추출 열 통합 증류계의 설계 및 최적화

조훈 ( Hoon Cho ),우대식 ( Dae Sik Woo ),최유미 ( Yu Mi Choi ),한명완 ( Myung Wan Han ) 한국화학공학회 2012 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.50 No.2

In this study, thermally coupled distillation system and conventional two-column process were investigated for extractive distillation. The two processes were simulated and optimized using Aspen plus. Objective function for the optimization was energy consumption and optimization results to reduce energy consumption were used to get guidelines for design and operation for the two extractive distillation processes. Comparison of these two processes showed that thermally coupled distillation system provided better energy efficiency and lower capital cost than conventional distillation system.

Novel retrofit designs using a modified coordinate descent methodology for improving energy efficiency of natural gas liquid fractionation process

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>

Energy efficiency improvement of dimethyl ether purification process by utilizing dividing wall columns

Le Quang Minh,Moon Yong Lee,Nguyen Van Duc Long 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.11

The alternative fuel, dimethyl ether (DME), which can be synthesized from natural gas, coal or biomass syngas, has been traditionally used as a diesel substitute or additive. DME purification processes with a conventional distillation sequence consume a large amount of energy. We used dividing wall columns (DWCs) to improve the energy efficiency and reduce the capital cost of the DME purification process. Various possible DWC arrangements were explored to find the potential benefits derived from thermally coupled distillations. The results show that utilizing DWCs can significantly reduce both the energy consumption and investment cost of the DME purification process. The lower energy consumption also results in the reduction of the CO2 emission.

A thermally coupled reactive distillation and pervaporation hybrid process for n-butyl acetate production with enhanced energy efficiency

Harvianto, G.R.,Ahmad, F.,Lee, M. The Institution ; distributed by Pergamon 2017 Chemical engineering research & design Vol.124 No.-

This paper presents a novel hybrid process combining thermally coupled reactive distillation with membrane-based pervaporation for enhanced production of n-butyl acetate. A conventional reactive distillation process was used as the base case and first optimized for the transesterification of methyl acetate with n-butanol to produce n-butyl acetate. It was observed that methyl acetate recovered in the recycle stream significantly affects the conversion in the reactive distillation column and overall energy efficiency of the whole process. The existing and proposed configurations were evaluated and optimized by simulation in Aspen Plus. The integration of thermally coupled reactive distillation and pervaporation improved the energy efficiency of the reactive distillation process by preventing remixing effect in the reactive distillation column and eliminating the azeotropic nature of the methanol and methyl acetate in the recycle stream, respectively. Finally, integration of the thermally coupled reactive distillation with a commercial pervaporation membrane was explored to take synergistic advantage of the thermally coupled reactive distillation and pervaporation hybrid configuration. As a result, the proposed hybrid design showed remarkably improved energy efficiency and economics. The total reboiler duty and total annual cost reduced to 63 and 43%, respectively, compared to those of the base case.

추출 열 통합 증류계의 프로필 위치 제어

조훈 ( Hoon Cho ),최유미 ( Yu Mi Choi ),이진홍 ( Jin Hong Lee ),조임표 ( Im Pyo Cho ),한명완 ( Myung Wan Han ) 한국화학공학회 2012 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.50 No.5

Extractive distillation system can be used when the components to be separated have close boiling points or form azeotropes. Extractive distillation is one of the most important and widely used separation methods in chemical process industry. The main disadvantage of the distillation is its high-energy requirements. Thermally coupled distillation system (TCDS) can provide significant savings in energy consumption and capital cost over the operation of sequences based on conventional distillation column. Despite such advantages of the thermally coupled distillation system, the process is not widely used in industry because control and operation of the column are difficult. In this study, we propose several control schemes for thermally coupled distillation system to overcome the difficulties and make the column stable when the process is confronted with feed disturbances. Profile position control scheme shows best control performance among the proposed control schemes.

Process simulation for the recovery of lactic acid using thermally coupled distillation columns to mitigate the remixing effect

김성영,김동민,이범석 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.5

The objective of this study was to find process simulations of the plant-wide scale lactic acid recovery process using thermally coupled distillation columns to mitigate the remixing effect. The remixing effect has been widely discussed because in a conventional column arrangement it induces a need for a significant amount of energy for repurification in lactic acid recovery processes. One way to overcome high energy consumption is by using thermally coupled distillation columns. This paper suggests and compares two types of thermally coupled distillation columns applied to the plant-wide scale lactic acid recovery process for removing the remixing effect considering a heavy organic impurity and lactic acid oligomerization in the process. The equilibrium stage model based on the RADFRAC module of Aspen Plus was employed for simulating the thermally coupled distillation columns. Simulation results showed that thermally coupled distillation columns can eliminate the remixing effect and reduce energy consumption compared to conventional lactic acid recovery processes.

Experimental evaluation of a modified fully thermally coupled distillation column

Young Han Kim,황규석,김병철 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.4

A modified fully thermally coupled distillation column replacing the conventional distillation system is introduced, and its performance is experimentally evaluated for the stable operation of the column. The existing distillation system is modified to an energy-efficient distillation column for the reduction of investment cost and energy requirement. The experiment is conducted for the separation of methanol, ethanol and n-propanol mixture using a 4-in sieve tray column. The temperatures at seven different locations of the column are measured to monitor the column operation, and the measurements indicate that the column is stably operable. The stable operation proves that neither compressor nor pump is necessary for the vapor or liquid flow between tray sections. The experimental result is compared with that of the HYSYS simulation to show how satisfactory the separation is. The modeling of temperature variation provides a successful prediction of the temperature variation.

A hybrid technology combining heat pump and thermally coupled distillation sequence for retrofit and debottlenecking

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>

Application of a thermally coupled distillation column with separated main columns to gas concentration process

Young Han Kim,Su Yeung Jeong,Moon Yong Lee 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.6

A modified fully thermally coupled distillation column (FTCDC) for operability improvement is utilized in a gas concentration process. The column consists of a prefractionator and two separated main columns having high distillation efficiency and flexible control structure. The operability of the proposed column is evaluated by examining the open-loop dynamic responses of step input variations with the HYSYS simulation. The simulation result indicates that the modified system can give better control than the original FTCDC. The energy saving and reduction of construction cost are discussed, and the ease of vapor flow manipulation and the elimination of a compressor in the vapor transfer are also evaluated as possible improvements.

Approximate estimation of operational variables in fully thermally coupled distillation columns using pseudo-pinch points

Moon Yong Lee,Dae Woong Choi,Young Han Kim 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.3

An approximate procedure for the estimation of operational variables in fully thermally coupled distillation columns (FTCDCs) using two pseudo-pinch points of the feed and side draw trays is proposed, and its performance is examined with two example processes. The estimates from the proposed procedure show some 20% error compared with the results of rigorous simulation using commercial design software, the HYSYS. In addition, the relation between vapor flow rate and composition at one stage above the feed tray-required in the estimation of operational variables of the FTCDC-is analyzed to give information for the selection of the feed tray composition. A preliminary evaluation of operational variables helps to screen unrealizable design obtained often from iterative trial procedures employing the mathematical programming.