• 한국환경농학회지
• /
• 제21권4호
• /
• pp.248-254
• /
• 2002

가축분뇨를 혐기성소화하여 메탄가스를 생산하고 난 다음 혐기성 소화액비를 비료자원으로 활용하기 위하여 농가포장에서 액비의 시용적량을 구명하였다. 벼 생육상황은 액비 100%+화학비료구가 전 시기를 통해 가장 양호하였으며, 그 다음으로 표준시비구가 분얼기에만 양호하였으나 그 이후에는 표준시비구 액비 100%구 및 액비 150%구 간에는 서로 차이가 없었다. 시기별 식물체중 전질소함량은 분얼기 및 출수기에는 추비의 영향으로 표준시비구가, 유수형성기에는 액비 100%+화학비료구가 높았다. 벼 수량은 액비 100% 및 150%구들이 표준시비구와 비슷하거나 약간 증수되었으며, 액비 100%+화학비료구는 고중의 증가 및 도복으로 인하여 표준시비구보다 수량이 오히려 약간 낮았다. 수확기 질소흡수량은 표준시비구가 가장 높았고, 시비질소 효율은 액비 100%구에서, 시비질소 이용율은 액비 100%+화학비료구에서 높았다. 시기별 토양중 $NH_4-N$ 및 $NO_3-N$함량 변화는 액비 100%+화학비료구가 타 처리구보다 높았다. 시기별 관개수 중 $NH_4-N$ 및 $NO_3-N$함량 변화는 분얼비의 영향으로 급격히 증가하였다가 급격히 감소하였는데, 증가한 시기에는 표준시비구 및 액비 100%+화학비료구가 가장 높았다. 시기별 침투수 중 $NH_4-N$함량 변화는 액비 150%구들에서 많이 용탈되었고, $NO_3-N$ 함량은 액비에 화학비료를 추비한 구들에서 많이 용탈되었다. 혐기성 소화액비는 액비 중의 질소성분을 분석하여서 표준시비량의 질소성분에 맞추어 시용하여야 한다.

• 유기물자원화
• /
• 제24권2호
• /
• pp.51-58
• /
• 2016

일체형 2상 혐기성소화 방식은 기존 분리형 2상 혐기성소화의 단점을 보완할 수 있는 기술로 산발효조와 메탄발효조가 병합된 형태의 일체형으로 구성되어 유기물 부하변동 대처 용이, 설치부지면적 감소 등의 이점이 있다. 본 연구는 음폐수를 기질로 일체형 2상 혐기성소화의 유기물 분해효율 및 바이오가스 생산량 등에 대한 실험을 실시하여 기존 분리형 2상 혐기성소화와의 효율 비교를 통해 대규모 플랜트 설치의 타당성 여부를 검토하였다. 5ton/일 규모의 Pilot Plant를 구성하여 약 130일 간 소화조 내 유기물 변화, 바이오가스 생산량 및 메탄함량 등의 실험을 실시하였다. 실험 결과, 평균 음폐수 투입량은 $4.1m^3$/일이었으며, 이때 VS 제거효율은 약 77%로 나타났다. 바이오가스는 평균적으로 투입 음폐수 ton당 약 $63.0m^3$($0.724m^3/kg-VS_{added}$)가 발생되었으며, 메탄함량은 약 61.3%로 분석되었다. 일체형 2상 혐기성소화는 기존 산발효조와 메탄발효조가 분리된 소화방식과 유기물 제거 측면에서 다소 높게 나타났다. 결과적으로 일체형 2상 혐기성소화 방식은 충분히 고농도 유기성 폐수인 음폐수 처리에 있어서 상용화가 가능하다는 결론을 내릴 수 있었다.

• 대한기계학회논문집B
• /
• 제29권2호
• /
• pp.255-262
• /
• 2005

A comprehensive experimental and numerical study has been conducted to understand the influence of $CH_{3}Cl$ addition on $CH_4/O_2/N_2$ premixed flames under the oxygen enrichment. The laminar flame speeds of $CH_4/CH_{3}Cl/O_2/N_2$ premixed flames at room temperature and atmospheric pressure are experimentally measured using Bunsen nozzle flame technique, varying the amount of $CH_{3}Cl$ in the fuel, the equivalence ratio of the unburned mixture, and the level of the oxygen enrichment. The flame speeds predicted by a detailed chemical kinetic mechanism employed are found to be in excellent agreement with those deduced from experiments. Even though the molar amount of $CH_{3}Cl$ in a methane flame is increased, temperature at the postflame is not significantly varied, but the calculated heat release rate and emission index of NO are largely decreased for the oxygen enhanced flame. The function of $CH_{3}Cl$ as inhibitor on hydrocarbon flames becomes weakened as the level of the oxygen enrichment is increased from 0.21 to 0.5.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 춘계학술대회논문집B
• /
• pp.949-955
• /
• 2000

Numerical study with detailed chemistry has been conducted to investigate the NOx formation and structure in $CH_4/Air-CO_2$ counterflow diffusion flames. The importance of radiation effect is identified and the role of $CO_2$ addition is addressed to thermal and chemical reaction effects, which can be precisely specified through the introduction of an imaginary species. Also NO separation technique is utilized to distinguish the contribution of thermal and prompt NO formation mechanisms. The results are as follows : The radiation effect is dominant at low strain rates and it is intensified by $CO_2$ addition. Thermal effect mainly contributes to the changes in flame structure and the amount of NO formation but the chemical reaction effect also cannot be neglected. It is noted that flame structure is changed considerably due to the addition of $CO_2$ in such a manner that the path of methane oxidation prefers to take $CH_4 {\rightarrow}CH_3{\rightarrow}C_2H_6{\rightarrow}C_2H_5$ instead of $CH_4 {\rightarrow}CH_3{\rightarrow}CH_2{\rightarrow}CH$. At low strain rate(a=10) the reduction of thermal NO is dominant with respect to reduction rate, but that of prompt NO is dominant with respect to total amount.

• 한국수소및신에너지학회논문집
• /
• 제32권4호
• /
• pp.197-204
• /
• 2021

Pressure swing adsorption is a purification process which can get pure hydrogen. The purification process is composed of four process: compression, adsorption, desorption and discharge. In this study the adsorption process was simulated by using the Fluent and validated with experimental results. A gas used in experiment is composed of H₂, CO₂, CH₄, and CO. Adsorption process conducted under 313 kelvin and 3 bar and bituminous-coal-based (BPL) activated carbon was used as the adsorbent. Langmuir model was applied to explain the gas adsorption. And diffusion of all the gases was controlled by micro-pore resistances. The result shows that, the most adsorbed gas was carbon dioxide, followed by methane and carbon monoxide. And carbon monoxide took the least amount of time to reach the maximum adsorption amount. The molar fraction of the off-gas became the same as the molar fraction of the gas supplied from the inlet after adsorption reached the equilibrium.

• 한국수소및신에너지학회논문집
• /
• 제32권1호
• /
• pp.68-76
• /
• 2021

Climate change problems occur during the use of fossil fuel and the process of biogas production. Research continues to convert carbon dioxide and methane, the major causes of climate change, into high-quality energy sources. in order to present the performance potential for the novel plasma-recuperative burner reformer, the reforming characteristics for each variable were indentified. The optimal operating condition of was an O2/C ratio of 1.0 and a total gas supply of 20 L/min. At this time, CH4 conversion was 64%, H2 selectivity was 39%, and H2/CO ratio was 1.13, which were the results applicable to the solid oxide fuel cell fuel stack for RPG, or Residential Power Generator. Recirculation of reformed gas increases the amount of H2 and CO, which are combustible gases, especially the amount of H2. As a result, the H2 selectivity is improved, and high-quality gas can be produced.

• 한국해양공학회지
• /
• 제35권6호
• /
• pp.393-402
• /
• 2021

As greenhouse gas emissions from maritime transport are increasing, the International Maritime Organization is continuously working to strengthen emission regulations. Liquefied natural gas (LNG) fuel is less advantageous as a point of CO₂ reduction due to the methane leakage that occurs during the bunkering and operation of marine engines. In this study, greenhouse gas emissions from an LNG-fueled ship were analyzed from the perspective of the life cycle. The amount ofmethane emission during the bunkering and operation procedures with various boil-off gas (BOG) treatment methods and gas engine specifications was analyzed by dynamic simulation. The results were also compared with those of other liquid fuel engines. As a result, small LNG-fueled ships without a BOG treatment facility emitted 32% more greenhouse gas than ships utilizing marine gas oil or heavy fuel oil. To achieve a greenhouse gas reduction via a BOG treatment method, a gas combustion unit or re-liquefaction system must be mounted, which results in a greenhouse gas reduction effect of about 25% and 30%. As a result of comparing the amount of greenhouse gas generated according to the BOG treatment method used with each tank size from the perspective of the operating cycle with the amounts from using existing marine fuels, the BOG treatment method showed superior effects of greenhouse gas reduction.

• 대한환경공학회지
• /
• 제22권12호
• /
• pp.2197-2204
• /
• 2000

리그닌은 펄프나 제지공장에서 나무의 화학적 처리를 하는 과정에서 생성되는 주요한 부산물이다. 이런 리그닌은 난분해성 물질로서 제지폐수의 생물학적 처리에 어려움을 초래하며, 특히 함량이 높을 경우 혐기성 소화에서 억제(inhibition) 물질로 작용하는 것으로 알려져 있다. 본 연구에서는 회분실험을 통하여 혐기성 소화에서 온도와 혐기성 소화 슬러지의 양에 따른 고분자 활엽수 리그닌(lignosulfonate, MW $\geq$ 20,000)의 영향을 관찰하였다. 고분자 활엽수 리그닌은 혐기성 소화 초기에는 메탄생성에 강한 억제작용을 하였으나 일정한 시간이 지난 후에는 이런 억제작용은 사라지고 메탄생성이 정상적으로 이루어졌다. 즉, 고분자 활엽수 리그닌은 aceticlastic methanogen에 대해 bacteriocidal 작용보다는 bacteriostatic 물질로서 작용하였다. 리그닌이 첨가되지 않은 대조군의 경우에는 메탄생성이 10일간 이루어지는데 반하여 1.3%, 2.6%와 3.9%의 리그닌이 첨가된 경우에는 같은 양의 메탄올 생성하는데 각각 14.5일, 17.8일 과 21.1일이 소요되었다. 2.6%의 리그닌을 첨가한 경우 초기 8일간은 $30^{\circ}C$ 조건에서의 메탄생성속도가 가장 컸으나 12일째부터 $40^{\circ}C$에서의 메탄생성속도가 급속히 증가하여 14일 후에는 총 메탄생성량이 $30^{\circ}C$를 초과하였다. 그러나 $50^{\circ}C$에서는 줄곧 메탄생성이 거의 이루어지지 않았다. 즉, aceticlastic methanogen에 대한 리그닌의 억제작용을 중온 (mesophilic)보다 고온(thermophilic)에서 더 컸다. 리그닌에 의한 이런 억제작용은 또 리그닌의 양(L)과 초기 혐기성 소화슬러지의 농도(AnS)의 비와 중요한 관계가 있었다. L/AnS의 비가 작으면 작을수록 이런 억제작용은 감소되는 것으로 나타났다. 그리고 본 실험에서 고분자 활엽수 리그닌의 분해와 탈색은 이루어지지 않았다.

• 한국환경보건학회지
• /
• 제46권2호
• /
• pp.159-169
• /
• 2020

Objectives: The purpose of this study was to investigate changes among the nine kinds of reduction chemical substances in Korea over the period of 2008-2017. We will define basic data for improving the management methods for reducing chemical substances. Methods: A survey of hazardous pollutant emissions for 2008-2017 was conducted through the pollutant Release and Transfer Register homepage. Nine kinds of designated reduction chemical substances (Benzene, Vinyl chloride, Trichloro ethylene, 1,3-butadiene, Dichloro methane, Tetrachloro ethylene, N,N-dimethylformamide, Acrylo nitrile, and Chloroform) provided the study subjects. The emission of hazardous chemicals and health effects used the National Health Statistics and Integrated Chemicals Information System (ICIS) as a reference. Results: Hazardous pollutant emissions increased by 1.2 times over the past decade, and nine types of reduction chemical substances increased by 1.6 times. By region, the emissions of reduction chemical substances over the last 10 years were in the order of Chungbuk, Gyeonggi, and Gyeongbuk. Emissions of Dichloro methane was the highest in Chungbuk and Gyeongbuk. N,N-dimethylformamide was the highest in Gyeonggi. Carcinogen pollutant emissions showed a tendency to increase continuously. In addition, group 1 carcinogen emissions showed a tendency to decrease. Conclusion: In the last decade, the amount of hazardous chemical emissions has been continuously increasing. Hazardous chemical emissions require facility improvement for continuous emissions reduction. More research on reduction of emissions is needed.

• 한국수소및신에너지학회논문집
• /
• 제17권3호
• /
• pp.293-300
• /
• 2006

KIER has been developing a Ru-based preferential oxidation catalysts and a novel fuel processing system to provide hydrogen rich gas to residential PEMFCs system. The catalytic activity of Ru-based catalysts was investigated at different Ru loading amount and different support structure. The obtained result indicated that 2 wt% loaded Ru-based catalyst supported on ${\alpha}-Al_2O_3$ showed high activity in low temperature range and suppressed the methanation reaction. The developed prototype fuel processor showed thermal efficiency of 78% as a HHV basis with methane conversion of 92%. CO concentration below 10 ppm in the produced gas is achieved with separate preferential oxidation unit under the condition of $[O_2]/[CO]=2.0$. The partial load operation have been carried out to test the performance of fuel processor from 40% to 80% load, showing stable methane conversion and CO concentration below 10 ppm. The durability test for the daily start-stop and 8 h operation procedure is under investigation and shows no deterioration of its performance after 50 start-stop cycles. In addition to the system design and development.