KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 29 , Issue 4
Showing 1-25 articles out of 25 articles from the selected issue
Themodynamics, Physical Properties and Molecular Simulation
Transport Phenomena, Fluid Mechanics and Mixing
  • Yoshiyuki Yamada, Kuniaki Gotoh, Tatsuo Nishimura
    Type: Fundamental Research Paper
    Subject area: Transport Phenomena, Fluid Mechanics and Mixing
    2003 Volume 29 Issue 4 Pages 500-507
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    The effect of fuel particle shape on the combustion front propagation rate of the reverse combustion in a packed bed was studied experimentally. We used shredded rectangular papers having different aspect ratio and size as model particles. Our discussion focuses on the combustion in which the surface reaction is dominant.
    Experimental results showed that the combustion front propagation rates under constant gas velocity depended on the particle shape, but had no correlation with geometric parameters such as length, area and aspect ratio. We presumed that the difference in propagation rate depending on the particle shape was attributable to the difference in effective surface area in the surface reaction. Then, we estimated the effective specific surface area through the permeability method. It was found that the combustion front propagation rates at consrtant gas velocity increased with the effective specific surface area. This fact implies that the effective specific surface are are presents the difference in surface reaction rates dominating the combustion propagation rate under our experimental conditions.
    Furthermore, we estimated the mass transfer coefficient by means of analogy of j-factor. In the estimation, we defined the effective equivalent diameter calculated from the effective specific surface area as the representative length of the fuel particle. As a result, it was found that the propagation rate correlated with the mass transfer coefficient estimated by the effective equivalent diameter, independently of the particle size, shape and gas velocity. This fact shows that the effect of the particle shape on the combustion front propagation rate in a reverse combustion process of a packed bed can be evaluated by the permeability method.
    Download PDF (2555K)
  • Kazuhito Nagayama, Masanao Imai
    Type: Note
    Subject area: Transport Phenomena, Fluid Mechanics and Mixing
    2003 Volume 29 Issue 4 Pages 568-571
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    The effective diffusion coefficient (Deff) and partition coefficient (P) of fatty acids and alcohols with carbon numbers of 4 to 14 as substrates of an enzyme reaction were measured in di-2-ethylhexyl sodium sulfosuccinate (AOT)-gelatin combination microemulsion-based organogels (MBGs). The correlation equations between the effective diffusion coefficient and the molar volume of substrate (υ) were obtained as follows:
    for fatty acid: Deff[10-10m2s-1] = 6.55×10-12υ-0.43
    (109.0≤;υ[10-6m3mol-1]≤331.0)
    for alcohol: DeffAL[10-10m2s-1] = 2.67×10-13υ-0.71
    (103.6≤υ[10-6m3mol-1]≤325.6)
    The partition coefficient of substrate, the molar ratio of MBG phase to bulk organic phase, decreased with increasing carbon number of substrate and remained almost constant at a carbon number of 8 or above as follows: PFA = 2.03 (butanoic acid), 1.17 (hexanoic acid), ca. 0.85 (octanoic acid, decanoic acid, dodecanoic acid and tetradecanoic acid); PAL = 4.01 (butanol), 1.70 (hexanol), ca. 1.50 (octanol, decanol, dodecanol and tetradecanol). The partition coefficients of alcohols were about 2-fold higher than those of fatty acids.
    Download PDF (1048K)
Catalysis, Kinetics and Reactor Design
  • Tadaatu Ido, Tomoya Shimizu, Gong Jin, Shigeo Goto
    Type: Fundamental Research Paper
    Subject area: Catalysis, Kinetics and Reactor Design
    2003 Volume 29 Issue 4 Pages 534-540
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    Phenyl benzoate synthesis from benzoyl chloride and phenol was investigated in three kinds of reactors.
    When polyethylene glycol (average molecular weight 3000) was used as a phase transfer catalyst and toluene as an organic solvent, a third liquid phase that mainly consisted of the catalyst was formed when KOH concentration in the aqueous phase and the concentration of phenol were increased. However, the selectivity of phenyl benzoate was less than 0.6 in a well-mixed batch reactor because benzoyl chloride and phenyl benzoate both underwent hydrolysis.
    The selectivity could be raised above 0.9 by changing phenol and KOH concentrations in a phaseseparable batch reactor in which direct contact between the organic and the aqueous phases could be prevented by the third liquid phase.
    A new type of phase separable continuous stirred tank reactor (CSTR) in which benzoyl chloride and phenol were separately supplied to the organic and the aqueous phases, respectively, was devised to obtain the same high selectivity as the phase separable batch reactor.
    Download PDF (2193K)
  • Muneharu Goto, Chiaki Hatanaka, Kazuya Uezu, Masahiro Goto
    Type: Note
    Subject area: Catalysis, Kinetics and Reactor Design
    2003 Volume 29 Issue 4 Pages 565-567
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    Lipase from Rhizopus sp. was immobilized in the polymer matrix prepared by polymerization of n-vinyl-2-pyrrolidone, 2-hydroxymethacrylate or n-isopropyl acrylamide. The esterification of oleic acid and glycerol was carried out at 310 K by using the immobilized lipase or free lipase. The selectivity of monoolein was dependent on the hydrohobicity of the polymer matrix immobilizing lipase. The hydrophilic polymer provided a high selectivity for monoolein in the esterification. It was found that controlling the hydrophobicity of the enzyme-immobilized matrix allowed the final constitution of the equilibrium state to be shifted.
    Download PDF (749K)
  • Yasushi Sugawara, Kouichi Asari, Katsuyasu Sugawara, Takuo Sugawara
    Type: Note
    Subject area: Catalysis, Kinetics and Reactor Design
    2003 Volume 29 Issue 4 Pages 572-575
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    The catalytic activity of a flexible wire-net photocatalyst for ethylene decomposition was investigated to obtain fundamental infomation for the design of a compact titanium dioxide photocatalytic reactor.
    The initial activity change was first examined with a newly prepared wire-net photocatalyst: when 50 ppm of ethylene was decomposed by batchwise irradiation with a black light lamp, the time for complete conversion decreased with the increase in the number of cycles of irradiation. It became constant after a few cycles. The photocatalytic activity of 20-mesh wire-net photocatalyst was observed to be nearly equal to that of 350-mesh one under the same amount of titanium dioxide loading of 1.88 g (specific amount 7.2 g/m2 for 20-mesh wire-net, and 5.1 g/m2 for 350-mesh wire-net, respectively). The reaction rate of ethylene decomposition was represented by the 0.5th order of the ethylene concentration. The decomposition rate increased in proportion of the amount of titanium dioxide loaded in the range from 0.92 g (specific amount 3.5 g/m2) to 2.70 g (specific amount 10.4 g/m2), on a 20-mesh wire -net where 50 ppm of ethylene was treated.
    Download PDF (1260K)
  • Yoshiyuki Bando, Naoki Tsuno, Lingguang Meng, Masaaki Nakamura
    Type: Note
    Subject area: Catalysis, Kinetics and Reactor Design
    2003 Volume 29 Issue 4 Pages 576-578
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    Foam generation behavior in a rectangular bubble column was experimentally examined. A partitioning plate was vertically inserted in the column and a blockading plate was horizontally placed on the liquid surface. The location of these plates was changed, and the flow characteristics and foam generation behavior (foam layer height) were measured. These plates promoted the foam growth. The foam layer height was strongly governed by the gas velocity and gas holdup in the riser and the disturbance of liquid surface. The foam layer was generated on the liquid surface of downcomer due to the liquid circulation flow, and the water content in foam was very low like that of a mousse. In the treatment of wastewater containing a surfactant, both the removal and concentration ratio were higher in the proposed column than in the conventional one.
    Download PDF (740K)
Materials and Devices
  • Daisuke Nagao, Eiichi Mine, Toshihiko Katakura, Mikio Konno
    Type: Fundamental Research Paper
    Subject area: Materials and Devices
    2003 Volume 29 Issue 4 Pages 546-550
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    Seeded reactions of the hydrolysis and condensation of tetraethyl orthosilicate were carried out to study the influence of ammonia concentration on particle size distributions. Aggregation of seed particles was observed at a high ammonia concentration (1.0 kmol/m3), whereas a large number of new particles were formed at a low ammonia concentration (0.25 kmol/m3). An intermediate ammonia concentration (0.5 kmol/m3) was found to be suitable for particle growth that was scarcely accompanied with aggregation and new particle formation. Estimation of ionic strength from pH values during the reactions suggested that an increase in the ionic strength with an increase in ammonia concentration suppressed the new particle formation and lead to the particle aggregation. Seeded growth reactions in which KCl or LiCl was added demonstrated that new particle formation was highly suppressed by the addition of the electrolytes.
    Download PDF (1584K)
Separations
  • Kenji Kawasaki, Akira Matsuda, Takao Shinkura
    Type: Technical Research Paper
    Subject area: Separations
    2003 Volume 29 Issue 4 Pages 471-476
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    The freezing concentration efficiencies of water-NaCl and water-glucose systems were investigated over a wide range of freezing rate in cylindrical freezing columns (50 or 55 mm inner diameter). The effect of supersonic radiation on the concentration efficiency was also examined.
    As a result, freezing without supersonic radiation could hardly concentrate solutes at freezing rates above 5 mm/h, while of slower freezing rates below 3 mm/h the concentration efficiency increased. Supersonic radiation remarkably improved the freezing concentration efficiency, and slower freezing rate increased this efficiency. The dissolved oxygen concentration (namely, the dissolved air concentration) of solution also influenced this efficiency. When the dissolved oxygen concentration was higher than 7 mg/L, solutes could sufficiently be concentrated by the generation of cavitation, even at 40 mm/h (fast freezing rate). On the other hand, when the dissolved oxygen concentration was below 7 mg/L, where cavitation is hardly generated, solutes could be concentrated by vibration with supersonic radiation at freezing rates below 15 mm/h.
    Download PDF (1779K)
  • Kaoru Kondo, Yuji Imajo, Manabu Shimada, Kikuo Okuyama
    Type: Fundamental Research Paper
    Subject area: Separations
    2003 Volume 29 Issue 4 Pages 513-520
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    There are many reports on the in situ remote measurement by the LLS (laser light scattering) method for the spatial distribution of particles that are generated in the gas phase during the RF (radio frequency) plasma-processing. However, almost every report is limited to high-concentration particle clouds trapped at a plasma/ion sheath boundary region, since it is difficult to measure low-concentration particles by the LLS method. In this study, a sampling pipe was inserted into an RF plasma reactor to suck out test SiO2 particles fed from the outside of the reactor, and particles suspended in various positions were measured with a particle counter, which is operable under low-pressure conditions. This technique allows measurement of the distribution of low-concentration particles that cannot be achieved by the LLS method. Measurement of the process conditions under which particle-trapping clouds are formed in the plasma region revealed that particles overfed into the clouds did not flow out downward to the grounded electrode (substrate), but flowed out of the plasma region in the radially outward direction of the RF electrode. It was also found that the range of feeding gas flow rate in which the formation of particle clouds was hindered and thus particles flowed directly toward the grounded electrode depended on RF power and particle diameter. Furthermore, measurements of transport of trapped particles in the postplasma process suggested possible conditions under which particle contamination of substrate surfaces is likely to occur.
    Download PDF (3190K)
  • Junji Shibata, Masataka Morikawa, Norio Yoshikawa, Tomoko Yamada, Nori ...
    Type: Fundamental Research Paper
    Subject area: Separations
    2003 Volume 29 Issue 4 Pages 521-525
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    A separation process of acids from waste etching acid mixture discharged in a liquid crystal display manufacturing process was established by using solvent extraction. Acetic and nitric acids were extracted from the waste acid mixture, and phosphoric acid, which was the main components, was left in the raffinate. Tri-octyl phosphate (TOP) was used as an extractant to extract acetic and nitric acids. Fundamental studies were carried out for extraction and stripping of acetic, nitric and phosphoric acids, and a demonstration test was conducted using a mixer-settler equipment.
    TOP selectively extracts acetic and nitric acids from the waste acid mixture mainly containing phosphoric acid. Extraction of acetic and nitric acids is approximately 100% by applying the continuous countercurrent extraction with a phase ratio (A/O) of 0.4 and 6-stage extraction using TOP as an extractant. Acetic and nitric acids extracted in TOP are stripped with water as a stripping agent at 99 % and 99.5% under the conditions of a phase ratio (O/A) of 1.0 and 4-stage stripping. In the demonstration test using a mixer-settler equipment, 95% of acetic acid and 98% of nitric acid in the waste acid mixture were extracted, and phosphoric acid was left in the raffinate to give crude phosphoric acid as a product.
    Download PDF (2002K)
  • Hironobu Imakoma, Masayuki Eda, Katsuyuki Kubota, Masato Yamamura, Mas ...
    Type: Note
    Subject area: Separations
    2003 Volume 29 Issue 4 Pages 579-581
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    A new experimental apparatus was proposed for continuous measurement of drying curves of a coated web consisting of a liquid layer formed on a sheet basis by coating. In industry, double-sided convective dryers are often used to dry a coated web for a short time. However, it has been difficult to measure the small weight change of a coated sample with experimental apparatus based on the principle of the dryer.
    In this study, the authors produced a drying apparatus based on the double-sided dryer. The apparatus was placed where hot air blew on both sides of a coated sample that was located between two electronic weight balances. The balances were connected to a personal computer, allowing the weight change of the coated sample to be measured continuously. The apparatus performed well for air velocities of below 0.6 m/s.
    Download PDF (743K)
  • Hironobu Imakoma, Kiyotaka Nakai, Katsuyuki Kubota, Masato Yamamura, M ...
    Type: Note
    Subject area: Separations
    2003 Volume 29 Issue 4 Pages 582-584
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    A system of polyvinylalcohl (PVA), glycerol and water was examined as a multi-component solution model. Continuous or intermittent infrared drying was performed to obtain drying curves of thin layers of the solution system. Regardless of glycerol content, the drying rate curves for continuous drying with various glycerol contents arranged by PVA mass-basis mean moisture content coincided with drying rate of PVA solution over the whole range of the mean moisture content. Intermittent drying curves also coincided. These results will be useful for dryer design and operation.
    Download PDF (931K)
Particle Technology and Fluidization
  • Seiichi Deguchi, Masayuki Deguchi, Akira Nishimura, Yukihisa Fujima
    Type: Technical Research Paper
    Subject area: Particle Technology and Fluidization
    2003 Volume 29 Issue 4 Pages 493-499
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    An airtight oscillating fluidized bed, which can fluidize a particle bed in an airtight vessel without supplying a fluidization gas from outside, was proposed. This system is composed of an airtight vessel and a gas duct with a valve connecting upper and lower spaces of the vessel divided by a particle stopper and a distributor plate. It was considered that fluidization could be formed by rectifying the gas flow induced by the enforced oscillation of the airtight vessel and induced particle bed inertia with the help of the gas duct and valve. In this development study, the gas duct contained a valve comprising a steel ball, of which the length of vertical movement was restricted, and its pedestal was firstly prepared as a trial. Then, theoretical simulation was performed based on experimentally obtained pressure drop through the gas duct, demonstrating the possibility of fluidization in this supposed system. Fluidization was verified in conformity with the assumed fluidization mechanism in the trial model of the oscillating fluidized bed with this gas duct. As the oscillatiing frequency increased, the fluidization state changed from static bed to incipient fluidization, bubbling fluidization and bubbling fluidization with surface wave. Finally the structure of a gas rectifier to be placed in the gas duct for efficient operation of this system was presented.
    Download PDF (2236K)
  • Seiji Matsuo
    Type: Fundamental Research Paper
    Subject area: Particle Technology and Fluidization
    2003 Volume 29 Issue 4 Pages 526-533
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    Effective use of coal has been increasingly highlighted by the growing needs for energy sources. Among them low-rank coal including sub-bituminous coal and brown coal is an abundant resource, but it has not been competitive in thermal coal markets due to its low heating value and a tendency for spontaneous combustion. One solution to this problem is the fluidized method, Coal-Water Mixture (CWM) technique. This paper proposes a new rhelogical model of CWM. Several reports that have described the importance of a particle size distribution minimizes the void fraction among the coal particles in a low viscosity CWM. This model was semi-empirically derived from the concept of the average thickness of liquid layer among coal particles, and the relative viscosity of the slurry was described as a function of the void fraction and specific surface area of particles. The extension of the model to non-Newtonian fluids based on coagulation process was also discussed
    The relative viscosity of CWM estimated by this model was compared with experimental data. The results were in good agreement with the experimental data when the void fraction of sample could be accurately calculated from the particle size distribution. In paticular, a sample in which the void fraction of coal particles is minimal does not always show the lowest viscosity. It became clear that in theory, the relative viscosity of CWM is influenced not only by the void fraction but also by the specific surface area of particles.
    Download PDF (2559K)
  • Seiichi Deguchi, Masayuki Deguchi, Mikitaka Isobe, Akira Nishimura, Yu ...
    Type: Note
    Subject area: Particle Technology and Fluidization
    2003 Volume 29 Issue 4 Pages 585-587
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    Heat transfer rates in an airtight oscillating fluidized bed (AOFB) were compared with those in the same system operated as a conventional fluidized bed with a supply of fluidization air from beneath the distributor. Heat transfer rate in the AOFB increased with an increase in the oscillating frequency. Though fluidization air was intermittently introduced to the bed in the AOFB, the largest heat transfer rate obtained was roughly equal to that in a conventional fluidized bed. The vertical heat transfer rate distribution in the AOFB showed like sine curve, which could be qualitatively explained by the stagnating positions and frequencies of bubbles.
    Download PDF (1107K)
Process System Engineering
  • Hitoi Ono, Takashi Sonoda, Yuichi Ohtani, Hiroshi Kuraseko, Masaru Nod ...
    Type: Technical Research Paper
    Subject area: Process System Engineering
    2003 Volume 29 Issue 4 Pages 477-482
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    Solid Oxide Fuel Cell (SOFC) systems are subject to operational constraints on state variables, such as fuel cell temperature and pressure. In this research, considerations for optimal operation, which minimizes start-up time while satisfying various restrictions, were derived for SOFC systems. The simultaneous approach by which both state variables and control variables are converted to discrete points in the time domain was applied to the dynamic optimization problem of SOFC systems. Through the conversion, the optimization problem was reformulated as an NLP problem, which was solved using the reduced Hessian successive quadratic programming technique. The optimal operations of manipulated variables were derived to minimize start-up time while satisfying all restrictions, such as the difference in SOFC inlet temperatures, pressures, the rate of temperature change, and the highest temperatures. Furthermore, the design variable of SOFC systems was also optimized to achieve the theoretical minimum start-up time.
    Download PDF (2182K)
  • Zhang Wenlong, Masao Imaeda, Kyouji Hashimoto, Takaaki Kanbe, Hirofumi ...
    Type: Note
    Subject area: Process System Engineering
    2003 Volume 29 Issue 4 Pages 541-545
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    Modern control theories have recently been applied to many industrial plants, and among these applications is the Generalized Predictive Control (GPC) method. This paper considers stable temperature control in a distillation column. Distillation columns are widely used and important processes in the chemical industry. ARMAX dynamical models are built from operational data. The temperature in the middle of the distillation column is controlled by the generalized predictive control method. Control based on the GPC algorithm is applied to tune PID control parameters. Digital simulation of these controls shows excellent results.
    Download PDF (1417K)
Biochemical, Food and Medical Engineering
  • Taisuke Watanabe, Masanao Imai, Isao Suzuki
    Type: Chemical Engineering Data
    Subject area: Biochemical, Food and Medical Engineering
    2003 Volume 29 Issue 4 Pages 557-561
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    Sterilization of Escherichia coli using high pressure and supercritical carbon dioxide was investigated. The organism was treated at pressures ranging from 5 to 20 MPa and temperatures ranging from 298 to 323 K. Supercritical carbon dioxide was found to be superior for sterilization to liquud and gaseous carbon dioxide. At same temperature, survival ratio was drastically reduced by the elevation of pressure. It was also greatly decreased by increasing temperature. The configurational state of contact between the free surface of the test liquid phase and the dispersal device of supercritical coarbon dioxide had a dominant effect on the decrease of survival ratio. The apparent activition energy of sterilization of E. coli was obtained as 50 kJ· mol−1.
    Download PDF (1734K)
Safty, Enviroment and Energy
  • Shigekatsu Mori, Motohiro Kondoh, Yoshinori Itaya
    Type: Keynote Paper
    Subject area: Safty, Enviroment and Energy
    2003 Volume 29 Issue 4 Pages 453-465
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    Energy recycling is an important issue that should be developed urgently to remarkably reduce wastes and to utilize them as alternative renewable energy resources. However, a significant social problem takes place due to emission of toxic components in exhaust gas and ash. Thus the development of environmentally harmonious systems is required for practical application. A number of R & D on effective energy recycling technologies of wastes including combustion and gasification have already been carried out. Some new commercial or pilot plants to replace conventional furnaces have been constructed, tested and put into operation. This paper overviews the recent technologies in energy recycling processes of wastes, and also summarizes and reviews the main studies performed by the present authors and other researchers from Japan and abroad on the fundamental knowledge necessary for the plant design of combustion and gasification furnaces. Studies on the reaction kinetics of combustion and gasification rates of various RDFs, the emission of dioxins and hydrogen chloride, their interaction and processes to reduce emissions, and treatments for de-SOx, de-NOx and ash or slug are reviewed. Additionally based on these works, the future prospects for energy recycling processes are considered.
    Download PDF (4849K)
  • Hiroyuki Okamoto, Masao Inoue, Hideki Yamamoto, Junji Shibata
    Type: Technical Research Paper
    Subject area: Safty, Enviroment and Energy
    2003 Volume 29 Issue 4 Pages 466-470
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    Two analyzers were developed to evaluate the burning characteristics of charcoal. The burning rate analyzer measures the mass reduction rate of charcoals burning in a constant atmosphere; and the burning gas temperature analyzer measures the temperature change of burning charcoals in a constant atmosphere. In this study, the burning characteristics of beer lees charcoal, produced by successively drying, pressing under heating and carbonizing beer lees in a low oxygen atmosphere, were compared with those of two commercially available charcoals, Bincho-tan and Oga-tan, by using the two newly developed analyzers. The burning rate of Bincho-tan was found to be the slowest, while those of the beer lees charcoal and Oga-tan were similar to each other. The results showed the potential of the developed apparatuses for use in evaluating charcoal characteristics.
    Download PDF (1772K)
  • Tetsuya Ootake, Masahiro Shishido, Norio Ando, Masao Kobayashi
    Type: Technical Research Paper
    Subject area: Safty, Enviroment and Energy
    2003 Volume 29 Issue 4 Pages 483-487
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    Charcoal coated with polyethyleneglycol (PEG) was prepared by immersing charcool into PEG aqueous solution. The characteristics of humidity adsorption and desorption of PEG-coated charcoal were evaluated. The results showed that the humidity control capacity increased up to 2 to 7 times compared with that of untreated charcoal. The higher the heat treatment temperature was for charcoal, the larger was the amount of PEG on the charcoal surface and the larger the increase in humidity control capacity. Furthermore, under higher humidity conditions, the amount of adsorbed humidity on the PEG-coated charcoal was larger than that expected from the sum of the amounts of adsorbed humidity on charcoal and PEG alone. It seems that PEG in the cating film is deliquescent at higher water concentration, and then resulting PEG solution is transferred into micropores and held in microstructures of charcoal. Such behavior of PEG solution may be the couse of the enhanced humidity adsorption capacity under higher humidity conditions.
    Download PDF (2061K)
  • Naonobu Katada, Shigetoshi Ikeda, Motohiro Ozama, Takazumi Shido, Koju ...
    Type: Technical Research Paper
    Subject area: Safty, Enviroment and Energy
    2003 Volume 29 Issue 4 Pages 488-492
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    Treatment of wood with a nitrogen flow containing water vapor yielded charcool with surface area of 700 and 800 m2g−1, comparable to that of activated carbon, at 1,050 and 1,100 K, respectively. Analysis of the reaction products confirmed that water-gas reaction proceeded during the treatment to form micropores. Equipment for continuous treatment of wood with steam was assembled and shown to produce the activated carbon with surface area of ca. 700 m2g−1 at the capacity of ca. 1.4 kg h−1.
    Download PDF (1243K)
  • Kouichi Sato, Akira Hamauzu
    Type: Fundamental Research Paper
    Subject area: Safty, Enviroment and Energy
    2003 Volume 29 Issue 4 Pages 508-512
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    The photo-dechlorination rate was of CFC12 measured in order to develop equipment for converting CFC12 into fluoroether in NaOH-methanol by UV irradiation. CFC12 is converted into HCFC22 by the photo-dechlorination, and this is followed by Williamson ether synthesis give to fluoroether (CHF2OCH3). In this paper, the photo-dechlorination rate of the CFC12-fluoroether convertor was analyzed.
    It was found that the reaction rate was proportional to the one half power of the light intensity and the three-halves power of CFC12 partial pressure, and the rate was increased by NaCl particles which deposited in the methanol solution scattering the light. From these results, a photoreaction mechanism was proposed in which the methoxy ion radical participates in a chain reaction.
    Download PDF (1485K)
  • Jun Kobayashi, Takuya Fujita, Masateru Sugiyama, Norihiro Fukuta, Nori ...
    Type: Note
    Subject area: Safty, Enviroment and Energy
    2003 Volume 29 Issue 4 Pages 562-564
    Published: July 20, 2003
    Released: May 30, 2009
    JOURNALS RESTRICTED ACCESS
    To develop an adsorbent for an adsorption heat pump (AHP), active carbons were produced by means of low-temperature KOH chemical activation using polyethylene terephthalate (PET), which has attracted attention as a material for recycling.
    Water vapor adsorption isotherms were measured on activated carbons formed at KOH/raw material ratio (R) of 0.8–4, and activation temperature (Ta) of 673–873 K. From the result, it was found that the best of activated carbons have about 1.7 times the amount of water vapor absorbed as that of silica gel in the AHP operation range (φ : 0.1–0.35). Moreover, it became clear that R=3.2 and Ta=773 K were the optimum value in present experiment range. Also, yields of activated carbons were larger than that of decomposition product. These results show the potential for production of activated carbon for AHP by this method.
    Download PDF (2269K)
feedback
Top