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RISS 인기검색어
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- 저자 : 여영구 ( Hyun Jun Cho (검색결과 6 건)
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Design of a dividing wall column for fractionation of biodiesel
Hyun Jun Cho,Sungho Choi,Tae Young Kim,김진국,여영구 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.7
This study presents an efficient design method for DWC which can fractionate palm methyl esters (PME, biodiesel) into three more valuable product groups: a mixture of methyl laurate and methyl myristate as light-cut, pure methyl palmitate (≥99.5%) as middle cut, and the mixture of the remaining methyl esters (biodiesel), which has good low-temperature operability to such an extent as to come close to cold filter plugging point (CFPP) 0 oC, as heavy cut. The first step of the design was to determine numbers of stages for four sub-sections of DWC, liquid split ratio, and initial reflux ratio by the shortcut design, based on the component net flow model and the method of Fenske, Underwood, and Gilliland (FUG method). Secondly, optimal reflux ratio, vapor split ratio, locations of stages for feed and side product were found out by sensitivity analysis in rigorous simulation. The results from the simulation model developed by the method show that the reboiler duty of a single DWC is about 24% less than that of two simple columns in direct sequence and about 25% less than in indirect sequence. These energy saving ratios are almost close to 30%, which is popularly known as a typical value for energy saving of DWC.
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Faisal Ahmed,Hyun Jun Cho,Jin-Kuk Kim,Noh Uk Seong,여영구 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.6
The accurate and reliable real-time estimation of NOx emission is indispensable for the implementation of successful control and optimization of NOx emission from a coal-fired power plant. We apply a real-time update scheme to least squares support vector machines (LSSVM) to build a real-time version for real-time prediction of NOx. Incorporation of LSSVM in the update scheme enhances its generalization ability for long-term predictions. The proposed real-time model based on LSSVM (LSSVM-scheme) is applied to NOx emission process data from a coal-fired power plant in Korea to compare the prediction performance of NOx emission with real-time model based on partial least squares (PLS-scheme). Prediction results show that LSSVM-scheme predicts robustly for a long passage of time with higher accuracy in comparison with PLS-scheme. We also present a user friendly and sophisticated graphical user interface to enhance the convenience to approach the features of real-time LSSVM-scheme.
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열통합 기법을 통한 이산화탄소 막 분리공정 에너지 해석
김성훈,김태영,김범석,조현준,여영구,Kim, Seong Hun,Kim, Tae Yong,Kim, Beom Seok,Cho, Hyun-Jun,Yeo, Yeong Koo 한국플랜트학회 2016 플랜트 저널 Vol.12 No.2
이산화탄소 분리공정에 있어서 분리막 공정은 소형, 모듈성, 설치의 용이성, 작동의 유연성, 낮은 설치 비용 및 낮은 에너지 소비량 등의 장점들로 인하여 주목 받고 있다. 본 연구에서는 실험데이터와의 비교를 통해 교차흐름, 병류흐름, 향류흐름 3가지 모델의 정확도를 알아보았다. 실험에서 이용된 이산화탄소 분리공정을 가장 잘 나타내어주는 모델을 토대로 전산모사를 통하여 2단 막 분리 구조에서의 운전조건을 규명하고 분리막의 투과도 및 선택도가 분리성능에 미치는 영향을 알아보았다. 나아가 수증기 sweep을 이용하는 2단 막 분리 구조에서 열교환망 합성기법을 적용하여 열교환기 도입에 따른 소요 전력의 변화와 운전비용 절감효과를 살펴보았다. The membrane separation processes have received attention due to advantages such as compactness, modularity, ease of installation, flexibility of operation, lower capital cost and lower energy consumption. In this study, we evaluated accuracy of cross-flow, co-current and counter-current models. With the most accurate model, we identified the operating conditions of the two-stage membrane separation and examined the effects of permeance and selectivity of the membrane by simulation. Futhermore, power requirements and operating cost savings due to the introduction of the heat exchanger were investigated by applying heat exchanger network synthesis technique in the two-stage membrane separation using vapor sweep.
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Modeling of the non-catalytic semi-batch esterification of palm fatty acid distillate (PFAD)
Seok Won Hong,여영구,Hyun Jun Cho,Soo Hyun Kim 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.1
Biodiesel fuel is one of the most attractive alternatives to the traditional diesel fuel derived from a petroleum refinery. Development of a reliable model for the biodiesel production process requires maximizing economics and enhancing safety in the commercial operation of biodiesel plants. We propose a model which represents effectively the non-catalytic biodiesel production reaction. In the modeling of the reaction, we employ a nonlinear programming scheme to estimate reaction kinetic parameters which minimize a specified objective function. The behavior of the methanol during the reaction is investigated both experimentally and numerically. Imperfect mixing in the liquid phase at the initial reaction stage causes a little discrepancy between the experimental data and results of simulations. Overall,the proposed model represents the biodiesel production reaction effectively.
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김진국 ( Jin Kuk Kim ),조현준 ( Hyun Jun Cho ),여영구 ( Yeong Koo Yeo ) 한국화학공학회 2013 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.51 No.1
본 총설에서는 천연가스 액화공정의 최적설계에서 에너지 효율을 높이기 위해 고려해야 하는 주요 공정설계 인자들 에 대한 논의와 상용 LNG 플랜트에서 이러한 인자들이 어떻게 적용되고 있는지에 대하여 살펴보았다. 압축기에서 소 모되는 축일의 양을 최소화하기 위한 방법으로서 단일 냉매를 사용하는 냉각 사이클을 다단, 혹은 중첩 구조로 설계하 여 온도 범위가 넓은 영역에서 운용하는 방법과 혼합냉매를 사용하여 단순한 사이클 구조를 유지하면서 최적 냉각공 급 곡선을 유지하는 방법을 다루었고, 천연가스 액화조건에 맞추어 이러한 구조들의 최적 조합을 구성하는 원리를 소 개하였다. 열 통합(heat integration) 기법을 활용하여 상용화 공정들의 특징을 도식적으로 고찰하였으며 아울러 에너지 효율 및 경제성에 대한 분석을 수행하였다. 또한 액화 공정 설계에서 사용되는 대용량의 압축기들을 구동하는 에너지 시스템에 대한 설계 문제를 살펴보았으며 최적설계를 위한 여러 가지 요소들을 고찰하여 보았다. The paper reviews the state of art in the design of liquefaction processes for the production of liquified natural gas, and addresses key design aspects to be considered in the design and how these design issues are systematically reflected in industrial applications. Various design options to improve energy efficiency of refrigeration cycles are discussed, including cascaded or multi-level pure refrigeration cycles which are used for covering wide range of cooling temperature, as well as mixed refrigerant cycle which can maintain a simple structure. Heat integration technique has been used for graphically examining differences of commercial cycles discussed in this paper, while energy efficiency and economics of commercial liquefaction processes has been summarized. Discussion also has been made about how to select the most appropriate set of drivers for compressors used in the liquefaction plant.
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