• Environmental Engineering Research
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• 제19권4호
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• pp.299-308
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• 2014

This study presents a review on Chemical looping combustion (CLC) development, design aspects and modeling. The CLC is in fact an unmixed combustion based on the transfer of oxygen to the fuel by a solid oxygen carrier material avoiding the direct contact between air and fuel. The CLC process is considered as a very promising combustion technology for power plants and chemical industries due to its inherent capability of $CO_2$ capturing, which avoids extra separation costs of the of $CO_2$ from the rest of flue gases. This review covers the issues related to oxygen carrier materials. The modeling works are reviewed and different aspects of modeling are considered, as well. The main drawbacks and future research and prospects are remarked.

• Korean Membrane Journal
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• 제8권1호
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• pp.1-12
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• 2006

In semiconductor industries, dissolved oxygen is one of the most undesirable contaminants of ultrapure water. A method for dissolved oxygen removal (DOR) consists in the use of polymeric hollow fibres, loaded with a catalyst and fed with a reducing agent such as hydrogen. In this work, PVDF hollow fibres loaded with Pd were characterized by means of perporometry, scanning electron microscopy (SEM), energy dispersive X-ray (EDX). The hollow fibre analyzed shows a five-layer structure with remarkable morphological differences. An estimation of pore diameters and their distribution was performed giving a mean pore diameter of 100 nm. The permeance and selectivity of the fibres were measured using $H_2,\;N_2,\;O_2$ as single gases, at different operating conditions. An $H_2$ permeance of $37 mmol/m^2s$ was measured and $H_2/O_2$ and $H_2/N_2$ selectivities of ca. 3 were obtained. $H_2$ permeance was 1/3 when a water stream flows in the shell side. Catalytic fibrebehaviour was simulated using a mathematical model for a loop membrane reactor, considering only $O_2$ and $H_2$ diffusive transport inside the membrane and their catalytic reaction. Dimensionless parameters such as the Thiele modulus are employed to describe the system behaviour. The model agrees well with the experimental reaction data.

• 멤브레인
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• 제13권3호
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• pp.200-209
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• 2003

Ethyl cellulose(EC)와 platinum(II) acetylacetonate(Pt), rhodium(III)acetylacetonate(Rh)를 이용하여 용매증발법으로 고분자-금속 착체막을 제조하였다. 이때 최종 분리막의 제막조건을 최적화하기 위하여 금속염의 조성을 변화시켰다. (0.3-4.0 wt%). FTIR을 이용하여 EC-금속착체막을 분석하였으며 SEM을 이용하여 막의 구조를 관찰하였다. 그리고 산소, 질소, 이산화탄소, 메탄 가스들의 투과성능을 조사하였다. 금속염들은 모든 가스들의 선택도의 감소없이 투과도를 향상시킨다는 것을 알 수 있었다 그러나 Pt의 경우 산소와 질소가스의 투과성능에 더 영향이 있었으며, Rh은 이산화탄소와 메탄가스의 투과도에 더 영향이 있음을 알 수 있었다. EC-Pt 착체막의 경우에는, Pt의 산소와의 친화력특성에 기인하여 산소/질소의 선택도가 증가(37%)하는 것을 보여주었다.

• 한국수소및신에너지학회논문집
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• 제20권2호
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• pp.151-160
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• 2009

Natural gas combustion characteristics of mass produced oxygen carrier particles were investigated in a batch type bubbling fluidized bed reactor. Five particles, NiO/bentonite, OCN601-650, OCN702-1100, OCN703-950, OCN703-1100 were used as oxygen carrier particles. Natural gas and air were used as reactants for reduction and oxidation, respectively. During reduction reaction, high fuel conversion and high $CO_2$ selectivity were achieved for most of oxygen carriers. During oxidation, NO emission was very low. These results indicate that inherent $CO_2$ separation and low NOx combustion are feasible for the natural gas fueled chemical-looping combustion system. Among the five oxygen carriers, OCN703-1100 particle was selected as the best candidate for demonstration of long-term operation in large-scale chemical-looping combustor from the viewpoints of fuel conversion, $CO_2$ selectivity, $CH_4$ concentration, and CO concentration.

• 한국표면공학회지
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• 제50권3호
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• pp.212-218
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• 2017

$Mg_xNi_yZn_{1-x-y}Fe_2O_4$ ferrite powders were prepared by self-propagating high temperature synthesis followed by classifying with an ultrasonic wet-magnetic separation unit to get high pure nano-sized particles. The $Mg_xNi_yZn_{1-x-y}Fe_2O_4$ ferrites were well formed by using several powders like iron, nickel oxide, zinc oxide and magnesium oxide at 0.1 MPa of oxygen pressure. The ultrasonic wet-magnetic separation of pre-mechanical milled ferrite powders resulted in producing the powders with average size of 800 nm. The addition of a surfactant during the wet-magnetic separation process improved productivity more than twice. The coercive force, maximum magnetization and residual magnetization of the $Mg_xNi_yZn_{1-x-y}Fe_2O_4$ nano-powders with 800 nm size were 3651 A/m, $53.92Am^2/kg$ and $4.0Am^2/kg$, respectively.

• Environmental Engineering Research
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• 제18권2호
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• pp.71-75
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• 2013

This study is to evaluate the effects of the separation wall on the sediment quality and quantity in a combined sewer, by surveying the sewer overflow and sediments during a rainfall. Since the separation wall installed in the combined sewer separates the rainfall and the sewage, the flow rate of the sewage is increased, and the amount of the sediment deposited on the sewer is decreased. One sampling point was the outfall of Daesacheon with a separation wall, and the other was the outfall of Gwaryecheon without a separation wall, in Daejeon metropolitan city. The maximum control of the biochemical oxygen demand (BOD) overflow load was more than 38% in the Daesacheon point with the separation wall, during a rainfall of 0.11 mm/hr. The maximum control of the BOD overflow load was 24% in Gwaryecheon without a separation wall, during a rainfall of 1.0 mm/hr. According to the survey results of the sediment in the sewer, the discharged sediment deposited on the sewer in Gwaryecheon point was about 23% to 28% of the total suspended solid during the rainfall. In addition, the average velocity of sewage in the presence of sediment was about 0.30 m/s, and if the separation wall is installed, it was expected to be about 1.01 m/s, that is 3.4 times more than the same conditions, resulting in the reduction of the sediment deposit.

• BMB Reports
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• 제51권7호
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• pp.317-318
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• 2018

Plants are unable to relocate themselves to a more favorable location and thus have to deal with developmental programs and environmental cues wherever they happen to be. It is yet largely unknown how plant cells coordinate cellular activities and architectures to accomplish developmental processes and respond to environmental changes. By identifying and establishing a new cellular model system, we have discovered that two neighboring cell types in the abscission zone (AZ) of Arabidopsis flowers coordinate their activities to ensure a precise "cut" through a highly restricted area of plant tissue to bring about organ separation. From this perspective, we further discuss the essence of cellular coordination in AZ, the key molecules controlling the organ separation, and relevant implications.

• 자연과학논문집
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• 제8권1호
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• pp.41-45
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• 1995

부분적으로 양이온 교환된 Y 제올라이트를 특별한 반응조건하에서 예열 처리한 결과, 하소한 제올라이트는 수소, 질소, 산소, 일산화탄소 및 메탄기체 혼합물에 대한 분리특성을 보유하고 있으나 미처리한 시료, 예로서 A형 또는 X형 제올라이트보다 물 분자에 대한 친화성이 매우 낮음을 알 수가 있었다. 흡착성능, 흡착등온선 및 흡착열에 관한 측정결과를 근거로 하여 관찰효과를 검토하였다.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 춘계 총회 및 학술발표회
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• pp.180-183
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• 2004

Gas separation membranes are now used in a wide variety of application areas as oxygen enrichment, hydrogen recovery, acid gas treatment, and natural gas dehydration etc [1]. Since polymeric membranes offer attractive properties for gas separation application, they have been variously studied [2-4].(omitted)

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2010년도 춘계학술 발표회
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• pp.203-203
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• 2010