDF (805K) -
Masatsugu Yamagishi, Hirotsugu HattoriArticle type: Short Communication
2008 Volume 41 Issue 10 Pages 973-975
Published: October 20, 2008
Released on J-STAGE: October 20, 2008
JOURNAL RESTRICTED ACCESSIt is well known that, in the case of traditional spouted bed without a draft-tube, there exists a maximum spoutable bed height, beyond which stable spouting is no longer possible, and also that there is no limitation on the bed height in the case of a spouted bed with a draft-tube. However, to date, there has been no report that a minimum spoutable bed height, or lower limit of the bed height, exists in any type of spouted bed. It was, however, found that there exists a minimum spoutabe bed height in a screen-bottomed spouted bed. The screen-bottomed spouted bed has a draft-tube, but it has no gas-inlet nozzle or orifice. The gas is fed uniformly over the cross-section of the vessel. When the bed height was less than the minimum spoutable one, the solid particles in the annulus were fluidized and then stable spouting could not be achieved.View full abstractDownload PDF (595K) -
Naruyasu Okamoto, Toshiaki MatsuoArticle type: Short Communication
2008 Volume 41 Issue 10 Pages 976-979
Published: October 20, 2008
Released on J-STAGE: October 20, 2008
JOURNAL RESTRICTED ACCESSThis study examines reaction orders for concentrations of catalyst (tin octoate) and initiator (n-dodecanol) in the rate equation of PLA ring-opening polymerization. At first, the rate equation was proposed with their orders taken into account. Then, polymerization experiments were carried out on a flask scale to measure the time dependences of temperature and conversion ratio. The orders and the reaction rate constant were decided using the experimental results and mean square method. Reaction rate was nearly proportional to concentrations of both tin octoate and n-dodecanol. The ΔE≠ and k0 were 95.4 kJ/mol and 1.35 × 105 m3/(mol·ppm·s), respectively.View full abstractDownload PDF (524K)
Micro and Nano Systems
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Tomofumi Shiraishi, Takeyuki Kondo, Tsutomu Kawamura, Masashi OdaArticle type: Research Paper
2008 Volume 41 Issue 10 Pages 980-987
Published: October 20, 2008
Released on J-STAGE: October 20, 2008
JOURNAL RESTRICTED ACCESSSynthesis experiments and numerical analyses were conducted for competitive-consecutive reactions in microchannels in order to verify an evaluation method of chemical reactions by dimensionless numbers. The bromination reactions of dimethylphenol were used as models for the competitive-consecutive reactions. It was experimentally demonstrated that the product yield of the primary reaction depended on two dimensionless numbers: the mixing-reaction number which is the ratio of the diffusion time to the reaction time in the chemical reactions and the ratio of the secondary reaction rate to the primary reaction rate. The product yield of the primary reaction increased with decreasing mixing-reaction number and decreasing reaction rate ratio. The reaction rate constants of primary and secondary reactions could be evaluated by comparing the experimental results with calculated results. The evaluation of the diffusion length necessary to achieve the target product yield became possible using the evaluation diagram of the product yield of the primary reaction.View full abstractDownload PDF (2972K)
Materials Engineering and Interfacial Phenomena
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Keita Kubo, Takahiko Ban, Akihisa ShioiArticle type: Short Communication
2008 Volume 41 Issue 10 Pages 988-991
Published: October 20, 2008
Released on J-STAGE: October 20, 2008
JOURNAL RESTRICTED ACCESSThe instability at the boundary of particulate zone in gel, which is formed by the reaction-diffusion kinetics, is found. This takes place within a restricted region of the electrolyte concentrations in the reservoir. This suggests the presence of an excess energy in the boundary of the particulate zone. Possible explanations are discussed on the origin of the excess energy. This may be related to pattern formations of particulate zone in gel, which has provided a fundamental interest in science and technology for long years.View full abstractDownload PDF (1521K)
Energy
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Kazuo MatsudaArticle type: Research Paper
2008 Volume 41 Issue 10 Pages 992-996
Published: October 20, 2008
Released on J-STAGE: October 20, 2008
JOURNAL RESTRICTED ACCESSIn the 2000 fiscal year, we started a three year research project, which is the first study applying “area-wide pinch technology analysis”, supported by the New Energy and Industrial Technology Development Organization (NEDO), an affiliated organization of Japan’s Ministry of Economy, Trade and Industry. We have found a large amount of energy saving potential by the energy sharing between multiple sites in one major industrial area, which is a heavy chemical industry field. The found potential is 641,000 kL/year, annual crude oil conversion in the Chiba industrial area, which is one of the biggest heavy chemical complexes in Japan, which is almost the amount of crude-oil consumption in one day for all of Japan. We could establish a method of application of area-wide pinch technology analysis and a procedure to develop an energy sharing project between two sites in the industrial area. It is convincing that area-wide pinch technology could be helpful and useful to provide optimal information for energy saving in an industrial area.View full abstractDownload PDF (839K)
Environment
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Jiayu Xu, Yang Gao, Shigehisa Uchiyama, Toshiaki SodesawaArticle type: Research Paper
2008 Volume 41 Issue 10 Pages 997-1002
Published: October 20, 2008
Released on J-STAGE: October 20, 2008
JOURNAL RESTRICTED ACCESSIn order to understand the average concentrations of ambient volatile organic compounds (VOCs) in the urban atmosphere of Beijing, a diffusive sampling device (DSD-voc) was used to adsorb VOCs. The adsorbates were analyzed by gas chromatography/mass spectrometry (GC/MS) using a thermal desorption cold trap injector (TCT) and determined according to the EPA Method TO14. Sampling for 24 h a day was conducted at five sites continuously for one week from October 24 to 30, 2006. Sixteen VOCs were detected and the weekly average values were calculated for each site, with the maximum and minimum VOC concentration values of 135.1 and 77.3 μg/m3. Benzene, toluene, ethylbenzene, m,p-xylenes and o-xylene (BTEX) account for almost three quarters of the detected VOCs and these correlate well with each other among sites, suggesting the main emission sources are vehicular emissions.View full abstractDownload PDF (935K) -
Tserendorj Bolortamir, Ryuichi EgashiraArticle type: Research Paper
2008 Volume 41 Issue 10 Pages 1003-1009
Published: October 20, 2008
Released on J-STAGE: October 20, 2008
JOURNAL RESTRICTED ACCESSWe applied Mongolian natural zeolite to adsorptive removal of hexavalent chromium contained in tannery wastewater. At first, characterization was carried out for various kinds of natural zeolites obtained from Tsagaan Tsav and Urgon deposits in Dornogovi province, southeast part of Mongolia. From the X-ray diffractometry analysis, the zeolite samples were composed of mordenite, quartz, gismondine, clinoptilolite, and chabazite, and many of the samples contained clinoptilolite, which is the most abundant natural zeolite. The BET surface areas and the pore volumes of the samples were much lower than those of pure zeolites, and ranged from 15 to 160 m2·g–1 and from 0.03 × 10–6 to 0.1 × 10–6 m3·g–1, respectively. A part of the zeolite samples were modified by a metal cation, barium cation, in order to adsorb hexavalent chromium, which is anion of chromate in aqueous solution. The content of barium in the modified zeolite was much higher than that in the unmodified one, so that the successful zeolite modification could be confirmed. Secondly, batch equilibrium adsorptions of hexavalent chromium from aqueous solution, the model tannery wastewater, by the natural zeolites were carried out. Although the adsorption performances varied with the natural zeolite, all of the zeolites modified by barium cation could adsorb hexavalent chromium favorably and the fractional removal was over 0.9 at maximum, while the unmodified ones could not almost at all. The higher solution pH gave the higher adsorption performance and, then, main adsorbate was CrO42–, since this species is dominant in higher pH according to the speciation of hexavalent chromate anion. Consequently, we proposed to utilize Mongolian natural zeolite to treat the tannery wastewater containing hexavalent chromium.View full abstractDownload PDF (568K)
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