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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 32, Issue 6 - Dec 1994
Volume 32, Issue 5 - Oct 1994
Volume 32, Issue 4 - Aug 1994
Volume 32, Issue 3 - Jun 1994
Volume 32, Issue 2 - Apr 1994
Volume 32, Issue 1 - Feb 1994
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Solubility of Chlorodifluoromethane(R-22) and Dichlorodifluoromethane(R-12) in Olive Oil and Oleic Acid
Park, Dong-Myung ; Hong, Won-Hi ; Lee, Youn-Yong ; Lee, Youn-Woo ; Choi, Dae-Ki ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 747~747
The solubilities of chlorodifluoromethane(R-22) and dichlorodifluoromethane(R-12) in organic solvents were measured in the range of low pressures and several temperatures(278-338K). Organic solvents used in this system were olive oil and oleic acid. Henry’s law is applied in the lower temperature range and the solubilities of R-22 show negative deviations from Raoult’s law. In this study temperature and pressure dependence were correlated. The correlation of gas solubility data, using Krichevsky-Kasarnovsky equation and Van’t Hoff expression are obtained. Values of Henry’s constant, partial enthalpy and partial entropy in organic solvents have been determined for both gases. The solubilities increase with increasing pressure and decreasing temperature and both gases are more soluble in olive oil than in oleic acid. The solubilities of R-22 in organic solvents were higher than those of R-12 because of hydrogen bonding between solvents and solutes.
Scheduling of Multi-product Batch Processes Using Modified Simulated Annealing
Jung, Jae-Hak ; Won, Kee-Hoon ; Jung, June-Young ; Yang, Dae-Ryook ; Lee, In-Beum ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 753~753
As a trend toward multi-product batch processes is increasing in Chemical Process Industry(CPI), multi-product batch scheduling has been actively studied. But the optimal production scheduling problems for multi-product batch processes are known as NP-complete problems. So the methods which can obtain not exact optimal solution but near optimal solution have been studied. Heuristic methods have been used frequently for near optimal solutions but recently Ku and Karimi have studied the Simulated Annealing(SA) which acquires outperformed results in scheduling problems. But SA method can be improved for better results of batch process scheduling problems. In this paper, we suggest the Modified Simulated Annealing(MSA) which is composed of two stage search algorithms. At the first stage, Rapid Access Extensive Search(RAES) algorithm was used for better location of initial state. At the second stage, a modified Metropolis algorithm with adjusted control parameter was developed and used for better solution. A variety of examples are tested to evaluate the performance of MSA and to be compared with the SA method. From these tests we can show that the MSA is superior to the SA.
Theoretical Study on the Possible Existence of Multiplicity Features in Ethylene Hydrogenation
Han, Do-Hung ; Park, O-Ok ; Kim, Young-Gul ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 765~765
The possible existence of multiplicity features, including ignition and extinction phenomena, is theoretically examined for ethylene hydrogenation in the kinetic region with the exclusion of heat and mass transfer limitations, and then the ethylene hydrogenation is compared with CO oxidation for which it has been claimed in several studies that multiple steady states can come from a purely kinetic process. From both theoretical and numerical analyses, it is concluded that if each chemisorbed ethylene occupies less than two active sites of catalyst more strongly than hydrogen the multiple steady states can exist, but the multiplicity features can not be obtained if an ethylene molecule adsorbs strongly upon more than two active sites. From our experiment and another studies for chemisorptions, it is confirmed that the chemisorption of ethylene requires geometrically 3-4 active sites per each molecule and that is much more strong than one of hydrogen. Therefore, the existence of kinetically induced multiplicity will not be possible for ethylene hydrogenation. On the other hand, the kinetically induced multiplicity for CO oxidation will arise from the fact that carbon monoxide chemisorbs more strongly than oxygen upon less than two active sites. In our study, it is found that the number of geometrically occupied active sites rater than the chemical bonding number in the chemisorption of reactants might exert an important influence on the existence of the multiplicity features in the reaction proceeding via Langmuir-Hinshelwood mechanism.
Microporosity of Activated Carbon Fiber Prepared by Steam Activation
Kim, Je-Young ; Hong, Ik-Pyo ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 778~778
Pitch-based activated carbon fibers(ACF) were prepared by steam activation under various conditions. The adsorption isotherm of ACF measured by nitrogen adsorption at 77 K was Type I and ACFs were composed of mainly micropores. The specific surface area of ACF was higher than
at burn-off 50%. At the same burn-off %, ACF with higher specific surface area can be prepared under lower activation temperature. The pore size distribution of ACF determined by Horwath-Kawazoe method was very narrow for each samples.
The Performance of Raney Ni Hydrogen Electrode for Alkaline Fuel Cell
Cho, Jeong-Yoon ; Jo, Jang-Ho ; Kim, Hyung-Jin ; Moon, Sei-Kee ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 784~784
The polarization characteristics of semihydrophobic double-layered porous hydrogen electrode manufactured with Raney Ni and PTFE powder was investigated. The optimum PTFE powder content in the catalyst layer was 25wt%. Compared the electrode performance of Raney Ni with Ni, the former was by far better than the latter. There was little electrode performance difference among various Raney Ni electrodes without dopant. The activity of Raney Ni was improved by adding 9 wt% Mo power as dopant, and the electrode composed of this catalyst showed relatively a stable electrode performance. It was possible to improve the anodic performance of Raney Ni electrode by modifying the electrode structure according to the flooded agglomerate model. The preferred condition for the preparation of Raney Ni catalyst layer was mixing the water repellent catalyst with non-treated hydrophilic catalyst at the ratio of 5 to 1.
Gas Phase Homo- and Co-polymerization of Ethylene over
Chung, Min-Chul ; Kim, Il ; Kim, Jae-Ha ; Choi, Hong-Ki ; Woo, Seong-Ihl ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 792~792
Homo- and co-polymerization of ethylene were carried out in both gas and slurry phases over
catalysts in the range of temperature
and pressure 2-10 psig. In gas phase polymerization, maximum activity was measured at the Al/Ti mole ratio of 377, and reaction rate dependence on
concentration could be explained with the Langmuir-Hinshelwood adsorption model. Even though maximum activities were obtained at the same temperature,
in both gas and slurry phases, overall activation energy was higher for the slurry phase(13kcal/mol) than for the gas phase(4.7kcal/mol) polymerization. The molecular weight behavior has been examined by measuring intrinsic viscosity. The molecular weight was increased as the ethylene pressure increased, and as the temperature and the concentration of
and hydrogen decreased. Using two different comonomers(propylene and butene-1), the copolymerization of ethylene was carried out. The intrinsic viscosity and the melt index were decreased as comonomer concentration increased, and the maximum activity was observed when the concentration of comonomer is about 20 mol%.
Thermodynamic Calculation of Equilibrium Compositions in the Diamond Synthesis Using Hot-Filament Chemical Vapor Deposition Method
Choi, Yoon ; Park, Yong-Chan ; Kim, Jae-Young ; Rhee, Shi-Woo ; Moon, Sang-Heup ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 802~802
The thermodynamic equilibrium compositions of
systems used in the vapor-phase synthesis of diamond were calculated as a function of temperature in the presence of excess
gas. The composition changes of solid-phase graphite as well as gas species were also investigated, when oxygen and nitrogen sources were incorporated into the systems. It was proved that the reaction temperature to maintain the maximum amount of
species in the equilibrium compositions was about 2,000K. In the
systems, the formation reactions of HF and HCl were thermodynamically favorable. The equilibrium composition of solid-phase graphite reaction product was affected most strongly by the presence of oxygen sources.
Fuel Evaluation of Indonesian Roto Coal in a Pilot-scale Combustor
Kim, Jong-Won ; Sim, Kyu-Sung ; Son, Young-Mok ; Lee, Sang-Ho ; Park, Kee-Bae ; Myung, Kwang-Shik ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 809~809
Problems encountered in use of pulverized coal, in particular, have practical implications related to coal blending and up-grading of imported coals. Practically, significant problems are recognized in such aspects as control of the combustion process, fireside corrosion, ash and pollution. The methodology of predicting problems using pilot scale facility is less expensive, requires less coal and less time to execute, compared to the use of full scale facility. In this study, evaluation of Indonesian Roto coal was performed in a pilot scale coal combustion test facility. Burnout ratio of coal was higher then 98%, and increase of swirl number and preheat temperature of air made flame stabilize.
concentration in flue gas was lower in the range 0.5-0.9 of swirl number. Concentrations of oxygen and carbon dioxide in flue gas were constant in spite of variation of swirl number in this work.
Gas Holdup in the Bubble Columns with Viscous and Viscoelastic Liquids
Suh, Il-Soon ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 819~819
The effects of liquid viscosity and viscoelasticity on gas holdups were studied in a bubble column. For the sake of covering a wide range of the liquid properties, the newtonian sucrose, strongly pseudoplastic and weakly viscoelastic xanthan, strongly viscoelastic polyacrylamide(PAA) and moderately viscoelastic xanthan-PAA mixture aqueous solutions were used as the liquid phase. As increasing the liquid viscosity, the gas holdups decreased in the heterogeneous flow regime. On the other hand, the gas holdups in the slug flow regime increased with the effective viscosity. The gas holdups in the strongly viscoelastic solutions of PAA exhibited lower values than those in the weakly viscoelastic xanthan solutions.
Prediction of Temperature Distributions from Mass and Energy Balances and Effects of Operating Parameters in Molten Carbonate Unit Fuel Cell
Ahn, Young-Joo ; Chung, Gui-Yung ; Ju, Jae-Back ; Nam, Suk-Woo ; Oh, In-Hwan ; Lim, Tae-Hoon ; Hong, Seong-Ahn ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 830~830
A mathematical model is proposed to simulate the current density and the temperature distribution of molten carbonate unit fuel cell. In this model, conversion of gases, heat transfer by conduction, convection, and radiation, and heat generation by reaction were considered for the cross and the parallel flow type fuel cell. Additionally, the effects of the gas flow rate and the ratio of the flow rate of the cathode gas to that of the anode gas were studied. It was seen that the current density distribution was affected by the anode gas, while the temperature distribution by the cathode gas. It was also found that, in order to get an uniform temperature distribution, the ratio of the flow rate of the cathode gas to that of the anode gas should be around 0.25.
Hydrodesulfurization Activity of
Kim, Yu-Jeong ; Cho, Ihl-Hyun ; Park, Seung-Bin ; Ihm, Son-Ki ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 844~844
Sol-Gel Catalyst have been investigated by X-ray diffraction(XRD) FTIR BET and TEM, and thiophene hydrodesulfurization(HDS) and their activities were compared with that of impregnated catalyst. A series of sol-gel catalysts were prepared by mixing Co-, Mo-acetylacetonate(Co-, Mo-acac)with alumina sol, or by impregnating dried gel or calcined gel with these precursors. The alumina sol was obtained from hydrolysis of
with excess water and peptization of the resultant hydrate with
. The reference catalyst was prepared by impregnating
with aqueous solution of cobalt nitrate and ammonium molybdate. For the sol-gel catalyst formed from mixing all Co-Mo-acac with alumina sol, the HDS activity was lower than that of reference catalyst. However, HDS activity was significantly increased to the activity of the reference catalyst, when the half of Co-, Mo-acac were mixed with alumina sol and the rest of them were impregnated into calcined gel. For the catalyst first formed from alumina sol mixed with only Co-acac, followed by impregnating a Mo-acac solution into the calcined gel, HDS activity was lower than that of catalyst prepared by reversing the order of adding Co-acac and Mo-acac. This reduction of activity results from the absence of synergic effect due to the migration of cobalt into the alumina matrix during sol-gel process. The impregnated cobalt are, however, deposited on the surface of the preoccupied
fine crystallite, so that HDS activity is increased due to the synergic effect. The sol-gel catalysts have a micropore of about 2nm in radius which affects the access of thiophene reactants to active sites, thereby lowering the HDS activity of sol-gel catalysts than that of conventional cobalt-molybdenum on gamma alumina catalyst.
Preparation of Lithium Aluminate by Sol-gel Method
Jung, Jae-Myong ; Park, Seung-Bin ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 853~853
Dual metal alkoxide was prepared by reacting lithium isopropoxide and aluminum iso-propoxide in iso-propanol. The dual metal alkoxide, lithium aluminum iso-propoxide, was then hydrolized to form sol which turned into lithium aluminate powder gel with uniform particles of submicron sizes. The amorphous gel had
surface area and
pore size. After sintered at
for six hours, it was completely transformed to
surface area and
particle size. When the gel was sintered at
for 6 hours, peaks of
in the XRD spectrum began to appear and it almost turned into
. To compare microstructure, lithium aluminate powders were also prepared by solid state reactions. Lithium aluminates were hexagonal plate shape of
size, and were mostly
Structure and Thermal Properties of Cr and Cu Added
Suh, Jeong-Kwon ; Ha, Baik-Hyon ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 859~859
The structure and thermal properties of Cr and Cu added
System were investigated using XRD, BET, ESCA, TEM and DTA. During calcination the addition of chromium retarded the phase transition of
and improved the thermal stability of
System at highly temperature. However the addition of copper on
System accelerated the phase transition of support. The surface area after being calcined at
for 2 hours was
oxide. The sintering of
proceeded via surface diffusion and was not influenced by the Cr addition. The sintering of Cu added
System proceeded via viscous flow. The activation energy of the phase transition above
had a constant value about 600 kJ/mol, regardless of the Cr and Cu addition.
Simultaneous Ethanol Production and Enrichment in a Membrane Moderated Bioreactor
Kim, Jun-Seok ; Jeong, Yong-Seob ; Hong, Suk-In ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 866~866
The living cells, Saccharomyces cerevisiae, are sandwiched between ultrafiltration and reverse osmosis membranes. The ultrafiltration membrane separates the cells from the feed volume, while providing free passage for all nutrients to the cell mass below. Therein, the bioreaction starts to occur, leading to product ethanol. The reverse osmosis membrane, while immobilizing cells, also helps in separating the nutrients from the product stream preferentially. Therefor, the enriched ethanol solution could be obtained without much contamination from glucose and nutrients. Above the filtered cell mass a coarse filter paper was placed to provide the cells extra room for growth and to eliminate the partial closing of pores of the ultrafiltration membrane which is in contact with the cells. In order to minimize the back diffusion of ethanol from the yeast cell layer to the feed solution, the cellulose acetate ultrafiltration membrane was replaced into the more hydrophobic polysulfone ultrafiltration membrane. In these cases, performance data for glucose fermentation to ethanol by yeast cells were obtained. As a result, the maximum ethanol concentration was 70.3g/l after 400 hours of operation continuously and at the operating pressure of 2758 kPag(=400 psig) on the substrate solution for the forced convection flow of substrate to the cell layer.
Kinetic Study and Mathematical Model for the Production of Isomalto-oligosaccharides from Maltose by Transglucosylation of Aureobasidium pullulans
Yun, Jong-Won ; Suh, Jung-Ho ; Song, Seung-Koo ;
Korean Chemical Engineering Research, volume 32, issue 6, 1994, Pages 875~875
A mathematical model for the production of isomalto-oligosaccharides from maltose by transglucosylation reaction of Aureobasidium pullulans was proposed based on the kinetic study, and the predicted values were compared with the experimental results for two maltose concentrations. The formation of isomalto-oligosaccharides occurred from a consecutive set of disproportionation reactions
. The Michaels-Menten constants for maltose and panose were 154.5g/l and 55.6g/l, respectively at
. Competitive inhibition by glucose and panose was observed from kinetic analysis for the substrate maltose where the inhibition constants were 15.3g/l, 9.8g/l, respectively. In a similar manner, glucose was also proved a competitive inhibitor when panose was used as substrate, in which the inhibition constant was found to be 6.3g/l. The predicted carbohydrate profiles of the proposed model gave good agreements with the experimental results.