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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Korean Chemical Engineering Research
Journal Basic Information
Journal DOI :
The Korean Institute of Chemical Engineers
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Volume & Issues
Volume 28, Issue 6 - Dec 1990
Volume 28, Issue 5 - Oct 1990
Volume 28, Issue 4 - Aug 1990
Volume 28, Issue 3 - Jun 1990
Volume 28, Issue 2 - Apr 1990
Volume 28, Issue 1 - Feb 1990
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Control System Design of a Supercritical Fluid Extraction Process by INA Method
Kim, Won-Cheol ; Lee, Gwang-Sun ; Yu, Gi-Pung ; Lee, Won-Hong ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 131~131
A pressure and flowrate control system for a supercritical fluid extraction process was designed and its performance was investigated. First, a dynamic model was set up using performance equations of the control valve and the compressor, and a state equation of the supercritical fluid. From this model, pairs of manipulated and controlled variables which give least steady state interaction were determined through the relative gain analysis. These pairs, however, showed significant dynamic interaction when they were connected in closed loops. To solve this problem, the control pairs by the relative gain analysis were reassessed rigorously using the inverse Nyquist array method and compensators for noninteracting control system were constructed. Simulation study showed that the resulting compensated system had much better closed loop responses than those by the relative gain analysis.
Experimental Studies on Flocculation of Solid Particles and Solid-Liquid Separation with Couette Flocculators Part 3 : Scale-up of Couette Flocculators and its Application
Jeon, Gwi ; Choe, Chang-Gyun ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 142~142
The study of flocculation in Couette flocculators showing Taylor vortices and subsequent solid-liquid separation characteristics were conducted experimentally. In continuous experiments two flocculators were used to extract the hydrodynamic similarity and proper parameters for the flocculator scale-up. The optimum retention time was found about 150-180 seconds in the present experiments. Also, optimum flocculation conditions in two flocculators were reached at the same rotational speed of the inner cylinder. With these results a correlation of the optimum Taylor number was obtained as a function of the scale-up factor, the suspension concentration and the flocculant concentration. To facilitate the solid-liquid separation an inclined plate settler was attached to the Couette flocculator. Through continuous experiments in this combined apparatus it was found that the separation performance was excellent. All these results show that the Couette flocculator with the mclmed plate settler may be used efficiently in solid-liquid separation.
Study on Aggregation of Ferromagnetic Ultrafine Particles
Suh, Hong-Sub ; Kim, Sun-Geon ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 152~152
The shapes of aggregates of ferromagnetic ultrafine particles have been studied experimentally and theoretically. Experiment shows that the paricles form more chain-like aggregates when both the size and the saturation magnetization of the particles increase as far as their sizes remain within single domain. The chains become straightened under an external magnetic field. The primary particles in a single chain seem to have very narrow size distributions. The various shapes of the aggregates could be described mathematically by the concept of 'fractal'. The values of the efficiency factor which modifies the extent of Brownian coagulation were calculated from a model equation considering isotropic forces(van der Waals and hydrodynamic forces)and anisotropic force(magnetic force), respectively. It has turned out that the latter force dominates the formers in case of chain-forming particles and the model well supports the experimental observations on the chain linearization under the field and the monodispersity of the primary particles, described above.
Methanol Conversion over SAPO-34 Molecular Sieve Catalyst
Ko, Tae-Seog ; Seo, Gon ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 163~163
Methanol conversion over synthesized SAPO-34 molecular sieve catalysts was studied. Although the selectivity to olefin was very high and the formation of aromatics hydrocarbon was prohibited over SAPO-34 molecular sieve catalyst, the deactivation due to hydrocarbon deposition was serious. The acidity, product distribution in methanol conversion and deactivation of SAPO-34 molecular sieve catalyst were discussed comparing with those of HZSM-5 zeolite catalyst.
Cometabolism Process for Biodegradation of Phenolic Substances
Lee, Sang-Yeong ; Park, Bu-Gil ; Lee, Hyeon-Yong ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 172~172
A bioenergetic model has been developed to estimate cometabolism coefficient along with maintenance coefficient for cometabolism process where small amounts of toxic materials exist with major carbon and energy source(eg. glucose) in the waste water. Cometabolism coefficient and maximum bioenergetic yield were estimated as 0.1026 (1/h) and 0.585, respectively for the growth of Pseudomonas sp. under aerobic continuous cultivation. It also turned out that phenol was utilized as a cometabolic substrate where its concentration was below
. Pre-cultivation with a phenol analog, m-cresol enhanced biodegradation rates of phenol and also increased total biomass concentration along with the extension of stationary phase.
Fluidizing Particle Dispersion in a Liquid Fluidized Bed
Gang, Yong ; Na, Jong-Bok ; Min, Byeong-Cheol ; Lee, Gang-Il ; Kim, Sang-Don ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 177~177
The dispersion and frequency of fluidizing particles and the histogram of pressure fluctuations have been analyzed in a liquid fluidized bed. The effects of particle size (1.0-6.0mm) and liquid velocity (3-14cm/s) on the dispersion coefficient and frequency of fluidizing particles have been determined in a
high Plexiglas column. The dispersion coefficient and frequency of fluidizing particles exhibit their maximum values with an increase in liquid velocity and consequent increase in bed porosity. The maximum particle dispersion coefficient exhibits at the bed porosity where the flow transition of particles occurs in the bed.
Study on the Reaction of
using Distributed Pore Size Model
Chung, Soo-Hyun ; Kim, Dong-Chan ; Cho, Chong-Hyun ; Park, Chan-Young ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 184~184
After impregnating copper oxide by using a spherical
reacted with and/or adsorbed the sulfur dioxide on reaction conditions. Conversion of copper oxide was estimated under each condition and then the reaction and adsorption behavior between
and sulfur dioxide were analytically compared by using the distributed pore size model. From the results, it was shown that although the initial surface reaction rates varied with the impregnation concentration, the activation energy was constant as about 14.49KJ/mol, and that the final conversion of
was not affected by the particle Reynolds number. Also the values of activation energy of surface diffusion coefficients were shown to be
=5.39KJ/mol depending on the pore size region. Although conversion rates acquired by the analysis of distributed pore size model were close to the experimental values under most of reaction conditions, there were considerable deviations in the final conversion when the sulfur dioxide concentration changed from 2,000 to 3,000ppm and the impregnation concentration increased from 6 to 8wt%. Also below the optimum temperature of
the conversion rates based on the model were close to the experimental value, but over
, there were considerable deviations between the two values. The maximum experimental conversion was shown to be 63% at
with 2,000 ppm of
Heat Transfer in a Cube Heated from Below
Kim, Chong-Youp ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 196~196
In this research, a theoretical analysis was performed on the heat transfer in a cube heated from below. Being noted that radiation and conduction effects were not negligible in the room temperature range, model equations were derived and solved on the radiation between walls, turbulent convection inside the cube and conduction through walls based on the newly proposed "isothermal core postulate". The radiation equation was a classical 2-D integral equation and the conduction equation was a 3-D Laplace equation. The convection term was included in the overall energy balance and boundary conditions imposed on the Laplace equation. Parametric studies were performed by varying system parameters from a reference set which could be suitable to "ondol" system. Two major conclusions from this study were that the isothermal core postulate was appropriate and half of the heat flux from the bottom was due to radiation.
Effects of Influencing Parameters on the Electrode Performance in Phosphoric Acid Fuel Cell
Hyun, Jung-Hyug ; Augh, Ki-Han ; Rho, Yong-Woo ; Shul, Yong-Gun ; Lee, Tae-Hee ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 205~205
Effects of loading density of Pt and PTFE and operation temperature on the performance of carbon electrode were studied by a half cell in 85wt% phosphoric acid. As the Pt loading was varied to 5, 10, 15, and 20wt%, the Tafel slope was changed to 221, 176, 170, and 148mV/decade, respectively, and the exchange current density was changed to
, respectively. The optimum content of PTFE was found to be 20-30 wt%, and the apparent activation energy of the cathode reaction was found to be approximately 110 kJ/mol at the equilibrium potential, regardless of the electrode carbon materials.
Prediction of Pore Size and Distribution of Ultrafiltration Membrane by Solute Rejection Characteristic Curves
Lee, Sei-Jin ; Kim, Jong-Kuk ; Youm, Kyung-Ho ; Kim, Woo-Sik ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 212~212
In this study polysulfone membrane(MWCO: 3,000)was used and ultrafiltration experiment was carried out for 4 types of dextran solutions having different molecular weight to obtain the solute rejection characteristic curve, from which the membrane pore size and the distribution could be predicted with the aid of the concept of probability distribution. The result showed that the solute rejection characteristic curve had a linear relation on log-normal probability paper and the mean(
) and the standard deviation(
), which are the pore size distribution parameters, were influenced by the concentration polarization and solute conformation according to the operating conditions. The apparent mean pore radius and the pore radius distribution obtained from the solute rejection characteristic curve were
and in the range of
Effect of Horizontal Connection Pipe Length on Gas Holdup and Volumetric Oxygen Transfer Coefficient in External-Loop Airlift Reactor
Choe, Geun-Ho ; Han, Bong-Hui ; Lee, Won-Guk ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 220~220
In other to obtain information on the behavior of the external-loop airlift reactor operation with airwater mixtures, the gas holdup, overall volumetric oxygen mass transfer coefficient, vertical bubble length and bubble velocity were studied. The effects of gas velocity(0.02-0.18m/s)and the length of horizontal connection pipe(0.1-0.5m)with respect to the above mentioned parameters have been investigated. The results showed that the length of the horizontal connection pipe was a dey design parameter for the external-loop airlift reactor. The bubble rising velocity in the riser and bubble downcoming velocity in the downcomer increased due to increase of the circulation liquid velocity as the horizontal connection pipe length was increased. The downcomer gas holdup and vertical bubble length in the downcomer decreased due to increase in gas-liquid separating abilities of upper connection section as the horizontal connection pipe length was increased. The overall volumetric oxygen transfer coefficient in the external-loop airlift reactor with a short connection length was higher than that with a long one due to higher gas holdup.
A Study on the Synthesis of 2,4,6-Trichloroaniline by Chlorination of Aniline
Kim, Chul-Ung ; Jin, Hang-Kyo ; Lee, Soo-Bok ; Lee, Jung-Min ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 230~230
For the chlorination of aniline salt to synthesize 2,4,6-trichloroaniline in the solvent of chloroform, the reaction mechanism was suggested and the reaction kinetics was examined. The reaction rate constants were estimated by using the experimental results obtained in the range of
and the equations of reaction rates, which were derived from the reaction mechanism. The results calculated by applying the reaction constants to the theoretical equations of reaction rates were well agreed with experimental results. The reaction rate of formation of 2,4,6-trichloroaniline from aniline salt is 9 times greater than that of 2,6-dichloroaniline, and the activation energies of these two reactions are almost same. Therefore, the increase of 2,4,6-trichloroaniline yield cannot be expected by controlling the reaction temperature, and the obtainable maximum yield of 2,4,6-trichloroaniline is about 90%.
Deactivation and Regeneration of Titania-supported Palladium Catalyst for Acetylene Removal from Ethylene-Rich Feed
Lee, Dong-Keun ; Ihm, Son-Ki ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 237~237
The accumulation rates of green-oil on the titania-supported palladium catalyst for acetylene removal from ethylene-rich feed were measured through gravimetric analysis, and the changes in activity and selectivity were investigated before and after regeneration. Green-oil accumulation rates decreased with increasing reaction temperature, acetylene concentration and hydrogen to acetylene ratio, while the addition of small amounts CO enhanced the accumulation rate greatly. Volatile and non-volatile fraction of green-oil decomposed at
, respectively, and after regeneration by air the deactivated calalysts restored most activity and selectivity of the fresh ones irrespective of regeneration temperature.
Analysis of Steady state Behavior of a Blast Furnace using Two Dimensional Model
Lee, Il-Ok ; Choi, Tae-Wha ; Kim, Heung-Shik ; Lee, Kwang-Soon ;
Korean Chemical Engineering Research, volume 28, issue 2, 1990, Pages 243~243
A mathematical model of the blast furnace was developed and the effects of operating variables on internal phenomena of the blast furnace were investigated through numerical computation. To achieve these objectives, equations which represent the distributions of gas and solid temperatures, gas compositions, pressure and stepwise reduction of iron ore were established and then solved simultaneously. To reduce computation time, orthogonal collocation in radial direction was employed after transforming the blast furnace geometry into a cylinder using the technique proposed by Yun et al.. Besides these, a potential instability problem of the model was analyzed using a simplified 1-dimensional model. With the aid of this model, initial values of gas and solid temperature at the stock line, which give a meaningful stable solution, could be determined. Collocations with four, five and six internal points were tried for comparison but the results were similar. Simulation results based on the POSCO's operating data showed good agreement with the internal phenomena of real blast furnaces as well as with the results by other researchers. One of the important consequences through this work is that the temperature distributions are sensitively affected by a small change in the ratio of solid to gas flowrates.