JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
Online ISSN : 1881-1299
Print ISSN : 0021-9592
Search
Advanced search
OR
Browse
Search
Volume 27, Issue 2
Displaying 1-25 of 25 articles from this issue
Show all abstracts
    • |<
    • <
    • 1
    • >
    • >|
Review Paper
Original Papers
  • Pressure Fluctuations in a Multi-Solid Fluidized Bed
    Kyu Kyu Win, Wojciech Nowak, Hitoki Matsuda, Masanobu Hasatani
    1994 Volume 27 Issue 2 Pages 152-157
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.152
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The pressure fluctuations in a Multi-Solid Fluidized Bed (MSFB) are investigated under various experimental conditions with a lab-scale MSFB and a pilot-scale MSFB. The main purpose of the studies is to show the effect of coarse particles on pressure fluctuations in MSFBs and to identify the MSFB operating mode using power spectrum analysis. The dominant frequencies of pressure fluctuations are also determined under various experimental conditions. The pressure fluctuations show the difference in coarse particle bed behavior depending on whether fine particles are circulated or not.
    The power spectra of CFBs change qualitatively in the presence of a dense bed of coarse particles. If a sharp peak is observed in the power spectrum, it means that a dense bed of coarse particles exists in the bottom part of the riser; otherwise, coarse particles are dispersed in the riser and/or circulate in the reactor.
    View full abstract
    Download PDF (847K)
  • Effect of Secondary Air Injection on Axial Solid Holdup Distribution in a Circulating Fluidized Bed
    Yong Jun Cho, Won Namkung, Sang Done Kim, Sunwon Park
    1994 Volume 27 Issue 2 Pages 158-164
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.158
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The effects of secondary air ratio (0–50%), height of injection port (1.5–2.5 m) and injection types (radial and tangential) on the axial solid holdup distribution have been determined in a circulating fluidized bed (0.1 m I.D. × 5.3 m high). As the secondary air ratio is increased, solid holdup increases below the secondary air port, whereas it decreases slightly above the secondary air injection port. The dense bed height increases with increasing height of the secondary air injection port. Different types of secondary air injection system do not produce any significant difference in the overall axial solid holdup distribution. However, solid holdup just above the injection port in a tangential secondary air injection system exhibits somewhat higher values than those of radial secondary air injection system. The effect of secondary air injection on the axial solid holdup distribution in a circulating fluidized bed can be predicted by a modified freeboard-entrainment model with decay constants determined from the proposed correlation.
    View full abstract
    Download PDF (963K)
  • Uptake of a Few Divalent Heavy-Metal Ion Species from Their Aqueous Solutions by Coral Sand Heat-Treated at Various Temperatures
    Yoshitake Suzuki, Yasushi Takeuchi
    1994 Volume 27 Issue 2 Pages 165-170
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.165
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Mechanism and equilibrium relationships for the uptake of Cd2+, Cu2+ and Pb2+ by coral sand from their nitrate aqueous solutions were studied.
    The maximum amounts of Pb2+ and Cd2+ uptaken by coral sand dried at 403 K were about 1.3 and 0.9 mol·kg–1, respectively. That of Cu2+ was only about 1/100 that of Pb22+ at pH = 6.1–5.5. Equilibrium relationships between the concentrations of those ionic species and the amounts uptaken were expressed by either the Langmuir or the Freundlich isotherm.
    The amounts of those ions uptaken and the physical properties of the coral sand varied with the maximum temperature during treatment. For example, the B.E.T. specific surface area decreased with increasing heat-treatment temperature. This is due to the change in the crystallographic structure of calcium carbonate, which is the main component of the coral sand, from aragonite to calcite.
    View full abstract
    Download PDF (3132K)
  • Dissociation Equilibrium in Hydrolyzed Polyacrylamide Gel Accompanied by Swelling and Shrinking
    Shoichi Morohashi, Kazuhiro Hoshino, Toshisuke Sasakura
    1994 Volume 27 Issue 2 Pages 171-176
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.171
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    An experimental investigation concerning the dissociation equilibrium in a gel accompanied by swelling and shrinking was carried out by using hydrolyzed polyacrylamide gel and buffer or NaOH solution. It was found that the gel swelled or shrank to absorb or release mobile ions and water, and the degree of change depended on the pH of solutions. In the system of Na-type gel, -COONa, and buffer solution, the relationship between the degree of dissociation of the fixed carboxyl acid in gel and the concentration of hydrogen ions in the outer aqueous phase could be correlated by an equation based on the dissociation equilibrium. In the system of H-type gel, -COOH, and NaOH solution, though the mechanism differed according to pH, the relationships conformed to equations based on the reaction equilibrium. The analytical methods developed here may be expected to apply to the enriching separations of various polymer solutions and metal ions.
    View full abstract
    Download PDF (778K)
  • Predicting the Minimum Fluidization Velocity of Multicomponent Systems
    Jesusa Rincón , Jesús Guardiol ...
    1994 Volume 27 Issue 2 Pages 177-181
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.177
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    An expression is suggested to appropriately estimate the minimum fluidization velocity of either a perfectly mixed or a completely segregated multicomponent system. Based on experimental data from the literature and our own work it is found that agreement between predictions and experimental results is reasonably good in the context of the inherent limitation of the theory and the accuracy of the data.
    View full abstract
    Download PDF (743K)
  • The Effect of Charge Density on the Permeating Flux of Amino Acid through Positively Charged Membranes under Pressure Gradient
    Teruyuki Masawaki, Toyozo Hamada, Setsuji Tone
    1994 Volume 27 Issue 2 Pages 182-187
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.182
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Positively charged membranes having different charge densities were prepared. Ultrafiltration of aqueous amino acid solution was performed at various values of pH, concentration of amino acid in the feed solution, and operating pressure. The effect of charge density of the positively charged membrane on the solute flux was examined. Neither the volume flux nor the solute flux of amino acid at the isoelectric point was affected by the fixed charge of the membrane. On the other hand, both the volume flux and the solute flux in pH ranges below and above the isoelectric point decreased with increasing charge density of the membrane. According to the transport equations with respect to the volume flux and the solute flux, the permeation properties as determined from experimental data were successfully evaluated by considering the effective charge density of the membrane and the degree of dissociation of amino acid in pH ranges below and above the isoelectric point.
    View full abstract
    Download PDF (850K)
  • Analysis of Heat Demand and Supply in Multicomponent Distillation Systems
    Damrong Pradubsripetch, Yuji Naka, Zhang Fan
    1994 Volume 27 Issue 2 Pages 188-193
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.188
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The energy analysis of distillation systems, especially the identification of heating and cooling zones in a column, is useful in the application of various energy-saving technologies to the systems. A method of analyzing the heat demand and supply for a binary system has been established, but there are few practical applications for multicomponent systems. One of the reasons is that the installation of an intermediate heat exchanger in a multicomponent distillation system changes the composition profile.
    This paper proposes an energy analysis method for multicomponent distillation systems. With this method we defined appropriate locations of an intermediate heat exchanger, that is, heating and cooling zones, and its maximum exchangeable energy load. Especially, the relationships between the patterns of heating and cooling zones and the locations of pinch zones are investigated.
    As a result, the upper and lower hypothetical pinch zones in a multicomponent distillation column terminate the heating zone at lower temperature, and the cooling zone at higher temperature, respectively. The conclusions are generalized by using graphical representations of the composition profiles.
    View full abstract
    Download PDF (720K)
  • Segregation of Particles in Binary Solids Circulating Fluidized Beds
    Nobuyoshi Nakagawa, Dingrong Bai, Eiji Shibuya, Hideyuki Kinoshita, Ta ...
    1994 Volume 27 Issue 2 Pages 194-198
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.194
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The segregation pattern of particles in circulating fluidized beds, 0.097 m and 0.150 m in diameter and 3 m in height, was investigated by using two groups binary solid particles that are different in diameter and density. The influence of operating conditions on the extent of particle segregation were examined. An empirical correlation for describing the extent of segregation was proposed. For distinguishing the segregation/mixing flow pattern, a theoretical criterion was derived and a segregation diagram was then prepared.
    View full abstract
    Download PDF (2346K)
  • Gasification Reactivity of Coals Treated with Sulfuric Acid
    Yusaku Sakata, Tohru Matsutomi, Masao Matsunaga, Shigeaki Kasaoka
    1994 Volume 27 Issue 2 Pages 199-204
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.199
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Five coals (C: 76–88 wt%, daf) were treated with sulfuric acid, hydrochloric acid and nitric acid. The treated coal and the char were gasified with a H2O (24%)-N2 mixture and an O2 (2%)-N2 mixture at constant rates of 2°C/min and 20°C/min, and their reactivities were analyzed with our modified volume reaction (MVR) model. With nitric and hydrochloric acids, differences in coal properties and gasification rates among coals persisted after acid treatment. By contrast, after sulfuric acid treatment all of the coals showed similar levels of fixed carbon content and of moisture-holding capacity. These treated coals and chars show similar gasification reactivity. This confirms our previous proposal that the reactivity of coal char can be correlated with two characteristic properties of the parent coal: the fixed carbon content (FCf) and moisture-holding capacity (Ωf).
    View full abstract
    Download PDF (874K)
  • A Study of Oxygen-Vectors with a Model of Oxidation of Glucose in the Presence of Glucose Oxidase and Catalase
    Tai-Hsing Li, Yuh-Fan Su, Chia-Hong Hong, Teh-Liang Chen
    1994 Volume 27 Issue 2 Pages 205-210
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.205
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The oxidation of glucose in the presence of glucose oxidase and catalase was employed for studying the oxygen transfer enhancement in an aqueous solution by additions of both n-hexadecane and soybean oil. Like surface-active agents, antifoam agents can decrease the oxygen transfer rate dramatically and thus played an important role in the oxygen transfer process. In the absence of antifoam agents, addition of n-hexadecane or soybean oil to the reaction medium caused decreases in the oxygen transfer rate (OTR). The extent of decrease was greater in soybean oil than in n-hexadecane. The spreading coefficient of the oil on water was found to be adequate for explaining this phenomenon. If the antifoam agent KM-70 was added to the reaction medium, however, an increased OTR could be obtained with addition of n-hexadecane or soybean oil. The enhancement in OTR was thought to be due to the removal of the antifoam-agent molecules away from the air-water interface by the oil added. The enzyme kinetics was verified to be unaffected by additions of KM-70, n-hexadecane and/or soybean oil. The present enzyme system is therefore adequate as a model for studying oxygen-vectors.
    View full abstract
    Download PDF (2946K)
  • Product Distributions in the Liquid-Phase Oxidation of Cyclohexane over CoAPO-5
    Shiow-Shyung Lin, Hung-Shan Weng
    1994 Volume 27 Issue 2 Pages 211-215
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.211
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    CoAPO-5 has been found to be a potential catalyst for the one-step liquid-phase oxidation of cyclohexane to produce cyclohexanone and adipic acid (without any promoter being added and with no induction period). Effects of various reaction conditions, including catalyst loading (10–5–2.5 × 10–3 kg), concentration of cyclobexane (1.44–4.33 × 103 mol/m3), oxygen pressure (5–15 × 105 Pa), temperature of reaction (115–135°C) and amount of acetic anhydride (0–60 × 10–6 m3) on the conversion and selectivity of liquid-phase oxidation of cyclohexane using CoAPO-5 as catalyst have been investigated. The results reveal that the selectivity of adipic acid is higher at reaction conditions of higher cyclohexane concentration, higher reaction temperature (135°C) and higher oxygen pressure (15 × 105 Pa) before 4 hrs. Accumulated water in the reaction mixture will affect conversion and selectivity of reaction if its amount is large enough. Addition of acetic anhydride increases the rate of cyclohexane oxidation and the selectivity of cyclohexylacetate (from the esterification of cyclohexanol and acetic acid) and succinic acid but lowers the selectivity of adipic acid.
    View full abstract
    Download PDF (880K)
  • A Dynamic Model of Capillary Suction Apparatus
    D. J. Lee
    1994 Volume 27 Issue 2 Pages 216-221
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.216
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    A model for the dynamic behaviour of the wet front radius and the liquid saturation in a capillary suction apparatus (CSA) is developed. Governing equations based on mass/momentum balance are derived and solved numerically. The calculation shows that the effects of the initial conditions on system dynamics vanish rapidly, and that the system then evolves along a slow manifold which is independent of the initial conditions chosen. It is also noted that, after sufficient time, the log–log plot of the dimensionless wet front radius versus dimensionless time can be approximated by straight lines and the liquid saturation under the inner cylinder can be taken as constant with error less than 5%. The increase in solids concentration and/or the averaged specific resistance of cake increases the capillary suction time (CST) significantly. The proper range of experimental conditions is suggested. A rapid method based on the model for estimating the averaged specific resistance of cake is proposed and compared with experimental results.
    View full abstract
    Download PDF (739K)
  • Modeling of Multifrequency Infrared Multiphoton Dissociation for Laser Isotope Separation
    Yoshiki Okada, Kei Sunouchi, Shuji Kato, Hideo Tashiro, Kazuo Takeuchi
    1994 Volume 27 Issue 2 Pages 222-227
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.222
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    A mathematical model is proposed for multifrequency infrared multiphoton dissociation of polyatomic molecules with implications for laser isotope separation. In this model, the dissociation probability is expressed by the functional form based on the product of power-law terms for individual fluences. The data (on the fluence dependence of reaction volume) in the experiments performed on multiphoton dissociation of UF6 cooled at 90 K with multifrequency 16-μm laser beams are utilized to verify our proposed model. This model can show the fluence conditions for high contrast ratios where the dissociation probability for isotopically selective dissociation overwhelms that for nonselective dissociation.
    View full abstract
    Download PDF (2769K)
  • Monte Carlo Simulations of pVT Relations and Adsorption Equilibria of Ethane under Sub- and Supercritical Conditions
    Jun Yoneya, Tomoshige Nitta
    1994 Volume 27 Issue 2 Pages 228-234
    Published: 1994
    Released on J-STAGE: March 30, 2005
    DOIhttps://doi.org/10.1252/jcej.27.228
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Adsorption isotherms of ethane in slit pores of a single-plane wall model at 298 K and 323 K, from low to high pressures, are calculated by use of the Gibbs ensemble MC method. The two-site Lennard-Jones model (SS model) was used in the calculations by slightly adjusting the parameters of Jorgensen et al. (1984) to fit the experimental and calculated values of both vapor pressure and saturation liquid density of ethane near the critical point. The adsorption isotherms calculated from the SS model and those from the spherical LJ model, are found to be almost the same in shape and magnitude though slight differences are observed. That is, the maximum adsorption capacity of the SS model is slightly larger than that of the LJ model while the LJ model gives higher adsorption in the low-pressure region. The local density and orientational ordering of the dumbbell molecule of the SS model in slit pores are calculated. The molecular orientation to the surface is suggested to be sensitive to the ratio of the slit width and the site diameter.
    View full abstract
    Download PDF (1028K)
Short Communications
    • |<
    • <
    • 1
    • >
    • >|
feedback
 Top