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Volume 32, Issue 1
Displaying 1-28 of 28 articles from this issue
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Thermodynamics, Physical Properties and Molecular Simulation
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Ying Hui Wang, Yasushi Sasaki, Kuniyoshi Ishii1999 Volume 32 Issue 1 Pages 116-122
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSThe solubilities of Ar in molten nitrate mixtures were measured by using a modified gas probe, which injected He into molten nitrate through a nozzle, collected ascending bubbles of He-Ar gas mixture, and determined the concentration of Ar in the He-Ar gas mixture. The solubilities of Ar in molten LiNO3, NaNO3, and KNO3 are determined as a function of the temperature from 463 to 513 K, and those of LiNO3-NaNO3, NaNO3-KNO3, and LiNO3-KNO3 binary systems are determined as a function of composition at 623 K.
From the Ar solubility in molten nitrate mixtures, the thermodynamical properties of molten nitrate mixtures and the interaction with Ar are investigated.View full abstractDownload PDF (1215K) -
Takeshiro Shigeta, Tomoshige Nitta1999 Volume 32 Issue 1 Pages 150-152
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSThe distribution coefficients of naphthalene between slitpores and supercritical carbon dioxide at infinite dilution are calculated by the Monte Carlo simulation method in the range of entrainer (benzene) concentration from 0 to 2%. The addition of a small amount of benzene decreases the distribution coefficient dramatically. It is found that added benzene molecules prefer to adsorb onto the wall surface in the pore phase, which increases the pore density and excludes naphthalene molecules.View full abstractDownload PDF (388K)
Transport Phenomena, Fluid Mechanics and Mixing
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Meguru Kaminoyama, Muneko Watanabe, Kazuhiko Nishi, Mitsuo Kamiwano1999 Volume 32 Issue 1 Pages 23-30
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSWe present a method of estimating local heat transfer coefficients on the wall of a stirred vessel for highly viscous liquids fitted with various types of impellers using only numerical simulation.
We analyze simultaneously specific flow and heat transfer behaviors in an unsteady state due to heating from the side wall of the vessel by finely dividing the analyzed region within a temperature boundary layer in the vicinity of the wall.
The fluids used for analysis are a highly viscous Newtonian and a non-Newtonian pseudoplastic liquid. The impellers used are a six-blade paddle, a double-helical ribbon and an anchor type.
We clarify the dynamic changes of the Nusselt number distribution along the vessel height direction from the beginning of heating to the pseudo-steady state, as follows: The distributions are rather flat and at high values just after the beginning of the heating. Subsequently, the values decrease as the temperature boundary layer develops. Further, the maxima of the values grow at the points of the vessel wall where the discharge flows from the impellers impinge.
We also clarify that there is no striking difference in flow and heat transfer behaviors, except for the apparent viscosity distribution around the impellers, for each impeller vessel regardless of whether it is pseudoplastic or Newtonian, provided that both, the initial Red and Pr number are set to be identical for the two liquids.
We ascertaine the reliability of the simulated estimates by verifying them with experimental results from a multi-point, real-time temperature measuring system which we have developed.View full abstractDownload PDF (1303K) -
Koji Takahashi, Shin-ichiro Sasaki1999 Volume 32 Issue 1 Pages 40-44
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSThe minimum impeller speeds for complete drawdown and concentration distributions of floating solids in an agitated vessel are measured for impellers used commonly in process industries, namely disc turbine impellers and pitched paddle impellers. A correlation for the minimum impeller speed is developed for disc turbine impellers and pitched paddle impellers rotating to create downward flow. The relatively uniform concentration distributions are obtained in spite of different impeller geometries compared to those reported for solids heavier than the liquid media.View full abstractDownload PDF (823K) -
Toshiro Miyahara, Seiji Hashimoto, Hitoshi Matsunaga, Yasuharu Akagi1999 Volume 32 Issue 1 Pages 91-96
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSExperiments were performed to investigate bubble splitting by turbulent fluid flow. A liquid jet was discharged vertically upwards through an orifice into a large volume of the same liquid. A shear layer was thus formed around the jet as it entered the surrounding liquid. A bubble rising through the jet splits in the shear layer. The measured size spectra can be well represented by an upper limit log-probability function with two constant parameters and only one variable, the maximum stable bubble diameter, dbmax. Therefore, the critical Weber number including the maximum stable bubble diameter is correlated as a function of the Reynolds number based on the mean liquid velocity through an orifice.View full abstractDownload PDF (27360K) -
Koji Arafune, Masahiko Sugiura, Akira Hirata1999 Volume 32 Issue 1 Pages 104-109
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSThermal Marangoni convection in fluids with various Prandtl numbers (o[10–3]∼o[103]) inside a rectangular open boat is investigated experimentally and numerically. In particular, for low-Prandtl-number fluids, e.g., liquid metal, the observation of Marangoni convection is very difficult, because the existence of metal oxides on the free surface disturbs the generation of Marangoni convection. However, development of a double crucible system and control of the atmosphere around the liquid metal have made such experiments possible. In the present experiments, the velocity at the center of the free surface under various conditions is measured. Using the experimental and numerical results, correlation equations are derived using dimensionless numbers, Re, Ma, Pr and A (aspect ratio). These equations are applicable for estimating Re, and for judging which of either Marangoni or buoyancy convections is dominant in the fluid.View full abstractDownload PDF (1086K) -
Hanifi Saraç, Ö. Korkut1999 Volume 32 Issue 1 Pages 130-133
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSExternal and internal natural convection mass transfer rates were investigated at both vertical and horizontal cylindrical tubes using the electrochemical technique. Measurements were carried out with
a.the tube outside surface only active (external flow)
b.the tube inside surface only active (internal flow)
c.both the tube outside and inside surface active (simultaneous external and internal flow)
The electrode length and the electrolyte concentration were varied at constant temperature. External natural convection mass transfer rates were in good agreement with literature data. Internal natural convection mass transfer at vertical electrodes rates depended on the diameter-to-length ratio (d/L) and concentration. In the case of simultaneous external and internal natural convection, the measured mass transfer rate for internal convection was lower than that for external convection. Results were correlated in terms of d/L ratio, Sherwood, Schmidt and Grashof numbers.View full abstractDownload PDF (673K) -
Liang-Huei Chen, Yuh-Lang Lee1999 Volume 32 Issue 1 Pages 138-141
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSA small amount of surface active agent in a extraction column has the effect of decreasing mass transfer coefficient, while increasing the mass transfer area. The overall mass transfer efficiency is thus varied complicatedly with the surfactant concentration and the hydrodynamic behavior of the two phase in the extraction columns. In this work, spray-tower and packed-tower are used as extraction columns to obtain the overall performance of the equipment. The effects of surfactant on the mass transfer efficiency and interfacial area in the two apparatuses are studied. The results show that the effects of SLS on the decreasing of mass transfer coefficient is more prominent than that on the increasing of mass transfer area in the both apparatuses. In the packed-tower, a higher efficiency is obtained due to the effect of the packing. However, at the presence of SLS, the dispersion effect can not raise the interfacial area high enough to overcome the simultaneous decrease in mass transfer coefficient. The mechanisms to increase interfacial area by the surfactant are different at various concentrations of SLS and different between the two apparatuses, which are also discussed in this article.View full abstractDownload PDF (630K)
Catalysis, Kinetics and Reactor Design
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Mohamed Nakoua, Mahmoud Dribika, Elmarghani Besher1999 Volume 32 Issue 1 Pages 126-129
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSA mathematical model has been developed for absorption accompanied by chemical reaction of H2S and CO2 in alkanolamine solutions encountered in plants for natural gas sweetening in Libya. The model has been used to calculate actual number of plates in industrial columns. The model results errors in number of trays predictions due to the lack of procedures for estimating interfacial area for the in between flow regime that prevailed in two industrial plants. The developed correlation for interfacial area estimation for the in between flow regime gives zero error in number of trays prediction.View full abstractDownload PDF (530K) -
Hsing-Ya Li1999 Volume 32 Issue 1 Pages 134-137
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSThe effect of external mass transfer on the steady state multiplicity is studied. We analyzed a complex system of heterogeneously catalytic reactions in an isothermal CSTR, where the concentrations in bulk fluid are different from those on the surface of nonporous catalysts. The system is proved to admit multiple steady states by a zero eigenvalue analysis and a set of parameters generating multiplicity is constructed. Numerical result shows the hysteresis and bistability occur for certain range of external mass-transfer coefficients. As increasing either the flow rate or the feed concentration of a reactant, it is necessary to increase the mass-transfer coefficient to maintain the multiplicity.View full abstractDownload PDF (545K)
Materials and Devices
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Kiyoshi Suzuki, Noriaki Mizutani, Makoto Harada1999 Volume 32 Issue 1 Pages 31-39
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSCadmium dioleylphosphate (CDOLP) and sodium dioleylphosphate (SDOLP) are expected to form rigid microemulsion droplets. They were used as surfactants in place of sodium bis (2-ethylhexyl) sulfosuccinate (AOT), which has been often used for the preparation of cadmium sulfide (CdS) ultrafine particles in microemulsion (ME). CdS ultrafine particles were prepared by mixing hydrogen sulfide solution with the ME composed of CDOLP and SDOLP. The growth process of the particles through their coagulation is restricted more strongly, and the size distribution of the obtained particles was sharper than those in AOT-ME. Furthermore, in CDOLP/SDOLP-ME, the average number of cadmium ions per microemulsion droplet is larger and the number of contaminating “empty” ME droplets which contain no particle is much smaller than in AOT-ME systems. Dioleylphosphates are proper surfactants for the preparation of ultrafine particles with sharp size-distribution, because particle coagulation is restricted in the system. The restriction of the coagulation between larger particles is attributed to two mechanisms: 1) It is hard for larger particles to be exchanged between two fusing ME droplets through the “open channel” between them. 2) The ME droplets with the larger particles can hardly coalesce with the other ME droplets.View full abstractDownload PDF (1735K)
Separations
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Hideki Mori, Chikara Ito, Akiyoshi Oda, Tsutomu Aragaki1999 Volume 32 Issue 1 Pages 69-75
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSThis paper presents a simulation algorithm with a rate-based model for a packed distillation column at total reflux.
The proposed algorithm consists of 1) composition and temperature profile calculation, which is slightly modified from the one for steady-state continuous distillation at finite reflux, and 2) composition correction for accelerating convergence with the overall θ method based on the component material balance considering liquid hold-up within the distillation column.
Simulation results are compared with the experimental results of a ternary system obtained from a 0.21 m diameter packed distillation column. Fairly good agreement is obtained, though proper evaluation of the effective interfacial area and liquid hold-up distribution is essential for better simulation.View full abstractDownload PDF (1042K) -
Kazuharu Yoshizuka, Yuko Fujimoto, Keisuke Ohto, Katsutoshi Inoue1999 Volume 32 Issue 1 Pages 76-81
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSIn order to develop an effective separation process for catecholamine (CA), a basic investigation on solvent extraction of dopamine (DA), adrenaline (Ad) and noradrenaline (NA) from hydrochloric acid solution and their stripping is conducted at 30°C employing bis(2-ethylhexyl) hydrogen phosphate (D2EHPA) in chloroform, n-hexane and toluene as the organic diluents. From the dependencies of the distribution ratios on the concentrations of reactant species, i.e. CA, hydrogen ion and D2EHPA, it is elucidated that CA (RNH2) is extracted with D2EHPA (HR′) according to the ion exchange mechanism, as the complex type, RNH3R′(HR′)3, and the equilibrium constants (Kex, CA) for the extraction reactions are also evaluated. The quantitative structure property relationship (QSPR) of Kex, CA values for each organic diluent is discussed using molecular modeling with semi-empirical molecular orbital calculations considering the solvent effect.View full abstractDownload PDF (940K) -
Masahiro Goto, Tsutomu Ono, Akihiko Horiuchi, Shintaro Furusaki1999 Volume 32 Issue 1 Pages 123-125
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSDeoxyribonucleotide (DNA) from salmon testes was successfully extracted by reversed micelles that are formed by a cationic surfactant in isooctane. The degree of extraction of DNA was strongly influenced by the type of surfactant in the organic solvent and ionic strength in the material aqueous phase. The driving force of the DNA transfer was electrostatic interaction between cationic surfactants and negatively charged DNA. Cationic surfactants possessing two long-alkyl chains are one of the best candidates for the successful transfer of DNA from an aqueous solution to a reversed micellar solution.View full abstractDownload PDF (508K) -
Gladys Paz T. Cruz, Susumu Nii, Fumio Kawaizumi, Katsuroku Takahashi1999 Volume 32 Issue 1 Pages 142-145
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSA simulation for multistage electrodialysis for separation of metal ions is developed. The experimental results for the separation of potassium and sodium ions by a 4-stage electrodialyzer are compared, and can be satisfactorily reproduced by the present simulation method. It is observed that the separation factor increases largely with increasing stage number and flow rate of reflux. The increase in the stage number is effective to achieve a large separation factor and a large recovery fraction of potassium.View full abstractDownload PDF (482K) -
Izumi Taniguchi, Hiroki Yokoyama, Koichi Asano1999 Volume 32 Issue 1 Pages 145-150
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSMass transfer in the absorption of lean NH3 with water spray is examined under various experimental condition, using a small spray column. The absorption rates of NH3 are affected by both gas- and liquid-phase mass transfer resistances in the vicinity of the nozzle exit. The observed gas phase diffusion fluxes of NH3 show good agreement with the empirical correlation by Ranz-Marshall.
Taking the effect of gas- and liquid phase mass transfer resistances on the absorption rates into consideration, a new simulation technique is proposed for the absorption of lean gas using a small spray column. The present model can accurately predict the amount of absorbed NH3 by water spray.View full abstractDownload PDF (734K) -
Yasuhiro Shiraishi, Takayuki Hirai, Isao Komasawa1999 Volume 32 Issue 1 Pages 158-161
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSPhotochemical desulfurization of light oils of different sulfur contents and aromatic components, such as straight-run light gas oil (LGO) and light cycle oil (LCO), in an oil/hydrogen peroxide aqueous solution two-phase liquid-liquid extraction system is investigated. The entire wavelength region of light from a high-pressure mercury lamp was utilized to realize the direct excitation of sulfur-containing compounds. In the case of LGO of high sulfur content, 77% of the sulfur is removed by 36 h of photoirradiation, and the quantity of sulfur removed from LGO is six-fold greater than that in the case of commercial light oil (CLO). Although the desulfurization of LCO is suppressed by the presence of large quantity of 2-ring aromatics, the sulfur content is reduced to less than 0.05 wt% to meet with regulations in Japan. GC-AED analysis shows that benzothiophenes in all the feedstocks are more easily desulfurized than dibenzothiophenes. Highly substituted dibenzothiophenes in LCO, especially those having substituted carbon number of 4–6, are hardly desulfurized by the proposed method.View full abstractDownload PDF (585K)
Particle Technology and Fluidization
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Yasuhisa Adachi, Setsuo OoiArticle type: Research Papers
Subject area: Thermodynamics, Physical Properties and Molecular Simulation
1999 Volume 32 Issue 1 Pages 45-50
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSThe volume of sediment composed of flocculated materials is expressed as a function of floc diameter and the number of contacts between flocs. In this expression, the sediment is considered as a randomly packed bed of identical flocs with fractal dimension (D), which is determined by the number of bonds between clusters. The validity of this expression was experimentally tested using a monodispersion of polystyrene latex spheres coagulated with simple electrolytes. In the region near critical coagulation concentration, the formed sediment is characterized by a small effective volume reflecting the extremely small size of flocs composing the sediment. In the region of sufficiently high salt concentration to induce rapid coagulation, bulky sediments made of well-developed flocs are observed. Fairly good agreement between theoretical prediction and experimental result is confirmed for the ultimate sediment volume when experiments are carried out with a low volume fraction of particles. It is found that the volume of the sediment and creaming agree with each other when the absolute value of density difference between the solvent and the particle is the same. This result is an indication that the strength of floc formed with polystyrene latex particles is finite and constant against the ionic strength in the region of rapid coagulation. In order to introduce the factor of floc strength against compaction, we tested the result of scaling analysis on the elastic modulus. The experimental data of the sediment volume versus colloid concentration are found to be consistent with this analysis.View full abstractDownload PDF (693K) -
Ken-ichi Kikuchi, Hiroshi Takahashi, Takatoshi Koike, Shigeki Chiba1999 Volume 32 Issue 1 Pages 162-165
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSThe effect of probe clearance on the rising velocity and chord length of bubbles in a bubble column was examined in measurements with the two-channel U-shaped optical fiber probe method. The probe clearances ranged from 0.2 to 1.5 cm. A few restrictions required in the signal processing to obtain the reasonable data. With increasing probe clearance, the observed values of the bubble velocities slightly increase; however, those of the bubble chord lengths drastically increase to 160% in the coalesced bubble regime, though they are almost constant in the dispersed bubble regime. A simple theory is proposed considering the probability of bubbles contacting with the probes, and used to successfully explain the experimental results.View full abstractDownload PDF (594K)
Process Systems Engineering
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Hideyuki Matsumoto, Chiaki Kuroda, Seppo Palosaari, Kohei Ogawa1999 Volume 32 Issue 1 Pages 1-7
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSA neural network model as a macroscopic model is proposed to estimate the impurity and yield of fractionated BSA monomer in gel filtration chromatography (GFC) when the viscosity of an injected bovine serum is high and its volume is large. In the neural network model, input variables, i.e. the partition coefficient of BSA, the injection interval, and the fractionation time coefficient, are selected referring to physical models published.
The trained network model shows sufficient predictive performance and applicability when data points are estimated by interpolation. Furthermore, it is seen that the sensitivity of output variables to the injection interval and the fractionation time coefficient can be easily estimated using the model. Consequently the neural network model is found useful enough to easily predict the results of changing the operation, especially when a large injection volume of a viscous sample causes nonlinear and unstable behavior in the GFC fractionation process.View full abstractDownload PDF (1026K) -
Niniek Fajar Puspita, Tetsuo Fuchino, Masaaki Muraki1999 Volume 32 Issue 1 Pages 15-22
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSHeat recovery systems (HRS) combine heat exchanging and heat pumping to decrease energy demand and improve energy quality, respectively. The synthesis of such a system involves configuring heat exchangers and heat pumps into a network. The problem is more complex than that of conventional heat exchanger synthesis problem, because of a combinatorial nature in properly selecting of heat pump matches (HPMs) and heat matches (HMs).
In this work, an evolutionary approach is developed by interactively searching for design variables into total cost effect. The method consists of an initial HRS and neighboring alternatives generation. In the initial generation, a thermodynamic priority is considered to introduce a most preferable configuration of HPMs into the network. In alternative generation, alternative configurations of HPMs are repeatedly introduced to obtain an optimal HPMs as a search variable. An algorithm is proposed to find efficiently the best HRS and its effectiveness is demonstrated through an illustrative example problem.View full abstractDownload PDF (1255K) -
Yoshiaki Shimizu1999 Volume 32 Issue 1 Pages 51-58
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSWith the aim of developing a flexible optimization method for managing conflict resolution, this paper concerns itself with site location problems under multi-objectives. As known from the term NIMBY (Not In My Back Yard), disposal site location problems of hazardous waste is an eligible case study associated with environmental and economic concerns. After describing the problem generally as a multi-objective mixed-integer program, we have proposed an intelligence supported approach that extends the hybrid genetic algorithm developed by the author to derive the best-compromise solution. For this purpose, we have developed a novel modeling method of value function using neural networks, and incorporated it into the approach. As a result, we can provide a practical and effective method in which the hybrid strategy maintains its advantages of relying on good matches between the solution methods and the problem properties such as a genetic algorithm for unconstrained discrete optimization and a mathematical program for constrained continuous ones. Finally, by taking an example formulated as a multi-objective mixed-integer linear program, we have examined the effectiveness of the proposed approach numerically.View full abstractDownload PDF (1110K) -
Qiuping Hu, Gade Pandu Rangaiah1999 Volume 32 Issue 1 Pages 59-68
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSControl of neutralization processes is very difficult due to nonlinear dynamics, different types of disturbances and modeling errors. The objective of the paper is to evaluate two strategies (augmented internal model control, AuIMC and adaptive internal model control, AdIMC) for enhancing pH control by nonlinear internal model control (NIMC). A NIMC controller is derived directly from input output linearization. The AuIMC is composed of NIMC and an additional loop through which the difference between the process and model outputs is fed back and added to the input of the controller. For the AdIMC, an adaptive law with two tuning parameters is proposed for estimating the unknown parameter. Both AuIMC and AdIMC are extensively tested via simulation for pH neutralization. The theoretical and simulation results show that both the proposed strategies can reduce the effect of modeling errors and disturbances, and thereby enhance the performance of NIMC for pH processes.View full abstractDownload PDF (2431K) -
Tsuguhiko Nakagawa, Kazuaki Hara, Tomohiko Furuhata, Norio Arai1999 Volume 32 Issue 1 Pages 110-115
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSThe authors have developed a non-oxidizing heating system. The newly developed device, which is called an N2 jet heater, uses the principle of a storage type heat exchanger. By means of employing a set of two heaters, each containing a regenerator, it is possible to heat N2 gas to 1773 K. The high temperature nitrogen gas maintains a high furnace temperature under non-oxidizing condition. This system has been applied to the tundish heater of a real continuous caster. As a result, the rate of occurrence of inclusion-related defects in the quality of start slab has been reduced to one-fifth to one-third of the past level. This paper presents an outline of the device and describes the effect of its use on steel quality.View full abstractDownload PDF (847K)
Biochemical, Food and Medical
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Yu-Kuo Liu, Minoru Seki, Shintaro Furusaki1999 Volume 32 Issue 1 Pages 8-14
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSIn this study, we investigated the immobilization of loofa sponge as a carrier for plant cells using a novel immobilization reactor, namely, a two-way bubble circular (TBC) reactor, for analyzing the effects of medium flow pattern. A TBC reactor, in which two-way circular flow prevailed and was controlled by bubble flow and sparger adjustment, was developed as a suitable system for plant cell immobilization using loofa sponge. In this system, relatively small aggregates of cultured plant cells could be immobilized, and the entrapped cells grew quickly, avoiding cell leakage from the sponge throughout 31 days of incubation. The optimum immobilization conditions and immobilization mechanism in this system were investigated using Coffea arabica cells as a model cell line. By changing the flow direction of culture medium in the circular reactor periodically between down-flow and up-flow, cell immobilization efficiency of the loofa sponge was improved as compared with reactors using one-directional flows. The specific respiration activity of cells immobilized in loofa sponge was also studied. Uniform distribution of cell density and specific respiration activity were obtained along the axial direction of the loofa sponge. In the same reactor system, loofa sponge exhibited high immobilized cell concentration and specific respiration activity not less than those of polyurethane foam.View full abstractDownload PDF (13258K)
Safety, Environment and Energy
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Guangwen Xu, Bing Wang, Hironori Suzuki, Shiqiu Gao, Xiaoxun Ma, Nobuy ...1999 Volume 32 Issue 1 Pages 82-90
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSA combined desulfurization/denitration (DeSOx/DeNOx) process has recently been proposed by using the powder-particle fluidized bed (PPFB). In the process, SOx is removed by a fine DeSOx sorbent continuously supplied and NOx is reduced to N2 by ammonia under the catalysis of a coarse DeNOx catalyst, the fluidization medium particles. By using the simplest model gas, SO2-NO-Air, in a laboratory scale reactor, SO2 and NO removals in the process are evaluated in this paper by testing the possible side reactions related to SO2 and NO. Then, investigations are extended to the removal efficiency for the simulated flue gas SO2-NO-N2-H2O-Air and to the effects of operating conditions, both gas velocity and the static height of catalyst bed, upon the SO2 and NO abatements. The DeSOx sorbents used were CuO·V2O5·K2SO4/Al2O3 and NaHCO3, and the DeNOx catalysts were V2O5·WO3/TiO2 and WO3/TiO2. It was found that this process suffers little from SO3 exhaust at the reactor exit. SO2 may be chemically adsorbed onto DeNOx catalyst, but it can be suppressed by using a highly efficient sorbent such as CuO·V2O5·K2SO4/Al2O3. Under NH3/NO = 1, both NO and NO2 can be similarly reduced into N2 and the possible side reactions between sorbent and NOx can also be completely abated by the NOx reduction. SO2 and NO removals in the process are more or less affected by water vapor and oxygen fractions, but the removals greater than 90% for SO2 and no less than 80% for NO can still be maintained for actual flue gas, even in a shallow bed with a static catalyst load height of 0.1 m.View full abstractDownload PDF (1648K) -
Hsi-Jen Chen, Mann-Hsing Lin, Fu-Yuan Chao1999 Volume 32 Issue 1 Pages 153-157
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSLiquefied petroleum gas (LPG) is a very important fuel and chemical feed stock as well; however, the hydrocarbon has been involved in many major fires and explosions. One of these accidents is boiling-liquid, expanding-vapor explosion (BLEVE). It is a phenomenon that results from the sudden release from confinement of a liquid at a temperature above its atmospheric-pressure boiling point. The sudden decrease in pressure results in the explosive vaporization of a fraction of the liquid and a cloud of vapor and mist with the accompanying blast effects. Most BLEVEs involve flammable liquids, and most BLEVE releases are ignited by a surrounding fire and result in a fireball. The primary objective of this paper is to develop a computer model in order to determine the thermal response of a spherical LPG tank involved in fire engulfment accidents. The assessment of the safety spacing between tanks was also discussed.View full abstractDownload PDF (743K)
General Research
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Dong-Hyun Lee1999 Volume 32 Issue 1 Pages 97-103
Published: 1999
Released on J-STAGE: April 28, 2004
JOURNAL RESTRICTED ACCESSThe experiment for poly (vinyl chloride) suspension polymerization was performed in a small reactor with the volume of 0.005 m3 and pilot scale reactor with the volume of 0.28 m3, respectively. The influence of the physical properties of PVA (poly vinyl alcohol) suspending agents on the mean particle size of PVC resin was investigated in the small reactor and effect of agitation power on the mean size of PVC resin was examined in the pilot plant reactor. The mean particle diameter of PVC resin decreased with increasing solution viscosity of PVA suspending agent and increased with increasing interfacial tension between continuous and dispersed phases. For the concentration of suspending agents used, it decreased at the initial stage and then increased above the critical point. The mean particle diameters of PVC resin have been correlated with the physical properties of PVA suspending agent in a small reactor. And then, the mean particle diameters of PVC resin have been correlated with the energy dissipation rate per unit volume and the physical properties of PVA suspending agents.View full abstractDownload PDF (1028K)
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