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한국화학공학회> Korean journal of chemical engineering

Korean journal of chemical engineering

  • : 한국화학공학회
  • : 공학분야  >  화학공학
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  • : 연속간행물
  • : 기타
  • : 0256-1115
  • : 1975-7220
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수록정보
수록범위 : 19권2호(2002)~20권4호(2003) |수록논문 수 : 180
Korean journal of chemical engineering
20권4호(2003년 07월) 수록논문
최근 권호 논문
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1Process Systems Engineering, Process Safety, Transport Phenomena : Two Phase Visualization by Electrical Impedance Tomography with Prior Information

저자 : Min Chan Kim , Kyoung Youn Kim , Sin Kim

발행기관 : 한국화학공학회 간행물 : Korean journal of chemical engineering 20권 4호 발행 연도 : 2003 페이지 : pp. 601-608 (8 pages)

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Numerical and experimental work was conducted to develop a visualization technique for the phase distribution in a two-phase flow field with known internal structures by electrical impedance tomography technique, which reconstructs the resistivity distribution with the electrical responses that are determined by corresponding excitations. The finite element method is employed to solve the electrical field induced by the currents through electrodes placed along the boundary and a modified Newton-Raphson iterative method is used to determine the search step minimizing the error between the calculated and the measured voltages at the electrodes. The locations and resisitivities of the known structures are considered as prior information. To mitigate the ill-posedness of inverse problem and to incorporate prior information, the modified Tikhonov regularization technique is employed. Also, with an apparatus developed for impedance imaging this study attempts to reconstruct the images of the simulated bubble distributions and the reconstructed images imply the potential possibility of the electrical impedance tomography for the two-phase flow visualization.

2Process Systems Engineering, Process Safety, Transport Phenomena : Selection of Mass Transfer Correlations for Rate Based Liquid-Liquid Extraction Model

저자 : Debjit Sanpui , Ashok Khanna

발행기관 : 한국화학공학회 간행물 : Korean journal of chemical engineering 20권 4호 발행 연도 : 2003 페이지 : pp. 609-616 (8 pages)

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A rate-based model for mass transfer in liquid-liquid extraction (LLX) has been developed using three distinct stages of drop formation, drop fall or rise and drop coalescence. Binary diffusivities in infinite dilution as well as for concentrated multicomponent mixtures were used to estimate the Maxwell-Stefan binary mass transfer coefficients for both the phases. The mass transfer resistances associated with these coefficients have been categorized in four configurations. Because of the very large number of computations associated with repeated calculations of mass transfer coefficients, a local model has been incorporated. A comparative study between rate-based and non-equilibrium simulator and our bench scale experiments (LLX of toluene-acetone-water system) has been done. The stage-wise composition profiles of acetone in water and toluene phase of the experimental and simulation runs have been compared by using the relative error square analysis. Based on this analysis, best mass transfer combination and mass transfer resistance model has been selected.

3Process Systems Engineering, Process Safety, Transport Phenomena : Optimal Operation of the Pressure Swing Adsorption (PSA) Process for CO2 Recovery

저자 : Wan Kyu Choi , Tae In Kwon , Yeong Koo Yeo , Hwaung Lee , Hyung Keun Song , Byung Ki Na

발행기관 : 한국화학공학회 간행물 : Korean journal of chemical engineering 20권 4호 발행 연도 : 2003 페이지 : pp. 617-623 (7 pages)

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The operation of PSA (Pressure Swing Adsorption) processes is a highly nonlinear and challenging problem. We propose a systematic procedure to achieve the optimal operation of a PSA process. The model of the PSA process for CO₂ separation and recovery is developed first and optimization is performed to identify optimal operating conditions based on the model. The effectiveness of the model developed is demonstrated by numerical simulations and experiments using CO₂ and N₂ gases and zeolite 13X. Breakthrough curves and temperature changes in the bed are computed from the model and the results are compared with those of experiments. The effects of the adsorption time and reflux ratio on the product purity and the recovery are identified through numerical simulations. The optimization problem is formulated based on nonlinear equations obtained from simulations. The optimal operating conditions identified are applied to experiments. The results show higher recovery of CO₂ under optimal operating conditions.

4Process Systems Engineering, Process Safety, Transport Phenomena : Gas-Liquid Flow Through Coils

저자 : Sailendra Nath Mandal , Sudip Kumar Das

발행기관 : 한국화학공학회 간행물 : Korean journal of chemical engineering 20권 4호 발행 연도 : 2003 페이지 : pp. 624-630 (7 pages)

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Experimental investigations have been carried out to evaluate the two-phase pressure drop and the holdup for flow through helical coils. The coils were made of thick wall transparent PVC tube of diameter 0.01 m and 0.013 m. 24 coils were made at different coil diameter and different helix angles (0° to 12°). Three different liquids were used for the experimental studies and air was the gas. Empirical correlations have been developed to predict the two-phase friction factor and the liquid holdup as functions of the physical and dynamic variables of the system. Statistical analyses of the correlations suggest that they are of acceptable accuracy.

5Process Systems Engineering, Process Safety, Transport Phenomena : Conversion of CH4 and CO2 to Syngas and Higher Hydrocarbons Using Dielectric Barrier Discharge

저자 : Bae Bok Hwang , Yeong Koo Yeo , Byung Ki Na

발행기관 : 한국화학공학회 간행물 : Korean journal of chemical engineering 20권 4호 발행 연도 : 2003 페이지 : pp. 631-634 (4 pages)

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The conversion of methane to syngas and other hydrocarbons in dielectric barrier discharge plasma under the presence of CO₂ was investigated. Effects of the input voltage on the conversion of methane and CO₂ and the ratio of syngas were analyzed experimentally. The results of numerical simulations showed good quantitative agreement with those of experiments.

6Process Systems Engineering, Process Safety, Transport Phenomena : Identification of Heat Integration Retrofit Opportunities for Crude Distillation and Residue Cracking Units

저자 : Adrian L. Querzoli , Andrew F. A. Hoadley , Tony E. S. Dyson

발행기관 : 한국화학공학회 간행물 : Korean journal of chemical engineering 20권 4호 발행 연도 : 2003 페이지 : pp. 635-641 (7 pages)

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This study investigates improving the energy efficiency of two key refining processes: the Crude Distillation Unit (CDU) and the Residue Cracking Unit (RCU). The research methodology followed the 'targeting before design' approach. The CDU is a 'tightly pinched' system, with limited opportunities for further energy savings. The RCU actual △T_(min) is around 55℃ indicating a low level of current heat recovery. The Total-Site analysis shows that theoretically 18MW of heat could be transferred from the RCU to the CDU, reducing CDU requirements by 40% for a new or grass roots design. RCU retrofit designs were developed to increase steam generation by up to 35% and in line with targeting estimates would appear to have economic potential. The alternative CDU-RCU retrofit design was developed to decrease CDU hot utility use. Although the Total-Site profile demonstrated strong potential for heat integration, this retrofit design is not commercially attractive, as the decrease in CDU fuel does not offset the cost of reduced steam generation. This demonstrates the need to consider the different fuel and steam costs in the Total-Site analysis.

7Process Systems Engineering, Process Safety, Transport Phenomena : Experiences from Using Heat Integration Software to Determine Retrofit Opportunities within a Refinery Process

저자 : Michelle A. Phipps , Andrew F. A. Hoadley

발행기관 : 한국화학공학회 간행물 : Korean journal of chemical engineering 20권 4호 발행 연도 : 2003 페이지 : pp. 642-648 (7 pages)

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Heat integration techniques can be used to optimize the energy requirement for both new and retrofit plant designs. Software tools for identifying retrofit options are becoming available. This paper reports our experiences from using heat exchanger network (HEN) optimization software for a retrofit case study of an oil refinery process. The HEN optimization software was used to automate the search for the most beneficial retrofit designs following the twostage process proposed by Asante and Zhu. The software provided three potential retrofit designs. Results from this analysis were used as the basis of a rigorous mass and energy balance simulation of the plant. The simulation corroborated the energy savings, but there were some important differences. The simulation required 20% more heat exchange area. Furthermore, the retrofit design involving one topology change was shown to be less economic than an alternative design. These differences are discussed and a revised methodology is proposed.

8Catalysis Reaction Engineering, Industrial Chemistry : Synthesis and Catalytic Application of Ni-Supported Carbon Nanotubes for n-Heptane Cracking

저자 : Ai Min Zhang , Dong Cheng Han , Zhi Qing Zhu , Jung Woo Lee , Hyun Ku Rhee

발행기관 : 한국화학공학회 간행물 : Korean journal of chemical engineering 20권 4호 발행 연도 : 2003 페이지 : pp. 649-652 (4 pages)

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Carbon nanotubes were synthesized by chemical vapor deposition and subsequently purified and oxidized by repeated treatment with nitric acid. After acid treatment the walls of carbon nanotubes became thinner and the surface area increased. The Ni-supported carbon nanotubes prepared by impregnation were applied to the cracking of nheptane to show an excellent activity. This indicates that the carbon nanotubes can serve as a good catalyst support with high dispersion of metallic components. The optimum Ni loading turned out to be about 5.2 mmol/g. The cracking product was found to contain mainly small hydrocarbons; thus the Ni-supported carbon nanotubes may be applied as a potential catalyst to the cracking of heavy hydrocarbons.

9Catalysis Reaction Engineering, Industrial Chemistry : Catalytic Effect of Metal Elements on the Growth of GaN and Mg-doped GaN Micro-Crystals

저자 : Kee Suk Nahm , Tae Yun Kim , Sang Hyun Lee

발행기관 : 한국화학공학회 간행물 : Korean journal of chemical engineering 20권 4호 발행 연도 : 2003 페이지 : pp. 653-658 (6 pages)

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Catalytic effect of metal elements was observed in the growth of GaN and Mg-doped GaN micro-crystals. High quality GaN micro-crystals were synthesized by direct reaction of gallium and ammonia using a Ni-mesh catalyst. Mg-doped GaN micro-crystals were also grown by the same reaction scheme in the presence of MgCl₂. The growth rate of GaN micro-crystals markedly increased in the presence of the catalyst. The average grain size of GaN microcrystals synthesized in the presence of Ni and Mg metals was larger than that in the absence of the metals. The characterization of the catalytically grown GaN micro-crystals using transmission electron microscopy and X-ray and/or electron diffraction pattern showed the growth of dislocation free hexagonal GaN micro-crystals. Photoluminescence (PL) and Catholuminescence (CL) measurements also showed the growth of good quality n- and p-type GaN microcrystals using Ni catalyst

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In order to achieve a comprehensive understanding of the performance of the heteropoly compound (HPC) absorbent systems for H2S removal developed before this study, a comparable study was made concerning the desulfurization characteristics, sulfur loading capacity (SLC) and desulfurization product composition, taking Fe-EDTA system as a standard. The desulfurization effect of HPC multicomponent absorbent system can be greater than that of Fe-EDTA system during long time of operation; the regeneration effects of HPC and Fe-EDTA system are similar. The SLC of single HPC is almost the same as that of the Fe-EDTA system, and the multicomponent system of HPC has SLC which is 12.93% higher. Furthermore, the desulfurization product from HPC system contains sulfur mainly, which is superior to that from Fe-EDTA system. Hence, HPC absorbent system developed would be of promising application value.

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