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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 37, Issue 6 - 00 1999
Volume 37, Issue 5 - 00 1999
Volume 37, Issue 4 - 00 1999
Volume 37, Issue 3 - 00 1999
Volume 37, Issue 2 - 00 1999
Volume 37, Issue 1 - 00 1999
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Bulk Polymerization of Methylmethacrylate in a Continuous Filled Tubular Reactor
Yun, Won-Jung ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 815~815
Free radical polymerization of methylmethacrylate was studied using filled tubular reactor with some axial dispersion effect, such as a near plug flow pattern, due to intensive radical mixing induced by static mixers. It was of interest to investigate how the performance of the filled tubular reactor has been investigated by model simulations. Both start-up transient and steady state behaviors of reactor were investigated through model simulations. The model simulation results in continuous filled tubular reactor could obtain the monomer conversion of 0.6, which was higher than in CSTR. And the optimalinside diarmeter of filled tubular reactor was 2.54cm. The model simulation results suggested that the filled tubular reactor could be potentially a good continuous reactor for the polymerization of methlmethacylate. In this study, the filled tubular reactor was potentially a very important new polymerization technology.
The Effects of Process Variables in Preparing Ultrafine TiO₂ Particles by a Diffusion Flame Reactor
Chae, Beom-San ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 821~821
We have studied the process to prepare the ultrafine TiO2 powders by a diffusion flame reactor, theoretically/experimentally. In model equations, the mass balance of TiCl4 and the aerosol dynamic equation were considered. The effects. of TiCl4 chemical reaction, generation and coagulation of TiO2 particles were inclued in the aerosol dynamic equation. The TiO2 particle size increases, as the flame temperature and the inlet TiCl4 concentration increase of as the total gas flow rate decreases. The structure of TiO2 particles in experiments was basically in anafase phase and amount of rutile phase in TiO2 particles incerases as the maximum temperature increases, or as the total gas flow rate decreases. However, the amount of rutile phase in TiO2 particles was almost indepentdent of the inlet TiCl4 concentration. The specific area of TiO2 particles increases, as the flame temperature decreases.
The Pyrolysis of Waste Lubricating Oil in a Batch Reactor
Kim, Seung-Su ; Yun, Wang-Rae ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 828~828
Kinetic tests on pyrolysis of waste lubricating oil were carried out with thermo gravimetric technique at the heating rates of 0.5, 1.0, 2,0℃/min and pressure of 1 and 2 atm. The activation energy and the reaction order were determined at conversions of 1 to 100%. The activation energies were increased slowly at 1 atm, but took a constant value until a given degree of conversion at 2 atm. Waste lubrication oil was thermally cracked in semi-batch reactor of 400-460℃ at 1 and 2 atm for 2 hours. As the reaction temperature increased, the yields of products oils increased, but the product of light hydrocarbon oils decreased. The optimum temperature of pyrolysis of waste lubricating oil was 440℃ at 1 atm.
Adhesion between Copper Film-Plated Steel Cord and Rubber Compound Containing Adhesion Promoter
Jo, Pyeong-Rae ; Jeon, Gyeong-Su ; Ryu, Seung-Gyun ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 834~834
The adhesion properties between three copper film-plated steel cords (abbreviated hereafter as copper-plated cord) with different thicknesses of copper film and the rubber compounds containing different loadings of cobalt salt and resineous bonding promoter to rubber as well as that of brass-plated cord. The adhesion property between the copper-plated cord with thin copper film of 32nm and the rubber compound containing cobalt salt and resineous bonging promoter was similar to or higher than that of the brass-plated cord both before and after aging treatments, enabling the replacement of brass with thin copper film as a plating material for steel cord for adhesion with rubbber compound.
Activation of Nickel Catalysts under Multibubble Sonoluminescence Environment
Kim, Hong-Un ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 839~839
This article deals with the activation of metal catalysts under MBSL environment and their performance tests through the hydrogenation of cyclohexene, octene, nonene and decene to their corresponding alkanes. Natural Ni is well known to exhibit no catalytic activity for the hydrogenation reaction. However, when Ni powder of 3 μm was treated under MBSL, it showed catalytic activity. When Ni catalyst was prepared in an ultrasonic field of 110 W, the hydrogenation reaction yields increased up to 18% with decreasing molecular weight. When higher intensity of 193W was used, this trend was unobserved. However, the yield for the hydrogenation of octene to octane was 45%. This result implies that Ni catalysis formed under MBSL may replace more expensive Pt or Pd catalysts, leading to catalytic process innovations.
A Decentralized Controller Tuning Method with One Design Parameter of the Closed-loop Time Constant
Jeong, Jin-Hui ; Choe, Jin-Yeong ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 844~844
Extending the IMC tuning method for single variable processes, one parameter tuning method for multivariable processes where closed loops follow desired responses is proposed. With the proposed method designer''s effort can be minimized since multiloop control systems are tuned with only one design parameter of the closed loop time constant. Problems of simple decentralized controller design methods such as the very slow response by excessive detuning in the BLT method and the unsymmetrical response of the sequential loop closing method can be partially solved.
Analysis of Cement Kiln Burners by Using Computational Fluid Dynamics
Ju, Ji-Seon ; Sin, Sang-Baek ; Lee, Hyeon-Su ; Lee, Min-U ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 850~850
In this study, analysis of burner flame for cement kiln is performed by using computational fluid dynamics(CFD). Flame shape, temperature distribution and NOx/HCN formation are predicted to determine the performance of burners which P company designed. Type A burner has three concentric channels for swirl air, pulverized coal, and axial air in radial order. Type B burner has a special flame stabilizer at the center and channel for pulverized coal is relocated between flame stabilizer and swirl air. Velocity contours of both types show internal recirculation mear burner tip, which stabilizes the flame and assists early ignition. Due to strong swirling action, type A burner has a little divergent flame. On the contrary, the flame of type B burner is relatively slim and long. Temperature distribution core of type A burner flame. However, in the type B burner, NOx is formed at the outer flame where secondary air is supplied and NOx formation in the high temperature core is reduced by reducing atmosphere. The methodology and results suggested in this study could be successfully applied to not only design of burners but also optimization of operational conditions.
Optimal Retrofitting Design of Multisite Batch Plants
Lee, Ho-Gyeong ; Yu, Dong-Jun ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 857~857
In this paper, we present a model of an optimal retrofitting design for multisite batch plants in case there new warehouses to supply and increase of demands at existing warehouses. In the optimal retrofitting design problem, an objective function is defined as a net profit in a chemical company-total expected selling price minus the cost of new equipments and the expected shipping cost. We determine a revised plant configuration, sizes and operating modes of newly added equipments, new shipments from plant to warehouse and batch processing variables. A mixed integer nonlinear programming(MINLP) formulation is proposed. The effectiveness of its application is illustrated with two examples. The examples are solved with GAMS/DICOPT+++.
A Study on the Mass Transport of Copper Ions Induced by Natural Convection in a Horizontal Porous Layer
Yun, Do-Yeong ; Kim, Min-Chan ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 863~863
In the present study, the correlation of mass transport induced by natural convection in a horizontal porous layer has been derived theoretically. The coefficients appearing in the theoretical correlation were determined by experimental data. In the experiment, the mass transport of copper ions in CuSo4-H2SO4 solution was conducted by the electrochemical technique controlling diffusion and natural convection. The theoretical correlation for mass transport in a horizontal porous layer satisfying Forchheimer''''s flow equation was based on the microturbulence model. The resulting equation was proportional to the 1/2 power of Darcy-Rayleigh number as the magnitude of buoyancy forces increases. For the electrochemical system of copper ions, the mass transport correlation induced by natural convection is proposed assh = 0.000101(Scp. Rap)1/2/1-9.013(Scp.RaD)-1/10The present correlation looks fairly reasonable by comparing experimental results, and verypromising for the applications of its prototype into various systems involving heat transfer as wellas mass transfer, effectively.
Application of Model Verification Technique for Safety Evaluation in Batch Process Schedules
Lee, Han-Yong ; Kim, Jin-Gyeong ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 870~870
A new algorithm is proposed to detect errors in process schedules using SMV(symbolic model verifier). Two models, real time model and latch model, are developed to capture information on Gantt charts. The real time model is proved to be more efficient than the latch model. In addition, they can find errors related to the characteristics of the process and the product, which are difficult to be detected only by Gantt chart. It proves that the proposed algorithm can automate the procedure of detecting errors in batch process schedules.
Effect of Extractive Solvents on Separability of Toluene-n-Heptane Mixture by Liquid Membrane
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 877~877
In the separation of toluene-n-heptane mixture by liquid membrane, extractive solvents such as sulfolane, methyl sulfone and triethylene glycol were intermixed with membrane to improve the separability. Detailed analysis was carried out concerning the effects of such factors as the type and the concentration of extraction solvents and the contact time on the permeability and separation factor. As the extractive solvent concentration increased, the permeation of toluene and n-heptane increased. With 10 vol% of sulfolane a higher separation factor than with no sulfolane was achicved at the contact time of 10 minutes. The percentage of membrane breakup was smallest when the concentration of sodium lauryl sulfate was 0.5 wt% where the separation factor reached its highest value.
An Analysis on Multibed PSA Process for Hydrogen Purification
Jang, Dong-Geun ; Sin, Heung-Su ; Kim, Jong-Nam ; Jo, Sun-Haeng ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 882~882
Numerical simulation for hydrogen-recovery multibed PSA process was performed by orthogonal collocation method for the feed mixture gas of hydrogen, carbon dioxide, carbon monoxide, and methane in petrochemical plant. A fourbed and nine-step process using a layered-bed which was consecutively packed with two different adsorbents in one bed was employed to produce high-purity hydrogen. The packing raito of zeolite to activated carbon affected the purity and recovery of the product. The optimum length of zeolite layer and that of activated carbon layer were 60cm each. The optimum adsorption pressure and feed velocity could be determined to be 19 atm and 11.0 cm/s, respectively, for given packing ratio. The recovery and purity of the product were strongly affected by Difference-Pressure(DP) which was defined as the difference between the initial high pressure and the final low pressure at the cocurrent blowdown step which delivers purge gas to the low pressure bed. When the DP was larger than 1.3 atm, the purity did not change much and the recovery was continuously decreased with increasing DP. As DP increased, the pressure at the pressure-equalization cocurrent depressurization step was lowered and the pressure at the pressure-equalization countercurrent pressurization step following purge step was also lowered. Therefore, the amount of the high-pressure product to pressurize the low-pressure column increased.
Adsorption Equilibria of Maltooligosaccharides on Activated Carbon
Lee, Jae-Uk ; Jeong, Heung-Jo ; Mun, Hui ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 890~890
Adsorption equilibrium of maltooligosaccharides on activated carbon was studied as a separation and purification method for maltooligosaccharids dissolved in aqueous solutions. Single-species isotherms were represented by the Langextended Langmuir-Freundlich isotherm(ELFI), and ideal adsorbed solution theory(IAST)
Extraction and Oxidation of Neptunium from the Simulated Solution by TBP(tributyl phosphate)
Lee, Il-Hui ; Im, Jae-Gwan ; Kim, Gwang-Uk ; Gwon, Seon-Gil ; Yu, Jae-Hyeong ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 897~897
The extraction yields of Np(ENp) by solvent extraction with tribuyl phospate in n-dodecane(TBP/NDD) increased with concentration of HNO3 regardless of oxidant. Without oxidant, ENp was about 12% at 2 M HNO3 and increased to 56% at 4 M HNO3 due to the disproportionation of Np(V) to Np(VI) and Np(VI). Adding the NH4VO3 of 1 g/L, as a oxidant, ENp was about 75% at 2M HNO3. This was attributable to the oxidation of Np(V) to Np(VI). In the presence of U or Zr, ENp decreased with concentration of U and was about 66.3% at U of 10 g/L. On the other hand, ENp had no effect with concentration of Zr and was in the range of 88±2%. It was found that ENp adding Zr was more enhanced about 13-15% than that of Np only. In the presence of both U and Zr, ENp also had no effect with concentration of Zr and slightly decreased with concentration of U. When U was less than 5 g/L, ENp was in the range of 88±2% by the synergetic effect of Zr only. At U of 10g/L, however, ENp was 82±1% by the synergetic effect of Zr and decreasing effect of U. In the 9 components system containing the NH4VO3 of 1g/L, the extraction yields of Np and U were about 89% and 93%, respectively, and those of Fe, Mo, Zr, Y, Cs and Sr were below 5%. Therefore, Np and U could be effectively co-separated from the simulated HLW solution by controlling the oxidation state of Np.
Characterization of Inorganic Particles by Atomic Force Microscopy
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 904~904
AFM(Atomic Force Microscopy) is a device to observe morphology in atomic scale. Applications of AFM for inorganic particle research, however, has not been visible because the roughness of particle sample exceeds the AFM scan limit. Static charging of the tip also makes it dirricult to scan the sample without moving around the particles. In this report, zinc oxide particles of solid and hollow morphology and alumina particles of smooth and rough surfaces were prepared by spray pyrolysis and characterized by AFM. It was found that the particles were not moving when the particles were dispersed in isobutyl alcohol (20mg/ml) and post-treated at 150℃ in an electrical oven for 1 hour. The AFM was operated under the non-contact mode and the tip spring constant was 20-100N/m. Under these conditions, it was possible to obtain 3-D images from all the particle samples and to differentiate solid and hollow particles from the phase images. The several hundred nanometer roughness of alumina particles shown in SEM images was not observed by AFM, but the roughness of several tens of nanometer level was evident in AFM image analysis. It was also confirmed that the force-distance curve behaved differently for the hollow and solid zinc oxide particles.
The Analysis of Combustion Characteristics of Mixed-Firing with Bituminous and Anthracite Coal Using Pressure Fluctuation Properties in a Fluidized Bed Combustor(Multi-Sized Particle System)
Jang, Hyeon-Tae ; Park, Tae-Seong ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 910~910
The combustion characteristics of mixture of antharcite and bituminous coal were studied in a fluidized bed(0.155m-I.D., 2.2m-height). The pressure fluctuations were measured by a pressure transducer under the various operating conditions. The properties of the pressure fluctuatuons, such as the standard deviation of pressure fluctuations, static pressure, cross-correlation function, dominant frequency and the power spectral density function, were obtained from the statistical analysis. The pressure fluctuation properties, particle size distribution of ash and composition of flue gas were measured to interpret the combustion characteristics in a fluidized bed combustor uniform of multi-sized particles of mixed anthracite and bituminous coal have been compared with the particle size distribution, antharcite mixing fraction. From this study, the combustion characteristics of mixed fuels in a fluidized bed combustor coulde be intetpreted by using standard deviation of pressure fluctuation and power spectrum distribution.
Phase Holdup Characteristics in Three-Phase Circulating Fluidized Beds
Kim, Seong-Hun ; Jo, Yong-Jun ; Song, Pyeong-Seop ; Gang, Yong ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 916~916
Phase holdup characteristics have been investigated in a gas-liquid-solid circulating fluidized bed(0.102m I.D×3.5 m in height). Effects of velocities of dispersed gas and continuous liquid phases and solid circulation rate on the individual phase holdup and its axial distribution in the bed have been determined. Compressed air and water have been used as a dispersed gas and a continuos liquid phase, respectively, while glass beads with the diameter of 2.1 mm have been used as a fluidized solid phase. It has been found that the gas holdup has increased with increasing dispersed gas velocity, but liquid velocity and solid circulation rate have little effect on the gas holdup. The liquid holdup has increased with increasing liquid velocity, however, it has decreased with increasing gas velocity and solid circulation rate. The solid holdup has increased with increasing solid circulation rate and gas velocity, whereas, it has decreased with increasing liquid velocity. The axial distribution of solid holdup has become uniform with increasing liquid velocity. The gas holdup and bed porosity have been well correlated in terms of operating variables such as gas and liquid velocities and solid circulation rate.
Blue Emitting BAM Phosphor Particles with Spherical Morphology
Gang, Yun-Chan ; No, Hyeon-Suk ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 921~921
The blue emitting BAM phosphor particles with various compositions were prepared by the spray pyrolysis. The effect of composition on the morphology of BAM particles was investigated. In the case of BaMgAl10O22:Eu2+, the morphology of particles with sphericity and non-aggregation characteristics disappeared after post-treatment at 1,400℃ for 3 hrs. On the other hand, the other composition particles except BaMgAl10O22:Eu2+ maintained their original morphology after post-treatment, even if the particles were prepared at low temperatures in the spray pyrolysis. The BAM particles with MgAl2O4 as intermediate material at low post-treatment temperature had high thermal stability and maintained sphericity of particles after post-treatment. The BAM particles had submicron size and narrow size distribution before and after post-treatment. All the samples had main emission peak at 450nm, which corresponds to blue emission. the optimum post-treatment temperature of BAM : Eu2+ particles for the maximum PL(photoluminescence) intensity in the spray pylolysis was 1,400℃ because of high crystallinity, phase-purity, and good morphology.
Study of a Non-mechanical Solid Valve(Loop Seal)
Seon, Do-Won ; Bae, Dal-Hui ; Han, Geun-Hui ; Son, Jae-Ik ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 925~925
The characteristics of loop seal operation and particle flow were investigated by hydrodynamics study in a cold mode riser and loop seal system. The physical dimensiton of 0.2m×0.15m×0.2m cold mode loop seal and riser is serially connected to compose a experimental system. A coal ash was used for the experiment. The flow pattern of particle was investigated by variation of quanity of fluidizing air and location of aeration. The mathematical relationship of the limitation of particle flow rate and system pressure was analyzed. The particle flow rate increased by the increase of air flow of return leg. The pressure difference of down comer section was reduced as the increase of the particle flow rate.
Preparation and Characterization of YBCO
Superconductor Manufactured by Pyrophoric Synthetic Method
Kim, Yeong-Sun ; Lee, Yeong-Min ; Yang, Seok-U ; Kim, Yeon-Su ; Park, Jeong-Sik ;
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 930~930
The YBaCu3O7-x high-temperature superconductors were prepared by pyrohporic synthetic method from Y2O3, BaCO3, CuO and AgNO3 powders. The superconducting properties of YBaCu3O7-x and YBaCu3Ag(sub>yO7-x added to Ag of 0.1 mol, 0.2 mol, and 0.3 mol were investigated with particle size analyzer, differential scanning calorimeter(DSC), thermogravimetric analysis(TGA), X-ray diffractometer(XRD), 4-probe resistivity measuring equipment, scanning electron microcope(SEM), and electron prove micoranalysis(EPMA). The weight loss of 75% is observed in the temperature range of 210℃ to 240℃, which occurs with an exothermic peak of the powder neutralized and dried at 50℃. The powder prepared by pyrophoric synthetic method occurs with an endothermic peak and the weight loss in the temperature range of 810℃ to 975℃, and the simultaneous fomation of the YBaCu3O7-x. The Tc,zero of YBaCu3O7-x sintered at 880℃ for 24 hr was 99.2K, and microstructure of YBaCu3O7-x-Ag0.2 was enhanced.
Mixing Characteristics of Adsorption Column with Activated Carbon Slurry with Bubble-Agitation for the Separation of Pollutants
Korean Chemical Engineering Research, volume 37, issue 6, 1999, Pages 937~937
The mixing characteristics of powdered activated carbon slurry of relatively high concentration was studied to find the optimal mixing condition in an adsorption column with bubble-agitation. System adopted was an activated carbon slurry column with internal looping where the mixing of adsorbents are conducted by gas input. From th experiment, it was found that the mixing rate increased with gas input and decreased with increasing activated carbon content, but the mixing rate increased with increasing activated carbon concentration at the superficial gas velocity of 0.04-0.06m/s. From the analysis of gas holdup and the calculated slurry velocity, this tendency could be explained by the enhanced slurry fluidization due to coalescence of bubbles and the condition of high mixing with activated carbon concentration and input gas velocity could be suggested.