• Title, Summary, Keyword: Methane ($CH_4$)

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$CH_4$ Gas Sensor Utilizing Pd-SiC Schottky Diode (Pd-SiC 쇼트키 다이오드를 이용한 $CH_4$ 가스센서)

  • 김창교;이주헌;이영환
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.163-166
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    • 1998
  • The mechanism of methane sensing by Pd-SiC diode was investigated over the temperature range of 400~$600^{\circ}C$. The effects or methane gas reaction on the parameters such as barrier height, initial rate of methane gas reaction are investigated. The methane gas reaction kinetics on the device are also discussed. The physical and chemical mechanism responsible for methane detection are proposed. Analysis of steady-state reaction kinetics using I-V method confirmed that methane gas reaction processes are responsible for the barrier height change in the diode.

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Characteristics of Methane Production from Piggery Manure Using Anaerobic Digestion (혐기성 소화를 통한 돈분의 메탄 생성 특성)

  • Lee, Chae-Young
    • Journal of the Korea Organic Resources Recycling Association
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    • v.15 no.3
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    • pp.113-120
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    • 2007
  • Anaerobic batch tests were performed to evaluate the characteristics of methane production from piggery manure such as the ultimate methane yield (UMY), the kinetic constant and the maximum methane production rate. The kinetic behavior of anaerobic degradation of piggery manure was assumed as a first order reaction. The UMY, the first order kinetic constant and the maximum methane production rate were 0.27~0.44L $CH_4/gVS$, $0.161{\sim}0.280d^{-1}$ and 0.043~0.120L $CH_4/d$, respectively. Reactor of piggery manure as the self-seed source of anaerobic digestion resulted in longer acclimation time than reactors seeded with anaerobic digested sludge (ADS). But there was no little difference in the UMY between the two seed materials. The anaerobic digestion can be effective for the treatment of piggery manure containing high concentration of solids, the two-stage anaerobic digestion is, however, thought to be more effective than the traditional single one.

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Measurement of Methane Production from Ruminants

  • Bhatta, Raghavendra;Enishi, Osamu;Kurihara, Mitsunori
    • Asian-Australasian Journal of Animal Sciences
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    • v.20 no.8
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    • pp.1305-1318
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    • 2007
  • On a global scale agriculture and in particular enteric fermentation in ruminants is reported to produce about one fourth (21 to 25%) of the total anthropogenic emissions of methane ($CH_4$). Methane is produced during the anaerobic fermentation of hydrolyzed dietary carbohydrates in the rumen and represents an energy loss to the host besides contributing to emissions of greenhouse gases into the environment. However, there appears to be uncertainty in the $CH_4$ estimation from livestock due to the limited availability of data to document the variability at the farm level and also due to the significant impact of diet on the enteric $CH_4$ production. The methane mitigation strategies require robust prediction of emissions from rumen. There are many methods available which would be suitable for measuring $CH_4$ produced from the various stages of animal production. However, several factors need to be considered in order to select the most appropriate technique like the cost, level of accuracy required and the scale and design of the experiments to be undertaken. Selection of any technique depends on the accuracy as each one has its advantages and disadvantages. Screening of mitigation strategies may be evaluated using individual animal before large-scale trials on groups of animals are carried out. In this review various methods for the estimation of methane production from ruminants as well as for the determination of methane production potential of ruminant feeds are discussed. The advantages and disadvantages of the methods starting from respiration chamber, ventilated hood, facemask, sulphur hexafluoride ($SF_6$) tracer technique, prediction equations and meteorological methods to in vitro methods are detailed.

CO Emission Characteristics in the Interacting Counterflow Methane and Hydrogen Partially Premixed Flames (상호작용하는 대향류 메탄-수소 부분예혼합화염의 CO 배출특성)

  • Park, Ji-Woong;Oh, Chang Bo;Kim, Tae-Hyung;Park, Jongho
    • Journal of the Korean Society of Combustion
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    • v.17 no.3
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    • pp.1-8
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    • 2012
  • The CO emission characteristics of interacting hydrogen and methane partially premixed flames were numerically investigated. A counterflow geometry was introduced to establish interacting two partially premixed flames. An one-dimensional OPPDIF code was used to simulate the interacting flames. The GRI-v3.0 was used to calculate the chemical reactions. Emission index for CO(EICO) was evaluated to quantify the CO emitted from the interacting flames. The global strain rate and equivalence ratios for each flame(${\Phi}_{CH_4}$ and ${\Phi}_{H_2}$) were used as parameters to control the extent of interaction between two partially premixed flames. When ${\Phi}_{CH_4}$ was kept to stoichiometric condition and ${\Phi}_{H_2}$ was at rich condition, unburned H2 species of hydrogen flame was transported to the methane flame and affected reactions related with CO formation. When ${\Phi}_{CH_4}$ increased from a stoichiometry to rich condition while ${\Phi}_{H_2}$ was kept to stoichiometric condition, EICO increased initially, had a peak value at ${\Phi}_{CH_4}=1.5$ and decreased gradually. This could be elucidated with an analysis for the elementary reactions related with CO formation.

Assessment of CH4 oxidation in macroinvertebrate burrows of tidal flats (갯벌의 무척추 동물 서식굴 내 메탄산화 평가)

  • Kang, J.;Kwon, K.;Woo, H.J.;Choi, J.U.
    • Journal of Wetlands Research
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    • v.21 no.2
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    • pp.95-101
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    • 2019
  • In tidal flats that lack plants, methane ($CH_4$) fluxes are both positive (gas emission) and negative (gas "sinking") in nature. The levels of methanotroph populations significantly affect the extent of $CH_4$ sinking. This preliminary study examined $CH_4$ flux in tidal flats using a circular closed-chamber method to understand the effects of macroinvertebrate burrowing activity. The chamber was deployed over decapods (mud shrimp, Laomedia astacina and crab, Macrophthalmus japonicus) burrows for ~ 2 h, and the $CH_4$ and $CO_2$ concentrations were continuously monitored using a closed, diffuse $CH_4/CO_2$ flux meter. We found that Laomedia astacina burrow (which is relatively long) site afforded higher-level $CH_4$ production, likely due to diffusive emission of $CH_4$ in deep-layer sediments. In addition, the large methanotrophic bacteria population found in the burrow wall sediments has $CH_4$ oxidation (consumption) potential. Especially, nitrite-driven anaerobic oxidation of methane (AOM) may occur within burrows. The proposed $CH_4$-oxidation process was supported by the decrease in the ${\delta}^{13}C$ of headspace $CO_2$ during the chamber experiment. Therefore, macroinvertebrate burrows appear to be an important ecosystem environment for controlling atmospheric $CH_4$ over tidal flats.

Applying methane and carbon flow balances for determination of first-order landfill gas model parameters

  • Park, Jin-Kyu;Chong, Yong-Gil;Tameda, Kazuo;Lee, Nam-Hoon
    • Environmental Engineering Research
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    • v.25 no.3
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    • pp.374-383
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    • 2020
  • Landfill gas (LFG) emissions from a given amount of landfill waste depend on the carbon flows in the waste. The objective of this study was to more accurately estimate the first-order decay parameters through methane (CH4) and carbon flow balances based on the analysis of a full-scale landfill with long-term data and detailed field records on LFG and leachate. The carbon storage factor for the case-study landfill was 0.055 g-degradable organic carbon (DOC) stored per g-wet waste and the amounts of DOC lost with the leachate were less than 1.3%. The appropriate CH4 generation rate constant (k) for bulk waste was 0.24 y-1. The the CH4 generation potential (L0) values ranged 33.7-46.7 m3-CH4 Mg-1, based on the fraction of DOC that can decompose (DOCf) value of 0.40. Results show that CH4 and carbon flow balance methods can be used to estimate model parameters appropriately and to predict long-term carbon emissions from landfills.

Autothermal Reforming Reaction of Methane using Ni-Ru/$Al_2O_3$-MgO Metallic Monolith Catalysts (Ni-Ru/$Al_2O_3$-MgO 금속 모노리스 촉매체를 이용한 메탄의 자열 개질반응)

  • Lee, Chang-Ho;Lee, Tae-Jun;Shin, Jang-Sik;Lee, Jong-Dae
    • Journal of the Korean Applied Science and Technology
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    • v.28 no.3
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    • pp.321-328
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    • 2011
  • The autothermal reforming reaction of methane was investigated to produce hyd rogen with Ni/$CeO_2-ZrO_2$, Ni/$Al_2O_3$-MgO and Ni-Ru/$Al_2O_3$-MgO catalysts. Honeycomb metalli c monolith was applied in order to obtain high catalytic activity and stability in autothermal r eforming. The catalysts were characterized by XRD, BET and SEM. The influence of various catalysts on hydrogen production was studied for the feed ratio($O_2/CH_4$, $H_2O/CH_4$). The $O_2/CH_4$ and $H_2O/CH_4$ ratio governed the methane conversion and temperature profile of reactor. Th e reactor temperature increased as the reaction shifted from endothermic to exothermic reactio n with increasing $O_2/CH_4$ ratio. Among the catalysts used in the experiment, the Ni-Ru/$Al_2O_3$-MgO catalyst showed the highest activity. The 60% of $CH_4$ conversion was obtained, and th e reactor temperature was maintained $600^{\circ}C$ at the condition of GHSV=$10000h^{-1}$ and feed ratio S/C/O=0.5/1/0.5.

Hydrogen Production from Methane Reforming Reactions over Ni/MgO Catalyst

  • Wen Sheng Dong;No, Hyeon Seok;Zhong Wen Liu;Jeon, Gi Won;Park, Sang Eon
    • Bulletin of the Korean Chemical Society
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    • v.22 no.12
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    • pp.1323-1327
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    • 2001
  • The catalyst Ni/MgO (Ni : 15 wt%) has been applied to methane reforming reactions, such as steam reforming of methane (SRM), partial oxidation of methane (POM), and oxy-steam reforming of methane (OSRM). It showed high activity and good stability in all the reforming reactions. Especially, it exhibited stable catalytic performance even in stoichiometric SRM (H2O/CH4 = 1). From TPR and H2 pulse chemisorption results, a strong interaction between NiO and MgO results in a high dispersion of Ni crystallite. Pulse reaction results revealed that both CH4 and O2 are activated on the surface of metallic Ni over the catalyst, and then surface carbon species react with adsorbed oxygen to produce CO.

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Estimation of Ultimate Methane and Hydrogen Sulfide Yields for C&D Waste and MSW Using BMP Test (건설폐기물, 생활폐기물의 용출특성 분석과 BMP test를 통한 최종메탄(CH4) 및 황화수소(H2S) 수율 산정)

  • Jung, Sukyoung;Jeong, Seongyeob;Chang, Soonwoong
    • New & Renewable Energy
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    • v.10 no.1
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    • pp.30-40
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    • 2014
  • The main object of this study was to offer information about incoming waste in landfill and to evaluate biochemical methane and hydrogen sulfide potentials of landfill wastes. We examined brick, soil, mixed waste (C&D waste and MSW) samples for the study. The leaching experiments showed that BOD, COD and sulfate were determined in the range of 0~18,816 mg/kg, 85~21,100 mg/kg and 160~1,205 mg/kg, respectively in 6hr extraction test. An accumulated extraction tests for 140day were determined BOD 226~197,219 mg/kg, COD 436~242,588 mg/kg and Sulfate 1,090~25,140 mg/kg. Also, BMP (biochemical methane potential) tests were carried out to examine methane and hydrogen sulfide yields for the 3 different wastes. As a result, methane yield was determined to 262.68 mL $CH_4/g$ VS of MSW and 0~17.75 mL $CH_4/g$ VS in brick, soil and C&D waste. Higher hydrogen sulfide yield was observed to 0.079mL $H_2S/g$ VS in C&D waste. This result indicate that brick and soil could be sources of sulfate, and higher production of hydrogen sulfide could be odor problem and inhibitor of methane production.