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Volume 20 (1994)
- Issue 6 Pages 733-
- Issue 5 Pages 595-
- Issue 4 Pages 463-
- Issue 3 Pages 321-
- Issue 2 Pages 141-
- Issue 1 Pages 1-
Predecessor
Volume 20, Issue 3
Displaying 1-20 of 20 articles from this issue
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Takashi Ueno, Kohei Kawanishi1994 Volume 20 Issue 3 Pages 321-329
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSThe corrosion of tubes in the steam generators of pressurized water reactor nuclear power plants has become a problem. The corrosion is thought to be caused by highly concentrated impurities within the crevice between tube and tube support plate. An experimental study of chemical concentration for various crevice types has been performed, and an experimental method to obtain the maximum concentration ratio within the crevices has been developed.
It was found that the concentration ratio tends to be saturated with time and the saturated centration ratios Kf for various crevice types were obtained as follows. Kf=105107 for D-type (combination of circular tube and circular tube hole of tube support plate), Kf=103 tor BEC-type (combination of circular tube and tube hole having a flat-surfaced tube support plate), and Kf=45 for ribbed-tube-type combination of ribbed tube having 4 ribs at circumferential positions of tube and circular tube hole of the tube support plate. The latter two types of crevices are usable in the actual steam generator to reduce the potential of chemical concentration within the crevice.View full abstractDownload PDF (1121K) -
Yozo Takemura, Tsuneo Enokido, Toshiro Terakawa, Motoyuki Suzuki1994 Volume 20 Issue 3 Pages 330-338
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSThe fabrication process and the properties of the developed reticulated iron are as follows.
1) It is possible to make reticulated iron by sintering pig iron powder (chemical composition, 34 wt%C, 39 wt%O, <0.1 wt% Si, <0.3 wt%Mn, <0.04 wt%P, <0.04 wt%S, mean particle size 10, am) coated on urethane-foam with several binders under a non-oxidizing atmosphere.
2) Most surface iron oxides in the powder are rapidly reduced by the carbon in the powder at a temperature between 600 °C and 800 °C. The sintering reaction proceeds relatively fast from 700 °C because metallic iron reduced from iron oxides is active. If the O/C ratio of the powder composition is less than 1.2, it is impossible to make stable product because of partial melting due to eutectic reaction during sintering.
The product properties mainly depend on the powder compositions, sintering conditions and urethane foam's porosity. Representative properties of the product are as follows ; bulk density (0.61.4 g/cm3), bending strength (1.59 MPa), pressure drop (80-170 Pa at a ventilation rate of 2.5 m/s) porosity rate (8095 %) and specific surface area (0.1-1.0 m2/g).View full abstractDownload PDF (9324K) -
Fujio Watanabe, Jun Kozuka, Junya Ozaki, Mikio Kumita, Masanobu Hasata ...1994 Volume 20 Issue 3 Pages 339-345
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSA silica gel-tube module (ST-module) was provided as a heat exchanger for an adsorption heat pump (AHP). A multiple adsorbent-tube (MAT) type adsorber containing the ST-modules was proposed and applied to the AHP for the silica gel/ water vapor system. Heat transfer characteristics in the AHP with the MAT-type adsorber were studied on the basis of the results compared with those in the AHP with a packed bed type adsorber.
Both the maximum temperature rise in the evaporator and the times required to reach the initial temperatures in the adsorption and desorption processes for the AHP with the MAT-type adsorber were reduced to about one-tenth of those for the AHP with the packed bed type adsorber. In the evaporator of this AHP, cold heat below 280K was obtained at the adsorption process. Based on pressure profiles of water vapor in the adsorption process, it was found that the pressure difference between the adsorber and the evaporator contributed to pumping-up of the heat in the AHP. Therefore, enhancement of heat transfer in the adsorber of the AHP was achieved and the possibility of its application to an airconditioner for producing cold heat energy was suggested.View full abstractDownload PDF (775K) -
Hideo Miki1994 Volume 20 Issue 3 Pages 346-351
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSA former type manufactured as a crystallizer for aluminum hydroxide could not solve the problem of the violent defacement of a stirring impeller by the suspended crystals was serious.
In the operation of a new type of crystallizer designed for the reduction of the problem, large crystal size changes with elapsed time occurred owing to the imbalance between the number of secondary nuclei and the number of crystals drawn out. Therefore, for the maintenance of number balance in secondary nuclei and the crystals, a hydrocyclone for the purpose of the recovery of fine crystals suspending in the reflux solution from the crystallizer to the etching tank used as the surface treatment of aluminum formations, and a pump to circulate a part of the crystals suspended in the solution in the crystallizer was installed as a secondary nuclei generator.
It became possible to maintain the stability of product size and low degree of supersaturation, operating the pump as a nuclei generator for the maintenance of the fraction of fine particles in product crystals.View full abstractDownload PDF (4572K) -
Yukiyoshi Yamada, Hiroshi Murata, Eiji Shinoda, Koichi Iinoya1994 Volume 20 Issue 3 Pages 352-359
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSWhen particle diameter falls below a few microns, particles tend to agglomerate and hence to degrade the performance of air classifiers. The dispersion of agglomerated particles is a key technology to improve classification accuracy.
The dispersion effect of a ring nozzle jet on dry powder was examined. Fine alumina and toner were used as the sample powders. The performance can be expressed by a dispersability index, based on the size distributions of the powder before and after dispersion. Both powder concentration and air velocity at the nozzle throat were found to affect the dispersion performance, the dispersing boundary being determinable from these values. Dispersing boundary curves for fine alumina (D50=1.0 μm) and toner (D50= 6.4 μm) were obtained by experiments.
Classification performance, classification sharpness and division indices, for fine alumina and toner powders were improved by mounting the disperser immediately in front of the classifier.View full abstractDownload PDF (1041K) -
Yasuo Koseki, Nobuko Hashimoto, Kazuhiko Takino, Toshihiko Kaneko, Syu ...1994 Volume 20 Issue 3 Pages 360-366
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSTo improve the performance of a water purification system (WPS), water quality was measured using TOC (total organic carbon) and the removal rate of each treatment apparatus comprising the pure water process (PWP) line of WPS was evaluted.
The activated carbon (AC) adsorption tower had a lower TOC removal rate (13 %), but was useful for improving the TOC removal rate for reverse osmosis (RO).
From data analysis using TOC removal model of each apparatus with molecular weight (MW), it was thought that the AC tower was good for removing TOC components (MW : 501000) that were difficult to remove for RO.
Based on impurities removal analysis of both PWP line and ultrapure water process (UWP) line, a high-performance water purification system with a hybrid adsorption tower and a water quality control system using TOC and TS (total solid) monitor was proposed.View full abstractDownload PDF (1131K) -
Yoshiaki Sawada, Yoshiteru Kageyama, Masashi Iwata, Shigehisa Harada, ...1994 Volume 20 Issue 3 Pages 367-372
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSA technique for controlling secondary particle length and magnetic properties of ultrafine iron particles prepared by pyrolysis of Fe (CO) 5 were studied.
The distributions of length of the secondary particles are almost log-normal and their geometric standard deviations are 1.31.9. The length of secondary particles is closely related to the primary particle diameter ; the larger the diameter, the longer the length. It is affected by the feed concentration, residence time and pre-decomposition ratio of Fe (CO) 5. The strength of magnetic flux in the axial direction of the reactor also affects the length of secondary particles ; the length increases with increasing strength and becomes constant above a strength of 0.15T. The coercive force of the iron particle powder reaches its maximum value of 120 kAm-1 at a primary diameter of 2025nm. The squareness of video tapes is improved by using longer secondary particles. The static magnetic properties of video tapes and floppy disks prepared by the present iron particles compete with those of commercial ones.View full abstractDownload PDF (2993K) -
Kazuhiro Takeda, BohYoh Shibata, Yoshifumi Tsuge, Hisayoshi Matsuyama1994 Volume 20 Issue 3 Pages 373-381
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSIt is a weak point of the algorithm of fault diagnosis utilizing the signed digraph with delay that we cannot quantitatively estimate the affect of errors in delays on its diagnostic accuracy. In this paper, an algorithm of fault diagnosis is proposed in order to give the values of membership function to the candidates for the origin of failure by representing delays in fuzzy numbers. And a concept of the information content of the diagnostic result is presented to make a quantitative estimation of the diagnostic accuracy. Furthermore, experiments with the use of a mini-plant demonstrate that the amount of information of the diagnostic result by the proposed algorithm is little affected by the errors in delays.View full abstractDownload PDF (1344K) -
Yoshitomo Hanakuma, Takashi Sasaki, Kazutoyo Nakaya, Hidehito Iwase, E ...1994 Volume 20 Issue 3 Pages 382-386
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSA method to estimate dynamic characteristics of a process in control design by a simple genetic algorithm is developed. The method proposed in this study has the advantage of simultaneous determination of the dead time, which cannot be realized in the usual statistical modeling method. This method was applied to the reaction temperature of a catalyst synthesis column in a polypropylene plant to confirm the design philosophy. The result indicates that the proposed method is effective in identifying dynamic characteristics of the process.View full abstractDownload PDF (621K) -
Kazuo Nishii, Masayuki Horio1994 Volume 20 Issue 3 Pages 387-396
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSFailure behavior of fine powder beds by upward air flow was investigated experimentally with a two-dimensional column to clarify the mechanism of agglomerate formation in the bed. To analyze the crack formation process the stress distributions in beds of uniform structure were calculated with the finite element method based on an elastic model.
In any case the first step of the failure process was crack formation by the pressure gradient due to air throughflow in the bed. However, the second step depended on bed conditions.
In beds of cohesionless powders, the particles around cracks were easily agitated and locally fluidized by the penetrating air. Similar situations were observed in the case of cohesive powders if the bed was loosely packed. In beds of densely packed cohesive powders no agitation and fluidization were created immediately.
Primary cracks were formed at the bed bottom on wall sides. The stress distribution prediction by the finite element analysis with the elastic bed model provided satisfactory implications for the observed crack formation.View full abstractDownload PDF (8915K) -
Jusuke Hidaka, Junya Kano, Atsuko Shimosaka1994 Volume 20 Issue 3 Pages 397-404
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSA new theory to estimate the state variables of flowing particles in a bin-hopper system was presented. The flowing behaviour of particles in the system was simulated by the particle element method. It was suggested that converging of the flow path of particles in a hopper leads to the change of bulk density of flowing particles, where by particles in a hopper flow intermittently. On the basis of microscopic behaviour of flowing particles observed by the simulation, a flow model was derived to analyse the flow of particles in a conical hopper. The values and fluctuation of dynamic pressure acting on the wall during the flow of particles in a bin-hopper system were estimated and the generation mechanism of over pressure during flowing of particles was also presented on the basis of the model.View full abstractDownload PDF (1296K) -
Yoshiro Kitamura, Qingfa Huang, Teruo Takahashi1994 Volume 20 Issue 3 Pages 405-410
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSThe superheat limit of water-in emulsions was.experimentally investigated to provide fundamental information about microexplosion of emulsified fuels. The water-in-kerosene emulsions were prepared by a mechanical homogenizer and stabilized by Span 80; the mass fraction of dispersed phase was 1-60wt%. The emulsion samples were heated in a glass capillary of 1.14 mm diameter at the rate of 3 K/min. The 30-40 samples were used to determine the superheating temperature distribution. The superheating temperature decreases with increasing fraction of the dispersed phase. To explain such an effect, we suggest a model in which surfactants absorbed on the oil-water interface accelerate the nucleation rate. This model predicts that the increase in surface area reduces the superheating temperature; the superheat limit consequently decreases with increasing fraction of the dispersed phase. The prediction from this model is in good agreement with the experimental data.View full abstractDownload PDF (766K) -
Nobuyoshi Asai, Kazuhiro Tajiri, Genji Jimbo, Shigeki Toyama1994 Volume 20 Issue 3 Pages 411-417
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSIn this report, assuming that a kinetic resistance of packings (grinding media, etc.) in a mill pot is a viscous resistance, and to changes in phase angle generated by it in an equation of vibration, by taking photos of respective center positions and directions of mill body, driving shaft and vibrating unbalance weight from the outside, without attaching directly any measuring device to a vibrating ball mill unit body, one method capable of obtaining the energy consumed by vibrating ball mills was established with considerable accuracy by calculating moments applied to each above-stated component.View full abstractDownload PDF (2176K) -
Tomohiro Wada, Naotake Katoh1994 Volume 20 Issue 3 Pages 418-422
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSIt is well known that sustained oscillations in solute concentration often take place in a continuous crystallizer. From the standpoint of crystallizer operation, it is indispensable to clarify the effects of crystallizer instability on the crystal size distribution. In this work, relations between the instability and the crystal size distribution were examined both by simulation and by experiment. Mixtures of NaCl, water, and ethanol were used in the experiment.
It was observed that sustained oscillations were propagated from the fine-size crystals to the large-size crystals.View full abstractDownload PDF (596K) -
Hajime Ino, Koichi Tabei, Masao Fujishige, Mitsunori Hozawa1994 Volume 20 Issue 3 Pages 423-430
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSIn the ordinary high-voltage A.C. electric demulsification of W/O emulsion for liquid surfactant membranes, the breaking of the submicron droplets has been reported to be difficult.
In this work, by making the distance between the electrodes short in an A.C. electric demulsifier the submicron droplets were successfully broken.
In the experiments, the oil phase was kerosene with Span 80 as the surfactant, and the inner aqueous phase was NaCl solution for the non-extraction system and H2 SO4 solution for the extraction system. The original W/O emulsion, which was made with a disperser, was demulsified by an ordinary A.C. electric demulsifier.
The oil phase containing unbroken submicron droplets was used as the sample emulsion.
For the extraction system, W/O emulsion which experienced the extraction of Cu was used as the original emulsion.
It was found experimentally that the submicron emulsion can be demulsified by making the distance between the electrodes as short as 10 mm.
The effects of water concentration C [mol.m-3], surfactant volume fraction Cs [-], electrical potential E [V.m-1] and temperature T [K] on the demulsification rate, dC/dθ, was correlated by the experimental equation.
dC/dθ=-k·E·Cs-1.8·C3·exp (-E0·R-1·T-1)
Where θ [s] is time, R [J·mol-1·K-1] is gas constant, E0 [J·mol-1] is apparent activation energy and k [m7·mol-2·V-1·s-1] is constant; E0=43.0×103, h=1.54× 10-8, for the non-extraction system and E0 =53.9× 103, k= 4.4×10-6 for the extraction system.View full abstractDownload PDF (983K) -
Study of reactions in the UT-3 thermochemical hydrogen production cycleMakoto Sakurai, Naoto Miyake, Atsushi Tsutsumi, Kunio Yoshida1994 Volume 20 Issue 3 Pages 431-436
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSThe bromination of CaO-pellet, which is a reaction of 4-step UT-3 thermochemical hydrogen production cycle, was analyzed. It was found that CaBr2 was distributed in the pellet homogeneously after the completion of bromination. A reaction model of the bromination of CaO consisting of two kinds of agglomerates, CaO and CaTiO3, was proposed based on the result of structural change analysis. The simulated results showed good agreement with experimental results of four kinds of Ca-pellets with different molar ratios of CaO to CaTiO3.View full abstractDownload PDF (2371K) -
Yoshihito Kato, Setsuro Hiraoka, Yutaka Tada, Takashi Mori, Seiji Shir ...1994 Volume 20 Issue 3 Pages 437-444
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSThe mixing time of liquid in a horizontally shaking vessel, which was moved circularly at low shear stress, was measured by the electric conductivity method.
The flow pattern of liquid in the shaking vessel was visualized by the tracer method.
We observed the minimum circulating frequency for the complete mixing in the horizontally shaking vessel, which is referred to as “critical circulating frequency Nc”. Nc was empirically correlated with the vessel diameter D, the circulating diameter d and the kinematic viscosity of liquid v in our experimental ranges.
Nc=0.70D-0.44d-0.22ν0.06
The mixing time tm was well correlated with the circulating frequency N and the vessel diameter D by using the critical circulating frequency Nc as a parameter.
tm=114.8 (N-Nc) -1.3D1.0
In addition, the observed flow patterns were divided into two flow types, i.e., the progressive wave type (N ≤ Nc) and the rotational flow type (N ≥ Nc). Thus it was concluded that the complete mixing state could not be acheived with the progressive wave type.View full abstractDownload PDF (5293K) -
Control of catalytic activity by adjusting the sulfur contentChang Wang, Takayuki Takarada, Yuichi Fusegawa, Nobuyoshi Nakagawa, Ku ...1994 Volume 20 Issue 3 Pages 445-452
Published: May 15, 1994
Released on J-STAGE: February 19, 2010
JOURNAL FREE ACCESSIn a process of catalytic pyrolysis of coal using a powder-particle fluidized bed (PPFB), effects of sulfur content in the catalyst material were investigated, in order to obtain higher yield of light aromatic hydrocarbons. The pyrolysis of Taiheiyo coal was carried out by using commercial catalyst material, and the variations of products distributions and their yields with sulfur content in the catalyst adjusted by sulfuric acid were measured. It was found that catalytic activity can be controlled by adjusting the sulfur content. In the case of CoMo/Al2O3 (S : 2.26wt%), 7.2 [wt%, daf] of light aromatic hydrocarbons, i.e, benzene, toluene, xylene and naphthalen (BTX : 5.3 [wt%, daf], N : 1.9 [wt%, daf]) were obtained under the conditions of bed height of 0.08m, hydrogen flow rate of 0.24m·s-1 and pyrolysis temperature of 903K. Their yields were as high as that reported in the previous paper, but the amounts of catalyst loading and hydrogen flow rate were smaller.View full abstractDownload PDF (891K) -
Koichiro Shiomori, Yoshinari Baba, Yoshinobu Kawano, Tadashi Hano1994 Volume 20 Issue 3 Pages 453-458
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSAdsorption equilibria of acetic, propionic, crotonic, oxalic, succinic, itaconic, maleic, lactic and citric acids on activated carbon were measured at 283, 303 and 323 K, over a wide concentration range. The amounts of organic acid adsorbed decreased with increasing temperature. The results in the low concentration range were explained on the basis of the Langumuir adsorption isotherm. The B.E.T. adsorption isotherm, howerer, explained the adsorption results over an entire concentration range. The monolayer and multilayer adsorption constants decreased with increasing adsorption temperature, and were influenced by the hydrophobic properties of the organic acid.View full abstractDownload PDF (689K) -
Toshio Kajiuchi, Jin Won Park1994 Volume 20 Issue 3 Pages 459-462
Published: May 15, 1994
Released on J-STAGE: November 12, 2009
JOURNAL FREE ACCESSIn order to obtain a modified cellulase which can be stable and soluble in both water and organic solvent, such as benzene or toluene, the cellulase was modified with three types of copolymer or polyoxyalkylene and maleic anhydride. These polymers are different in hydrophilicity. Although native cellulase looses its activity upon contact with organic solvents, the modified cellulases increase their stability with increase in the degree of modification. The modification with rather hydrophobic copolymer also showed solubility in the organic solvent phase.View full abstractDownload PDF (409K)
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