• Transactions of the Korean hydrogen and new energy society
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• v.18 no.1
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• pp.75-84
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• 2007

The effects of hydrogen enrichment to methane on NOx formation have been investigated with swirl stabilized pre-mixed hydrogen enriched methane flame in a laboratory-scale pre-mixed combustor(nominally of 5,000 kcal/hr). The hydrogen enriched methane fuel and air were mixed in a pre-mixer and introduced to the combustor through different degrees of swirl vanes. The flame stability was examined for different amount of hydrogen addition to the methane fuel, different combustion air flow rates and swirl strengths by comparing equivalence ratio at the lean flame limit. The hydrogen addition effects and swirl intensity on the combustion characteristics of pre-mixed methane flames were examined using gas analyzers, and OH chemiluminescence techniques to provide information about species concentration of emission gases and flowfield. The results of NOx and CO emissions were compared with a diffusion flame type combustor. The results show that the lean stability limit depends on the amount of hydrogen addition and the swirl intensity. The lean stability limit is extended by hydrogen addition, and is reduced for higher swirl intensity at lower equivalence ratio. The addition of hydrogen increases the NOx emission, however, this effect can be reduced by increasing either the excess air or swirl intensity. The NOx emission of hydrogen enriched methane premixed flame was lower than the corresponding diffusion flame under the fuel lean condition.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.4
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• pp.276-282
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• 2008

The effects of hydrogen enrichment to methane have been investigated with swirl-stabilized premixed hydrogen-enriched methane flame in a laboratory-scale pre-mixed combustor. The hydrogen-enriched methane fuel and air were mixed in a pre-mixer and introduced to the combustor through different degrees of swirl vanes. The flame characteristics were examined for different amount of hydrogen addition to the methane fuel and different swirl strengths. The hydrogen addition effects and swirl intensity on the combustion characteristics of pre-mixed methane flames were examined using micro-thermocouple, particle image velocity meter (PIV) and chemiluminescence techniques to provide information about flow field. The results show that the flame area increases at upstream of reaction zone because of increase in ignition energy from recirculation flow for increase in swirl intensity. The flame area is also increased at the downstream zone by recirculation flow because of increase in swirl intensity which results in higher centrifugal force. The higher combustibility of hydrogen makes reaction faster, raises the temperature of reaction zone and expands the reaction zone, consequently recirculation flow to reaction zone is reduced. The temperature of reaction zone increases with hydrogen addition even though the adiabatic flame temperature of the mixture gas decreases with increase in the amount of hydrogen addition in this experiment condition because the higher combustibility of hydrogen reduces the cooler recirculation flow to the reaction zone.

• Journal of the Korean Institute of Gas
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• v.17 no.5
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• pp.22-27
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• 2013

HCNG engine is performed as a future engine because of high combustion efficiency and eco-friendly property, and is predicted to a brdge of hydrogen vehicles. As EURO-6 regulagion is due to be applied in 2014, consolidated regulations of methane gas that is exhausted from CNG and HCNG vehicles will come into effect. In this studies, methane oxidation catalyst is introduced to remove methane gas from HCNG emissions. Methane oxidation efficiency on catalyst was studied when it is driven long time. And characterization like metal dispersion, surface area was performed to investigate the correlation of catalyst efficiency and characteristics.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.1
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• pp.81-89
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• 2018

Fuel blend technique is one of the most effective way of using biomass to replace the coal. Many studies on combustion characteristics with coal and biomass blends have been conducted. In this study, char reactivity and emission characteristics of coal (Suek) and biomass (EFB) blends has been investigated by TGA and DTF to evaluate the applicability of the pre-treated (torrefaction, ash removal technology) EFB to pulverized coal boiler. In all blending cases, char reactivity improved as the blending ratio increases (10, 20, and 30%), especially torrefied EFB blended at 30%. Also, unburned carbon decreased as the blending ratio increases in all types of EFB. NOx emission showed the increase and decrease characteristics according to the content of fuel-N of raw EFB and torrefied EFB. But the amount of NOx emission at ashless EFB blends is greater than that of Suek despite of lower fuel-N. It indicated that co-firing effect of using the pretreatment biomass fuel is relatively better than those of the untreated biomass fuel about char reactivity and emission characteristics.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.175.1-175.1
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• 2011

우드칩을 포함하는 화석연료대비 발열량이 낮은 바이오매스를 가스화를 통하여 활용하는 경우 타르 및 수트를 포함하는 저열량의 합성가스가 생성된다. 이러한 합성가스를 엔진을 통한 발전, 스팀, 수소 및 화학제품 생산으로 활용하기 위해서는 고효율의 타르 정제 및 제거가 필수적이다. 특히 착화가 어렵고 연소온도 및 연소율이 낮으며, 화염구간이 좁은 저열량의 합성가스를 이용하여 스팀을 생산하기 위해서는 많은 문제점으로 인하여 기술 개발이 필요하다. 본 연구에서는 하향류식 가스화기를 이용하여 우드칩을 연료로 합성가스를 제조하였으며, 합성가스에 포함되어 있는 타르 및 수트와 같은 미반응 물질을 제거할 수 있는 집진, 세정장치를 설계 및 제작하였다. 특히 고효율 타르의 제거를 위하여 두 종류의 산화촉매를 이용한 합성가스 내 타르의 제거 연구를 수행하였다. Ru 촉매를 이용하는 경우 합성가스 내 타르의 농도를 100ppb 정도까지 저감이 가능하였다. 정제된 합성가스는 유류 혼소 버너를 통하여 보일러 연소실에서 혼합연소되어 30만kcal/h의 열을 공급함으로써 스팀을 생산 하였으며, 생성된 스팀은 블록 건조 시설에서 이용하였다.

• Clean Technology
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• v.30 no.2
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• pp.71-93
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• 2024

Recently, the establishment of a hydrogen-based economy and the utilization of low-carbon energy sources, particularly for shipping and power generation, have been in high demand in order to achieve carbon neutrality by 2050. In particular, ammonia is gaining renewed attention because it is capable of serving as a key facilitator for high-efficiency green hydrogen storage and transportation and it is also capable of serving as a low-carbon energy source. Although ammonia can be synthesized through the Haber-Bosch process, the high energy consumption and carbon emissions associated with this process result in minimal carbon reduction. To address the critical drawbacks of the traditional Haber-Bosch process, various thermochemical synthesis methods have been developed recently, allowing for the synthesis of ammonia with lower carbon emissions and a higher energy efficiency. Research is also progressing in the development of high-performance catalyst materials that are capable of demonstrating sufficient ammonia synthesis performance under milder process conditions compared to conventional methods. Additionally, a variety of different processes such as chemical-looping ammonia synthesis, plasma synthesis, and mechanochemical synthesis are being applied diversely. This review aims to provide a detailed overview of the emerging ammonia synthesis technologies that have been developed to effectively store green hydrogen for future applications.

• Korean Chemical Engineering Research
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• v.62 no.3
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• pp.225-232
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• 2024

The reduction of CO₂ emissions in the energy production sector, which accounts for 86.8% of total greenhouse gas emissions, is important to achieve carbon-neutrality. At present, 60% of total power generation in South Korea is coal and natural gas. Replacing fossil fuel with renewable energy such as wind and solar has disadvantages of unstable energy supply and high costs. Therefore, this study was conducted through the co-firing of natural gas, ammonia and hydrogen utilizing the natural gas combined cycle process. The results demonstrated reduction in CO₂ emissions and 34%~238% of the power production compared to using only natural gas. Case studies on mass fractions of natural gas, ammonia and hydrogen indicated that power production and NO_x emissions were inversely proportional to the ammonia ratio and directly proportional to the hydrogen ratio. This study provides guidelines for the use of various fuel mixtures and economic analysis in co-firing power generation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.420-427
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• 2017

Recently, the depletion of fossil fuels, global warming and environmental pollution have emerged as a worldwide problem, and studies of new renewable energy sources have been progressed. Among the many renewable energy sources, the use of bio fuel has the potential to displace fossil fuels due to low price, easy to handle, and the abundant sources. Pyrolysis oil (PO) derived from waste wood and sawdust is considered an alternative fuel for use in diesel engines. On the other hand, PO is limited to diesel engines because of its low cetane number, high viscosity, high acidity, and low energy density. Therefore, to improve its poor properties, PO was mixed with alcohol fuels, such as ethanol. Early mixing with ethanol has the benefit of improving the storage and handling properties of the PO. Furthermore, a PO-ethanol blended fuel was injected separately, which can be fired through pilot-injected diesel in a dual-injection diesel engine. The experimental results showed that the substitution of diesel with blended fuel increases the amount of HC and CO, but reduces the NOx and PM significantly.