• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.114.2-114.2
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• 2010

마이크로 반응기술은 작은 반응기 부피, 높은 열전달, 넓은 반응 면적/부피 및 정확한 반응시간 조절이 가능하기 때문에 화학공정의 고집적화, 반응 선택도의 향상 및 안전도 향상을 꾀할 수 있는 장점이 있다. 이러한 마이크로 반응 기술을 중소형 천연가스 및 국내에서 소규모로 국지적으로 발생하는 메탄의 활용 방안으로서 개발함은 청정 합성유를 제조함으로서 석유 자원의 고갈과 고유가에 대비하여 에너지 자원의 다변화 및 자립을 확보 할 수 있다. 본 연구에서는 마이크로 반응기술을 적용한 미세 유로 반응기(Micro Channel Reactor)를 사용하여 메탄 스팀 개질 반응 특성을 연구하였다. 미세유로 반응기는 내부 홀이 존재하는 plate를 적층함으로 반응기내에 반응가스가 이동할 수 있는 미세유로가 존재하게 하였다. 이러한 미세유로는 반응기의 크기가 작음에도 반응기내에서 반응가스가 충분히 반응할 수 있는 시간과 높은 열전달 효율을 가질 수 있게 한다. 메탄 스팀 개질 반응에 사용된 촉매는 Ni 촉매를 사용하였고, 반응에 필요한 열원으로는 수소 연소에서 발생한 열을 사용하여 반응을 유도하였다. 본 반응기는 외부의 열원을 사용하지 않고, 반응기 내부의 수소 연소에서 발생한 열을 사용함으로 적은 발생 열만으로 메탄 스팀 개질 반응에 필요한 에너지를 얻을 수 있고, 열의 손실이 적다. 또한 메탄 스팀 개질 반응으로 발생한 일부의 수소를 열원으로 이용하여 에너지 사용면에서도 효율적인 반응 공정이다.

• Membrane Journal
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• v.19 no.1
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• pp.1-6
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• 2009

Hydrogen energy id the 2nd clean energy able to be produced from the abundant resources, and the products of combustion or reaction do not spread an environmental pollution. Also, the hydrogen is the chemical media easily to transport and storage as energy source. The hydrogen production technology using by water splitting through electrolysis could be usable as a permanent renewable energy system without the environmental impact. The key technology of high temperature steam electrolysis is the development of an electrolyte rapidly to conduct an oxygen or proton ion decomposed from water. Subsequently, the important technology is to keep the joining technology of an electrolyte membrane and electrode materials to affect into the current efficiency.

• Korean Journal of Materials Research
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• v.9 no.3
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• pp.282-289
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• 1999

티타늄 수소화물(TiH$_2$) 분말을 원료로 사용하여 Ti 소결체를 제조하였다. 원료분말은 수소화-탈수소화법(HDH법)에 의해 제조한 상용분말이었으며 비교를 위해 동일한 입도를 갖는 Ti 분말도 함께 소결하였다. $TiH_2$는 소결체의 밀도를 현저하게 촉진하였으며 $TiH_2$$\longrightarrow$$Ti+H_2$의 탈수소반응에 의해 생성되 청정한 Ti분말이 소결을 촉진하기 때문인 것으로 판단된다. 같은 이유로 $TiH_2$소결체의 산소농도는 Ti 소결체보다 낮게 나타났다. 소결체의 잔류수소는 소결온도가 증가함에 따라 감소하였으며 $1200^{\circ}C$ 이상에서는 5 ppm 이하의 낮은 값을 나타냈다. 소결체의 경도는 소결밀도 및 산소량에 비례하는 것으로 나타났다. $TiH_2$분말의 cubic$\longrightarrow$tetragonal 변태온도는 X-선 회절분석 결과 $16~20^{\circ}C$ 구간으로 밝혀졌다.

• Explosives and Blasting
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• v.40 no.3
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• pp.19-32
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• 2022

Hydrogen is a fuel having the highest energy compared with other common fuels. This means hydrogen is a clean energy source for the future. However, using hydrogen as a fuel has implication regarding carrier and storage issues, as hydrogen is highly inflammable and unstable gas susceptible to explosion. Explosions resulting from hydrogen-air mixtures have already been encountered and well documented in research experiments. However, there are still large gaps in this research field as the use of numerical tools and field experiments are required to fully understand the safety measures necessary to prevent hydrogen explosions. The purpose of this present study is to develop and simulate 3D numerical modelling of an existing hydrogen gas station in Jeonju by using handheld LiDAR and Ansys AUTODYN, as well as the processing of point cloud scans and use of cloud dataset to develop FEM 3D meshed model for the numerical simulation to predict peak-over pressures. The results show that the Lidar scanning technique combined with the ANSYS AUTODYN can help to determine the safety distance and as well as construct, simulate and predict the peak over-pressures for hydrogen refueling station explosions.

• Clean Technology
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• v.26 no.2
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• pp.96-101
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• 2020

In this paper, the commercial feasibility of trigeneration, producing heat, power, and hydrogen (CHHP) and using biogas derived from macroalgae (i.e., seaweed biomass feedstock), are investigated. For this purpose, a commercial scale trigeneration process, consisting of three MW solid oxide fuel cells (SOFCs), gas turbine, and organic Rankine cycle, is designed conceptually and simulated using Aspen plus, a commercial process simulator. To produce hydrogen, a solid oxide fuel cell system is re-designed by the removal of after-burner and the addition of a water-gas shift reactor. The cost of each unit operation equipment in the process is estimated through the calculated heat and mass balances from simulation, with the techno-economic analysis following through. The designed CHHP process produces 2.3 MW of net power and 50 kg hr^-1 of hydrogen with an efficiency of 37% using 2 ton hr^-1 of biogas from 3.47 ton hr^-1 (dry basis) of brown algae as feedstock. Based on these results, a realistic scenario is evaluated economically and the breakeven electricity selling price (BESP) is calculated. The calculated BESP is ¢10.45 kWh^-1, which is comparable to or better than the conventional power generation. This means that the CHHP process based on SOFC can be a viable alternative when the technical targets on SOFC are reached.

• Clean Technology
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• v.18 no.2
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• pp.209-215
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• 2012

The performance and removal efficiencies of a pilot scale biofilter were estimated by using ammonia and hydrogen sulfide as the odorous gases. Expanded polyurethane foam coated with powdered activated carbon and zeolite was used as a biofilm supporting medium in the biofilter. Odorous gases from the sludge thickener of a municipal wastewater treatment plant were treated in the biofilter for 10 months and the inlet ammonia and hydrogen sulfide concentrations were 0.1-1.5 and 2-20 ppmv, respectively. The removal efficiencies reached about 100% at the empty bed retention time (EBRT) of 3.6-5 seconds except for the adaptation periods. The pressure drop of the biofilter caused by the gas flow was also low that the maximum attained was 31 mm $H_2O$ during the operation. Its stability was confirmed in the long term due to the fact that the biofilter and the polyurethane medium had a minimum plugging and compression. The microbial community on the medium is critical for the performance of the biofilter especially the distribution of ammonia oxidizing bacteria (AOB) and sulfur oxidizing bacteria (SOB). The distribution of Nitrosomonas sp. (AOB) and Thiobacillus ferroxidans (SOB) was confirmed by FISH (fluorescence in situ hybridization) analysis. The longer the operation time, the more microbial population observed. Also, the medium close to the gas inlet had more microbial population than the medium at the gas outlet of the biofilter.

• Clean Technology
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• v.18 no.1
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• pp.95-101
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• 2012

The Co and Ni catalysts supported on $Al_2O_3$ for partial oxidation of methane producing hydrogen were synthesized using impregnation to incipient wetness. And the promotion effects of metals such as Mg, Ce, La and Sr in partial oxidation of methane over these $Co/Al_2O_3$ and $Ni/Al_2O_3$ were investigated. Reaction activity of these catalysts for the partial oxidation of methane was investigated in the temperature range of 450~$650^{\circ}C$ at 1 atm and $CH_2/O_2$ = 2.0. The catalysts were characterized by BET, XRD and SEM/EDX. The results indicated that the catalytic performance of these catalysts was improved with the addition of 0.2 wt% metal promoter. The Mg promoted $Co/Al_2O_3$ catalyst showed the highest $CH_4$ conversion and hydrogen selectivity at higher temperature than $500^{\circ}C$. The Ce and Sr promoted Ni catalysts superior to Co-based catalysts in the low temperature range. The addition of metal promoter to $Co/Al_2O_3$ and $Ni/Al_2O_3$ catalysts increased the surface area.

• Clean Technology
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• v.14 no.3
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• pp.204-210
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• 2008

A series of $V_{2}O_{5}-TiO_2$ xerogel catalysts were prepared by nonhydrolytic sol-gel method and analysed by various characterization techniques. These catalysts showed much higher surface areas and total pore volumes than conventional V$V_{2}O_{5}-TiO_2$ xerogel and impregnated $V_{2}O_{5}/TiO_2$ catalysts. It was found that the textural property of $V_{2}O_{5}-TiO_2$ material varies with the method and conditions of synthesis. Surface vanadates and $TiO_2$ anatase phase are the crucial factors to obtain high catalytic activities. The selective oxidation of hydrogen sulfide in the presence of excess water and ammonia was studied over these catalysts. Xerogel catalysts prepared by non-hydrolytic sol-gel method showed very high conversion of $H_{2}S$ without harmful emission of $SO_2$. The highest catalytic activity shown by these $V_{2}O_{5}-TiO_2$ catalysts may be due to their high surface area and good dispersion of vanadia species in the titania matrix.

• Clean Technology
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• v.15 no.1
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• pp.47-53
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• 2009

Mesoporous aluminas (A-C, A-A, and A-N) were prepared by a templating method using cationic(C), anionic(A), and non-ionic(N) surfactant as a structure-directing agent, respectively. Nickel catalysts supported on mesoporous alumina (Ni/A-C, Ni/A-A, and Ni/A-N) were then prepared by an impregnation method, and were applied to hydrogen production by steam reforming of liquefied natural gas (LNG). Regardless of surfactant type, nickel species were finely dispersed on the surface of mesoporous alumina in the calcined catalysts. It was revealed that interaction between nickel species and support in the reduced catalysts was strongly dependent on the identity of surfactant. LNG conversion and $H_2$ composition in dry gas increased in the order of Ni/A-C < Ni/A-A < Ni/A-N. It was found that catalytic performance increased with increasing nickel surface area in the reduced catalyst. Among the catalyst tested, Ni/A-N catalyst with the highest nickel surface area showed the best catalytic performance.

• Clean Technology
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• v.19 no.1
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• pp.51-58
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• 2013

In this study, kinetics data was obtained for steam reforming reaction of ethane over the nickel catalyst. The variables of steam reforming reaction were reaction temperature, partial pressure of ethane, and mole ratio of steam and ethane. Parameters for the power rate law kinetic model and the Langmuir-Hinshelwood model were obtained from the kinetic data. Also, sizing of steam reforming reactor was performed by using PRO/II simulator. For the steam reforming reaction of ethane, Langmuir-Hinshelwood model determining the reaction rate by the surface reaction was better suited than a simple power rate law kinetic model. On water-gas-shift reaction, power rate law kinetic model was well fitted to the kinetic data. Reactor size can be calculated for production of hydrogen through PRO/II simulation.