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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Korean Chemical Engineering Research
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Journal DOI :
The Korean Institute of Chemical Engineers
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Volume & Issues
Volume 36, Issue 6 - 00 1998
Volume 36, Issue 5 - 00 1998
Volume 36, Issue 4 - 00 1998
Volume 36, Issue 3 - 00 1998
Volume 36, Issue 2 - 00 1998
Volume 36, Issue 1 - 00 1998
Selecting the target year
A Study on the Preparation of Partially Activated PAN Composite Fiber Containing Zeolite Particles
Hwang, Deok-Geun ; Jeong, Gyeong-Taek ; Seol, Yong-Geon ; Lee, Hwa-Seop ; Mun, Je-Gwon ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 627~627
Partially activated polyacrylonitrile(PAN) composite fiber containing zeolite particle was prepared by using acrylonitrile(AN) as a precursor. Weight average molecular weight(Mw) and polydispersity index of spinning dope was 630,000 and 1.30 respectively. Dry-jet wet spinning technique was used for making PAN composite fiber. During, the dry-jet wet spinning process, PAN composite fiber of 35-45㎛ in diameter shows increased orientation. Initial elastic modulus of PAN composite fiber containing zeolite particles was 89 % of PAN fiber at the same experimental condition. The cyclization and activated state of PAN fiber were conformed by Fourier transform infrared(FT-IR) spectroscopy and X-ray diffraction(XRD). After the activation process, characteristic peaks of PAN composite fiber could be observed due to the incorporation of zeolite particles from XRD. Partially activated PAN composite fiber containing zeolite particles is expected to use as an organic-inorganic composite absorbent.
Non-uniform Properties of Composites of Expanded Graphite and Metal Chlorides for Chemical Heat Pumps
Choe, Seung-Hun ; Park, Seong-Ho ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 634~634
The chemical heat pump using the reversible reactions of NH₃ and metal chlorides is being expected to wide applications like the alternative refrigeration and cooling system and effective energy managements. The distinguishing characteristics of this system is utililization of the expanded graphite as a support in the chemical reactor to overcome the deactivation of reaction and improve the heat and mass transfer of reactive medium. In contrast with ordinary reaction block of uniform properties such as apparent density and ratio of expanded graphite, the non-uniform reaction block was designated to increase the apparent density with radial direction, which is able to improve heat transfer properties and solve the troubles which the permeability of ammonia gas get worse while increasing heat transfer. Based on the experimental results, the rate of reaction of the non-uniform block is progressed rapidly and has larger thermal conductivity in the heat transfer zone than the uniform blocks. Additionally the non-uniform blocks are proved to have betterment of reactivity for the decompositive reaction.
Effect of HCI Gas on Sulfation Reaction of Limestone Slurry in a Jet Bubbling Reactor
Yu, Gyeong-Seon ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 641~641
Effect of the presence of HCl gas on the SO₂ removal efficiency and the characteristics of gypsum crystal formation has been investigated in a jet bubbling reactor. The presence of HCl gas reduces the SO₂ removal efficiency, which results from the decrease of equilibrium constant of SO₂ hydrolysis reaction by the production of
ions with absorbing, HCl gas. SO₂removal efficiency decreases rapidly below the pressure drop of 90㎜Aq in the sparger, while HCl gas removal efficiency is sustained up to 50 ㎜Aq because the removal rate of HCl gas is more faster than that of SO₂. When the concentration of
ions is augmented using, CaCl₂,
removal efficiency shows maximum value at about 10-30 g/ℓ and then decreases gradually. Maximum SO₂removal efficiency appears at the concentration of about 500 ppm by the increase of HCl gas. The decrease of SO₂ removal efficiency using HCl gas occurs at lower concentration of
ions than using CaCl₂, which might implicate that concentration of
ions at the gas-liquid interface is higher than that in bulk phase. The product particles are identified as gypsum in spite of the presence of HCl gas and the size of gypsum crystal decreases with increasing the concentration of HCl gas.
The Effect on the Physical Properties of Polymer Impregnated Concrete by Ultrasonic Wave
Lee, Won-Muk ; Jo, Heon-Yeong ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 646~646
Polymer impregnated concrete(PIC) which is made from ordinary portland cement concrete(OPC) has many merits as a new concrete composit because it can be reinforced over 300% in the mechanical strengths of concrete and very strongly increased in the durabilities of concrete from freezing-tawing and chemical solution by 4-6% impregnation of polymer in concrete. For the manufacturing of PIC, the drying process of base concrete, the vaccum evacuation process, the impregnation process and the polymerization process of monomer in situ are need. These complicate problems make slow progress to the practical using of PIC in the field. So, in this research to improve the manufacturing process and the mechanical properties of PIC, ultrasonic waves were applied to the PIC during the impregnation process. By applying the ultrasonic waves the impregnated amounts of MMA in concrete is increased about 20 % than that of simple ponding method and the physical properties of PIC are increased about 25% than those of simple ponding method.
Preparation of Porous Alumina Membrane by Anodic Oxidation in Sulfuric Acid
Jang, Yun-Ho ; Lee, Chang-U ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 653~653
Porous alumina membranes were prepared by anodic oxidation using DC power supply of constant current mode in an aqueous solution of sulfuric acid. The aluminum metal plate was pretreated with thermal oxidation, chemical polishing and electropolishing before anodic oxidation. Membrane thickness, pore size and distribution were examined with several anodizing conditions ; reaction temperature, cumulative charge, electrolyte concentration and current density. Scanning electron microscopy was used to determine pore size, pore density and membrane thickness. The pore size and thickness of membrane were dependent on the cumulative charge, the reaction temperature, the current density and the concentration of sulfuric acid. The membrane pores obtained uniformly had almost straight cylindrical forms having average pore diameter of 20-40 nm and thickness of 30-60μm.
Effect of Temperature Variation on Breakthrough Curve in H₂/CO System
Seo, Bong-Guk ; Jang, Jae-U ; Lee, Chang-Ha ; Baek, Gi-Hwang ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 661~661
The effect of temperature variation on the breakthrough curve in the bed packed by zeolite 5A was studied theoretically in the isothermal, adiabatic and nonisothermal- nonadiabatic systems. The
/CO(70/30 volume %) mixture which is two major components of coke oven gas was used as a feed gas. The commercial ADSIM/SU program was used for the simulation incorporating the mass, energy and momentum balances with linear driving force and Langmuir-Freundlich isotherm models. The validity of nonisothermal-nonadiabatic model used in this study was confirmed by using the nonisothermal experimental breakthrough curve obtained from the bench scale bed. The tailing of breakthrough curve in the nonisothermal-nonadiabatic condition occurred due to the decrease of temperature profile in the small scale bed by the feed gas. In the case of the pilot scale bed, the temperature profile and breakthrough curve under the nonisothermal-nonadiabatic condition showed similar behavior with those under the adiabatic condition because of the adiabatic effect of the adsorbent in the bed. Since the dynamics of adsorption bed is affected by the temperature variation in the bulk .separation, the isothermal model makes large errors predict the breakthrough curve.
The Effect of Porogen Solution Component Ratio on the Morphology of PolyHEMA Beads
Im, Jae-Hong ; Park, Jong-Ho ; Jang, Sun-Ho ; Han, Hak-Su ; Jo, Yeong-Il ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 669~669
It was investigated how the component ratio changes of porogen solution(cyclohexanol, 1-octanol) in suspension polymerization of poly hydroxyethylmethacrylate(PolyHEMA) beads affects the morphology of PolyHEMA beads(shape, size distribution, pore). As the concentration of 1-octanol increases, shape becomes irregular and average size, porosity, average pore radius grow.
Micellization Behavior of AB Block Copolymers in S Homopolymer Matrix
Kim, Gwang-Gyu ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 674~674
Present study extends the previous studies on the micelle formation in that A-B block copolymer is mixed with homopolymer S of which the chemical structure is different from that of either block. The total free energy is minimized with respect to aggregation number P, the fraction of block copolymer in corona region η and the fraction of block copolymer outside the micelle Φ₁to obtain critical micelle concentration(CMC), micelle size and aggregation number. When homopolymer S is more selective to A block than B block in the A-B block copolymer, the CMC is remarkably decreased in comparison with the athermal case. As
is increased, the core size af micelle increases while the corona size decreases, thus the overall micelle size is almost constant. While the micelle core size increases with the increase of B block length due to the increase, in aggregation number P and decreases with the increase of A block length for the athermal case, the slight increase in
causes the aggregation number P to be increased thus the micelle core size increases.
Flow Characterization of Upward Air-Aqueous Phenol Flow in Vertical Capillaries
Kim, Sang-Yong ; Kim, Tak-Hyeon ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 682~682
In this study, the hydrodynamic behavior and flow patterns of vertical upward gas-liquid flow have been studied. A bundle of square glass capillaries was used to observe and evaluate the hydrodynamic behavior of flow. The flow pattern was found by using the flow visualization technique. The effects of gas flow rate, size of capillaries and phenol concentration upon the flow regime were studied. The trends of the transitions were more evident with respect to the change of gas flow rate than that of liquid flow rate. The, range of gas Reynolds numbers supporting a well-developed slug flow was relatively narrow and almost independent on the liquid flow rate. For three different concentrations, almost the same flow patterns were obtained. Finally, the effects of capillary size, surface tension, and flow rates were combinded by using dimension-less groups such ss Froude number and Eotvos number.
A Study on the Simulation of High-Temperature Desulfurization Process in a Fixed-Bed Reactor
Sin, Sang-Baek ; Yun, Yeo-Il ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 687~687
Zinc and iron-based sorbents were considered as prime candidate sorbents to remove H₂S in coal-derived gas. The performance of sorbents was tested at temperature range of 400-700℃, in a fixed-bed reactor using the simulated coal gas, Then, the effective product-layer diffusion coefficient,
was estimated from the best-fittings of the experimental breakthrough curves and simulated breakthrough curves by the grain model and unreacted core model, respectively. These two models showed that the predicted and experimental breakthrough curves were in good agreement. Apparent, activation energies and frequency factors were obtained for the product-layer diffusion coefficient of various sorbents by plotting in Arrhenius farm.
A Study on the Peptization Reaction Accompanied with γ-Al₂O₃ Particles Preparation by Sol - Gel Method
Yu, Seung-Jun ; Lee, Jeong-Un ; Hwang, Un-Yeon ; Yun, Ho-Seong ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 695~695
In the previous study, we showed that the, microstructure of γ-AlO(OH) andγ-Al₂O₃, particles was affected by aging stage in tate γ-AlO(OH) sol preparation process. We investigated the effects of peptization as a continuous process after aging in γ-AlO(OH) sol preparation process on characterization of γ-Al₂O₃ particles in this study. From the results, we found that there was no crystallinity and microstructure changes of γ-Al₂O₃ particles as well as γ-AlO(OH) particles according to peptization. Rut there was a decrease of average pore diameter in γ-AlO(OH) particles at the beginning of the peptization. It shows that the adsorbed H₂O molecules on agglomerated γ-AlO(OH) particles were replaced by H₃O^+ of added peptization agent and then γ-AlO(OH) particles were repulsed against each other. As the result, the macropores within γ-AlO(OH) particles disappeared. Here, the peptization phenomenon occurred since agglomerated particles binded hydrogen bands and olation bonds have been broken their bonds by the added H₃O^+, there was happened to be peptization phenomenon. In summary, we concluded that microstructure of γ-Al₂O₃particles was controlled by aging stage in sol preparation process and peptization was the process of finely suspended γ-AlO(OH) sol preparation
Particle Size Control in the Preparation of Hollow Silica Microspheres by Emulsion/Extraction Method
Lee, Gyu-Hyeok ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 701~701
Hollow silica microspheres were prepared by emulsion/extraction method, where the changes of particle size distribution and surface state of the final microspheres were examined considering the effects of a number of processing variables. First, silica sols were emulsified by 2-ethyl-1-hexanol and then the formed droplets were water extracted to form the gelled hollow microspheres. Average particle size of the final microspheres decreased with increasing stirring speed in emulsion formation step and decreasing colloid concentration. Higher colloid sol concentration gives smaller hollowness of the final microspheres. Solid microspheres formed at colloidal silica sol concentration over 60wt%. In addition, average particle size of the final microspheres decreases with increasing percentage of Span80, but aggregation of the final microspheres occurred in the excessive addition. Moderate volume ratio of silica sol to dispersing agent was 1:5, where silica sol were completely used to from liquid droplets. Also the effects of sintering temperature and the volume of dehydrating liquid were examined.
Separation of Pd from the Simulated Liquid Wastes by using Hypophosphorous Acid
Gwon, Seon-Gil ; Hwang, Du-Seong ; Jeong, Dong-Yong ; Lee, Il-Hui ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 707~707
The separation of palladium from the simulated liquid wastes was experimentally examined in a reduction process with hypophosphorous acid. The obtained main results were as follows: A favorable hypophosphorous acid concentration region was found to be from 0.03 M to 1.0 M, The appropriate nitric acid concentration was confirmed to be about 1.0 M. The suitable stagnant time was found to be within 48 hours. The precipitation fraction of palladium in the simulated liquid wastes was determined to be over 99%. The precipitation fraction of other elements(Rh, Ru, Cs, Ni and Fe) in the simulated liquid wastes was extremely low, and that of Sr was about 25%. The precipitation fraction of palladium was improved with increasing hypophosphorous acid concentration and decreasing nitric acid concentration.
Studies on the Synthesis of Polymethacrylamide Derivative with a Triphenylamine Moiety in the Side Chain as a Polymer Hole Transport Material and Its Optoelectrical Characteristics
O, Se-Yong ; Choe, Yong-Jun ; Lee, Chang-Ho ; Yun, Jang-Ho ; Choe, Jeong-U ; Kim, Hyeong-Su ; Lee, Hui-U ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 713~713
We have synthesized polymethacrylamide derivative with a triphenylamine moiety in the side chain, and then examined the feasibility of its application as a polymer hole transport material. Thermal and optoelectrical characteristics of the polymer were investigated by TGA, DSC, cyclic voltammetry, and photoluminescence measurements. Organic electroluminescent devices consisting of ITO/ hole transport material, polymethacrylamide derivative/luminescent material, Alq/MgAg were constructed using multilayer organic thin films. The redox potential of the polymer has a low value of 0.94 V, which represented the high durability and low drive voltage of the device owing to the small energy barrier for hole injection. Green emission with a luminance of 150cd/㎠ was achieved at a de drive voltage of 15V.
Absorption Behavior of Carbon Dioxide in Potassium Carbonate Aqueous Solution Using Hollow Fiber Membrane Contactor
Yeom, Bong-Yeol ; Kim, Min-Su ; Lee, Yong-Taek ; Park, Yu-In ; Lee, Gyu-Ho ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 720~720
The effects of various system parameters on the absorption of carbon dioxide into the absorbent liquid were investigated in a hydrophobic microporous hollow fiber membrane contactor with a configuration of countercurrent. An aqueous potassium carbonate solution was used as an absorbent and its permeation results were compared to those obtained with pure water to figure out the effect af chemical reaction. The mixture of carbon dioxide and nitrogen wav used as an inlet gas and the pore condition of the hollow fiber membrane was hold to be nonwetted through an appropriate control of pressures of a mixture gas and an absorbent. In case of an aqueous potassium carbonate solution used as an absorbent, the permeation rate of carbon dioxide was about 4-6 times higher than that in pure water. The permeation rate was increased with the increments of the concentration of potassium carbonate in an absorbent, the pressure and the flow rate of a mixture gas.
Effect of Temperature and Carrier Concentration on a Facilitated Transport of CO₂ Across a Liquid Membrane of Potassium Carbonate Aqueous Solution
Lee, Yong-Taek ; Yeom, Bong-Yeol ; Lee, Yong-Hui ; Park, Yu-In ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 726~726
Model analysis was carried out using the system controlling equations which include the reversible reactions of carbon dioxide with potassium carbonate to predict the permeation behavior of carbon dioxide in a potassium carbonate liquid membrane. The physicochemical properties of reaction rate constants, equilibrium constants, solubility and diffusion coefficient were represented as a function of the concentration of carbonate ion and the temperature; the calculated solubility and the predicted diffusion coefficient were found to be identical to those published data. The permeation rates could be successfully predicted with several important parameters : the thickness of liquid membrane, the partial pressure of carbon dioxide, the concentration of carrier and the temperature. The increment of the permeation rate was represented in terms of the facilitation factor as a function of carrier concentration, It was found that the permeation rate of carbon dioxide increases significantly as the concentration of carrier increases. The facilitation factor considerably increases together with the permeation rate as the temperature increases. The effective operating conditions could be obtained through this model analysis for the permeation rate as well as the facilitation factor of carbon dioxide across the liquid membrane.
Evaluation of Environmental Impact with Environmental Burden Factor
Cha, Sun-U ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 732~732
Life Cycle Assessment(LCA) is known as a method investigating the potential effects of products or any processes an the environments. LCA is composed of goal & scope definition, inventory analysis, impact assessment and interpretation. The evaluation stages for the LCA are raw material collection manufacturing products, transport, usage and recycle or disposal. In this study a LCA methodology is proposed based on the concepts that materials and energy used are converted into various types of wastes and that the wastes generated affect the environment. The wastes released are classified into gaseous, liquid and solid types. The environmental burden factor for each chemical compound in the wastes is introduced to assess the effect of hazardous waste on the environment during the LCA procedure. Results show that the propose evaluation mothod of environmental impact in LCA provides the quantified criteria for the improvement of products and processes. A case study is presented to address the advantage of the proposed LCA method.
Effects of Oxy-coal Injection on Blast Furnace Raceway Temperature
Jeong, Jin-Gyeong ; Park, Pan-Uk ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 743~743
Oxy-coal injection effects on blast furnace raceway temperature were discussed based on coke sampling experiments through the tuyere of blast furnace, measurement by R-type thermocouple and two-color pyrometer. To analyze the reason for the increase of coal combustion ratio by oxy-coal injection, the oxygen concentration was measured in the simulated experimental of oxy-coal burner. The one-dimensional mathematical model considering the kinetics of coal and coke combustion was developed in other to simulate the combustion characteristics, such as gas temperature and composition in the raceway. It was found that the calculated peak temperature of gas well concurred with the measured temperature according to oxygen enrichment through the oxy-coal burner.
A Study on Electrochemical Reduction of CO₂ by using the Perovskite Electrode
Park, Jeong-Hun ; Lee, Seung-Ik ; Wi, Jeong-Ho ; Im, Jun-Hyeok ; Lee, Je-Geun ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 751~751
By using the electrode made of Cu based perovskite which has high conductivity and excellent redox power, the characteristics of electrochemical reduction of carbondioxide were studied. After carbondioxide is dissolved in the KOH electrolyte and carried out electrochemical reduction at the negative potential (range: -2.0 -3.0V vs. Ag/AgCl), alcohois (mathanol, ethanol, and propanol) and acetaldehyde are produced. The total efficiency of products is optimum at -2.0 V vs. Ag/AgCl and with the exception of methanol, the efficiency of products is inversely proportional to the reaction temperature. The optimum reaction temperatures at which the highest efficiency could be got for individual products are 5℃ for acetaldehyed and ethanol, 10℃ for propanol and 30℃ for methanol. And according to the tentative mechanism for the reduction of carbondioxide on the basis of these experimental efficiencies of products, ethanol and acetaldehyde were intermediates in this electrochemical reaction.
Studies on Office-Waste Paper Recycling Using Cellulase from Trichoderma reesei Rut C-30
Han, U-Seok ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 759~759
Deinking of office-waste paper using crude cellulase from Trichoderma reesei Rut C-30 was studied, and compared with enzymatic deinking with commercial enzyme, Novozym 342, and conventional chemical deinking method using sodium hydroxide. Maximum brightness and freeness were obtained when 2units of the crude cellulase(CMCase activity unit) was used per gram oven dry paper. Physical strengths af the pulp, deinked with crude cellulase, showed similar behaviors with the brightness and the freeness, but decreased at higher crude cellulase concentration. The recovery yield decreased with the increase of crude cellulase concentration. The brightness and the freeness of deinked pulp using Rut C-30 crude cellulase were better than those using Novozym 342. Enzymatic deinking method gave better results than conventional chemical deinking method in deinking efficiency and physical strengths of deinked pulp. The ratio of endoglucanase and exoglucanase of crude cellulase, known to be an important parameter in determining deinking efficiency and the physical properties, was comparable to that of commercial enzyme.
Dynamic Optimisation of a Catalytic Tubular Reactor System
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 764~764
A mathematical model of a catalytic reactor system, which products phthalic anhydride from o-xylene, is constructed. Based an the mathematical model, dynamic optimisation of the system is carried out. The mathematical statement of the system is IPDAEs and they are converted into DAEs using, MOL. Within the framework of CVP, control variables can be, described in terms of a weighted combination of simple polynomials, and this leads an infinite dimensional dynamic optimisation problem to a finite dimensional NLP problem. The reformulated dynamic optimisation problem using CVP can be solved with repeated calculation of the NLP outer loop and the time integration inner loop. Dynamic optimisation is carried out for various control strategies, and the results are compared. The maximum objective function is obtained for the 4 step strategy and we compare its results with intuitively chosen control cases. From the comparison, we noted that the objective function of the optimal case is improved about 3.6-235%.
The Removal of Low Concentration Combustible Pollutant Gas Using MeO/NMD Catalysts in a Fluidized Bed Reactor
Park, Tae-Seong ; Jeong, Sun-Gwan ; Yun, Jae-Seong ; Hong, Seong-Chang ; Do, Dong-Seop ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 772~772
For the removal of combustible pollutant gas at low concentration, the experiment about oxidation of CH₄,
, CO, was carried out using platinum, paladium-impregnated NMD(Natural Manganese Dioxide) in the fluidized bed reactor for several variables. At the same flow velocity the effect of particle size on conversion appeared most efficient in the size of 0.359 ㎜. The oxidation was excellent at low flow velocity and large aspect ratio because of the effect of residence time of reactant. Also the, noble metal-impregnated catalyst oxidated VOCs at more low temperature than catalyst without impregnation. For methane oxidation ability of PdO/NMD decreased in the reason that experimental temperature was so high that the structural transformation was caused.
Hydrocracking of Vacuum Gas Oil on CoMo-Zeolite/Alumina(or Silica-Alumina)
Choe, U-Seok ; Lee, Gyeong-Hwan ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 778~778
Precipitated alumina(or silica-alumina) was mixed with zeolite Y(or mordenite), and then cobalt and molybdenum oxide were impregnated on these substrates. These prepared catalysts and commercial desulfurization catalysts were characterized by measuring specific surface area, pore volume and average pore diameter, and examined for the hydrocracking of vacuum gas oil in a batch reactor. The catalysts mixed with silica-alumina have larger mesopore size and smaller surface area than those mixed with alumina. The former showed higher activity and smaller coke amount than that of the latter. The conversion of VGO was increased with the Y content in substrate up to 33 wt%, and then decreased due to probable decrease of cracking rate on substrate. It was suggested that benzene, toluene and xylene(BTX) were formed from n-paraffin produced via VGO cracking on the substrate because they were increased with Y content. The boiling point distribution of the product on zeolite/alumina was smaller than that on zeolite/silica-alumina
Optimization of Ammonia Recycled Percolation Process for Lignocellulosic Biomass Pretreatment
O, Gyeong-Geun ; Hong, Seok-In ; Lee, Yoon-Y. ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 784~784
ARP(Ammonia Recycled Percolation) process was developed as the effective treatment process for removing the lignin from cellulose and hemicellulose of lignocellulosic biomass. In this article, as the basic study of ARP, the properties and the optimum conditions of process were estiblished, and then the overall efficiency of ARP was investigated. The important independent variables for ARP process were selected as ammonia concentration, percolation temperature, and flow rate of solvent. The percolation condition for maximizing the content of cellulose, the enzymatic digestibility, the remaining percent weight, and the lignin removal was optimized using the RSM(Response Surface Methodology). The determined optimum condition is ammonia concentration; 17.5%, percolation temperature; 185℃, and flow rate of solvent; 1.5ml/min. The satisfying results were obtained under this optimized condition, that is, the results are as follows : cellulose content; 72.33%, lignin content ; 11.16%, and enzymatic digestibility ;92.13 %.
Characteristics of CaTiO₃ : Pr Phosphor Prepared by Spray Pyrolysis
Choe, Jeong-Su ; Kim, Yun-Chan ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 792~792
Spray pyrolysis using FEAG(Filter Expansion Aerosol Generator) process was applied to the preparation of multicomponent oxide phosphor ; red emitting perovskite CaTiO₃:Pr. The morphology, particle size and crystalline phase were investigated by scanning electron microscopy(SEM), centrifugal particle size analyzer(CPSA) and X-Ray diffraction pattern(XRD). Optimum conditions for the preparation and post-treatment of particles for good luminescence were determined by cathodoluminescence(CL) and photoluminescence(PL). Spherical and non-agglomerated particles of micron size were prepared by the spray pyrolysis. As the solution concentration increased from 0.04 M to 0.54 M, the mean size of the particles increased from 0.9 ㎛ to 1.68 ㎛. The optimum temperature and holding time for the post-treatment of CaTiO₃: Pr were 1,200℃ and 5 hours, respectively. The PL intensity of CaTiO₃: Pr particles prepared by spray pyrolysis was twice larger than that by solid state reaction. The spray pyrolysis reduced optimum post-treatment time from 12 hours to 5 hours at 1,200℃.
Gas Mixing Characteristics in a Fast Fluidized Bed
Nam, Gung-Won ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 797~797
The effects of gas velocity and solid circulation rate on the radial gas mixing and backmixing characteristics have been determined in a fast fluidized bed(0.1 m-I.D. ×5.3 m-high). Radial gas mixing coefficient(D_r) increases with increasing solid holdup. Radial gas mixing coefficient has been correlated with the Froude number and the pertinent dimensionless groups. The considerable amount of backmixed tracer gas near the wall region is observed due to the downflow of solids. However, at the center region of the bed, gas backmixing is negligibly small due to high upward flow of gas-solid mixture. Gas backmixing coefficient in terms of Peclet number has been correlated with the dimensionless groups.
Design of Intermediate Storage in Noncontinuous Process under Periodic Batch Failure
Jeong, Seong-Yun ; Lee, Gyeong-Beom ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 804~804
Batch process which is operated in unsteady state mode is subject to various process imbalances. Consequently intermediate storage. vessel can take an important role for mitigating parameter variations, increasing plant availability and providing flexibility in sequencing and scheduling. A mathematical model of intermediate storage vessel sizing in parallel batch units subject to batch failure is derived. The case in which the inlet flow rate to the storage vessel is greater than or equal to the outlet flow rate from the storage vessel followed by the opposite case is considered. Two operation mode is considered, that is, in-phase operation and out of-phase operation. In phase operation refers to the delay times in parallel units while out of operation to distintly different delay times in the set of units. Analytical expressions for the limiting volume are obtained for several network configurations, i.e. multiple, input single output(MISO) system, multiple input multiple output(MIMO) system and serial system
Completion Times in Serial Multiproduct Batch Processes with Storage Time Restriction
Ha, Jin-Guk ; Lee, Beom-Seok ; Lee, In-Beom ; Lee, Ui-Su ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 813~813
The scheduling literature dealing with serial multiproduct systems has focussed on the determination of completion times for the various types of the intermediate storage policies such as UIS, FIS, NIS and ZW. In practical applications, time limitations will exist while storing the intermediate products in the storage vessel due to the time dependent changes of the chemical and physical properties. This paper presents an completion time calculation model for serial multiproduct batch process with storage time constraints. A set of recurrence relations for serial multiproduct processes in ZW and NIS policy is suggested. These results are used to describe an completion time algorithm for the case where NIS and ZW mode is used between pair of processing stages. Finally, these models were extended to treat the more usual case involving both policies in systems. The effectiveness of the proposed model is illustrated with a example.
Two-Stage Strategy to Improve Methanol Yield in the Carbon Dioxide Hydrogenation Reaction
Lee, Eun-Gu ; Kim, Sang-Beom ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 821~821
hydrogenation reaction was conducted to increase methanol yield. At 1st-stage,
was converted to CO by reverse water-gas shift reaction with Cu/ZnO/
catalysts, then at 2nd- stage, methanol was synthesized by a commercial methanol synthesis catalyst, Cu/ZnO/
. In the case of two-stage
hydrogenation reaction, CO which was produced by 1st-stage reverse water-gas shift reaction contributed to the methanol synthesis and increased the methanol yield. In particular, for the two-stage
hydrogenation reaction, methanol yield was two or three times higher than single-stage's one. In the two-stage
hydrogenation reaction, the highest methanol yield was obtained when
ratio was 4. Finally, to increase the methanol yield the more
should be converted to CO in the 1st-stage, and the feed gas ratio of the 1st-stage should be adjusted, so the effluent gas composition of the 1st-stage becomes to be close to the composition of commercial processes.
Effect of Mixed Organic Acid Additives on SO₂ Absorption in Wet Flue Gas Desulfurization Process
Kim, Eun-Ho ; Lee, Jae-Cheon ; Lee, Hyeong-Geun ;
Korean Chemical Engineering Research, volume 36, issue 5, 1998, Pages 827~827
In the existing wet flue gas desulfurization processes which have problems of low SO₂ removal efficiency, formation of scale and low limestone utilization, the adding additives to the reactants help enhance SO₂ removal. This is quite attractive since no process changes or large capital expenditure are needed. The organic acid additives enhance the rate of mass transfer. In this work, the properties of additives were studied to improve the reliability and to increase SO₂ removal efficiency. SO₂ absorption into organic solution were modeled by approximate surface removal theory and equilibrium reaction equations and a solution algorithm for numerical solution was developed. Also the criteria of selection of additives were suggested. The mass transfer enhancement by mixed organic acid, which was a byproduct of a company, was tested theoretically as an inexpensive alternative additive.