• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2010년 춘계학술대회논문집
• /
• pp.228-232
• /
• 2010

In this paper, various operating parameters of stream reforming process from methane in preconverter for MCFC is studied by numerical method. Commercial code is used to simulated the porous catalyst with user subroutine to model three dominant chemical reactions which are Stream Reforming(SR), Water-Gas Shift(WGS), and Direct Stram Reforming(DSR). The hydrogen production is tested with different wall temperature, Gas Hourly Space Velocity(GHSV), and different reactor shapes.

• 한국전산유체공학회지
• /
• 제16권1호
• /
• pp.42-47
• /
• 2011

In this paper, various operating parameters of stream reforming process from methane in stream reformer and preconverter for MCFC is studied by numerical method. Commercial code is used to simulated the porous catalyst with user subroutine to model three dominant chemical reactions which are Stream Reforming(SR), Water-Gas Shift(WGS), and Direct Stram Reforming(DSR). The hydrogen production is tested with different wall temperature and different reactor shapes. The calculated results of the concentration of hydrogen in stream reformer are very well consistent with experimental results. This numerical study gives the design reactor wall temperature condition and size of reactor to satisfy the required fuel conversion.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2011년 춘계학술대회논문집
• /
• pp.112-116
• /
• 2011

In this paper, a preconverter of MCFC for an emergence electric power supplier is numerically simulated to increase the hydrogen production from natural gas (methane). Commercial code is used to simulated the porous catalyst with user subroutine to model three dominant chemical reactions which are Stream Reforming(SR), Water-Gas Shift(WGS), and Direct Stram Reforming(DSR). To get 10% fuel conversion rate in preconverter. the required external heat flux is supplied from outer wall of preconverter. The calculated results show that very nonuniform temperature distribution and chemical reaction happen near the wall of preconverter. These phenomena can be explained by the low heat conductivity of porous catalyst and the endothermic reforming reaction.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2009년도 추계학술대회 논문집
• /
• pp.218-221
• /
• 2009

Solid oxide fuel cells (SOFCs), as high-temperature fuel cells, have various advantages. In some merits of SOFCs, high temperature operation can lead to the capability for internal reforming, providing fuel flexibility. SOFCs can directly use CH4 and CO as fuels with sufficient steam feeds. However, hydrocarbons heavier than CH4, such as ethylene, ethane, and propane, induce carbon deposition on the Ni-based anodes of SOFCs. In the case of the ethylene steam reforming reaction on a Ni-based catalyst, the rate of carbon deposition is faster than among other hydrocarbons, even aromatics. In the reformates of heavy hydrocarbons (diesel, gasoline, kerosene and JP-8), the concentration of ethylene is usually higher than other low hydrocarbons such as methane, propane and butane. It is importatnt that ethylene in the reformate is removed for stlable operation of SOFCs. A new methodology, termed post-reforming was introduced for removing low hydrocarbons from the reformate gas stream. In this work, activity tests of some post-reforming catalysts, such as CGO-Ru, CGO-Ni, and CGO-Pt, are investigated. CGO-Pt catalyst is not good for removing ethylene due to low conversion of ethylene and low selectivity of ethylene dehydrogenation. The other hand, CGO-Ru and CGO-Ni catalysts show good ethylene conversion, and CGO-Ni catalyst shows the best reaction selectivity of ethylene dehydrogenation.

• 한국수소및신에너지학회논문집
• /
• 제13권1호
• /
• pp.3-12
• /
• 2002

In this study, it achieved life cycle assessment to estimate environmental performance for naphtha steam reforming that account for the production over 50% of total hydrogen output. Although hydrogen dosen't emit air emissions, especially, $CO_2$, a large of $CO_2$ is emitted in hydrogen production process. In the result of this study, it ascertained the truth that $CO_2$ is emitted at the rate of $6.3kg/kgH_2$ and that result from steam reforming reaction and use of fossil fuel in hydrogen manufacturing process. Above all, 57% of total $CO_2$ emissions is emitted in process of steam reforming of naphtha and so it knew that the principle of steam reforming is key issue in aspect to environment. Also, it compared hydrogen by fuel of fuel cell vehicle with gasoline fuel of general gasoline vehicle to analyze relative environment of hydrogen for fossil fuel during the life cycle. As the result, it might be difficult in improvement of environment because $CO_2$ emissions during the hydrogen manufacturing process is nearly the same with that during the use of gasoline.

• 에너지공학
• /
• 제12권2호
• /
• pp.145-153
• /
• 2003

석탄이용 무공해 발전공정의 핵심기술인 탄화공정을 개발하기 위하여, 본 공정의 주반응인 메탄 수증기 개질에 대한 특성을 조사하였다. 개질촉매를 이용한 메탄수증기 개질에서는 공간속도, 수증기/탄소-비, 압력에 대한 영향을 조사하였다. 공간속도 7,000$hr^{-1}$ 이하에서 평형 전화율을 얻었다. 혼성반응으로 구성된 탄화공정 중 메탄 수증기 개질 반응조건인 700~80$0^{\circ}C$, 수증기/탄소-비 2.5~3에서 생성물 조성분포는 상압에서 수소 75~78%, 이산화탄소 8~10%, 1~30기압에서 수소 60~78%, 이산화탄소 9~11%를 얻었다.

• 대한기계학회논문집B
• /
• 제36권4호
• /
• pp.425-430
• /
• 2012

본 연구에서는 비상시 전기 공급용 MCFC 프리커버터의 천연가스(메탄)로부터 수소의 생산량을 증가시키는 경우를 수치적으로 해석하였다. 상용 코드를 사용하였으며 촉매는 다공성 매질로 시뮬레이션 하였다. 3가지 주요 화학반응인 수증기 개질반응(SR), 수성 가스 전환(WGS) 및 직접 수증기 개질 반응(DSR)은 사용자 부프로그램을 사용하여 해석하였다. 프리컨버터에서 10%의 연료전환율을 얻기 위해 요구되는 추가 열량을 벽면을 통해 공급하게 되면 프리컨버터의 벽면 부근에서만 매우 불균일한 온도 분포와 화학반응이 일어나는 것으로 분석되었다. 이와 같은 현상은 매우 작은 열전도율을 갖는 다공성 매질의 촉매와 흡열반응으로 설명되어질 수 있다. 해석결과 프리컨버터의 길이가 짧은 경우가 보다 균일한 연료전환율을 보여 주며, 촉매의 유지 보수 면에도 길이가 짧은 경우가 유리함을 보여 주었다.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
• /
• pp.720-722
• /
• 2009

This work is mainly focused at developing the hydrogen production unit with the capacity of 20 $Nm^3/h$ of high purity hydrogen. At present steam reforming of natural gas is the preferable method to produce hydrogen at the point of production cost. The developed hydrogen production unit composed of natural gas reformer and pressure swing adsorption system. To improve the thermal efficiency of steam reforming reactor, the internal heat recuperating structure was adopted. The heat contained in reformed gas which comes out of the catalytic beds recovered by reaction feed stream. These features of design reduce the fuel consumption into burner and the heat duty of external heat exchangers, such as feed pre-heater and steam generator. The production rate of natural gas reformer was 41.7 $Nm^3/h$ as a dryreformate basis. The composition of PSA feed gas was $H_2$ 78.26%, $CO_2$ 18.49%, CO 1.43% and $CH_4$ 1.85%. The integrated production unit can produce 21.1 $Nm^3/h$ of high-purity hydrogen (99.997%). The hydrogen production efficiency of the developed unit was more than 58% as an LHV basis.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 추계학술대회 초록집
• /
• pp.136.2-136.2
• /
• 2011

A dynamic simulation study on SCR process in GTL process was carried out in order to find optimum operation conditions for pilot plant operation. Optimum operating conditions for SCR synthesis gas process were determined by changing operation variables such as feed temperature and pressure. It was also assumed that physical properties of reaction medium were governed by RKS (Redlich-Kwong-Soave) equation. The effect of temperature and pressure on synthesis gas process $H_2$/CO ratio were mainly examined. Dynamic simulation results were fed back to feed operation condition for optimizing productivity, especially for appropriate condition to FT (Fischer-Tropsch) synthesis unit.

• 대한기계학회논문집B
• /
• 제37권8호
• /
• pp.753-758
• /
• 2013

본 연구는 MCFC용 벽면가열 방식 프리컨버터의 낮은 열전도율 때문에 발생하는 벽면 고온 발생 문제를 해결하기 위한 두 가지 방안을 수치해석을 통해 연구하였다. 프리컨버터 내부에 열전도율이 높은 다공성판을 설치한 경우 벽면에서 중심부위로 열전달이 향상되어 수소 생성이 벽면부위에 국한되지 않고 촉매내부에 좀 더 균일하게 발생되는 것을 확인하였다. 그리고 촉매 내부에 일정한 두께의 빈 공간을 중심, 1/2 그리고 4/5 위치에 두고 해석하여 결과를 비교하였고, 1/2위치의 빈 공간이 다른 경우에 비해 연료전환이 보다 이상적인 경우에 근접하지만 열전도율이 높은 다공성판의 설치가 보다 효과적임을 확인하였다.