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Intensified Distillation‐Based Separation Processes: Recent Developments and Perspectives
Long, Nguyen Van Duc,Minh, Le Quang,Ahmad, Faizan,Luis, Patricia,Lee, Moonyong VCH VERLAGSGESELLSCHAFT 2016 Chemical Engineering & Technology Vol.39 No.12
<P><B>Abstract</B></P><P>Greater sustainability can be achieved by decreasing the production costs, energy consumption, equipment size, and environmental impact as well as improvement of the raw material yields, remote control, and process flexibility. Process intensification (PI) as the main route for improving the process performance is used widely in heat transfer, reactions, separation, and mixing, which results in plant compactness, cleanliness, and energy efficiency. Some of the main intensified separation processes and improvement mechanisms are reviewed briefly with the main focus on the PI of distillation processes, which are the most important separation methods. In addition to these technologies, the potential and reliability of reactive separation processes are addressed briefly, which will enable higher efficiency and capacity.</P>
Nguyen Van Duc Long,이동영,Thi Hiep Han,박선용,황병봉,이문용 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.11
Many design variables and constraints, such as operating temperature and pressure of existing batch distillation or operating temperature of existing cooling and heating media, must be verified and satisfied during design and optimization when an existing batch distillation column is utilized for new mixture. The convergence of batch distillation simulation is sensitive with the initial values of these variables. Thus, a new systematic methodology was proposed to design and optimize separation of a new mixture using an existing batch column. The systematic methodology was based on an industrial case study of dichlorodifluoromethane (R-12) reclamation from a waste refrigerant mixture. Based on a comparison of the Pxy diagram with experimental data, “REFerence fluid PROPerties” was selected as the thermodynamic model. After design and optimization using shortcut and rigorous methodologies, the existing batch distillation unit was operated to validate the proposed methodology. The experimented performance match well with the simulated results. Under the optimized operating condition, complete purification of R-12 (purity=99.5%) was achieved experimentally after 28.3 h. The advantages and disadvantages of the proposed methodology were then discussed.
Long, Nguyen Van Duc,Lee, Moonyong Elsevier 2015 ENERGY Vol.81 No.-
<P><B>Abstract</B></P> <P>Increasing the capacity of an existing distillation process has been a major focus of the chemical process industry. On the other hand, entrainment flooding can occur as a result, which can create a bottleneck in the distillation process. This paper reports the results of a techno-economic feasibility study to debottleneck the distillation column using a proposed hybrid process combining a heat pump and thermally coupled distillation sequence. Fractional utilization of the area was used to identify flooding problems in the column as well as how much area is available for vapor flow on an existing stage. A heat pump aided thermally coupled distillation sequence (HPTCDS) was designed and optimized using a response surface methodology. Two cases were examined to test the proposed sequence. The results showed that the proposed sequence can achieve significant energy savings and remove the bottleneck problem.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Energy efficient hybrid technology was efficiently proposed for debottlenecking. </LI> <LI> Optimal design is efficiently done by response surface methodology. </LI> <LI> Significant saving in operating cost could be achieved. </LI> <LI> The proposed sequence is an attractive option for industrial implementation. </LI> </UL> </P>
Solvent-gradient SMB to separate o-xylene and p-xylene
Nguyen Van Duc Long,구윤모,이주원,Thai-Hoang Le,Jin-Il Kim 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.4
In batch chromatography, solvent-gradient operations (SG) produce significant improvement in terms of the enrichment of products and the separation time and the solvent consumption as compared with isocratic operations. This work studied solvent-gradient operation in reversed-phase simulated moving bed unit to separate ortho-xylene and para-xylene. In a solvent-gradient mode, different mobile phase compositions lead to a different retention behavior of solutes, i.e., different adsorption isotherms. Frontal analysis experiments for ortho-xylene and para-xylene were carried out with a reversed-phase column to measure adsorption parameters at several different mobile phase compositions,such as 45%, 50%, 60%, 75% and 90% acetonitrile. Therefore, the parameters in the retention model for solvent-gradient operation in the case of reversed-phase chromatography were estimated and applied to the design of an SMB system. A modified design method for solvent-gradient simulated moving bed chromatography (SG-SMB)was proposed. The robust operating conditions were obtained within the separation region on ( ϕ_R, ϕ_E) plane ( ϕ_R and ϕ_E are the volumetric content of organic modifier in the raffinate and the extract streams, respectively). The performance results of isocratic and solvent-gradient SMB were compared. A partial-discard strategy and increasing of the solvent gradient level were also applied to improve the performance of the SG-SMB.
The Belt and Road Initiative (BRI): Opportunities and Risks from Vietnamese Perspective
Long Duc Bao NGUYEN,Tracy Trang LY,Doan Cong TRAN,Ai Van TRAN,An Quoc LE,Alan HUDSON 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.4
The goal of this research is to look at the Belt and Road Initiative’s (BRI) goals, principles, and priorities, as well as criticisms and concerns. Another goal is to determine the Vietnamese government’s best response to the BRI. Finally, the study looks at the Vietnamese viewpoint. Document review is used in conjunction with PESTELED analysis and EIU country risk model technique in this study. The study is focused on in-depth interviews with 38 top government leaders, researchers, and scholars by adopting the Delphi technique to determine major factors of risks and opportunities as well as obtain a clearer view on the Vietnamese perspective of the BRI. The main conclusion is that Vietnam’s participation in the BRI could result in a variety of benefits and risks, including economic development, connectivity and integration, development finance, cooperation, coordination, trade facilitation, and people-to-people communication, as well as diplomatic and political risks, financial risks, environmental challenges, and job creation. Another conclusion is suggested that careful and case-by-case negotiation with China is needed for Vietnam to exploit the future benefits of BRI. There is a need to set up the strategy to mitigate the risk impacts, reduce the risk level, avoid risk, at last turn the risk into opportunities.
Long, Nguyen Van Duc,Minh, Le Quang,Pham, Tram Ngoc,Bahadori, Alireza,Lee, Moonyong Elsevier 2016 Journal of natural gas science and engineering Vol.33 No.-
<P><B>Abstract</B></P> <P>Tough environmental regulations, intense competition, expensive fossil energy use, and the strong growth predictions of the natural gas market have prompted efforts to retrofit the existing purification processes to reduce their energy requirements. The important goals of retrofit design are to analyze, evaluate and propose suitable technologies to improve the energy efficiency and/or increase the capacity. This paper reports the results of a techno-economic feasibility study to retrofit a natural gas liquid (NGL) fractionation process. A novel hybrid system, side reboiler and heat pump-assisted, thermally-coupled distillation sequence to maximize the energy efficiency, was proposed. Fractional utilization of the area was used as a hydraulic performance indicator to determine if a bottleneck occurs in a retrofit design. A modified coordinate descent methodology was employed to solve the optimization problem. As a result, the modified coordinate descent methodology was successful in finding the optimal proposed sequence structure and the operating variables, which resulted in operating cost savings of 44.55% compared to the representative base case. The short payback period of 14 months and reduced CO<SUB>2</SUB> emissions of up to 42.05% showed that the proposed sequence is an attractive option for retrofitting in industrial implementation. This sequence can be employed for both grass-root and retrofit designs. This study also showed that even the heat pump can reduce the energy requirements significantly, and may have higher exergy loss than the existing conventional distillation columns.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An energy efficient hybrid technology was proposed for retrofit. </LI> <LI> Optimal design is efficiently done by modified coordinate descent methodology. </LI> <LI> Operating cost saving of 44.55% could be achieved. </LI> <LI> A TCDS can increase the energy efficiency of a heat pump. </LI> <LI> The proposed sequence is an attractive option for industrial implementation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>