• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.344-351
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• 2005

Hydrogen energy will be considered one of the most important energy carries for the future not only as raw material of petroleum chemical industry but also as the fuel of the fuel cell. The hydrogen production based upon the water electrolysis system combined renewable energy or atomic power energy is being watched as long-term hydrogen sources. Hydrogen from fossil fuel, especially natural gas steam reforming, is the economical mass production method at this time. But the cost of $CO_2$ reduction is added in the economic analysis of hydrogen production processes. Therefore many different results are suggested from these analyses about old processes, and modified schemes are studying for the efficient development. In this review, status for the technology of hydrogen production from natural gas are summarized.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.159.1-159.1
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• 2011

Partial oxidation reformer was fabricated and operated using commercial transportation fuels. Fuel injector and heating coil were used for fuel atomization and startup, respectively. The reformer was designed to produce syngas for $150{\sim}200W_e$ class solid oxide fuel cell. The reformer was operated in the $O_2$/C range between 0.6 and 0.8 while the capacity was fixed at $150W_e$. The temperature range in catalyst bed was between $500^{\circ}C$ and $900^{\circ}C$. Only 83% fuel was converted to $H_2$, CO, $CO_2$ and $CH_4$ at the operating conditions. The lowest temperature increase to $700^{\circ}C$ when the reformer was operated at $200W_e$, Although the temperature profiles was improved, fuel conversion was 88%. On the other hand, fuel was completely converted when micro-reactor operated at the same condition. This difference maybe due to aromatic compounds formation at homogeneous region. In addition, a significant amount of coke deposition was observed at vent line. Homogeneous reaction depends on the degree of mixing. For this purpose, two fluid nozzle and Ultra sonic injector were compared to investigate the effect of atomization. Sauter mean diameter(SMD) of Ultra sonic injector was lower than two-fluid nozzle at test condition. However, conversion efficiency and fuel conversion were not improved by using two-fluid nozzle. these results imply that the temperature of homogeneous reaction region should be controlled to prevent coke formation.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.4
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• pp.528-535
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• 2017

Fuel cells have been spotlighted in the world for being highly efficient and environmentally friendly. A hydrogen which is the fuel of fuel cell can be obtained from a number of sources. Hydrogen source for operating the polymer electrolyte membrane fuel cell(PEMFC) in the current underwater environment, such as a submarine and unmanned underwater vehicles are currently from the metal hydride cylinder. However, metal hydride has many limitations for using hydrogen carrier, such as large volume, long charging time, limited storage capacity. To solve these problems, we suggest diesel reformer for hydrogen supply source. Diesel fuel has many advantages, such as high hydrogen storage density, easy to transport and also well-infra structure. However, conventional diesel reforming system for PEMFC requires a large volume and complex CO removal system for lowering the CO level to less than 10 ppm. In addition, because the preferential oxidation(PROX) reaction is the strong exothermic reaction, cooling load is required. By changing this PROX reactor to hydrogen separation membrane, the problem from PROX reactor can be solved. This is because hydrogen separation membranes are small and permeable to pure hydrogen. In this study, we conducted the pressurized diesel reforming and water-gas shift reaction experiment for the hydrogen separation membrane application. Then, the hydrogen permeation experiments were performed using a Pd alloy membrane for the reformate gas.

• Journal of Hydrogen and New Energy
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• v.30 no.3
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• pp.201-208
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• 2019

Recently, a fuel reforming plant for supplying high purity hydrogen is being applied to submarines. Since steam reforming is an endothermic reaction, it is necessary to continuously supply heat to the reactor. A fuel reforming plant for a submarine needs a multi-stage burner (MSB) to acquire heat and convert the combustion gas to $CO_2+H_2O$. The MSB has problems that the combustion imbalance occurs during start-up due to the temperature restriction of the combustion gas. This problems can be solved by burning $H_2O$ together with fuel and $O_2$. In this study, the simulation results of MSB were analyzed to determine the optimum flow rate of $H_2O$ supplied to the 6-stage burner. When the flow rate of $H_2O$ was low, combustion was concentrated on the burner#6 in comparison with the burner#1-#5. This combustion concentration improved as the supply amount of $H_2O$ increased. As a results, it was necessary to supply at least 4.9 kmol/h of $H_2O$ (per 1 kmol/h of fuel) to burner#1 in order to maintain the combustion gas temperature of each stage at $750^{\circ}C$ and to convert the final stage burner gas composition to $CO_2+H_2O$.

• Journal of Hydrogen and New Energy
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• v.28 no.4
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• pp.377-383
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• 2017

This paper presents the performance characteristics of a 1 kW solid oxide fuel cell (SOFC) stack under various internal reforming and fuel utilization conditions. The Research Institute of Industrial Science & Technology (RIST) developed the 9-cell stack using a $20{\times}20cm^2$ anode supported planar cell with an active area of $324cm^2$. In this work, current-voltage characteristic test, fuel utilization test, continuous operation, and internal reforming test were carried out sequentially for 765 hours at a furnace temperature of $700^{\circ}C$. The influence of fuel utilization and internal reforming on the stack performance was analyzed. When the 1 kW stack was tested at a current of 145.8 A with a corresponding fuel utilization of 50-70% (internal reforming of 50%) and air utilization of 27%, the stack power was approximately 1.062-1.079 kW. Under continuous operation conditions, performance degradation rate was 2.16%/kh for 664 hours. The internal reforming characteristics of the stack were measured at a current of 145.8. A with a corresponding fuel utilization of 60-75%(internal reforming of 50-80%) and air utilization of 27%. As fuel utilization and internal reforming ratio increased, the stack power was decreased. The stack power change due to the internal reforming ratio difference was decreased with increasing fuel utilization.

• The Korean Journal of Petroleum Geology
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• v.14 no.1
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• pp.45-52
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• 2008

The GTL(Gas to Liquids) technology, manufacturing synthesized oil from natural gas, had been developed about 1920 for the military purpose by Fischer and Tropsch, German scientists. And 1960, Sasol company had started commercializing the FT(Fischer-Tropsch) synthesis technology, for the transport fuel in South Africa. Until a recent date, the commercialization of GTL technology had been delayed by low oil price. But concern about depletion of petroleum resources, and development in synthesizing technology lead to spotlight on the GTL businesses. Especially, Qatar, which has rich natural gas fields, aims at utilizing natural gas like conventional oil resources. Therefore, around this nation, GTL plants construction has been promoted. There are mainly 3 processes to make GTL products(Diesel, Naphtha, lube oil, etc) from natural gas. The first is synthesis gas generation unit reforming hydrogen and carbomonoxide from natural gas. The second is FT synthesis unit converting synthesized gas to polymeric chain-hydrocarbon. The third is product upgrading unit making oil products from the FT synthesized oil. There are quite a little sulfur, nitrogen, and aromatic compounds in GTL products. GTL product has environmental premium in discharging less harmful particles than refinery oil products from crude to the human body. In short, the GTL is a clean technology, easier transportation mean, and has higher stability comparing to LNG works.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.4
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• pp.391-397
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• 2011

The use of Hydrogen as a fuel is receiving considerable attention and as a result, research on novel methods of hydrogen production is necessary so that the hydrogen demands in the future can be satisfied. This study presents experimental data on methanol Autothermal Reformation that quantifies the relationship between the oxygen-to-methanol ratio ($O_2/CH_3OH$) and reformer efficiency. For each catalyst configuration, the $O_2/CH_3OH$ was varied from 0.1 to 0.4, with an increment of 0.05, to investigate the effects of $O_2/CH_3OH$ on the reactor performance, including temperature profile, conversion, and efficiency. $O_2/CH_3OH$ was increased from 0.15 to 0.20, and the catalyst bed temperature increased by $235^{\circ}C$ to approximately $550^{\circ}C$. The catalyst bed temperature increased with increasing $O_2/CH_3OH$ as the reaction shifted from endothermic to exothermic reaction and as a result, excess heat, which raised the reactor temperature, was generated. The reactor performance was shown to be highly dependent on $O_2/CH_3OH$. The optimum $O_2/CH_3OH$ = 0.30 found in the experimental tests is 30% higher than the theoretical optimum of 0.23. This is attributed to a combination of factors such as the concentrations of the $O_2$ and $CH_3OH$ gas, reaction rate, catalyst effects, heat loss from the reactor, and the difference between the actual amounts of reaction products formed and the theoretical amounts of the reaction products.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.205-212
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• 2004

In this paper the design of a 1-[KVA] fuel cell powered line-interactive UPS system employing modular (fuel cell & DC/DC converter) blocks is proposed. The proposed system employs the two fuel cell modules along with suitable DC/DC converters and these modules share the DC-Link of the DC/AC inverter. A supercapacitor module is also employed to compensate for the instantaneous power fluctuations and to overcome the slow dynamics of the fuel processor. The energy stored in the supercapacitor can also be utilized to handle the overload conditions for a short time period. Due to the absence of batteries, the system satisfies the demand for an environmentally friendly and dean source of the energy. A complete design example illustrating the amount of hydrogen storage required for 1hr power outage, and sizing of supercacpacitor for transient load demand is presented for a 1-[KVA] UPS.

• Journal of Hydrogen and New Energy
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• v.22 no.3
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• pp.357-362
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• 2011

Complete mixture preparation of reactants prior to catalytic reforming is an enormously important step for successful operation of a fuel reformer. Incomplete mixing between fuel and reforming agents such as air and steam can cause temperature overshoot and deposit formation which can lead the failure of operation. For that purpose it is required to apply computational models describing coupled kinetics and transport phenomena in the mixing region, which are computationally expensive. Therefore, it is advantageous to analyze the gas-phase reaction kinetics prior to application of the coupled model. This study suggests one of the important design constraints, the required residence time in the mixing chamber to avoid substantial gas-phase reactions which can lead serious deposit formation on the downstream catalyst. The reactivity of various gaseous and liquid fuels were compared, then liquid fuels are far more reactive than gaseous fuels. n-Octane was used as a surrogate among the various hydrocarbons, which is one of the traditional liquid fuel surrogates. The conversion was slighted effected by reactants composition described by O/C and S/C. Finally, threshold residence times in the mixing region of a hydrocarbon reformer were studied and the mixing chamber is required to be designed to make complete mixture of reactants by tens of milliseconds at the temperature lower than $400^{\circ}C$.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.77.2-77.2
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• 2010

일산화탄소를 수소로 변환하는 수성가스전환반응(WGSR)은 수소 생산, 연료개질 시스템뿐만 아니라 암모니아 제조, 제철소 제련과정등 일선 산업현장에서 널리 활용되고 있다. 상용공정에서의 WGS반응은 두 단계의 반응기(HTS/LTS)에서 각각 Fe/Cr, Cu/Zn기반 촉매를 사용하여 이루어진다. 하지만 이러한 촉매들은 공기중 자연발화성이 있고 사용전 환원과정이 필요하다. 또한 최근에 많은 연구가 진행되고 있는 귀금속 담지 촉매는 기존 촉매의 단점을 극복하고 활성이 높은 장점이 있다. 이에 본 연구에서 제시한 페로브스카이트 촉매는 상용 촉매, 귀금속 담지촉매 시스템과의 비교를 위하여 제작된 촉매를 사용한 반응시스템과 기존 상용촉매를 사용한 반응시스템을 비교하여 개발 촉매의 성능 수준을 검토하였다. 이러한 결과 페로브스카이트 구조 촉매는 상용촉매의 공정상의 단점과 귀금속 담지촉매의 가격적인 측면에서의 단점을 동시에 극복한 촉매로서 성능 및 메탄화반응 억제 측면에서 우수성을 보유하고 있다는 것을 증명하였다. 이러한 페로브스카이트 구조 촉매의 반응특성을 규명하기 위해 문헌조사해본 결과 기존 수성가스전환반응에서 쓰이는 촉매들의 반응매카니즘은 대표적으로 formate와 redox 반응 두가지가 있었다. 페로스브스카이트 구조 촉매는 그 구조와 귀금속 함량, 활성 등 성능측면에서 귀금속 촉매와 상당히 유사한 측면이 있기 때문에 귀금속 담지 촉매의 반응속도식을 기본으로 하여 실험결과와 일치시켜 페로브스카이트구조 촉매에 맞는 반응속도식을 제시하고 이를 통한 반응파라미터 값을 도출하였다.