• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.9
• /
• pp.885-894
• /
• 2012

A numerical study of a microchannel steam methane reforming reactor has been performed to understand the characteristics of heat and mass transfer. The integration of Rh-catalyzed steam methane reforming and Pt-catalyzed methane combustion has been simulated. The reaction rates for chemical reactions have been incorporated into the simulation. This study investigated the effect of contact time, flow pattern (parallel or counter), and channel size on the reforming performance and temperature distribution. The parallel and counter flow have opposite temperature distribution, and they show a different type of reaction rate and species mole fraction. As the contact time decreases and channel size increases, mass transfer between the catalyst layer and the flow is limited, and the reforming performance is decreased.

• Transactions of the Korean hydrogen and new energy society
• /
• v.26 no.5
• /
• pp.477-483
• /
• 2015

LFG (Land-Fill Gas) includes components of $CH_4$, $CO_2$, $O_2$, $N_2$, and water. The preparation of synthesis gas from LFG as a DME (Dimethyl Ether) feedstock was studied by methane reforming of $CO_2$, $O_2$ and steam over $NiO-MgO-CeO_2/Al_2O_3$ catalyst. Our experiments were performed to investigate the effects of methane conversion and syngas yield on the amount of LFG components over $NiO-MgO-CeO_2/Al_2O_3$ catalyst. Results were obtained through the methan reforming experiments at the temperature of $900^{\circ}C$ and GHSV of 8,800. The results were as following; it has generally shown that syngas yield increase with the increase of oxygen and steam amounts and then decrease. Highly methane conversion of above 98% and syngas yield of approximately 60% were obtained in the feed of gas composition flow-rate of 243ml/min of $CH_4$, 241ml/min of $CO_2$, 195ml/min of $O_2$, 48ml/min of $N_2$, and 450ml/min of steam, respectively, under reactor pressure of 1 bar for 200 hrs of reaction time. Also, it was shown that catalyst deactivation by coke formation was reduced by excessively adding oxygen and steam as an oxidizer of the methane reforming.

• 한국연소학회:학술대회논문집
• /
• 2005.10a
• /
• pp.50-57
• /
• 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.

• Transactions of the Korean hydrogen and new energy society
• /
• v.33 no.6
• /
• pp.749-760
• /
• 2022

An efficient computational fluid dynamics model was proposed for simulating microchannel-type steam/methane reformers with thin washcoat catalyst layers. In this model, by using the effectiveness factor correlations, the overall reaction rate that occurs in the washcoat catalyst layer could be accurately estimated without performing the detailed calculation of heat transfer, mass transfer, and reforming reactions therein. The accuracy of the proposed model was validated by solving a microchannel-type reformer, once by fully considering the complex steam/methane reforming (SMR) process inside the washcoat layer and again by simplifying the SMR calculation using the effectiveness factor correlations. Finally, parametric studies were conducted to investigate the effects of operating conditions on the SMR performance.

• Korean Chemical Engineering Research
• /
• v.52 no.6
• /
• pp.727-735
• /
• 2014

For improved sustainability of the biorefinery industry, biorefinery-byproduct glycerol is being investigated as an alternate source for hydrogen production. This research designs and optimizes a hydrogen-production process for small hydrogen stations using steam reforming of purified glycerol as the main reaction, replacing existing processes relying on steam methane reforming. Modeling, simulation and optimization using a commercial process simulator are performed for the proposed hydrogen production process from glycerol. The mixture of glycerol and steam are used for making syngas in the reforming process. Then hydrogen are produced from carbon monoxide and steam through the water-gas shift reaction. Finally, hydrogen is separated from carbon dioxide using PSA. This study shows higher yield than former U.S. DOE and Linde studies. Economic evaluations are performed for optimal planning of constructing domestic hydrogen energy infrastructure based on the proposed glycerol-based hydrogen station.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.156.1-156.1
• /
• 2011

It is of great importance to predict operating parameter characteristics of an integrated fuel processor by the increased life-time and system performance. In this study, computational analysis is performed to gain fundamental insights on transport phenomena and chemical reactions in reformer which consists of preheating, steam reforming, and water gas shift reaction beds. Also, a top-fired burner locates inside of the reforming system. The combustor is providing thermal energy necessary for the steam reforming bed which is a endothermic catalytic reactor. Two-dimensional numerical model of the integrated fuel processing system is introduced for the analysis of heat and mass transport phenomena as well as surface kinetics and catalytic process. A kinetic model was developed and then computational results were compared with the experimental data available in the literature. Subsequently, parameter study using the validated steam methane reforming model was conducted by considering operating parameters, i.e. steam to carbon ratio and temperature.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.33 no.1
• /
• pp.60-68
• /
• 2009

The steam reformer for hydrogen production from methane is studied by a numerical method. Langmuir- Hinshelwood model is incorporated for catalytic surface reactions, and the pseudo-homogeneous model is used to take into account local equilibrium phenomena between a catalyst and bulk gas. Dominant chemical reactions are Steam Reforming (SR) reaction, Water-Gas Shift (WGS) reaction, and Direct Steam Reforming (DSR) reaction. The numerical results are validated with experimental results at the same operating conditions. Using the validated code, parametric study has been numerically performed in view of the steam reformer performance. As increasing a wall temperature, the fuel conversion increases due to the high heat transfer rate. When Steam to Carbon Ratio (SCR) increases, the concentration of carbon monoxide decreases since WGS reaction becomes more active. When increasing Gas Hourly Space Velocity (GHSV), the fuel conversion decreases due to the heat transfer limitation and the low residence time. The reactor shape effects are also investigated. The length and radius of cylindrical reactors are changed at the same catalyst volume. The longer steam reformer is, the better steam reformer performs. However, system energy efficiency decreases due to the large pressure drop.

• New & Renewable Energy
• /
• v.20 no.1
• /
• pp.126-134
• /
• 2024

Biogas, composed mainly of methane (CH₄) and carbon dioxide (CO₂), is a renewable gas that can serve as an alternative energy source. In this study, we developed a new microwave reformer and analyzed its reforming characteristics. We observed that higher temperatures of the microwave receptor led to increased reforming efficiency. By supplying appropriate amounts of methane and steam, we could prevent carbon generated from the thermal decomposition reaction of carbon dioxide from depositing on the catalytic active layer, thus avoiding the inhibition of catalytic activity. Hydrogen generation was enhanced when maintaining the biogas ratio and steam supply at adequate levels. Increasing the SiC ratio in the receptor improved the uniformity of temperature distribution and growth rate, resulting in higher conversion rates of the reforming process.

• 한국신재생에너지학회:학술대회논문집
• /
• 2008.05a
• /
• pp.186-189
• /
• 2008

Solar simulator를 이용한 메탄의 수증기 개질은 집광된 태양에너지를 이용하기 위한 목적으로 수행되었다. 본 연구에서는 이와 같은 태양열에너지의 화학적 축열을 실시하기 위해 Solar Simulator를 이용한 메탄의 수증기 개질을 연구하였다. 태양열 모사 램프로 1.2kW급 Xenon-arc lamp를 사용하였다. 반응기는 앞면의 Quartz Window와 촉매지지층으로 구성되어 있다. 램프의 빛은 Quartz Window를 통하여 촉매층에 직접적으로 방사되고, 방사된 빛으로 촉매지지층에서 흡열반응이 일어난다.메탄의 수증기개질 반응은 고온에서 일어나기 때문에 촉매지지체를 열에 강한 SiC로 만들어진 Ceramic foam을 사용하였다. 이 촉매지지체에 촉매를 Wash-coat하여 사용하였으며, 담지된 촉매는 Ni을 활성성분으로 하는 ICI 46-6을 사용하였다. 반응기는 318 SUS 재질로 제작되었으며, 반응기 외부는 Insulation을 하여 열손실을 감소시켰다. 실험은 온도와 공간속도에 따른 Solar Steam reforming의 반응특성을 분석하였다.

• Journal of the Korean Ceramic Society
• /
• v.53 no.5
• /
• pp.483-488
• /
• 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.