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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
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Three-Dimensional Simulation of the Stoker-type Incinerator Considering Chemical Reactions
Gwon, Sun U ; Lee, Jong Hyeop ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 353~353
A three-dimensional simulation study is performed to provide a design basis for maximum performance operation of the stoker-type incinerator. The model equations consider turbulent flows and gaseous chemical reactions to investigate the flow field, the amount of CO and NO emissions and the residence time in the furnace and boiler parts among the incinerator systems. Results show that the concentrations of CO and NO emitted decrease with the increase of the secondary excess air under given conditions. However, the residence times in the temperature cone above 1,123K(850℃) are less than 2 seconds, when the primary excess air of 100% is supplied with the secondary excess air of 100% and 150%. Based on the simulation results, the emission of air pollutants would be minimized for the primary excess air of 100% and the secondary air of 50% when considering chemical reactions and residence time in the incinerator. Comparison of characteristic times of the chemical reactions and the turbulent mixing of gases shows that the mixing effect is dominant. However, in the cases of the total excess air of 200% and 250%, the effect of chemical reactions on the incineration efficiency could not be neglected because of the relatively long characteristic time of the combustion reactions. The methodology suggested in the study would be applied to obtain the design parameters of new incinerators and determine the operating ranges of incinerators for the maximum performance.
Hydrothermal Stabilities and Adsorption Properties of Titania Loaded on MCM-41 and KIT-1 Mesoporous Materials
Gang, Tae Gu ; Kim, Jong Ho ; Seo, Gon ; Park, Heung Cheol ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 364~364
The changes in hydrothermal stabilities and adsorption properties of MCM-41 and KIT-1 mesoporous materials with titania loading were investigated. The MCM-41 mesoporous material was weak to hydrothermal treatment, but titania loading brought about the improvement of hydrothermal stability. The titania-loaded KIT-1 mesoporous material showed an excellent hydrothermal stability, so there were no remarkable differences in X-ray diffraction pattern and adsorption isotherm of nitrogen, even after hydrothermal treatment of 80℃ and 85% of relative humidity for 110h. The uptake of water was decreased considerably by titania loading, while that of cyclohexane was not altered. The partial loss of hydrophilic site for water adsorption on mesoporous materials gave rise to improve the hydrothermal stability.
Physico-Chemical Characteristics of the ZSM-5 Crystallized at Atmospheric Pressure and Conversion of Propene on the ZSM-5
Park, Jin U ; Ham, Hyeon Sik ; Kim, Jo Ung ; Ha, Jae Mok ; Jeong, Taek Seo ; Park, Hyeon Yeong ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 369~369
The ZSM-5(Si/Al2≃70) crystallized at atmospheric pressure for 60h was stable in structure. Concentration of aluminium at the inner of crystalline was higher than that at the surface. Compared with commercial ZSM-5(Si/Al2≃80, PQ), the surface area of ZSM-5 synthesized in this study was larger by 50m2/g. Based on the result of DTA, thermal stability of this ZSM-5 was so excellent that it was not destructed up to 1,100℃. Conversion of propane into aromatics was performed at 400, 450, and 500℃ with GHSV=1,300h-1. As the result, selectivity of total aromatics was changed slightly at these temperatures, but distributions of produced aromatics were very different. Activity of this ZSM-5 was studied at 500℃ for 20.5h. The result showed that the selectivity of aromatics was maintained about 42wt% consistently but the conversion of propene was decreased by about 1.5%.
Characteristics of the Liquid Phase Reduction of 2-Nitro-2'-Hydroxy-5'-Methyl Azobenzene over Pd/C Catalysts
Choe, Ju Hong ; Lee, Jeong Won ; Kim, Su Gwon ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 375~375
An experimental study was carried out to characterize the formation of 2-(2'-hydroxy-5'-methy1-pheny1)-2H-triazobenzene[tinuvin P] from the liquid phase reduction of 2-nitro-2'-hydroxy-5'-methyl azobenzene[methylazo dye] over Pd/C catalysts in the xylene-water-n-butylamine system. It was observed that this reaction was fully affected by the presence of water and n-butylamine. In older to investigate the effects of Pd/C states on the reaction, the effects of carbon preliminary treatment and palladium precursor were observed. According to the experimental results, reduced state of palladium was related to the formation of tinuvin P. The residual chloride on the catalyst prepared from palladium chloride deterred the reduction activity.
Analysis of Foaming Phenomena of Binary Mixtures in Sieve Plate Columns
Yun, Ho Byeong ; Hong, Won Hui ; Lee, Tae Yong ; Kim, Chang Sik ; Song, Ik Su ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 380~380
For analysis of the foaming in distillation and absorption tower the simulated distillation in a sieve tray column was performed. The 2 inch-diameter sieve tray was used. Foam height was measured for various air flow and liquid flow rates. Foam height data were correlated by dimensional analysis. The physical properties such as surface tension, density and viscosity and the operating such as vapor velocity and liquid flow rate were used as variables. The results of dimensional analysis show that the foam height could be expressed as a function of Weber number and Reynolds number.
Fabrication of the Electrode for Proton Exchange Membrane Fuel Cell by Using Activated Carbon Fiber
Sin, Chang Seop ; Lee, Gyeong Deok ; Lee, Seung Jae ; Lee, Tae Hui ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 387~387
The electrodes for proton exchange membrane fuel cell were prepared by mixing carbon black with activated carbon fiber which has well-developed micropore and the performances of electrodes were observed in a unit cell. The performances were compared with pore structure, dispersion of platinum and preparation procedure of electrodes. The optimal mixing ratio showing the highest single cell performance was 30wt% ACF to 70wt% carbon black. This ratio could be directly related with the highest dispersion of platinum and the lowest charge transfer resistance.
Reaction Mechanism and Thickness of Thin Film in Interfacial Polymerization
Park, Jong Won ; Jin, Byeong Bok ; Min, Byeong Ryeol ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 393~393
To manufacture aromatic polyamide which is active layer in reverse osmosis composite membrane, interfacial polymerization using MPD(m-phenylene diamine) in water phase and TMC(trimesoyl chloride) in HCFC(1,1-dichloro-1-fluoroethane) organic solvent was researched. By using UV absorbance analysis method, thin film formation process was studied according to time. As a result, aqueous phase diffusion was dominant in the control of interfacial polymerization of early time, but when the concentration of monomers in organic phase was low(0.125wt%), organic phase diffusion controlled the reaction. In addition, interfacial reaction which proceeded with delayed time of early 20 seconds was completed within 60 seconds unstoichiometrically. Also concentration change on the interface was mathmatically perdicted and the thickness of thin film was calculated by using this result. The calculated value of thickness of thin film provides good consistence with experimental results. Also theoretical equation of thickness in thin film is as follows.
δ=∫t1t2N1ʝ1dt + ∫t1t2N2ʝ2dt
Effect of Curing Kinetics on the Cross-link Density and Mechanical Property of Resol Type of Phenolic Resin
Choe, Min Ho ; Jeong, In Jae ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 399~399
Resol type of phenolic resin was cured investigating the effect of curing kinetics on the cross-link density and mechanical property. Its conversion and cross-link density increased with isocuring temperature and time. It had almost the same value of activation energy for curing as general epoxy resins. The resol resin showed the increase in tensile strength, tensile modulus and toughness with isocuring time. It showed the decrease in elongation at break with isocuring time when cured at a fixed temperature. The resol resin cured at 210℃ had lower or equal mechanical properties with those resins cured at 150℃ and 180℃ because water vapor was generated as a by-product.
Performance Estimation of Tubular Supported Liquid Membrane for Heavy Metal Removal Processes
Yun, Byeong Hun ; Kim, Jeong Hu ; Lee, Jong Hyeop ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 407~407
Modeling studies are carried out to estimate the performance of the processes for the removal and recovery of heavy metal ions in aqueous solutions using the shell-and-tube type modules of supported liquid membranes. The mathematical model includes the boundary mass transfer resistance in the bulk solutions, the interfacial reaction between metal ions and impregnated chelating agents, and the diffusion in the membrane pores. Analytic solutions are obtained for coccurrent and countercurrent flows of feed and strip solutions respectively, when the hydrogen ion concentration(pH) is constant. The metal ion removal efficiency of the membrane modules is examined when the feed side pH is constant and when changed. Results show that the performances of cocurrent and countercurrent operations of feed and strip solutions have similar trends, when the dimensionless length is less than 0.2 under the given conditions. However, the effluent metal concentration for the countercurrent flow of feed decreases to zero value for the dimensionless membrane module length greater than 0.2, while the feed concentration approaches to equilibrium for the coccurrent flow. It is also found that the metal ion flux is decreased by slow interfacial reaction rate which results from decreasing pH of the feed when the feed is operated without pH adjustment. The selectivity and removal rate of the metal ion could be increased by constant pH operation in the feed side. The effects of interfacial reaction rate constants and diffusivities of metal-complex ions on the performance of membrane modules are studied. The results would provide a basis for the design and operation of tubular supported liquid membrane modules to select chelating agents and operation conditions.
Optimization of a Utility Plant Operation Based on a Hierarchical Method
Lee, Seong Je ; Lee, Mu Ho ; Jang, Geun Su ; Han, Jong Hun ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 415~415
A utility plant is one of key unit plants in large scale refinery and petrochemical plants that supplies the steam and the electricity using fuel oil and gases. As the energy cost and the concern on the environmental pollution have been increasing, the energy saving and the operation optimization of the utility plant have received attention from both academia and industry. This paper proposes a hierarchical optimization method for the utility plant optimization that consists of top and bottom level optimization. At the upper level, the total utility plant including electricity supply and demand is optimized. At the lower level, the solution for the steam generation obtained from the top level is refined to achieve the optimal load allocation for the boilers. Various unit process models have been developed from the operation data and the material and energy balances. The key variables that mainly determine the operation cost for the utility plant have been selected and optimized. The optimization result has shown that the operation cost was reduced by 6.2% and the average efficiency of the boilers was improved by 0.3 to 1.7% through optimal boiler load allocation.
Optimization of A Utility Plant for Multi-period Operations
Lee, Seong Je ; Lee, Mu Ho ; Jang, Geun Su ; Han, Jong Hun ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 422~422
A utility plant is one of key unit plants in large refinery and petrochemical plants that generates steam and electricity and supplies them to the main plants according to their utility demands. The dynamic market situation has led to the frequent changes of the demands for the steam and electricity. Consequently, the frequent demand changes have led to the frequent changes of the operation conditions of utility plant. This paper proposes a real-time optimization methodology that determines the optimal operation conditions that reduce the energy cost of the utility plant and satisfy the utility demands at the same time. We have developed a utility plant model in open form for its flexibility in selection of decision variables. The case studies have shown that the proposed methodology can be applied to the optimization of a utility plant that has a variety of demand patterns for multi-period operations and energy cost saving can be achieved by 4-8.9% compared with usual operation.
Oxidative Coupling of Methane over BiOCl-Li₂CO₃-Sm₂O₃ Catalyst
Baek, Seong Hyeon ; Jeong, Jin Seok ; Lee, Hwa Yeong ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 429~429
Addition effect of BiOCl to Li2CO3-Sm2O3, a mixed oxide catalyst, on oxidative coupling of methane(OCM) was studied in a differencial fixed bed reactor. When Li2CO3-Sm2O3 catalyst in absence of BiOCl was used for OCM reaction, it showed severe deactivation with the reaction time. This may be due to the loss of an active lithium during the reaction. On the other hand, however, Li2CO3-Sm2O3 catalyst promoted with BiOCl showed almost the same conversion of methane, higher selectivity to C2, and the enhancement of catalyst stability. It was found from the catalyst characterization by means of XRD and FT-IR that BiOCl stabilized the acitive lithium and supressed its loss. TPD of ammonia on Sm2O3 showed that acidity of Sm2O3 decreased with the addition of Li2CO3 or BiOCl. Decrease of acidity was found to be closely related to the inhibition of total oxidation to CO and CO2 and to the enhancement of the C2 selectivity. When Bi2O3 in place of BiOCl was added to Li2CO3-Sm2O3, it showed no promotion. This suggests that promotor is not Bi but BiOCl. If BiOCl was added to Sm2O3 in absence of Li2CO3, activity change was negligible. From these results, it is concluded that BiOCl promotes OCM reaction by suppressing the loss of the active lithium and by reducing the acidity of Sm2O3.
The Effects of Polycarbosilane Precursor on the Properties of Carbon-Fiber/SiC Composites
Kim, Jin Gu ; Lee, Myeong Cheon ; Kim, Hong Beom ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 434~434
The binder for the fiber-reinforced ceramic composites should have high ceramic yield and density after sintering and should penetrate into the fibers easily. For this purpose, vinyl polycarbosilane precursor was synthesized for the carbon-fiber/SiC composite as a binder. To investigate the effects of VPS, the traditional β-PCS was also used to compare material properties. And also, to find the optimum properties of binder, VPS was blended with β-PCS. Because the synthesized VPS is soluble in solvent well, it has advantages in slurry infiltration process and can penetrate into fibers easily as well as it has high ceramic density because of its cross-linkable side-chain. As a result, the composites made using VPS have higher flexural strength, flexural modulus, ultimate flexural strain and density compared to those made using β-PCS. VPS, however, has a lower ceramic yield than the β-PCS. Therefore, better material properties were earned when we used VPS mixed with proper quantities of β-PCS.
Prediction of Average Concentration of Each Plate using Binary Plate Efficiency Data in Ternary Mixture Distillation
Lee, Jin Yeong ; Hong, Won Hui ; Kim, Chang Sik ; Song, Ik Su ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 438~438
In the multicomponent distillation, the concentration profiles for the n-hexane/n-heptane/n-octane system and the methanol/2-propanol/water system are predicted by following three methods:
(1) assumption of constant number of overall vapor phase transfer units, [Nov]
(2) solution of Maxwell-Stefan equation based on linearized theory
(3) the general solution of Maxwell-Stefan equation
The experiments are performed in a 1 in. diameter Oldershaw column with 10 plates and 15 plates respectively, in order to compare the predicted concentration profiles with the measured concentration profiles. The predicted concentration profiles using the assumption of constant [Nov] are deviated from the measured concentration profiles for both systems. But the predicted concentration profiles using other two methods are in good agreement with the measured concentration profiles. And three methods are used to predict the required number of stages for a specified separation. In non-ideal system the predicted numbers of stages are different from each other. But in ideal system three methods predict almost same numbers of stages with each other.
Liquid-phase Catalytic Cracking of Polyethylene Wax to Liquid over H-beta Zeolite
Sim, Jong Seop ; Kim, Gi Beom ; Kim, Jong Ho ; Seo, Gon ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 447~447
Liquid-phase cracking of polyethylene(PE) wax was studied over H-beta zeolite catalysts with various Si/Al ratio(13-120) and impregnated with phosphorus or cerium. The yield and carbon number distribution of liquid products, and the deactivation rate over various catalysts were depended on the amount and the location site of acid sites. H-beta catalyst(Si/Al=28) showed the highest yield of liquid product due to its high cracking activity and the slow deactivation rate. The cracking rate increased with increasing the reaction temperature or the loading amount of catalyst, while liquid product showed wide distribution in carbon number. Ihe cracking proceeded mainly in the pore over cerium-modified catalyst which acid sites on the external surface were masked, resulted in the narrow distribution in carbon number of liquid product.
Separation of Carbon Dioxide using Polytetrafluoroethylene and Polysulfone Membrane Contactors
Lee, Gi Ra ; Go, Jun Seong ; Yang, Seung Man ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 453~453
Microporous membrane absorbers were used for separation of carbon dioxide and nitrogen mixture. The membrane was made of either polysulfone(PS) or polytetrafluoroethylene(PTFE) and the absorbents were distilled water and monoetanol amine(MEA)/water solution. The results showed that the hydrophilicity of the membrane materials was a very important factor in determining the separation efficiency and rather hydrophobic PTFE membrane exhibited better performance due to its hindrance to the absorbent wettability. Considering the separation efficiency alone, the chemical absorbent MEA was better than the physical absorbent water. Among the practically important features of the present results was that the removal rate of carbon dioxide was increased with the volume flow rate of an absorbent and saturated at a certain value. Finally, the theoretical predictions by the model for mass transport through the membrane absorber agreed reasonably well with the experimental results.
A Study on the Characteristics of Polypyrrole Electrodes Prepared by Electrochemical Polymerization Method
Kim, Gwang Cheon ; Park, Jong Ho ; Im, Jae Hong ; Han, Hak Su ; Jo, Yeong Il ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 460~460
In this study, the p-type PPy/ClO4- and polyanion-doped PPy/PVS- polymer electrodes were prepared at various polymerization electric charges by incorporating electrolyte anions of different molecular weight during potential step polymerization. The surfaces of the prepared electrodes were inspected by SEM and their electrochemical properties were investigated with CV and ac impedance method. The results suggested that anion was mobile ion for PPy/ClO4- electrode and cation for PPy/PVS- electrode during redox reaction. As polymerization electric charges increased, the charge transfer resistances were decreased and the electric double layer capacitances were increased in the both electrodes. The surface areas of both electrode increased as polymerization electric charges increased. Especially, the morphological exchanges of surface may be more important effect in the electric double layer capacitance for PPy/ClO4- electrode than for PPy/PVS- electrode.
Effects of Diffusion on the Fabrication of Composites Reinforced with Layered Fibers by CVI
Kim, Yeong Jun ; Lee, Seong Ju ; Im, Byeong O ; Jeong, Gwi Yeong ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 467~467
Effects of diffusion on the fabrication of ceramic/ceramic composites reinforced with layered fibers by chemical vapor infiltration of SiC from dichlorodimethylsilane have been studied in this research. Samples of 2, 4, 6, 8-ply woven carbon fabrics were used. At a low DDS concentration, SiC was deposited in a small amount, even though it was deposited for a long reaction time, and a needle-shape deposit appeared inside the sample. Since each ply could be separated easily, the shape of deposit in each ply could be observed. There was less deposition in the inner plies than in the outer plies, which reflected effects of diffusion. These experimental results matched with the results of mathematical modelling calculated with the value of deposition rate constant, 10 cm/min at 950℃. The results were also supported by the scanning electron microphotographs and the pore size distribution analyses.
Production and Distribution of Multisite Batch Plants Considering an Uncertain Demand at Warehouses
Lee, Ho Gyeong ; Lee, In Beom ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 472~472
In this paper we develop a model of an integrated production and distribution system comprised of multisite batch plants and several warehouse. An integration of production and distribution system may generate significant savings by trading off the costs associated with the whole, rather than minimizing production and distribution costs separately. The mathematical approach is presented in this research. The problem consists of two or more multiproduct batch plants producing several products to supply several warehouse. The demands of each product at warehouses are treated as uncertain parameters described by normal distribution functions. A mixed integer nonlinear programming(MINLP) formulation is proposed. The effectiveness of the application of the suggested approach for the production and distribution of multisite batch plants will be illustrated with an example problem. The problem is solved with GAMS/DICOPT++.
Development of Dynamic Simulator Modules of Charge, Reaction Processes and Interface for Intelligent Batch Process Auto-design Package
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 478~478
Recently Stephanopoulos developed an automatic intelligent batch process design and simulation tool, named BatchDesign-Kit(BDK). For the updated version of BDK, dynamic simulator modules were highly required. At this research we developed dynamic simulator modules for BDK with charge and mixing operation and several reaction operation processes. In this research we accomplished three main achievement. First, we developed gPROMS input codes for batch process dynamic simulation. Second, we developed the Graphic User Interface program far non-specialized users and interfaces with main body of BDK. The third achievement was to generate the programs which can access and control the outer executing programs(gPROMS, MS-Excel etc.) and to develop the dynamic link library program for accessing database in BDK.
Development of Transdermal Therapeutic Systems using Crosslinked Chitosan and Chitosan
Na, Jae Un ;
Korean Chemical Engineering Research, volume 36, issue 3, 1998, Pages 484~484
Chitin, the natural polymer has been known as harmless and innoxious material to human and been also known to be biodegradable. Chitosan was prepared by the deacetylation of chitin. The crosslinked chitosan was prepared from chitin after reaction with epichlorohydrin followed by deacetylation at C2-position. Epidermal releasing polymeric matrix was prepared after swelling drug carriers(chitosan and crosslinked chitosan) with distilled water, and adding silver sulfadiazine and glycerine. The release behavior of drug from polymeric matrix was studied in pH 7.4 phosphate buffer solution by varying the silver sulfadiazine content, glycerine concentration, and the thickness of the matrix. The drug release time was delayed by increasing the content of silver sulfadiazine and the thickness of the matrix, whereas decreased as glycerine concentration increased. The apparent constant(K) of release rate was independent upon the matrix thickness, but was proportional to the content of drug or glycerine. Thus the drug release rate at the crosslinked chitosan matrix was more delayed than at the chitosan matrix. These results indicated that the drug carriers matrix showed some potential as drug delivery systems for transdermal therapeutic applications.