• Applied Chemistry for Engineering
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• v.20 no.2
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• pp.186-190
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• 2009

This study is purposed to analyze thermodynamic properties on the hydrogen production by dimethyl ether steam reforming. Various reaction conditions of temperatures (300~1500 K), feed compositions (steam/carbon = 1~7), and pressures (1, 5, 10 atm) were applied to investigate the effects of the reaction conditions on the thermodynamic properties of dimethyl ether steam reforming. An endothermic steam reforming competed with an exothermic water gas shift reaction and an exothermic methanation within the applied reaction condition. Hydrogen production was initiated at the temperature of 400 K and the production rate was promoted at temperatures exceeding 550 K. An increase of steam to carbon ratio (S/C) in feed mixture over 1.5 resulted in the increase of the water gas shift reaction, which lowered the formation of carbon monoxide. The maximum hydrogen yield with minimizing loss of thermodynamic conversion efficiency was achieved at the reaction conditions of a temperature of 900 K and a steam to carbon ratio of 3.0.

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

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.198-203
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• 2014

In this study, steam reforming reaction and surface characteristics of Ni metal foam plate were investigated. Valence state of Ni could be changed by pretreatment, and metallic Ni species exposed on surface as a active site play important role in steam reforming reaction. Porous catalytic membrane also was prepared by mixing of Ni metal foam plate and Ni-YSZ catalyst to control the pore size and assign the catalytic function in Ni metal foam plate. In SEM analysis results, Pore size of Ni metal foam plate could be controlled and Ni-YSZ catalyst well dispersed on surface. Ni based porous catalytic membrane had a similar steam reforming activity regardless of space velocity.

• 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.

• Journal of the Korean Society of Combustion
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• v.16 no.3
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• pp.1-11
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• 2011

The main objective of this paper is to investigate characteristic of steam reformer at various geometries and operating conditions. In this paper, the steam reforming is studied by a numerical method and three dimensional simulations were used for effective analytical study. User - Defined Function (UDF) was used to simultaneously calculate reforming and combustion reaction. And the numerical model is validated with experimental results at the same operating conditions. In order to understand the relationship between operating conditions such as gas hourly space velocity(GHSV), mass flow rate of combustor inlet, various numerical investigations are carries out for various geometries. Numerical results show that cylindrical geometry is more effective than rectangular geometry for heat transfer to reactors and reforming efficiency. As mass flow rate of combustor inlet increase, reaction occurs more faster and temperature increase with each geometry. On the other hand, reaction and hydrogen conversion decrease as mass flow rate of reactor decreases.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.64-68
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• 2005

Methane reforming processes to obtain hydrogen were investigated experimentally by using atmospheric plasma source. Among possible reforming processes, such as a $CO_2$ reforming(dry reforming), a partial oxidation (POx), a steam reforming(SR), and a steam reforming with oxygen(SRO or auto-thermal reforming), partial oxidation and the steam reforming with oxygen were considered. We choose a rotating arc plasma as an atmospheric plasma source, since it shows the best performances in our preliminary tests in terms of a methane conversion, a hydrogen production, and a power consumption. Then, the effects of a feeding flow-rate, an electrical power input to a plasma reaction, an $O_2/C$ ratio and a steam to carbon ratio in the case of SRO on the reforming characteristics were observed systematically. As results, at a certain condition almost 100% of methane conversion was obtained and we could achieve the same hydrogen production rate by consuming a half of electrical power which was used by the best results for other researchers.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.7
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• pp.497-503
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• 2008

Hydrogen is considered as a fuel of the future for its renewability and environmental compatibility. The reforming of hydrocarbon fuels is currently the most important source of hydrogen, which is expected to continue for next several decades. In this study, extensive CFD simulations on the steam-methane reforming process were conducted to study the performance of four reaction models, i.e. three Arrhenius-type models and a user-defined function (UDF) model. The accuracies of different reaction models for various operating temperatures and steam carbon ratios (SCRs) were evaluated by comparing their CFD results with zero-dimensional intrinsic model of Xu and Froment. It was found that the UDF model generally produced more accurate results than Arrhenius-type models. However, it was also shown that Arrhenius-type models could be made sufficiently accurate by choosing appropriate reaction coefficients, and thus could also be useful for the simulation of the steam-methane reforming process.

• Journal of the Korean Solar Energy Society
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• v.25 no.4
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• pp.13-19
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• 2005

The reaction of steam reforming of methane with commercial catalysts was conducted for thermochemical heat storage. The reaction conditions were investigated for temperature range of 700 to $900\;^{\circ}C$ and steam to carbon mole ratios between 3.0 and 5.0. The reactor was made of stainless steel and it's dimension was 12 cm inside diameter and 6cm long. The effects of space velocity and reactants mole ratio and temperature on the methane conversion and CO selectivity were examined. Optimum reaction condition was determined. There was not a significant difference of methane conversion and CO selectivity compared to conventional reactor.

• New & Renewable Energy
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• v.2 no.4 s.8
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• pp.56-63
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• 2006

In this paper, heat and mass transfer characteristics through experimental and numerical study are extensively investigated in steam reforming reactor under given operating conditions. In order to get simulated data at outlet of the reformer, heterogeneous reactor model is incorporated. As the reaction also takes place in porous media, two medium approach is used to take into account thermally non-equilibrium phenomena between catalyst and bulk gas. From various parametric studies, significance of heat transfer is emphasized in steam reforming reaction.

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