• Transactions of the Korean hydrogen and new energy society
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• v.23 no.3
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• pp.264-273
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• 2012

In this paper, two types of integrated gasification combined cycle (IGCC) plants using either an air separation unit (ASU) or an ion transport membrane (ITM), which provide the oxygen required in the gasification process, were simulated and their thermodynamic performance was compared. Also, the influence of adopting a pre-combustion $CO_2$ capture in the downstream of the gasification process on the performance of the two systems was examined. The system using the ITM exhibits greater net power output than the system using the ASU. However, its net plant efficiency is slightly lower because of the additional fuel consumption required to operate the ITM at an appropriate operating temperature. This efficiency comparison is based on the assumption of a moderately high purity (95%) of the oxygen generated from the ASU. However, if the oxygen purity of the ASU is to be comparable to that of the ITM, which is over 99%, the ASU based IGCC system would exhibit a lower net efficiency than the ITM based system.

• Journal of the Korean institute of surface engineering
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• v.48 no.1
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• pp.11-22
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• 2015

Pd alloy hydrogen membranes for hydrogen purification and separation need thermal stability at high temperature for commercial applications. Intermetallic diffusion between the Pd alloy film and the porous metal support gives rise to serious problems in long-term stability of Pd alloy membranes. Ceramic barriers are widely used to prevent the intermetallic diffusion from the porous metal support. However, these layers result in poor adhesion at the interface between film and barrier because of the fundamentally poor chemical affinity and a large thermal stress. In this study, we developed Pd alloy membranes having a dense microstructure and saturated composition on modified metal supports by advanced DC magnetron sputtering and heat treatment for enhanced thermal stability. Experimental results showed that Pd-Cu and Pd-Ag alloy membranes had considerably enhanced long-term stability owing to stable, dense alloy film microstructure and saturated composition, effective diffusion barrier, and good adhesive interface layer.

• Membrane Journal
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• v.7 no.3
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• pp.136-141
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• 1997

Humic acid has been extracted and purified from biologically nondegradable humic substances. Using the ion exchange capability of carboxylic acids which are the main component of the humic acids, a membrane was prepared with poly(viny1 alcohol). Its transport behavior of biologically active ions, $K^+$and $Na^+$, were investigated. The ion transport velocity increased with hydrogen ion concentration, especially, in the range of $10^-1$~$10^0$. The selectivity increased with increasing the concentrations of $K^{＋}$ and Na$^{＋}$, In particular, the transport velocity of $K^+$ increased twice compared to that of $Na^+$ at the 100 hydrogen ion concentration. In this regards, humic acid may be used as a new material for ion exchange membranes.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.1
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• pp.90-96
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• 2024

In this paper, a new technology to obtain electronic grade, highly pure carbon dioxide by using membrane and liquefied natural gas (LNG) cold heat assisted cryogenic distillation has been proposed. PRO/II with PROVISION release 2023.1 from AVEVA company was used, and Peng-Robinson equation of the state model with Twu's alpha function to predict pure component vapor pressure versus temperature more accurately was selected for the modeling of the membrane and cryogenic distillation process. Advantage of using membrane separation instead of selecting absorber-stripper configuration for the concentration of carbon dioxide was the reduction of carbon dioxide capture cost.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.77-83
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• 2023

Energy consumption is increased by rapid industrialization. As a result, climate change is accelerating due to the increase in CO₂ concentration in the atmosphere. Therefore, a shift in the energy paradigm is required. Hydrogen is in the spotlight as a part of that. Currently 95% of hydrogen is fossil fuel-based reforming hydrogen which is accompanied by CO₂ emissions. This is called gray hydrogen, if the CO₂ is captured and emission of CO₂ is reduced, it can be converted into blue hydrogen. There are 3 technologies to capture CO₂: absorption, adsorption and membrane technology. In order to select CO₂ capture technology, the analysis of the exhaust gas should be carried out. The concentration of CO₂ in the flue gas from the hydrogen production process is higher than 20%if water is removed as well as the emission scale is classified as small and medium. So, the application of the membrane technology is more advantageous than the absorption. In addition, if LNG cold energy can be used for low temperature CO₂ capture system, the CO₂/N₂ selectivity of the membrane is higher than room temperature CO₂ capture and enabling an efficient CO₂ capture process. In this study, we will analyze the flue gas from hydrogen production process and discuss suitable CO₂ capture technology for it.

• Membrane Journal
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• v.28 no.2
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• pp.113-120
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• 2018

Global warming due to indiscriminate carbon dioxide emissions has a profound impact on human life by causing abnormal climate change and ecosystem destruction. As a way to reduce carbon dioxide emissions, in this study, we presented a polymeric membrane prepared by blending a self-crosslinkable P(GMA-g-PPG)-co-POEM (SP) copolymer and commercial polymer polyvinylpyrrolidone (PVP). As the content of PVP increased, it was observed that the gas permeance decreased and $CO_2/N_2$ selectivity increased. At 30 wt% PVP content, the $CO_2$ permeance of the membrane decreased from 72.9 GPU of pure SP polymer to 12.6 GPU, while $CO_2/N_2$ selectivity improved by 79% from 28.1 to 50.4. It results from the hydrogen bonding between the SP copolymer and PVP, leading to more compact structure of the polymer chains, which was confirmed by FT-IR, TGA, XRD and SEM analysis. Therefore, we suggest that the permeance and selectivity of the membranes can be easily adjusted as desired by controlling the PVP content in the SP/PVP polymer blend.

• Plant Journal
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• v.18 no.4
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• pp.58-65
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• 2023

In this study, to increase the methane content of biogas supplied from Nanji Water Regeneration Center and to purify impurities, a three-stage membrane purification process was designed and installed to demonstrate operation. The methane concentration of biomethane produced in the 2 Nm3/h purification process was set to three cases: 95%, 96.5%, and 98%, and the membrane area ratio of the membrane was 1:1, 1:2, 1:1:1, The optimum conditions for the membrane area of the separator were derived by changing to five of 1:2:1 and 1:2:2. 3 stage separation membrane process of 30 Nm3/h was installed to reflect the optimum condition of 2 Nm3/h, and biomethane production of 98% or more of methane concentration was demonstrated. As a result of the operation of the 2 Nm³/h refining device, the methane recovery rate at the 98% methane concentration was 95.6% when the membrane area ratio was 1:1 as the result of the two-stage operation of the separator, and the recovery rate of methane at 1:2 was increased to 96.8%. The methane recovery rate of the membrane three-stage operation was highest at 96.8% when the membrane area ratio was operated at 1:2:1. The carbon dioxide removal rate was 16.4 to 96.4% and the 2:2 to 95.7% film area ratio in the two-step process. In the three-step process, the film area ratio was 1:2:1 to 95.4%, and the two-step process showed higher results than the three-step process. In the 30 Nm3/h scale biogas purification demonstration operation, the methane concentration after purification was 98%, the recovery rate of methane was 97.1%, the removal rate of carbon dioxide was 95.7%, and hydrogen sulfide, the cause of corrosion, was not detected, and the membrane area ratio was 1:2:1 demonstration operation, biomethane production with a methane concentration of 98% or higher was possible.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.1
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• pp.17-23
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• 2003

$H_2$ permeation flux though a $100{\mu}m-thick$ Pd-Ru (6wt%) membrane was measured at various temperatures and pressures. The permeation flux followed the Sievert's law and thus the rate-limiting step of the hydrogen permeation was the bulk atomic diffusion step. The activation energy of the permeation flux was obtained at 17.9 kJ/mol and this value is consistent with those published previously. While no degradation of the permeation flux wasfound in the membrane exposed to the $O_2$ and $CO_2$ environments for 100 hours, the membrane exposed to $N_2$ environment for 100 hours showed the degradation in the $H_2$ permeation flux. The $H_2$ permeation was decreased as the exposure temperature to $N_2$, environment was increased. The $H_2$ permeation flux was fully recovered after the membrane was kept in the $H_2$ environment for certain time. The permeation flux degradation might be caused by the formation of metal nitride on the membrane surface.

• Journal of the Korean institute of surface engineering
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• v.51 no.5
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• pp.277-290
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• 2018

In this study, Pd-Ni-Ag alloy hydrogen separation membranes were fabricated by Pd/Ag/Pd/Ni/Pd multi-layer sputter deposition on the modified MIM(Metal Injection Molding)-PSS(Porous Stainless Steel) support and followed heat treatment. Nickel, used as an alloying element in Pd alloy membranes, is inexpensive and stable material in a hydrogen isotope environment at high temperature up to 1123 K. Hydrogen perm-selectivity of Pd-Ni-Ag alloy membranes is affected not only by composition of membrane films but also by other factors such as surface properties of PSS support, microstructure of membrane films and inter-diffused impurities from PSS support. In order to clarify the effect of surface Ni composition on hydrogen perm-selectivity of Pd-Ni-Ag alloy membranes, the other effects were significantly minimized by the formation of dense and homogeneous Pd-Ni-Ag alloy membranes. Hydrogen permeation test showed that hydrogen permeability decreased from $7.6{\times}10^{-09}$ to $1.02{\times}10^{-09}mol/m{\cdot}s{\cdot}Pa^{0.5}$ as Ni composition increased from 0 to 16 wt% and the selectivity for $H_2/N_2$ was infinite.

• Proceedings of the Membrane Society of Korea Conference
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• 1992.04a
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• pp.49-49
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• 1992

분리막법이 기체 분리에 응용된후 에너지 소비의 절감, 열안정성 등과 같은 장점들로 인해 수소회수 및 $H_2/CO_2$의 비율조정, $CH_4/CO_2$ 분리, $O_2/N_2$의 분리 등에 이용되고 있다. 이러한 분리막의 특성은 투과도와 선택투과도에 의해 결정되어지는데, 이들은 서로 상반된 경향을 나타낸다. 즉 투과도가 높으면 선택투과도는 낮아지고, 선택투과도가 높으면 투과도는 감소하게 된다. 그러나 이러한 두가지 특성 모두를 높이기 위한 연구가 활발히 진행되고 있는데, 그 연구방향은 새로운 고분자의 합성 및 고분자의 개질, 복합재료의 개발, 액정, 촉진수송법 등으로 나눠질 수 있다. 이중 촉진수송이란 특정한 기체와 가역적 친화력 혹은 흡착력을 갖는 운반체를 액체 혹은 고체막에 분산시켜 원하는 특정 기체만을 선택적으로 수송하는 것을 말한다.