• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.231-234
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• 2005

수소 기반의 에너지 사회는 중소규모 분산 발전과 연료 전지 자동차에서 시작될 거라는 예측이 지배적이다. 가정용 고분자 연료전지 시스템은 상업화에 가장 가까운 소규모 분산 발전 시스템중의 하나이며, 에너지기술연구위원에서는 가정용 고분자 연료전지에 수소를 공급하기 위한 천연가스 수증기 개질시스템의 개발을 진행해 왔다. 효율 향상과 제작의 용이성, 그리고 소형화에 초점을 맞추어 개발된 prototype-I은 $2.0Nm^3/hr$의 순수 수소 생산 용량을 가지고 있으며, 수증기 개질기와 수성가스 전이 반응기 수중기 생성 장치, 그리고 반응열 공급에 필요한 버너 등을 이중 동심원관에 통합한 형태이다. 수중기 개질과 수성가스 전이 반응을 거쳐 나오는 개질 가스의 조성은 $72.3\%\;H_2,\;4.8\%\;CH_4,\;0.7\%\;CO,\;22.2\%\;CO_2$이며, 이때 S/C 비율은 2.5였다. 고분자 연료 전지 공급 시 요구되는 CO 농도가 10ppm 이하이기 때문에, 본 시스템에는 선택적 산화 반응기를 2단으로 설치하여 CO. 농도를 10ppm 이하로 낮추어주었다. 전체 시스템의 열효율은 LHV 기준으로 $68\%$. Prototype-I의 운전을 통해 설계 개선안을 도출하였으며, 이를 적용해 제작한 prototype-II가 시험 운전 중이다,. 통합된 개질 시스템에서는 각 단위 반응기사이의 열교환을 최적화하여 단위 반응들이 적정 온도 범위에서 일어나도록 유도하는 것이 중요하다. Prototype-II는 수증기 개질 반응기와 WGS 반응기, 수증기 생성 장치 사이의 열교환율을 향상시켜 농도를 $2.5\%$로 감소시키면서 CO의 농도는 $1\%$이하로 유지하였다. 이 결과를 바탕으로 얻어진 메탄 전환율은 $87\%$이고, 열효율은 LHV 기준으로 $75\%$이다. 아울러 개선점을 적용한 선택적 산화 반응기를 제작하였다. 개질 가스와 산소의 혼합을 유도하고, 반응기 온도의 제어를 통해 선택적 산화 반응의 속도와 선택성을 향상시키고자 한다. 시스템의 운전을 통해 메탄 전환율과 열효율의 개선을 진행할 예정이다.

• Clean Technology
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• v.10 no.4
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• pp.203-213
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• 2004

Natural gas thermal decomposition method is the technology of converting natural gas (methane) into hydrogen and carbon at high temperature. The most advantage of thermal decomposition method is that hydrogen and carbon can be produced without emitting carbon dioxide. In this study, the generation of hydrogen and carbon was investigated by this natural gas (methane) thermal decomposition method. We found that pyrocarbon was created on the surface of reactor, carbon black was deposited on the pyrocarbon and final plugging phenomenon took place. To solve this problem, we tried several attempts such as introduction of double pipe reactor instead of single pipe reactor or oxidization of carbon black using $O_2$ or $CO_2$ at regular intervals of reaction. Therefore, some plugging phenomenon was resolved by this methods. Also, carbon particle size was measured by SEM (Scanning Electron Microscope) image and the size was about 200 nm.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.3
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• pp.45-52
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• 2016

This study is to predict the biogas production and the content analysis of the organic wastes of three islands located in the City of I. Content analysis for a total of six sections, including pH, BOD, COD, three components (Moisture, Ash, Combustibles)was conducted on the specimens of organic wastes from the representative spots of three islands. From the analysis result of organic waste, it is confirmed that more than $1,750,000m^3$ of methane gas per year will be generated through the calculation of the total methane generation for the COD value. Therefore, if the incineration facility for the organic waste in island region is converted into a biogas production facilities which is non-incineration facility, it seems that the organic waste of efficient utilization is available.

• Applied Chemistry for Engineering
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• v.18 no.1
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• pp.94-97
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• 2007

Carbon nanotubes and nanowires were prepared by methane pyrolysis over Pd(5)/SPK catalyst by changing oxygen molar ratio in a fixed bed flow reactor under atmospheric condition and also analyzed by SEM and TEM. When the $CH_4/O_2$ molar ratio was 1, carbons were not almost deposited on the catalyst bed support, but when it was 2, carbons were deposited as much as plugging reactor. TEM and SEM images for the deposited carbons showed a number of single-walled carbon nanotubes and carbon nanowires. The growth mechanism of carbon nanotubes produced on the catalyst surface was the tip growth mode. It should be played an important role in carbon nanotubes and nanowires produced on the catalyst bed support to formate the carbon growth velocity vectors and nuclei of ring structure of carbon nanowires. SPK carrier was $N_2$ isotherm of IV type with mesopores, and excellent in the thermal stability.

• Journal of Korean Society on Water Environment
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• v.26 no.5
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• pp.810-815
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• 2010

Ultrasonic sludge pre-treatment has been studied to enhance the performance of anaerobic digestion by increasing sludge hydrolysis which is regarded as the rate-limiting-step of anaerobic digestion. In this study, the effect of ultrasonic pre-treatment on sludge hydrolysis (solubilization) and methane production was investigated. Sludge solubilization efficiency increased with ultrasonic energy input. However, it is uneconomical to apply more than 720 kJ/L as the solubilization efficiency per energy input declines afterwards. Volatile fatty acids concentration increased after the ultrasonic sludge hydrolysis. Anaerobic batch digestion showed that methane volume reached 64.7 and 84.5 mL after 18 days of incubation with the control sludge and ultrasonically hydrolyzed sludge, respectively. Methane production potential, maximum methane production rate, and the lag time of modified Gompertz equation were changed from 70 mL, 6.4 mL/day, and 1.2 days to 89 mL, 9.6 mL/day, and 0.5 day, respectively, after the ultrasonic sludge treatment. The results proved that ultrasonic pre-treatment contributed significantly not only for the methane production but also for the reduction of anaerobic digestion time which is critical for the performance of anaerobic sludge digestion.

• Journal of the Korean Society of Combustion
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• v.4 no.2
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• pp.63-74
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• 1999

The effects of EGR and premixedness on NO formation have been numerically investigated. The flame structure is classified into three categories; premixed flame($=1)$, rich/lean premixed flame(${\alpha}=0.6$ and 0.8) and diffusion flame(${\alpha}=0$). NO formation/destruction mechanisms are assorted to thermal, reburn and Fenimore mechanisms. The temperature of unburned gas is arranged to 298 and 500 K to have access to the condition in a real internal combustion engine. The results show that all three NO formation/destruction reaction rates in the fuel rich flame zone could be decreased by EGR for rich/lean premixed flames, while those in the fuel lean flame zone are not significantly changed. Near the stagnation plane, however, only the thermal NO reaction rate is decreased. The contribution of reburn and Fenimore mechanisms for the net NO production becomes less significant as the premixedness of a flame increases. The larger amount of NO reduction with EGR is expected under the higher temperature and/or higher fuel/air premixedness conditions due to the increased contribution of the thermal mechanism. The role of Fenimore and reburn mechanisms could be important for rich premixed and diffusion flames; therefore, the effect of EGR on NO reduction could vary with fuel/air premixedness. The premixedness of a partially premixed flame changes the flame structure and could affect the NO production characteristics.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.18-25
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• 2009

Nitrogen removal and methane production from piggery wastewater were investigated in two-phase anaerobic digestion (TPAD) coupled with biological nitrogen removal (BNR) process at $35^{\circ}C$. Methane production rate was about $0.7L/L{\cdot}day$ at organic loading rate (OLR) of $1.2g{\cdot}TCOD/L{\cdot}day$ in methanogenic UASB. Conversion efficiency of the removed TCOD into methane in UASB was as high as 72% and overall TCOD removal efficiency in this system was over 97%. Ammonia nitrogen were stably removed in BNR system and overall efficiency were 98%. With recirculation of the nitrified final effluent to TPAD, nitrogen oxides were completely removed by anaerobic denitrification in the acidogenic reactor, which did not inhibit the acidogenic activities. Overall TN removal efficiency in the TPAD-BNR system was as high as 94%.

• Explosives and Blasting
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• v.33 no.3
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• pp.1-13
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• 2015

Accidents related to gas explosion are frequently happened in foreign countries and in Korea. For the evaluation and the analysis of gas explosions, TNT equivalent methods are used. In this study, the influence of the selection of chemical equation in TNT explosion and the selection of enthalpy of the products on the explosion energy, detonation pressure, velocity of detonation, and temperature was calculated. Depending on the chemical equations, the maximum detonation pressure can be 2 times higher than the minimum. As an example for applying TNT equivalent method, an explosion of methane gas in a confined volume was assumed. With the TNT equivalent, it was possible to predict the variation of peak overpressure and impulse with the distance from the explosion location.

• Korean Journal of Organic Agriculture
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• v.27 no.4
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• pp.529-540
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• 2019

The present study investigated the effect of forage sources and their inclusion levels in diet on the rumen fermentation of Korea traditional goat. Timothy and alfalfa were used as forage sources. Forages were mixed with concentrate diet in different ratios. The ratios of forage to concentrate diets were varied to 1:9, 5:5 and 9:1. The rumen fluid of goat was gathered from slaughter house. Dry matter digestibility was decreased and methane production was increased as forage levels in diet was increased. When forage sources, timothy and alfalfa, were compared, groups with timothy showed greater methane production than the groups of alfalfa. Molar ratio of produced acetate and valerate were increased when forage level in diet was increased. In the case of propionate and butyrate, they were decreased as elevated forage levels in diet. The result of this study provided a basic information for rumen fermentation of Korean traditional goat and these information could be applied in the development of nutritional and feeding strategy.

• Journal of the Korean Solar Energy Society
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• v.29 no.4
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• pp.34-40
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• 2009

$1m^3$ hydrate of pure methane can be decomposed to the maximum of $216m^3$ methane at standard condition. If these characteristics of hydrate are reversely utilized, natural gas is fixed into water in the form of hydrate solid. Therefore, the hydrate is considered to be a great way to transport and store natural gas in large quantity. Especially the transportation cost is known to be 18-24% less than the liquefied transportation. In the present investigation, experiments and theoretical calculation carried out for the formation of methane hydrate in NaCl 3.5wt% solution. The results show that the equilibrium pressure in seawater is more higher than that in pure water, and methane hydrate could be formed rapidly during pressurization if the subcooling is maintained at 9K or above in seawater and 8K or above in pure water, respectively. Also, amount of consumed gas volume in pure water is more higher that in seawater at the same experimental conditions. Therefore, it is found that NaCl acts as a inhibitor.