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ISAO SHIROMARU, SHIGEYUKI AKIYAMA
2000 Volume 26 Issue 3 Pages
313-320
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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In thermal power plants, the nitrogen oxides produced by the boilers are removed by de-NO
x devices. For efficient operation of the de-NO
x device and stable control of the power plant, the speeding up of the response of the NO
x analyzer in the flue gas is effective. In past research, we developed high response NO
x analyzer for LNG-fired power plants by using a technique of increasing sampling gas flow. However, for a coal-fired power plant, it was difficult to develop the high response NO
x analyzer using the same technique as previous development, because the coal-fired flue gas contains much dust. In this research, we developed a high response NO
x analyzer for coal-fired power plant with one-ninth the response time by development of a dust removal system, and this analyzer can maintain the high dust removal efficiency under the high volume sampling. Then, we applied this high response NO
x analyzer to an actual coal-fired power plant, and we checked the performance of it.
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TAKANOBU ASAKAWA, KATSUTOSHI INOUE, TAKESHI TANAKA
2000 Volume 26 Issue 3 Pages
321-326
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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Dithiocarbamate (DTC) -type chemically modified chitosan was synthesized by incorporating functional groups of dithiocarbamate onto polymer matrices of chitosan, and the adsorptive separation characteristics of precious metals were investigated, among which silver in particular was examined in detail. DTC-chitosan is found to exhibit high selectivity not only towards silver but also towards gold and palladium. The adsorptive separation characteristics of DTC-chitosan are superior to raw material chitosan and commercial chelating resin containing the same functional group (DTC), which is considered to be attributable to synergistic effects by a combination of dithiocarbamate group and polymer matrices of chitosan. Furthermore, adsorptive recovery of silver from waste cynaide and noncyanide solution for silver plating is found to be achievable. The maximum adsorption capacity of DTC-chitosan for silver is 3.6mol/kg. From the above-mentioned results, it is concluded that DTC-chitosan is a practical candidate for an adsorbent.
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ZENNOSUKE TANAKA, JUN OSHITANI, TOYONOBU NAKAMURA, TAKAYUKI SYOUJI, AY ...
2000 Volume 26 Issue 3 Pages
327-331
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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A raw coal consists of two components, light coals containing combustibles and heavy coals containing ashes. The heavy coals raise transportation expenses of the raw coals, and the costs of ash disposal after combustion. Sulfur contents in the heavy coals become a cause of SOx generation. In this study, a process of separating the heavy coals from the raw coals by a fluidized bed of dry heavy medium is developed. The principle of separation using specific gravity, that is, an object whose density is smaller than the apparent density of the fluidized bed floats and a heavier one settles, and removing mechanisms of float-coals and sink-coals are employed for the process.
Density distributions and ash contents of Datong, Taiheiyo and Yanzhou raw coals are measured. As a result of separating the heavy coals from these raw coals by a process with calcium carbonate for the dry heavy medium, Newtons' efficiency and combustible recovery become up to 90%, and ash recovery becomes 50-80%. The effectiveness of the process and the possibility of practical utilization are proven by good results.
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HIROKAZU NISHIMURA, NORIAKI OKAMURA
2000 Volume 26 Issue 3 Pages
332-335
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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To reduce the manufacturing cost of semiconductors, some systems have been proposed that use a cheap and high purity Clean Dry Air (CDA) CDA can reduce process step such as wafer cleaning, because CDA flow in stocker prevents the wafer surface from adsorbing of moisture and organic impurities. We have already optimized a two-stage rotary dehumidifier and have conducted a study of methods for cheaply manufacturing air that has a low dew-point of -70°C to -50°C. We have further developed the method in which a dry dehumidifier is used, and developed an ultra low dew-point air generator. The air generator is a three-stage rotary dehumidifier in which a further stage is added to the two-stage rotary dehumidifier. The main component of the rotors is metal silicate. The air generator can supply dry air with a dew point of -110°C. or less, in which the concentration in all gaseous contaminants is far below 1 ppb. We made a trial calculation of the manufacturing cost, and an average cost of 0.25 yen/m
3 was obtained.
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YOSHIO MIYAIRI, SIGEHIRO SUGIYAMA
2000 Volume 26 Issue 3 Pages
336-341
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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Some glycol-ether aqueous solutions change themselves to be hydrophilic, and then lipophilic according to their concentrations under homogeneous solutions. As the aqueous solutions exhibit phasetransition followed by temperature change, the lipophilic solutions at higher temperature region (e. g. 60°C) enable cleaning of oily dirt adhering to washing materials, and the hydrophilic ones in lower temperature regions (e. g. 40°C) separate the oily dirt dissolved into themselves. A cleaning process is designed, which possesses special features with non-distilled regeneration of dirty cleaning solution and non-waste water, based on the various data that had been obtained for high efficiency and industrial usefulness. Furthermore, a demonstration unit is designed, manufactured and operated for cleaning of various mechanical parts.
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YUICHI OHIRA, TAKEHARU ABE, YOSHIKAZU KUGA, KOJI ANDO
2000 Volume 26 Issue 3 Pages
342-346
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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S. platensis media were irradiated with intermittent light interrupted by a slit in a rotating disk. The effects of the light periodicity, irradiation time, and dark time during a cycle on the oxygen production rate of S. platensis are experimentally discussed. The following oxygen production ratio was used as the index to compare the oxygen production rate between the intermittent light and the continuous light. (Oxygen production ratio) = (Oxygen volume produced by intermittent light) / (Opening ratio of the disk) (Oxygen volume produced by continuous light) When S. platensis media were irradiated with the intermittent light having a periodicity of 0.0044-0.60s-1, the oxygen production ratio increased with an increase in light periodicity. The value of the oxygen production ratio is greater than one when the irradiation time during a cycle is shorter than 1s. Under these conditions, the oxygen production ratio increases with increasing dark time. The effect of the intermittent light on the oxygen production rate of S. platensis was found to be qualitatively described by the simple model which combined the oxygen production rate of S. platensis and the respiration rate.
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TAKUJI YAMAMOTO, TATSUHIKO MIYATA, KEN-ICHI KURUMADA, MASATAKA TANIGAK ...
2000 Volume 26 Issue 3 Pages
347-353
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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The diffusion of polystyrene latex microparticles dispersed in gels formed from worm-like molecular assemblies of surfactant cetyltrimethylammonium-bromide (CTAB) was studied using dynamic light scattering (DLS). The initial relaxation mode of the field correlation function obtained by DLS corresponds to the localized translational displacement of the microparticle entrapped by the gel structure. The frictional coefficient for this localized movement is dominated by the viscosity of the solvent (water), irrespective of CTAB concentration determining the density of cross-links. On the other hand, the final relaxation mode was attributed to the net translational displacement of the microparticle in the gel. The diffusion coefficient for this net displacement differs much from the value evaluated from shear viscosity of the gel. The net displacement was visually illustrated as a step-wise displacement whose rate is dominated by an activation energy determining the average time interval of the step-wise motion. The interval is estimated as 0.2-0.3s assuming that the step-length corresponds to the gel mesh size obtained as the correlation length of the CTAB gel free from the microparticles.
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HIDEO NAKAKURA, HISASHI OHTA, SHIGEO SADAI, KUNIHISA OSASA, MASAO SAMB ...
2000 Volume 26 Issue 3 Pages
354-359
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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The crossflow microfiltration process was experimentally investigated with four kinds of particle suspensions to clarify the effects of both cake-compressibility and operational variables on the filtrate flux. The experimental results of filtration rate for incompressible cake (microsilica, polystyrene latex) and moderate compressible cake (yeast) show the usual filtration behavior, namely increasing crossflow velocity and/or transmembrane pressure increases in the filtration rate. On the other hand, with a highly compressible cake such as agar-agar gel, the filtration rate results in a remarkable reduction with increasing transmembrane pressure, because of the irreversible behavior of the cake structure. Furthermore, the crossflow microfiltration process is analyzed based on a model formulated by incorporating the particle adhesion probability information together with the conventional cake filtration theory. The calculated results coincide favorably with the experimental results of crossflow microfiltration for an incompressible cake.
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SANG-ROK LEE, DAE-YOON JUNG, EIICHI KUNUGITA
2000 Volume 26 Issue 3 Pages
360-365
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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In the case of a chemical reaction followed by precipitation in a semibatch reactor, there are possibilities that no precipitate deposits because the concentration of chemical reaction product does not exceed its solubility, and the coprecipitation or adsorption of impurities contaminates the precipitate as the concentration of reaction product becomes too high temporarily. Proper operation to keep the state in a semibatch reactor suitable for precipitation is established with isocline analysis on the phase plane, as follows: (1) The flow rate of feed is increased with time exponentially so that the concentrations of reactant and reaction product in a semibatch reactor have a pseudo-steady state. (2) The concentration of reactant in feed, which keeps the concentration of reaction product at a pseudo-steady state over its solubility can be calculated from an isocline equation. (3) If the concentration of reactant in the reactor at the beginning of the operation is not higher than that of the pseudo-steady state, then the concentration of reaction product approaches the pseudo-steady state with time monotonously, not going beyond the pseudo-steady state.
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SHINICHI OOKAWARA, KOHEI OGAWA
2000 Volume 26 Issue 3 Pages
366-373
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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In this study, flow characteristics of rigid particle suspensions are derived theoretically based on the model which assumes particle collision-induced momentum transport. The theoretical equation predicts a linear increase of viscosity with shear rate, viz., shear thickening behavior of the suspension. Further, the increase of viscosity is expected to be proportional to the square of volume fraction of particles, and to show the theoretical linear dependency on density and diameter of particle. For verification of the theory, the experimental results of Clarke (1967) are utilized since the paramoters were varied independently in his study. The derived equation has only one experimental constant. It is confirmed that a unique value of it could correlate the viscosity dependency on all factors under some experimental condition ranges. Further, it is suggested that usage of the value which corresponding to particle shape promises wide application of the derived flow characteristics equation.
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MASATOSHI KOBAYASHI, TOMOHIKO FURUHATA, YUNYING WU, NORIO ARAI, KATSUY ...
2000 Volume 26 Issue 3 Pages
374-380
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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In this study, we investigate desulfurization characteristics of granules made of limestone powder. Their characteristics have been compared with those of crushed limestone which is conventionally used as a desulfurization agent. The granules have larger surface area than crushed limestone, and therefore, are expected to be highly efficient desulfurization agents. The results obtained from the experiments using thermogravimetry (TG) and a fluidized bed demonstrate that the granules are easily calcined (CaCO3→CaO+CO2), and have a higher desulfurization rate than the crushed limestone. Furthermore, we calculated the reaction rate costant and activation energy in the initial stage of desulfurization reactions, and the results also show that the granules have a higher activity than crushed limestone. A fluidized bed conducted under similar conditions shows that flying dust formation of the granules is higher than that of the crushed limestone. It is suggested that the granules are powdered in the initial stage of fluidization.
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HIROYUKI OSORA, SHINYA TACHIBANA, TETSUYA IMAI, TAKEHIKO MORIYA
2000 Volume 26 Issue 3 Pages
381-386
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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Under supercritical conditions, polyethylene (PE) decomposition experiments were conducted in a batch reactor, and the reaction mechanism and effects of supercritical water were examined.
According to analysis of experimental data, the mechanism of PE decomposition is based on random break of carbon-carbon (C-C) bonding. During C-C breaking, PE molecules are decomposed into small oils molecules which contain paraffin and olefins, and then aromatic compounds are produced by polymerization of olefins. NMR measurement showed that hydrogen of H2O is incorporated into the products under supercritical condition of water.
A fundamental model of PE decomposition is proposed, and its performance is discussed by comparing calculations and experimental data. Additionally, reaction rates of coking are evaluated as quite small compared with PE thermal degradation.
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TAKAYA NAGAFUNE, YUSHI HIRATA
2000 Volume 26 Issue 3 Pages
387-393
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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The shape and size of a cavern of localized flow region around a Rushton turbine impeller, which appears in mixing a yield stress fluid under an insufficient power input, are investigated by coloring the agitated fluid with a pH indicator and by measuring velocities with LDA. An aqueous solution of carboxybinyl polymer was used as the yield stress fluid, the flow curve of which was well approximated by the Herschel-Bulkley model. A normal stress effect associated with secondary flows was observed at extremely low rotational speeds. Measurements of cavern shape and size have been carried out under the condition of Re>10 where the normal stress effect disappears. In the case where the cavern does not meet the vessel wall, the cavern shape is like a disk with round corners and hollows near the center.
After reaching the vessel wall, the cavern surface is like a disk which is round near the center. From a comparison of the contours of total velocity with those of tangential velocity, it has been confirmed that the flow is essentially tangential in the cavern. A fluid having tangential velocity below 1% of the impeller tip velocity occupies considerable volume near the cavern boundary, since the velocity variations in the region of low velocity becomes very small due to the high apparent viscosities of the fluids. It has been found that growth of the cavern based on the 1% tip velocity closely corresponds to the variation of power number with Reynolds number, and its size is well correlated with the previous model which is derived from the balance of torque acting on the cylindrical cavern surface with the impeller torque.
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Extension to the case that part of azeotropic data in the ternary mixture are unavailable
YOSHIFUMI TSUGE, KENICHI YAMAGATA, SHIGEYUKI TATENO, HISAYOSHI MATSUYA ...
2000 Volume 26 Issue 3 Pages
394-401
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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In the development of azeotropic distillation processes, screening potential entrainers that make separation feasible is generally acknowledged to be very difficult. The system developed in the previous paper can present entrainers that satisfy the necessary condition to make separation feasible through azeotropic distillation and the corresponding feasible process configurations derived from them, by use of qualitative information obtained from azeotropic databases. However, in the ternary mixture (
X+Y+S) constituted of a binary mixture (
X+Y) to be separated and an additional material (
S), the system requires that data for a ternary azeotrope (
X-Y-S) and three of binary azeotropes (
X-Y, X-S, Y-S) must be available from an azeotropic database. In this paper, the system has been improved so as to determine whether the material (
S) become a candidate for entrainer even if part of the data for
X-Y-S, X-Y, X-S and
Y-S are unavailable from an azeotropic database.
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MUNEHARU GOTO, CHIAKI HATANAKA, TOSHIHIDE HARAGUCHI
2000 Volume 26 Issue 3 Pages
402-405
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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Lipase from Candida cylindracea or Rhizopus was immobilized in gel beads prepared by copolymerization of N-isopropylacrylamide, N-N'-methylenebisacrylamide, and acrylamide. The hydrolysis reaction of castor oil was carried out at 37°C by using immobilized lipase or free lipase. The optimal condition of immobilization of lipase and the productivity of ricinoleic acid is investigated. It is found that thermal inactivation of enzyme was suppressed and the formation of by-products such as estolide decreases by immobilization into the gel compared with free lipase.
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TAKETOSHI KUROOKA, YUH YAMASHITA, HIROKAZU NISHITANI
2000 Volume 26 Issue 3 Pages
406-412
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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Exact input-output linearization, which is one method of nonlinear control, was applied to multivariable control of a distillation column. First, a four-input four-output system was transformed to four SISO systems by input-output linearization based on a simplified model of the distillation column. For this purpose, an appropriate set of outputs must be selected. Second, a control system was designed for the linearized four SISO systems, considering the influence of model mismatch. Firlally, the performances of the control system were evaluated with simulation of a methanol-water distillation column. The simulation model was much more rigorous than the simplified one used for controller design. From the various viewpoints, such as the speed of response, recovery of the materials, and energy efficiency, the control system by input-output linearization showed better performance than the conventional multiloop control system. These characteristics were clearly noticed under large scaled disturbances.
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MITSUO TANAKA, ATSUSHI FUJIMOTO, RYOJI MITSUI
2000 Volume 26 Issue 3 Pages
413-417
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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Cellulase preparation derived from
Trichoderma viride was chromatographed in one step by a column. The fraction which had cellulase activity (PEAK I) had little β-glucosidase activity. PEAK I was used for continuous hydrolysis of MCC. Holding PEAK I (3.0g/l) in a reactor and supplying MCC suspension (12.8mg/h) into a reactor continuously, the hydrolysis of MCC in a reactor was performed. As the result, during the steady state from 168h to 576h, the concentration of cellobiose in a reactor is about 3.5 to 3.0g/l, the content ratio of cellobiose in reaction solution collected, 75%, and the ratio of cellobiose to glucose, 3.0. Moreover, the yield of cellobiose is 60%. All these values are considerably high, compared with the experimental value in the previous paper. The system of continuous MCC hydrolysis in this paper has two main merits, in that the hydrolysis of cellobiose to glucose is prevented because the reaction products are taken out of the reactor continuously, and the loss of enzyme is low because inactivation of the enzyme hardly occurrs during the reaction.
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MITSUO TANAKA, MASAKAZU MORITA, RYOJI MITSUI
2000 Volume 26 Issue 3 Pages
418-422
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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The expression mechanism of synergistic effect is investigated by using two cellulase components obtained from Meicelase CEP-6000 by purification. Purified cellulose components are classified into two types. One, tentatively named CMCase-type (FIE and FIIIE), has relatively low values of the ratio of MCC hydrolysis to CMC hydrolysis, and considerably high values of the ratio of Km for MCC and CMC. The other, tentatively named MCCase-type (FIIE and FIVE), has largely different values about those properties. In the case of MCC hydrolysis with FIVE alone, the particle diameter of MCC decreases (fragmentation) and the particle number of MCC increased rapidly in the early stage of reaction, and both decrease gradually in the late stage of reaction. In the case of a mixture of the above two components, hydrolysis on the MCC surface by FIIIE stimulates the activity of fragmentation of MCC with FIVE. That is, the expression of synergistic effect during MCC hydrolysis with a mixture of the above two components is for an increase in amounts of reaction site in the substrate for FIIIE, dependent on fragmentation of MCC by FIVE, and the activity of FIVE is stimulated by FIIIE. In the case of the mixture of FIE and FIIIE, the synergistic effect is not expressed. This finding suggests that these two components do not have the activity of fragmentation of MCC.
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HIROMOTO USUI, KEISUKE KISHIMOTO, HIROSHI SUZUKI
2000 Volume 26 Issue 3 Pages
423-430
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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A thixotropy model is developed for the prediction of the viscosity of silica suspensions. The model can be applied for the prediction of non-Newtonian viscosity of agglomerative suspensions with particle size distnibution. Since the model assumed that the particle shape was spherical, a mixture of monomodal spherical silica particles was used to prepare the concentrated suspensions. Viscosity measurement results have proved that the present model was able to predict the non-Newtonian suspension viscosity under steady simple shear flow conditions, although more discussion on the physical meaning of inter-particle bonding energy was needed. The applicability of the present model must be checked for the suspensions prepared using non-spherical particles with particle size distribution in the future.
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TOSHIO FURUKAWA, HIRONORI KOBAYASHI, KEN-ICHI KOKUBO, ATSUO WATANABE
2000 Volume 26 Issue 3 Pages
431-436
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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Although since the 1980's Japanese soy sauce manufactures have developed cross-flow membrane filtration systems to recover soy sauce from its lees, the mechanisms by which the membrane fouls during filtration have not been theoretically discussed. Calculated flux declines using a theoretical equation developed for cross-flow cake filtration were compared against experimental results involving the filtration of soy sauce lees using polysulfone ultrafiltration and microfiltration membranes. Membrane fouling due to the deposition and intrusion of soy sauce lees was evaluated from the hydraulic resistances of the membrane and the cake layer. Calculated flux declines with time agree with the experimental results. Specific resistance of the cake layer which is an adjustable parameter of the equation, decreases with increasing cross-flow velocity. Hydraulic resistance exhibited by the membranes is independent of feed flow velocity. However, the resistance of the cake layers decreases with increasing cross-flow velocity. This corresponds to the steady-state flux increase. In conclusion, the main cause of fouling in the filtration of soy sauce lees is cake layer formation. By using the cake filtration model for cross-flow, the flux decline with time during the filtration is capable of being predicted.
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KENZO FUJII, TORU YAMAMOTO, MASAHIRO KANEDA
2000 Volume 26 Issue 3 Pages
437-442
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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PID control schemes have been widely used in petroleum refinery and chemical processes. However, suitable tuning of PID parameters in order to maintain product quality and stability of reaction processes is required, especially, where in the polybutene reactor with exothermic reaction, the process dynamics change greatly due to the change of the catalyst activity, the product grade, and so on. Therefore, the operator has to determine the parameters as fairly conservative values taking the stability of the reactor into consideration through trial and error. In order to overcome these problems, the authors have proposed a self-tuning PID control scheme whose PID parameters were tuned automatically following the change of the dynamics. In this paper, the effectiveness and implementation are investigated by applying the above method to temperature control of a polybutene reactor. In particular, it is shown that deterioration of the control performance due to wrong initial setting of the PID parameters is proved suffcient.
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SUSUMU HASHIZUME, SOUYOU YOMOGIDA, KUNIYOSHI UEDA, TOMOYUKI YAJIMA, KA ...
2000 Volume 26 Issue 3 Pages
443-449
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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A batch control system consists of several components which run in parallel and influence each other. To reduce system design complexity, a modular approach is useful, in which the whole system is designed by composing subsystems (modules) designed independently. In this paper, we propose a modular design approach for the synthesis of sequential control systems. Sequential control systems are modeled by condition/event nets, and their behaviors are described by partial languages. We also present a method of constructing sequential controllers from condition/event net system models.
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XINGHE FAN, MASAHIRO YOSHIDA, YOSHIMITSU UEMURA, HIDEKAZU YOSHIZAWA, T ...
2000 Volume 26 Issue 3 Pages
450-456
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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We synthesized a ferroelectric liquid crystal monomer possessing both carboxyl p-benzolxybenzoate and carboxyl (S) - (-) -2-methylbutyl ester in its side chain. The liquid crystal monomer and styrene monomer were utilized to form matrices of microspheres, which were prepared by suspension, dispersion, or emulsion polymerization. In this study, we characterize in detail physicochemical properties, thermo-response, and electro-optical response in the microspheres. We demonstrate the following results: (1) The volume-averaged diameters of microspheres prepared by the suspension, dispersion, and emulsion polymerization are of 45μm, 1.5μm, and 85nm, respectively; (2) the microspheres prepared showed a liquid crystalline behavior at the prescribed temperature; (3) the phase transition temperature toward the liquid crystal phase of microspheres prepared by co-polymerizing the liquid crystal monomer and styrene monomer decrease with increasing styrene monomer concentrations; and (4) the microspheres obtained remarkably exhibite electro-optical responses at the appointed voltage.
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YOSHIYUKI YAMASHITA, HIROSHI KOMORI, EIJI AOKI, KINJI HASHIMOTO
2000 Volume 26 Issue 3 Pages
457-461
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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As an application of ART 2 neural networks, computer aided monitoring of pump efficiency is successfully examined for an industrial waste-liquid treatment process with measured data of valve openness and liquid flow rates. By running the neural networks in parallel, we confirm that accuracy to detect system changes is good, and the adjustment of classifier parameters is relatively easy. Investigating the resulting classes carefully, frequency of each class is correlated with pump efficiency. The relative amount of variables are also related to the classes.
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HIDEHIRO KAMIYA, SACHIKO KAGAWA, HIDEKO SUGIYAMA, MASAYUKI HORIO
2000 Volume 26 Issue 3 Pages
462-466
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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The present paper focused on the chlorine distribution during RDF combustion in fluidized beds. To discuss the captured mechanism of chlorine by bottom ash at relatively high temperature (above 1, 000 K) and water vapor concentration (about 10%) in which this phenomenon thermodynamically did not occur, the structure and chemical composition distribution on the surface and cross section of bed materials and bottom ash after RDF combustion in fluidized bed at 1, 073K were observed by SEM and EPMA. The thin layer of several μm thickness with Ca and Si were formed on the surface of bed materials and bottom ash, and chlorine was captured in this layer. Furthermore, by the fundamental gas/solid reaction test of the hydrogen chloride inclusion gas (1, 000ppm) with the different water vapor concentration through CaO fixed bed and, it was confirmed that the amount of captured hydrogen chloride by CaO surpassed a thermodynamic equilibrium calculation result on condition of relatively high water vapor concentration up to 7.9%.
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NOBUO MATSUDA, YUTAKA TADA, SETSURO HIRAOKA, YOSIRO MIZUTANI, YOUNG-SE ...
2000 Volume 26 Issue 3 Pages
467-473
Published: May 10, 2000
Released on J-STAGE: July 27, 2010
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To clarify very low frequency fluctuations in the torque in an agitated vessel, the dynamical behavior of the torque fluctuations was examined from power spectrum analysis and chaotic time series analysis of the measured torque time series in an agitated vessel with paddle impellers. The maximum Lyapunov exponent of the very low frequency torque fluctuations in an agitated vessel had positive value, which means that the fluctuations have the chaotic nature. The critical value of the fractal dimension of the fluctuation decreased and the irregular frequency region became larger with an increase in the rotational speed in the region of 1.0-2.0s-1. The magnitude of the fractal dimension increased with an increase in the aspect ratio.
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EIJI NAKAJIMA, TAKESHI YAMANE, MASAMICHI YOSHIDA, HISASHI MIYASHITA
2000 Volume 26 Issue 3 Pages
474-479
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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Double-diffusive convection in a solutally stratified, two-layered solution destabilized by lateral heating and cooling is studied numerically. A simulation was carried out for Pr=6.67, Le=184, RaT=2.43×10
7, Rac=3.13×10
7 and A=1.1. Experiments were also performed with aqueous solutions under the same condition. Time evolutions of flow and temperature fields obtained numerically show qualitative agreement with that obtained by the visualization of flow and temperature. Moreover, numerical results of the molar flux of solvent through the interface agree very closely with experimental ones. Thus the numerical algorithm employed here is proved to be appropriate for the analysis of doublediffusive convection. Using the numerical results, the mechanism of mass transfer, which is usually hard to investigate through experiments, is discussed. The double-diffusion process until the two layers start mixing can be divided into three periods; (A) a period until a thin interface is formed between the two layers, (B) a period during which the temperature field is in quasi-steady state, and (C) a period when the interface between the two layers is unstable. Numerical results show that each period has different mechanism of mass transfer.
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SHINICHI YUU, TOSHIHIKO UMEKAGE, TAKASHI SAITO
2000 Volume 26 Issue 3 Pages
480-482
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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A probe for simultaneous measurement of normal and shear stresses on wall surfaces of a powder bed is developed. Experimental results show that the probe makes it possible to independently measure the small normal and shear stresses at the same point, since the normal and shear stresses which act on the probe are mechanically separated by a shaft which is supported by miniature ball bearings. The measured data has been compared with calculated results using the incremental finite element method. Measured results are in fairly good agreement with calculated results and other known characteristics on the statics of powder beds.
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MUTSUHIRO ITO, RYOU FUJISAWA, FUJIO WATANABE, MASANOBU HASATANI
2000 Volume 26 Issue 3 Pages
483-485
Published: May 10, 2000
Released on J-STAGE: March 15, 2010
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Heat transfer characteristics in an adsorption heat pump (AHP) using a packed silica gel module (PS-module) were experimentally studied on the basis of results compared with those for the AHP with a direct heat exchange module (DS-module) type adsorber. Ultimate heat transfer enhancement for an adsorber of AHP is almost achieved by using the PS-module because of high packing density and thermal conductivity, and the possibility of its application to a refrigerator for producing low temperature cold heat energy is suggested.
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