• 한국수소및신에너지학회논문집
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• 제23권3호
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• pp.213-218
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• 2012

Steam reforming of methane (SRM) is the primary method to produce hydrogen. Commercial Ni-based catalysts have been optimized for SRM with excess steam ($H_2O/CH_4$ > 2.5) at high temperatures (> $700^{\circ}C$). However, commercial catalysts are not suitable under severe conditions such as stoichiometric steam over methane ratio ($H_2O/CH_4$ = 1.0) and low temperature ($600^{\circ}C$). In this study, 15wt.% Ni catalysts supported on $Ce_{0.8}Zr_{0.2}O_2$ were prepared at various calcination temperatures for SRM at a very high gas hourly space velocity (GHSV) of $621,704h^{-1}$. The calcination temperature was systematically varied to optimize 15wt.% $Ni-Ce_{0.8}Zr_{0.2}O_2$ catalyst at a $H_2O/CH_4$ ratio of 1.0 and at $600^{\circ}C$. 15wt.% $Ni-Ce_{0.8}Zr_{0.2}O_2$ catalyst calcined at $500^{\circ}C$ exhibited the highest $CH_4$ conversion as well as stability with time on stream. Also, 15wt.% $Ni-Ce_{0.8}Zr_{0.2}O_2$ catalyst calcined at $500^{\circ}C$ showed the highest $H_2$ yield (58%) and CO yield (21%) among the catalysts. This is due to complex NiO species, which have relatively strong metal to support interaction (SMSI).

• 대한기계학회논문집B
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• 제31권11호
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• pp.942-948
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• 2007

Popular techniques for producing hydrogen by converting methane include steam reforming and catalyst reforming. However, these are high temperature and high pressure processes limited by equipment, cost and difficulty of operation. Low temperature plasma is projected to be a technique that can be used to produce high concentration hydrogen from methane. It is suitable for miniaturization and fur application in other technologies. In this research, the effect of changing each of the following variables was studied using an AC GlidArc system that was conceived by the research team: the gas components ratio, the gas flow rate, the catalyst reactor temperature and voltage. Results were obtained for methane and hydrogen yields and intermediate products. The system used in this research consisted of 3 electrodes and an AC power source. In this study, air was added fur the partial oxidation reaction of methane. The result showed that as the gas flow rate, the catalyst reactor temperature and the electric power increased, the methane conversion rate and the hydrogen concentration also increased. With $O_2/C$ ratio of 0.45, input flow rate of 4.9 l/min and power supply of 1 kW as the reference condition, the methane conversion rate, the high hydrogen selectivity and the reformer energy density were 69.2%, 32.6% and 35.2% respectively.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.731-734
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• 2009

KIER has been developed a compact and highly efficient fuel processor which is one of the key component of the residential PEM fuel cells system. The fuel processor uses methane steam reforming to convert natural gas to a mixture of water, hydrogen, carbon dioxide, carbon monoxide and unreacted methane. Then carbon monoxide is converted to carbon dioxide in water-gas-shift reactor and preferential oxidation reactor. A start-up time of the fuel processor is about 1h and CO concentration among the final product is maintained less than 5 vol. ppm. To achieve high thermal efficiency of 80% on a LHV basis, an optimal thermal network was designed. Internal heat exchange of the fuel processor is so efficient that the temperature of the reformed gas and the flue gas at the exit of the fuel processor remains less than $100^{\circ}C$. A compact design considering a mixing and distribution of the feed was applied to reduce the reactor volume. The current volume of the fuel processor is 17L with insulation.

• 대한기계학회논문집B
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• 제33권7호
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• pp.527-534
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• 2009

Flame stabilization characteristics were experimentally investigated in a fuel-air cross flowing mixing layer. A combustor consists of a narrow channel of air steam and a cross flowing fuel. Depending on the flow rates of methane and air, flame can be stabilized in two modes. First is an attached flame which is formulated at the backward step where the methane and air streams meet. Second is a lifted-flame which is formulated within the mixing layer far down steam from backward step. The heights and flame widths of the lifted flames were measured. Flame shapes of the lifted flames were similar to an ordinary edge flame or a tribrachial flame, and their behavior could be explained with the theories of an edge flame. With the increase of the mixing time between fuel and air, the fuel concentration gradient decreases and the flame propagation velocity increases. Thus the flame is stabilized where the flow velocity is matched to the flame propagation velocity in spite of a significant disturbance in the fuel mixing and heat loss within the channel. This study provides many experimental results for a higher fuel concentration gradient, and it can also be helpful for the development and application of a smaller combustor.

• 한국세라믹학회지
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• 제53권5호
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• pp.483-488
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• 2016

Anode supported solid oxide fuel cells (SOFCs), consisting of Ni+YSZ anode, YSZ electrolyte, and LSM+YSZ cathode, were fabricated and constant current tested with direct internal reforming of methane (steam to carbon ratio ~ 2) as well as hydrogen fuel at $800^{\circ}C$. The cell, operated under direct internal reforming conditions, showed relatively rapid degradation (~ 1.6 % voltage drop) for 95 h; the cells with hydrogen fuel operated stably for 170 h. Power density and impedance spectra were also measured before and after the tests, and post-test analyses were conducted on the anode parts using SEM / EDS. The results indicate that the performance degradation of the cell operated with internal reforming can be attributed to carbon depositions on the anode, which increase the resistance against anode gas transport and deactivate the Ni catalyst. Thus, the present study shows that direct internal reforming SOFCs cannot be stably operated even under the condition of S/C ratio of ~ 2, probably due to non-uniform mixture (methane and steam) gas flow.

• 설비공학논문집
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• 제22권1호
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• pp.40-48
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• 2010

The purpose of the research is to develop the high performance solar chemical reactor for producing hydrogen using steam reforming reaction of methane. A specific shape chemical reactor is suggested : spiral type reactor. The reactor is installed on the dish-type solar thermal system of Inha University. The temperatures, $CH_4$ conversion rates, and Hz proportion are measured. At specific condition, $CH_4$ conversion rates of the spiral type reactor are about 91%, and Hz proportion are about 66%. The spiral type reactor gives reasonably good performance without any problems caused by highly concentrated solar radiation.

• 전기학회논문지P
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• 제58권4호
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• pp.639-643
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• 2009

A reformer, which produces hydrogen from natural gas, plays a major role for producing quality hydrogen to fuel-cell system. In this paper, fuel processor is designed to deliver hydrogen(75%) from the reformer to 200W fuel-cell system, and the electrical output power of the fuel-cells is examined by being injected different hydrogen concentrations to the system. We verified that the output power characteristics of the fuel-cells with 75% reformed hydrogen was lower about 7% than the case of pure hydrogen supplied. The type of reformer in this experiment takes SMR(Steam methane reforming) process, and the temperature variation characteristics of reforming process by reactions are examined in operation.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.50-57
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• 2005

The aim of this study is to numerically investigate a compact reformer system currently under development and to design a better reforming system with more efficient heat transfer and reforming reactions. Numerical models were established separately for both the combustion part and the reforming reaction part. A comparison between the calculation results and experimental data showed that the concentration of the reformate at the exit of the reforming system was in good agreement with the measured data, but for the temperature at the exit little difference between them was found. After checking the validity of the numerical models, the heat transfer between the combustion gas and reforming catalysts was estimated and the behavior of the catalyst bed was investigated as a function of the operation parameters.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
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• pp.55-60
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• 2009

The purpose of the research is to develop the high performance solar chemical reactor for producing hydrogen using steam reforming reaction of methane. A specific shape chemical reactor is suggested: spiral type reactor. The reactor is installed on the dish-type solar thermal system of Inha University. The temperatures, $CH_4$ conversion rates are measured. At specific condition, $CH_4$ conversion rates of the spiral type reactor are about 92%. The spiral type reactor gives reasonably good performance without any problems caused by highly concentrated solar radiation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.383-386
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• 2008

The four-bed PSA process using a layered bed of activated carbon and zeolite 5A was studied to produce a high purity hydrogen product from SMR off-gas. At a desired product purity (99.999%+), the recovery increased with decreasing the linear velocity. However, the difference of the increasing of the recovery became smaller with the decreasing of the linear velocity and then was similar from below the linear velocity 3.9 cm/s. When the adsorbents, the feed gas composition, and the operating conditions are given, the residence time is mainly a function for design of the PSA bed size. The minimum residence time exists to obtain the maximum recovery at desired product purity.