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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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Effects on Activating Agents(CO₂, steam) as Preparating of Activated Carbon Fibers
Park, Byeong-Bae ; Yu, Seung-Gon ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 491~491
Activated carbon fibers(ACF) show different activation behaviors and adsorptive properties, which depend on the activating conditions and starting materials used. So, PAN- and pitch-based activated carbon fibers were prepared by flow rates of varying the activating agents(
, and steam) and temperatures in activation process. The pitch-based activated carbon fibers were microporous materials of high specific surface areas(>2,500 ㎡/g). The reactivity in steam as activating agent was about three times faster than in
, the reactivity of pitch-based carbon fibers as starting materials was higher than PAN-based carbon fibers. The ranges of average pore diameter for steam and
were about 15-17Å and 11-13Å, respectively. It implies that smaller and more uniform micropores are developed in
. Optimum conditions of the activation process for preparing high quality ACF are pitch based carbon fiber as starting material, lower temperature(800℃),
as activating agent, flow rate of 38 ml/hr.
A Study on Deacetylation of Chitin for Preparation of Chitosan
Lee, Cheon-U ; Lee, Hyeon-Ju ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 496~496
The relationships between the concentration of alkali solution for hydrolysis, reaction temperature, reaction time and deacetylation of chitin were studied for the preparation of pure chitosan. It was possible to prepare complete deacetylation of chitosan products from low degrees of deacetylation. The intermediate products of partially deacetylated chitosan through the deacetylation process was intermittently washed with distilled water to neutralize preventing serious degradation of molecular chain. It could be prepared the highly deacetylated chitosan by the concentration and reaction time of alkaline hydrolysis. The activation energy was presented 7 kcal/mol by the deacetylation of chitin in the range of 25-110℃ with 47% alkali solution.
Concentration Profiles and Murphree Efficiencies of Acetone-Methanol-2-Propanol System in a Batch Distillation Column
Kim, Jeong-Geun ; Kim, Seok-Jong ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 502~502
Concentration profiles of acetone-methanol-2-propanol system, obtained experimentally using a 10 cm I.D.-, 10 stages sieve-plate distillation column, were compared to theoretical profiles. The experiments were performed under 1atm, total reflux condition and 2.8 gmol/min of vapor boil-up rate. Theoretical profiles were calculated by five different methods : use of binary number of transfer units estimated AIChE, Zuiderweg and Harris empirical correlations, numerical integration of the Maxwell-Stefan equation and use of constant Murphree efficiency for all components. All theoretical profiles were found to give good agreement with experimental ones, among which the profiles obtained using AIChE method showed the excellent coincidence within 0.32% AAD. Being about 60%, the component Murphree efficiencies were similar in most stages but discontinuity in efficiency for methanol was observed for such stage showing the maximum concentration in the column.
Study on Thermal Decomposition and Crystal Structure of Yttrium Oxalate Produced by Reaction Crystallization
Seong, Min-Hyeon ; Kim, U-Sik ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 510~510
Study on thermal decomposition of yttrium oxalate produced by reaction crystallization of yttrium chloride and oxalic acid was carried out. The yttrium oxalate having three crystal waters belonged to monoclinic crystal system and the crystal waters of yttrium oxalate were dehydrated before the yttrium oxalate was thermally decomposed. The dehydration of crystal water in yttrium oxalate did not changed the molecular bonding and crystal structure of yttrium oxalate but gave significant influence on shape and size of yttrium oxalate crystal. Thermal decomposition of yttrium oxalate occured above 366℃. Between 366-465℃ the yttrium oxalate was thermally decomposed and it resulted in a non-stable and non-crystalline product. Above 500℃, however, yttrium oxide having cubic crystal system was produced by the thermal deccomposition. By using Hyper-Chem it was predicted that the yttrium oxalate synthesized by the reaction crystallization and the yttrium oxide produced by the thermal decomposition had three dimensional molecular structures, which were preferred thermodynamically. The results of thermal decomposition of yttrium oxalate under nitrogen gas were same with those under air.
The Preparation of Poly(vinylalcohol) Hydrogel by the Freezing/Thawing Method and Its Mass Transfer Characters
Jeong, Ha-Gyeon ; Jo, Seong-Yun ; Im, Jae-Hong ; Jo, Yeong-Il ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 517~517
Polyvinylalcohol hydrogels for microbial immobilization were prepared by freezing/thawing method by varying several parameters such as freezing/thawing cycle number, freezing time and initial PVA solution concentration. By determining and calculating mesh size, average molecular weight between crosslinks and crosslinking density, the characteristics of prepared hydrogels were investigated and then glucose permeability experiments were carried out. The more freezing/thawing cycle number, the longer freezing time, and the concentrated initial PVA solution, the denser the hydrogel. Mesh size was 68-266Å and equilibrium volume swelling ratio was from 6 to 27. Glucose diffusion coefficients were 2.478×
Pervaporation Characteristics of Aqueous Isopropanol Solution Using Tubular Type PDMS/Ceramic Composite Membrane
Hong, Yeon-Gi ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 524~524
PDMS(Polydimethylsiloxane)/ceramic composite membrane was used in pervaporation process in order to enhance the flux with maintaining proper selectivity. In pervaporation of IPA(Isopropanol) from aqueous IPA solution, selectivities of IPA decreased and fluxes increased with concentration of IPA in feed mixtures. In removal of IPA from aqueous IPA solution by using PDMS/ceramic composite membrane, selectivities of IPA increased with operating temperature in the range from 0 to 20 wt% of IPA in feed mixtures. This phenomenon could be explained in terms of coupling effects between permeant and composite membrane and between permeants. Among these effects, capillary condensation could be importantly considered due to hydrophilicity and porous structure of ceramic support. In order to investigate the effect of ceramic support on pervaporation characteristics, pervaporation with homogeneous PDMS membrane without ceramic support was carried out with the same feed mixtures. In the case of non-supported membrane, the selectivities of IPA decreased with operating temperature in all the concentration range of IPA in feed mixtures.
Plasma Surface Modification of Plasma Polymerized Trifluoromethane Films
Hwang, Seung-No ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 530~530
The surface modification of plasma polymerized
plasmas treatment was investigated from the point of view of the hydrophilicity and the functionality of the generated surface. The surface treated with plasma was generated carbonyl, carboxyl, and aldehyde groups and showed the increase in the oxygen content and O/C atomic ratio. Also, the effects of process parameters on the hydrophilic surface of the plasma treated plasma polymerized
have been determined in rf-plasma reactor. The contact angle of plasma polymerized
decreased with increasing rf-power and treatment time. It was found that the plasma polymerized CHF3 was hydrophilic surface, and the optimum condition for hydrophilic surface modification was 300-400(GJs/kg), in the composite parameter[(W/FM)t].
Consolidation Pressure Control in Thermally-Expandable Rubber-Tool Process for Polymeric Composite Materials
Gu, Mi-Gyeong ; Geum, Seong-U ; Lee, Yeong-Gwan ; Nam, Jae-Do ; Ha, Jong-Min ; Choe, Heung-Seop ; Lee, Seok-Hyeon ; Seo, Mun-Ho ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 536~536
As a novel composite manufacturing process, the thermally-expandable rubber-tool process was investigated in order to obtain the enhanced laminate consolidation and resin infusion in both thermoplastic- and thermoset-based composite systems. A silicon-based rubber tool was chosen for the primary applications in aircraft environment. The thermal expansion coefficient and bulk modulus of the rubber tool were measured by a 1-D radial expansion system and subsequently used to predict the pressure generated by the expanding rubber tool as a function of temperature. The generated pressure was expressed by the thermo-physical properties and as a function of processing temperature. Finally, the mold configurations including the relative gap and rubber tool volumes influenced the characteristic features of the pressure build-up in rubber-tool based thermal processing.
Quantitative Analysis of Calcium Carbonate Polymorphs by X-Ray Diffraction
Yu, Seong-Gu ; Ryu, Si-Ok ; Park, Yeong-Hae ; Ryu, Jong-Ha ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 543~543
Samples of calcium carbonate were analyzed by X-ray diffraction to determine the polymorphic compositions of calcite, vaterite and aragonite. Standard curves were taken from the peak heights of binary polymorphs mixtures. The content of vaterite in the mixture of calcite and vaterite was obtained from the ratio of the peak heights at 29.32° and 24.81°, 27.09° and 32.75°. In this work the experimental error is estimated at about 3%. For the binary mixture of calcite and aragonite the content of aragonite was determined from the ratio of the peak height of calcite, 29.32°, to the peak heights of aragonite, 26.06°, 38.40°, and 45.81°. The experimental error is estimated at about 3%. Compositions of three polymorphs were estimated from the standard curves. The results from the experiments for the pure synthetic components gave excellent agreement with the calculations.
Varicella-Zoster Virus Propagation Model in Human Lung Fibroblast Cells
Ryu, Jae-Nam ; Park, Jeong-Geuk ; Kim, Hyeon-Su ; Kim, Su-Ok ; Jeong, Yong-Ju ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 548~548
Varicella-zoster virus(VZV) is known to be an unstable virus. Infectious cells infect directly adjacent cells and VZV has the strongly cell-associated nature. Kinetics analysis of VZV proliferation shows different experimental values due to the environmental sensitivity of VZV. So the prediction of exact yield of VZV is difficult. In order to solve this problem, a theoretical model is required to estimate more precise yield of VZV. The yield of VZV is related to multiplicity of infection(MOI) and time of culture in the proliferation of VZV. A model was developed by using the finite element method considering the cell-to-cell infection characteristic of VZV. The spreading time of plaque forming cells to the neighboring cells was determined as 8 hours by several experiments. It was assumed that plaque forming cells lost infectivity within 48 hours after it was infected. From the simulation of two-dimensional model used in this work, it was confirmed that the maximum yield of VZV could be obtained at the MOI of 1:10, which corresponded with experimental results. The VZV propagation model can be extended to the future 3-dimensional model which is closer to real VZV propagation.
Determination of Air/Water Partition Coefficient for Environmental Pollutant by Using Modified EPICS Method and the Relationship between Partition Coefficient and Physical Properties
Ryu, Seon-A ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 554~554
Environmental organic chemicals disappear by means of transport and mixing phenomena and alterations of the structure of a compound. The transport phenomena can be represented by partition coefficient. In this work, the air/water partition coefficient(
) was measured by using our own modified EPICS(equilibrium partitioning in closed system) method. The accuracy and reproducibility of this method were reliable since measured data were agreed well with the literature values within 1% average deviation for n-alkanes. The
and Henry's law constants for n-alkenes, aromatic and chlorinated compounds were measured. The relationships between
and molar volume, vapor pressure and water solubility were also analysed. The
was linearly proportional to molar volume and inversely proportional to vapor pressure and water solubility except chlorinated benzene compounds. The chlorinated benzene compounds didn't show the consistent tendency for molar volume, vapor pressure and water solubility. It may be caused from the difference of intermolecular force. The
was changed by difference of molecular structure. The weaker the bond energy of chemicals, the larger the
Simulation of PSA Process for CO₂Recovery from Flue Gas
Kim, Yu-Chang ; Yeo, Yeong-Gu ; Lee, Hwa-Ung ; Song, Hyeong-Geun ; Jeong, Yeon-Su ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 562~562
The simulation of pressure swing adsorption(PSA) process for recovering highly pure
from flue gas was performed. Seven different processes including blowdown, pressure equalization, rinse and/or evacuation step were compared to obtain optimal process. In this study, bed dynamics was considered for the better simulation result. Activated carbon was used as an adsorbent. Pressure equalization contributed to increase the recovery and purity by preventing
loss at blowdown and redistributing the components in the bed. And also, rinse, recycling the product gas recovered at evacuation step, conduced to increase the purity by readsorbing highly concentrated
. Especially, pressure equalization step combined with rinse step plays a key role in improving the performance of process because of minimizing the concentration of
in bed and increasing pressure difference between the bed pressure and atmospheric pressure. Maximum purity was about 97% and recovery at that point was about 55%.
Skeletal Isomerization of 1-Butene over Alkali-Modified Silica-Alumina Catalysts
Kim, Na-Hyeon ; Kim, Jong-Ho ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 571~571
Variations of conversion and selectivity in the skeletal isomerization of 1-butane with the loading of alkali on silica-alumina catalysts were investigated. Surface area and the number of acid site of silica-alumina decreased with the alkali modification. The conversion of 1-butene decreased but the selectivity to iso-butene increased when the loading level of alkali increased. The decrease in the conversion, the increase in the selectivity to iso-butene and the depressed deactivation of alkali-modified catalyst were related to the acid site concentration. The improvement of the selectivity to iso-butene with alkali loading was due to the decrease in the acid site concentration, resulting in suppression of multi-molecular oligomerization followed by cracking.
Coking Pressure Behaviour during Coal Carbonization in a Movable-Wall Test Coke Oven
Lee, Un-Jae ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 576~576
Coal carbonization for various kinds of coals has been carried out in a movable-wall test coke oven(0.2W×0.4H×0.45L) to investigate the variation of coking pressure when dried coal is charged in the coke oven. Also fluidity properties of single coals and coal blends have been determined in a Gieseler plastometer. Fluidity of single coal increases with increasing volatile matter content. Fluidity of coal blends is largely depended on that of single coal rather than volatile matter content of coal blends.
reactivity and coke strength index after reaction with
CSR) of coke produced from single and coal blends also have been evaluated. With increasing the amount of strong-coking coal, CSR of the coal blend increased but
reactivity of the coal blend decreased. Effects of coal rank and moisture content on coking pressure in a 30kg of test coke oven were determined. Coals(PH, DP) with high fluidity exhibit high coking pressure but despite of low fluidity a coal(NP) represents the largest coking pressure among the coals tested. Bulk density of the dried coal(5-6 wt%) is 13-20% higher than that of the wet coal(7-9 wt%). Coking pressure of the dried strong-coking coal is approximately two times as high as that of the wet coal and internal gas pressure in the dried coal charge center is also much higher than that in the wet coal charge center.
Supercritical Fluid Extraction for Reuse of Waste Lube Oil
Bae, Hyo-Gwang ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 584~584
The experimental study for reuse of waste lubricating oil was carried out, by using flow-type apparatus newly manufactured for supercritical propane extraction. The weight ratio of solvent and waste lube oil was changed between 1.5 and 19. The recovered lube oil extracted under the supercritical condition of 150℃ and 10MPa was ca. 85% of the waste oil, that was good agreement with the results of our previous work. The physical properties and contents of impurities in the recovered lube oil were measured according to ASTM and the relation between weight ratio or solvent and removal of impurities was discussed.
Effects of Sodium Salicylate on the Removal of tert-Butyl Phenol Using Micellar-Enhanced Ultrafiltration
O, Min-Ho ; Hong, Jeong-Jin ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 588~588
Micellar-enhanced ultrafiltration was performed to remove an organic compound of low molecular weight such as tert-butyl phenol(TBP) from aqueous solution. The surfactant used here was cetyltrimethylammonium bromide(CTAB) and sodium salicylate(NaSal) was added to enhance the rejection efficiency. By using batch type ultrafiltration cell, the effects of the additive NaSal concentration in the retentate were investigated on the rejection efficiencies of TBP in terms of the molecular weight cut-offs or the membrane and molar ratios or NaSal, CTAB and TBP. When CTAB was added to the solution at concentrations well above its critical micelle concentration, the surfactant formed micelles and TBP molecules were dissolved into the micelle. And then, the micellar solution was forced to pass through an ultrafiltration membrane of which pore size was smaller than the micelle size. In ultrafiltration process, the micelle which contained TBP was rejected by the membrane. Thus, very little amounts of CTAB and TBP were contained in the permeate. As the filtration of the micellar solution proceeded, not only the solution viscosity was rapidly increased but the gel layer of highly concentrated CTAB was formed on the membrane surface. Consequently, the flux was reduced considerably. The results showed that, for a given molar ratio of NaSal to CTAB, there existed a critical concentration of NaSal, above which the flux was declined rapidly and the solution exhibited a remarkable viscoelasticity. However, below the critical concentration of Nasal, the rejection efficiencies of TBP were maintained above 98% due to the transition of micellar structure from spherical to worm-like networked micelle.
A Numerical Analysis of the Supersonic Convergent-Divergent Nozzle and the Grinding Characteristics of a Target-type Jet Mill
Gil, Jun-Ho ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 594~594
In this study, we dealt with numerical analysis of the velocity distribution in the flow of gas-solid mixture about the various shapes of supersonic convergent-divergent nozzle by using the computational fluid dynamics CODE, FLUENTTM. We also studied grinding characteristics of a target-type jet mill. It was found that the results of the present numerical analysis and experiment were in good agreement. We could select the optimum nozzle shape with respect to the grinding efficiency. And then the optimum grinding conditions were investigated with respect to the following parameters : the grinding pressure, the distance from the nozzle outlet to the target plate, the angle between the jet flow direction and target surface, and the mixing ratio by weight. The results show that the optimum conditions of the collision length, target angle, and mixing ratio are 2-3 times the distance of the nozzle outlet diameter, 60-90。, and < 0.5, respectively.
Optimal Design and Production Plan of Multi-Product Batch Processes Considering Equipments Costs and Energy Savings
Jo, Ik-Sang ; Lee, Beom-Seok ; Lee, In-Beom ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 601~601
Differently from continuous processes, the processing schedule of batch processes should be modified for heat exchange between batch streams. In most batch processes in which ZW policy is adopted, the heat integration causes the increased production cycle time that requires the bigger batch equipments sizes. Process design engineers usually finish the initial batch process design neglecting the possibilities of heat integration due to the increased equipment costs in that case. In this study, the schedule of multi-product processes, the required equipments sizes and the heat exchange between batch streams are mathematically formulated in a mixed integer nonlinear programming. A solution of this formulation can be readily obtained with a commercial MINLP solver. Numerical examples are presented to illustrate the possibilities of heat exchange in a multi-product batch process.
The Effects of the Radiative Heat Transfer on the Water Droplet Evaporation in Uniform Gaseous Flow
Choe, Mun-Gyu ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 607~607
The phenomenon of water droplet evaporation in hot gaseous flow is investigated numerically in the present study. In the past researches the effects of radiation on the droplet evaporation have not been taken into consideration or only the internal heat generation due to radiation was calculated without considering the droplet evaporation. Since the infrared light, which the droplet in hot environments is subject to, has a wavelength range comparable to the droplet size, the light transverses to heat generated in the droplet. By employing the Mie solution to obtain heat generation inside the droplet, the fluid flow, the heat transfer and the mass transfer inside and outside the droplet are calculated simultaneously. To prove that the numerical algorithm has been correctly applied, the drag coefficient, the Nusselt number and the Sherwood number calculated numerically at steady state are shown to agree well with experimental correlations. To find out the effects of radiation on the droplet evaporation, the water drop at the initial temperature of 300 K and the air of 1,300 K or 1,900 K are employed for case study, and Nuf and Shf are calculated. The higher the gas phase temperature is, the more heat generation occurred inside the droplet. The radiation, however, made no influence on the flow pattern inside the droplet, the transport phenomena, the evaporation, etc., since the imaginary part of the refractive index for water is very small, resulting in negligible heat generation.
Batch Scheduling and Robust Production Planning using Benders Decomposition
Bok, Jin-Gwang ;
Korean Chemical Engineering Research, volume 36, issue 4, 1998, Pages 618~618
Benders decomposition algorithm to improve the computation for the decision problems involved in chemical processes is addressed. Using nonlinear duality algorithm. a large scale problem is decomposed into two stage problems, SUB and MASTER, respectively. The target problems are short-term scheduling and design problems, and long-term planning problems including capacity expansions. In the first issue, the net present cost involving design cost and operation cost with consideration of inventory is minimized. The latter addresses robust models that are insensitive to future uncertainty. The problems presented in this paper are so computationally complex that enhanced algorithms have been required. The effectiveness of the improved algorithm is illustrated through examples relevant to scheduling and design problem, and long-term capacity expansion problem, respectively.