• Title/Summary/Keyword: Gas methane

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Effects of Temperature, Pressure, and Gas Residence Time on Methane Combustion Characteristics of Oxygen Carrier Particle in a Pressurized Fluidized Bed Reactor (가압 유동층 반응기에서 산소공여입자의 메탄 연소 특성에 미치는 온도, 압력 및 기체체류시간의 영향)

  • Ryu, Ho-Jung;Park, Sang-Soo;Moon, Jong-Ho;Choi, Won-Kil;Rhee, Young-Woo
    • Transactions of the Korean hydrogen and new energy society
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    • v.23 no.2
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    • pp.173-182
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    • 2012
  • Effects of temperature, pressure, and gas residence time on methane combustion characteristics of mass produced oxygen carrier particle (OCN706-1100) were investigated in a pressurized fluidized bed reactor using methane and air as reactants for reduction and oxidation, respectively. The oxygen carrier showed high fuel conversion, high $CO_2$ selectivity, and low CO concentration at reduction condition and very low NO emission at oxidation condition. Moreover OCN706-1100 particle showed good regeneration ability during successive reduction-oxidation cyclic tests up to the 10th cycle. Fuel conversion and $CO_2$ selectivity decreased and CO emission increased as temperature increased. These results can be explained by trend of calculated equilibrium CO concentration. However, $CO_2$ selectivity increased as pressure increased and fuel conversion increased as gas residence time increased.

Hydrogen Gas Production from Methane Reforming Using Oxygen Enriched Compression Ignition Engine (산소부화 압축착화기관을 이용한 메탄으로부터 수소 생산)

  • Lim, Mun-Sup;Hong, Sung-In;Hong, Myung-Seok;Chun, Young-Nam
    • Journal of Korean Society for Atmospheric Environment
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    • v.23 no.5
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    • pp.557-562
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    • 2007
  • The purpose of this paper is to investigate the reforming characteristics and maximum operating condition for the hydrogen production by methane reforming using the compression ignition engine induced partial oxidation. An dedicated compression engine used for methane reforming was decided operating range. The partial oxidation reforming was investigated with oxygen enrichment which can improve hydrogen production, compared to general reforming. Parametric screening studies were achieved as $O_2/CH_4$ ratio, total flow rate, and intake temperature. When the variations of $O_2/CH_4$ ratio, total flow rate, and intake temperature were 1.24, 208.4 L/min, and $400^{\circ}C$, respectively, the maximum operating conditions were produced hydrogen and carbon monoxide. Under the condition mentioned above, synthetic gas were $H_2\;22.77{\sim}29.22%,\;CO\;21.11{\sim}23.59%$.

Techno-economic Analysis of Power to Gas (P2G) Process for the Development of Optimum Business Model: Part 1 Methane Production

  • Roy, Partho Sarothi;Yoo, Young Don;Kim, Suhyun;Park, Chan Seung
    • Clean Technology
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    • v.28 no.2
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    • pp.182-192
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    • 2022
  • This study provides an overview of the production costs of methane and hydrogen via water electrolysis-based hydrogen production followed by a methanation based methane production technology utilizing CO2 from external sources. The study shows a comparative way for economic optimization of green methane generation using excess free electricity from renewable sources. The study initially developed the overall process on the Aspen Plus simulation tool. Aspen Plus estimated the capital expenditure for most of the equipment except for the methanation reactor and electrolyzer. The capital expenditure, the operating expenditure and the feed cost were used in a discounted cash flow based economic model for the methane production cost estimation. The study compared different reactor configurations as well. The same model was also used for a hydrogen production cost estimation. The optimized economic model estimated a methane production cost of $11.22/mcf when the plant is operating for 4000 hr/year and electricity is available for zero cost. Furthermore, a hydrogen production cost of $2.45/GJ was obtained. A sensitivity analysis was performed for the methane production cost as the electrolyzer cost varies across different electrolyzer types. A sensitivity study was also performed for the changing electricity cost, the number of operation hours per year and the plant capacity. The estimated levelized cost of methane (LCOM) in this study was less than or comparable with the existing studies available in the literature.

Advanced estimation and mitigation strategies: a cumulative approach to enteric methane abatement from ruminants

  • Islam, Mahfuzul;Lee, Sang-Suk
    • Journal of Animal Science and Technology
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    • v.61 no.3
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    • pp.122-137
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    • 2019
  • Methane, one of the important greenhouse gas, has a higher global warming potential than that of carbon dioxide. Agriculture, especially livestock, is considered as the biggest sector in producing anthropogenic methane. Among livestock, ruminants are the highest emitters of enteric methane. Methanogenesis, a continuous process in the rumen, carried out by archaea either with a hydrogenotrophic pathway that converts hydrogen and carbon dioxide to methane or with methylotrophic pathway, which the substrate for methanogenesis is methyl groups. For accurate estimation of methane from ruminants, three methods have been successfully used in various experiments under different environmental conditions such as respiration chamber, sulfur hexafluoride tracer technique, and the automated head-chamber or GreenFeed system. Methane production and emission from ruminants are increasing day by day with an increase of ruminants which help to meet up the nutrient demands of the increasing human population throughout the world. Several mitigation strategies have been taken separately for methane abatement from ruminant productions such as animal intervention, diet selection, dietary feed additives, probiotics, defaunation, supplementation of fats, oils, organic acids, plant secondary metabolites, etc. However, sustainable mitigation strategies are not established yet. A cumulative approach of accurate enteric methane measurement and existing mitigation strategies with more focusing on the biological reduction of methane emission by direct-fed microbials could be the sustainable methane mitigation approaches.

Meta-analysis on Methane Mitigating Properties of Saponin-rich Sources in the Rumen: Influence of Addition Levels and Plant Sources

  • Jayanegara, Anuraga;Wina, Elizabeth;Takahashi, Junichi
    • Asian-Australasian Journal of Animal Sciences
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    • v.27 no.10
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    • pp.1426-1435
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    • 2014
  • Saponins have been considered as promising natural substances for mitigating methane emissions from ruminants. However, studies reported that addition of saponin-rich sources often arrived at contrasting results, i.e. either it decreased methane or it did not. The aim of the present study was to assess ruminal methane emissions through a meta-analytical approach of integrating related studies from published papers which described various levels of different saponin-rich sources being added to ruminant feed. A database was constructed from published literature reporting the addition of saponin-rich sources at various levels and then monitoring ruminal methane emissions in vitro. Accordingly, levels of saponin-rich source additions as well as different saponin sources were specified in the database. Apart from methane, other related rumen fermentation parameters were also included in the database, i.e. organic matter digestibility, gas production, pH, ammonia concentration, short-chain fatty acid profiles and protozoal count. A total of 23 studies comprised of 89 data points met the inclusion criteria. The data obtained were subsequently subjected to a statistical meta-analysis based on mixed model methodology. Accordingly, different studies were treated as random effects whereas levels of saponin-rich source additions or different saponin sources were considered as fixed effects. Model statistics used were p-value and root mean square error. Results showed that an addition of increasing levels of a saponin-rich source decreased methane emission per unit of substrate incubated as well as per unit of total gas produced (p<0.05). There was a decrease in acetate proportion (linear pattern; p<0.001) and an increase in propionate proportion (linear pattern; p<0.001) with increasing levels of saponin. Log protozoal count decreased (p<0.05) at higher saponin levels. Comparing between different saponin-rich sources, all saponin sources, i.e. quillaja, tea and yucca saponins produced less methane per unit of total gas than that of control (p<0.05). Although numerically the order of effectiveness of saponin-rich sources in mitigating methane was yucca>tea>quillaja, statistically they did not differ each other. It can be concluded that methane mitigating properties of saponins in the rumen are level- and source-dependent.

Effect of Tannin and Species Variation on In vitro Digestibility, Gas, and Methane Production of Tropical Browse Plants

  • Gemeda, Belete Shenkute;Hassen, A.
    • Asian-Australasian Journal of Animal Sciences
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    • v.28 no.2
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    • pp.188-199
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    • 2015
  • Nineteen tanniferous browse plants were collected from South Africa to investigate their digestibility, gas production (GP) characteristics and methane production. Fresh samples were collected, dried in forced oven, and ground and analyzed for nutrient composition. In vitro GP and in vitro organic matter digestibility (IVOMD) were determined using rumen fluid collected, strained and anaerobically prepared. A semi-automated system was used to measure GP by incubating the sample in a shaking incubator at $39^{\circ}C$. There was significant (p<0.05) variation in chemical composition of studied browses. Crude protein (CP) content of the species ranged from 86.9 to 305.0 g/kg dry matter (DM). The neutral detergent fiber (NDF) ranged from 292.8 to 517.5 g/kg DM while acid detergent fiber (ADF) ranged from 273.3 to 495.1 g/kg DM. The ash, ether extract, non-fibrous carbohydrate, neutral detergent insoluble nitrogen, and acid detergent insoluble nitrogen and CP were negatively correlated with methane production. Methane production was positively correlated with NDF, ADF, cellulose and hemi-cellulose. Tannin decreased GP, IVOMD, total volatile fatty acid and methane production. The observed low methanogenic potential and substantial ammonia generation of some of the browses might be potentially useful as rumen manipulating agents. However, a systematic evaluation is needed to determine optimum levels of supplementation in a mixed diet in order to attain a maximal depressing effect on enteric $CH_4$ production with a minimal detrimental effect on rumen fermentation of poor quality roughage based diet.

Development of a Biogas Engine for Cogeneration System (바이오스가스를 이용한 열병합 발전용 엔진 개발)

  • Kim, Yeong-Min;Lee, Jang-Hui;Ju, Seong-Ho
    • 연구논문집
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    • s.30
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    • pp.33-42
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    • 2000
  • We must stabilize quickly increasing waste matters in urban life and livestock industry. Biogas including landfill gas and digester gas is byproduct of anaerobic decomposition of organic waste matter and contains 40%-70% methane, which can be used for energy purposes. Utilization of biogas reduce the emission of methane into the atmosphere to minimize greenhouse effect and the carbon dioxide (CO2) emitted when biogas is converted to energy has been taken out of the atmosphere by growing plant. Recently, bioenergy is world-widely noticeable as all contributing to the greenhouse effect. This paper presents development process of a biogas engine for cogeneration system and results of application to digester gas and landfill gas in site. The biogas engine is a dual fuel engine operated on biogas with a diesel pilot. At present, the engine can substitute biogas for diesel fuel up to 85%. but it can be said that there is a possibility of improvement in performance.

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Characteristics of methane sorption in surface modified activated carbon (표면개질 된 활성탄의 메탄흡장 특성)

  • Yun, Seok-Min;Kim, Ju-Wan;Jo, Won-Jun;Kim, Young-Ho;Lee, Young-Seak
    • 한국신재생에너지학회:학술대회논문집
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    • 2007.06a
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    • pp.73-76
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    • 2007
  • In this study, methane gas adsorption ability of activated carbon (AC) with surface functional group effect, adsorbed methane amount was evaluated after nitric acid and ureatreatment of AC surface. Specific surface area and pore distribution of AC were studied though nitrogen adsorption isotherm at 77 K. Micro pore volume was calculated through H-K method. Adsorbed methane amount was evaluated through volume method at room temperature by using auto adsorption apparatus. Adsorbed methane amount of AC was found to increase with to specific surface area increase.Correlation proposed between the methane adsorption amount and surface nature indicates that the surface nature plays an important role on the adsorption amount at a given temperature.

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Study on Characteristics of the Anaerobic Filter by Nitrate Adding Points (질산화수 주입 방법에 따른 혐기성필터 거동 고찰)

  • Lim, Seung-Joo;Lee, Yoon-Jin
    • Journal of Environmental Health Sciences
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    • v.33 no.1 s.94
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    • pp.57-62
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    • 2007
  • Characteristics of the upflow anaerobic filter process have been studied with six other conditions. When nitrate was mixed with influent in the bottom of the reactor, removal efficiencies of TBOD and TCOD were lower than those of TBOD and TCOD when nitrate was injected to the side of the reactor. In addition, when nitrate was injected to the side of the reactor the concentration of volatile acids of effluent was not high and ORP of effluent was lower than the mixture when nitrate was mingled with influent. It means that the bottom of the anaerobic filter played an important role in making volatile acids, methane production, and denitrification. Moreover, percentage of methane in the gas increased in accordance with increasing nitrate injection. It was because there were a lot of methane producing microorganisms which would rather use hydrogen than acetate. This reactor condition gets unstable due to provide nitrate. Therefore, higher hydrogen Pressure, shorter generation time, and lower standard Gibb's free energy gave great portion of methane of gas.

Performance of Solid Oxide Fuel Cells with Direct Internal Reforming of Methane

  • Kim, Young Jin;Lim, Hyung-Tae
    • Journal of the Korean Ceramic Society
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    • v.52 no.5
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    • pp.325-330
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    • 2015
  • Performance of solid oxide fuel cells (SOFCs), in comparison with that under hydrogen fuel, were investigated under direct internal reforming conditions. Anode supported cells were fabricated with an Ni+YSZ anode, YSZ electrolyte, and LSM+YSZ cathode for the present work. Measurements of I-V curves and impedance were conducted with S/C (steam to carbon) ratio of ~ 2 at $800^{\circ}C$. The outlet gas was analyzed using gas chromatography under open circuit condition; the methane conversion rate was calculated and found to be ~ 90% in the case of low flow rate of methane and steam. Power density values were comparable for both cases (hydrogen fuel and internal steam reforming of methane), and in the latter case the cell performance was improved, with a decrease in the flow rate of methane with steam, because of the higher conversion rate. The present work indicates that the short-term performance of SOFCs with conventional Ni+YSZ anodes, in comparison with that under hydrogen fuel, is acceptable under internal reforming condition with the optimized fuel flow rate and S/C ratio.