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Papers by Hyeonhui Lee
Industrial & Engineering Chemistry Research, 2012
The recycling partial-discard (RPD) strategy was developed to improve the performance of simulate... more The recycling partial-discard (RPD) strategy was developed to improve the performance of simulated moving bed (SMB) chromatography in partial-discard (PD) strategy by a simulation study. In the RPD operation, each discarded product portion of extract and raffinate is recycled as part of the feed. This strategy was applied to a binary mixture with a nonlinear isotherm in a four-zone SMB with two columns per zone. The two additional operating variables, recycle length (RL) and recycle flowrate (RF), were suggested for the RPD strategy in order to determine the time duration and flowrate of the recycle feed. Compared to those of the PD operation, extract and raffinate with higher purities can be produced from the RPD operation. Simultaneously, the losses in the other performance parameters (recovery, productivity, and eluent consumption) stemming from the PD operation could be favorably reduced by controlling the recycle length and recycle ratio in the RPD operation. The two variables, RL and RF, in the RPD ...
Chemical Engineering Journal, 2011
Enhanced coal bed methane (ECBM) recovery has been proposed as an attractive way to store capture... more Enhanced coal bed methane (ECBM) recovery has been proposed as an attractive way to store captured CO 2 while recovering CH 4. The adsorption and desorption behaviors of CO 2 and CH 4 on dry and wet coal (anthracite) were studied at 318 and 338 K and up to 150 atm. The sorption capacity of CO 2 and CH 4 on anthracite coal was higher at lower temperatures and dry coal condition, but smaller than those on bituminous coals at a similar condition. In wet coal, the sorption capacity and stability of high pressure CO 2 stored at 318 K could be lower than those at 338 K in the supercritical region because higher density of CO 2 at 318 K could lead to the structural change of wet coal. The difference in the excess adsorbed amount between dry and wet coal was only noticeable under the subcritical conditions at 338 K but became more significant under the supercritical conditions with pressure at 318 K. In dry and wet coal, the CO 2 desorption isotherms had different shapes, depending on temperature, but all the CH 4 desorption isotherms showed a weak positive hysteresis. The mutual solubility between the CO 2-rich (or CH 4-rich) phase and aqueous phase as well as coal swelling should be considered in evaluating the sorption capacity of a wet coal seam. Fluid density in free volume was the important variable to estimate the CO 2 storage capacity or ECBM recovery because the density variation significantly influenced the isotherm shape.
Chemical Engineering Journal, 2013
h i g h l i g h t s Sorption of a CO 2 /CH 4 mixture on an anthracite coal was measured up to 13 ... more h i g h l i g h t s Sorption of a CO 2 /CH 4 mixture on an anthracite coal was measured up to 13 MPa. The high selectivity of CO 2 on coal resulted in the negative excess sorption of CH 4. The moisture effect on sorption in wet coal was decreased in supercritical region. The sorption behavior of mixture was similar to that of pure CO 2 at the same density. The mixture density in free volume was an important variable of isotherm shapes.
AIChE Journal, 2010
A “FeedCol” strategy was developed to improve separation performance in simulated moving bed (SMB... more A “FeedCol” strategy was developed to improve separation performance in simulated moving bed (SMB) processes. In the FeedCol operation, a short chromatographic column was simply added to the SMB unit and feed was supplied by a pulse input through the column to the SMB process. Because the feed was made in the shape of partially separated chromatographic peaks through the column, the purities in the raffinate and extract products were improved efficiently in the SMB process. All the performance parameters for a binary mixture with low selectivity (α = 1.1) were better for the FeedCol operation than for the conventional SMB operation (2-2-2-2). Because the feed injection through the feed column was synchronized with the SMB process during the switching period, two new operating variables were introduced: injection length and injection time. Their effects on the suggested strategy were evaluated in terms of performance parameters through a detailed simulation study. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Industrial & Engineering Chemistry Research, 2012
The recycling partial-discard (RPD) strategy was developed to improve the performance of simulate... more The recycling partial-discard (RPD) strategy was developed to improve the performance of simulated moving bed (SMB) chromatography in partial-discard (PD) strategy by a simulation study. In the RPD operation, each discarded product portion of extract and raffinate is recycled as part of the feed. This strategy was applied to a binary mixture with a nonlinear isotherm in a four-zone SMB with two columns per zone. The two additional operating variables, recycle length (RL) and recycle flowrate (RF), were suggested for the RPD strategy in order to determine the time duration and flowrate of the recycle feed. Compared to those of the PD operation, extract and raffinate with higher purities can be produced from the RPD operation. Simultaneously, the losses in the other performance parameters (recovery, productivity, and eluent consumption) stemming from the PD operation could be favorably reduced by controlling the recycle length and recycle ratio in the RPD operation. The two variables, RL and RF, in the RPD ...
Chemical Engineering Journal, 2011
Enhanced coal bed methane (ECBM) recovery has been proposed as an attractive way to store capture... more Enhanced coal bed methane (ECBM) recovery has been proposed as an attractive way to store captured CO 2 while recovering CH 4. The adsorption and desorption behaviors of CO 2 and CH 4 on dry and wet coal (anthracite) were studied at 318 and 338 K and up to 150 atm. The sorption capacity of CO 2 and CH 4 on anthracite coal was higher at lower temperatures and dry coal condition, but smaller than those on bituminous coals at a similar condition. In wet coal, the sorption capacity and stability of high pressure CO 2 stored at 318 K could be lower than those at 338 K in the supercritical region because higher density of CO 2 at 318 K could lead to the structural change of wet coal. The difference in the excess adsorbed amount between dry and wet coal was only noticeable under the subcritical conditions at 338 K but became more significant under the supercritical conditions with pressure at 318 K. In dry and wet coal, the CO 2 desorption isotherms had different shapes, depending on temperature, but all the CH 4 desorption isotherms showed a weak positive hysteresis. The mutual solubility between the CO 2-rich (or CH 4-rich) phase and aqueous phase as well as coal swelling should be considered in evaluating the sorption capacity of a wet coal seam. Fluid density in free volume was the important variable to estimate the CO 2 storage capacity or ECBM recovery because the density variation significantly influenced the isotherm shape.
Chemical Engineering Journal, 2013
h i g h l i g h t s Sorption of a CO 2 /CH 4 mixture on an anthracite coal was measured up to 13 ... more h i g h l i g h t s Sorption of a CO 2 /CH 4 mixture on an anthracite coal was measured up to 13 MPa. The high selectivity of CO 2 on coal resulted in the negative excess sorption of CH 4. The moisture effect on sorption in wet coal was decreased in supercritical region. The sorption behavior of mixture was similar to that of pure CO 2 at the same density. The mixture density in free volume was an important variable of isotherm shapes.
AIChE Journal, 2010
A “FeedCol” strategy was developed to improve separation performance in simulated moving bed (SMB... more A “FeedCol” strategy was developed to improve separation performance in simulated moving bed (SMB) processes. In the FeedCol operation, a short chromatographic column was simply added to the SMB unit and feed was supplied by a pulse input through the column to the SMB process. Because the feed was made in the shape of partially separated chromatographic peaks through the column, the purities in the raffinate and extract products were improved efficiently in the SMB process. All the performance parameters for a binary mixture with low selectivity (α = 1.1) were better for the FeedCol operation than for the conventional SMB operation (2-2-2-2). Because the feed injection through the feed column was synchronized with the SMB process during the switching period, two new operating variables were introduced: injection length and injection time. Their effects on the suggested strategy were evaluated in terms of performance parameters through a detailed simulation study. © 2010 American Institute of Chemical Engineers AIChE J, 2011