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Development of Chemical Accident Classification Codes and Tool for Management in Process Industries
Jang, Namjin,Han, Kyusang,Koo, Jamin,Yoon, Yi,Yong, Jongwon,Yoon, En Sup The Society of Chemical Engineers, Japan 2009 Journal of chemical engineering of Japan Vol.42 No.10
<P>In this study, domestic and international chemical accident databases are analyzed, and a chemical accident reporting system is developed using chemical accident classification codes. These codes are revised by adopting the data collected in 2115 cases of chemical accidents that occurred in S. Korea over the last 20 years. The revised classification codes are composed of 12 upper, 64 middle, and 276 lower classes. The developed database is composed of data input, data list, and data search modules as well as statistic and analysis modules. Module operations help obtain information on relationships between accident data attributes that are not apparent, in addition to simple statistical results. The chemical accident tracking system is available on the Internet, and the data are treated using an on-line analytical system. The records are statistically analyzed to identify type of accidents that occurs frequently in Korean chemical companies, as well as the accident data and materials involved. We expect the results of this study to be useful in reporting for developing a management of system for prevention of chemical accidents, and improve the manageability of the designed system.</P>
Chemical Recycling of Poly(Ethylene Terephthalate) Using a New Hybrid Process
Kim, Bo-kyung,Kim, Dongpil,Cho, Youngmin,Han, Myungwan The Society of Chemical Engineers, Japan 2008 Journal of chemical engineering of Japan Vol.41 No.9
<P>In this study, we propose a new hybrid process consisting of glycolysis/methanolysis and then a vapor methanolysis process to obtain dimethyl terephthalate (DMT) and ethylene glycol (EG) in the depolymerization of waste poly(ethylene terephthalate) (PET). Zinc acetate was used to catalyze the reactions. We found that the depolymerization rate increased remarkably when glycolysis and methanolysis reactions were simultaneously carried out than when the glycolysis reaction was performed alone. We explored the possibility of the hybrid process and examined optimal weighting between glycolysis and methanolysis in the glycolysis/methanolysis step to increase the DMT yield and production rate. We also investigated the effect of major process variables such as reaction pressure, reaction temperature, reaction time, amount of EG, and methanol feed rate on process performance. We found that methanolysis has a greater role than glycolysis in the glycolysis/methanolysis step and the DMT yield has a maximum at a reaction temperature of 513.15 K and EG/PET mole ratio of 0.52, and increases with reaction pressure.</P>
A Hybrid Model for Fault Diagnosis Using Model Based Approaches and Support Vector Machine
Lee, Chang Jun,Lee, Gibaek,Han, Chonghun,Yoon, and En Sup The Society of Chemical Engineers, Japan 2006 Journal of chemical engineering of Japan Vol.39 No.10
<P>The procedure followed in chemical processes can be expressed in simple terms such as the flow of events from the raw materials to the product. To obtain the best final product, chemical engineers have to consider many factors including environmental effects, stability, economic considerations, and so on. In particular, when considering the stability if the process and the purity of the product, it is very important to detect any faults in the chemical process immediately.In this paper, a hybrid fault diagnosis model based on the signed digraph (SDG) and support vector machine (SVM) is proposed. By means of the system decomposition based on SDG, the local models of each measured variable are constructed and more accurate and fast models are using an SVM, which has no loss of information and shows good performance, in order to obtain the estimated value of the variable, which is then compared with the measured value in order to diagnose the fault. To verify the performance of the proposed model, the Tennessee Eastman (TE) Process was studied and the proposed method was found to demonstrate a good diagnosis capability compared with previous statistical methods.</P>
Seo, Chung-Seok,Jeong, Sang Mun,Park, Sung-Bin,Jung, Jin-Young,Park, Seong-Won,Kim, Sung Hyun The Society of Chemical Engineers, Japan 2006 Journal of chemical engineering of Japan Vol.39 No.1
<P>The electrochemical reduction of Ta<SUB>2</SUB>O<SUB>5</SUB> in an LiCl–Li<SUB>2</SUB>O molten salt system has been studied in an electrolytic cell with an integrated cathode assembly at 650°C. The integrated cathode assembly consists of an electric conductor, Ta<SUB>2</SUB>O<SUB>5</SUB> and a porous magnesia membrane. The metallic tantalum is prepared successfully by the mechanism of an electrode reaction followed by a chemical reaction in the range of voltage between –2.47 V and –3.46 V. The chemical and physical properties of the metallic tantalum are influenced by the applied current related to the reaction rate. The XRD analysis indicates that the tantalum samples prepared at the applied current above 1.0 A have both of bcc and tetragonal structures. The particle size of those samples is similar to that of the fresh Ta<SUB>2</SUB>O<SUB>5</SUB>.</P>
Bench Scale Carbon Dioxide Recovery from the Flue Gas by Monoethanolamine
Lee, Ji Hyun,Kim, Jun-Han,Lee, In Young,Jang, Kyung Ryoung,Shim, Jae-Goo The Society of Chemical Engineers, Japan 2010 Journal of chemical engineering of Japan Vol.43 No.8
<P>A bench scale unit (2 m<SUP>3</SUP>N/h) for removing CO<SUB>2</SUB> from flue gas was operated. Based on a chemical absorption/regeneration process with aqueous monoethanolamine (MEA) solution, we have evaluated the energy requirement for regeneration and degree of CO<SUB>2</SUB> removal as a function of reboiler temperature, MEA concentration, CO<SUB>2</SUB> concentration in the flue gas and ratio of the flow rate of liquid and flue gas. For verification of the experimental results from the bench scale CO<SUB>2</SUB> capture unit, we have also calculated the regeneration energy by the summation of the reaction enthalpy of CO<SUB>2</SUB>, the sensible heat and the heat of vaporization of MEA solution and have compared these results with those of bench scale tests. It was observed that the regeneration energy using a 30 wt% MEA solution was 4.29 GJ/ton CO<SUB>2</SUB> (experiment) and 4.55 GJ/ton CO<SUB>2</SUB> (estimation), respectively. Also, the degree of CO<SUB>2</SUB> removal increases with an increase in reboiler temperature and ratio of the flow rate of liquid and flue gas, while CO<SUB>2</SUB> regeneration energy decreases with an increase in MEA concentration and CO<SUB>2</SUB> concentration in the flue gas.</P>
Synthesis of an Optimizing Control Structure for Dual Mixed Refrigerant Process
Husnil, Yuli Amalia,Lee, Moonyong Society of Chemical Engineers, Japan 2014 Journal of chemical engineering of Japan Vol.47 No.8
<P> This study examines the optimal operation of the dual mixed refrigerant (DMR) process by steady-state optimality analysis. The purpose of this analysis is to discover the optimizing variable that can maintain the DMR process in the optimal compressor duty. First, a rigorous dynamic simulation of the DMR process was built in the Aspen Hysys interface. Second, numerous step tests on the refrigerant flow rate were conducted and the resulting total compressor duty was recorded. The steady-state operational map that correlates the refrigerant flow rate and total compressor duty was drawn to locate the optimal operation region of the DMR process. The map also contains information on the state variables in the DMR process that in particular combinations, will allow the process to be operated at the optimal compressor duty. The comprehensive information on the map makes it an excellent tool for selecting the proper optimizing variable for the DMR process. The resulting steady-state optimality map suggests that, when the flow rate ratio of the two refrigerants (WMR/CMR ratio) is kept constant, the operational of DMR process will remain within optimal region. This suggests that the WMR/CMR ratio is the proper optimizing variable for the DMR process. From a control viewpoint, the control structure that includes the WMR/CMR ratio loop also showed excellent performance compared to the other possible structures in terms of maintaining the stability and fulfilling the control objectives of the DMR process. </P>
Analytical Design of Multi-Loop PI Controllers for Interactive Multivariable Processes
Vu, Truong Nguyen Luan,Lee, Moonyong The Society of Chemical Engineers, Japan 2010 Journal of chemical engineering of Japan Vol.43 No.2
<P>In this paper, a simple and efficient design method of multi-loop PI controllers is proposed by extending the Maclaurin series approach to a multi-loop control system. The controller parameter of a multi-loop system is related to that of a SISO non-interacting system with an interaction factor in the simple multiplication form. Based on this relation, analytical tuning rules for a multi-loop PI controller are derived for several representative process models. In order to improve both performance and robustness of the multi-loop control system, the multi-loop Ms criterion is utilized as a performance cost function. The simulation studies confirm the effectiveness of the proposed method.</P>