• 한국수소및신에너지학회논문집
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• 제29권4호
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• pp.393-400
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• 2018

To confirm the operating range of two oxygen carriers for chemical looping combustion system, the effects of operating variables on solid circulation rate were measured and discussed using a two-interconnected circulating fluidized bed system at ambient temperature and pressure. Moreover, suitable operating ranges to avoid choking of the fast fluidized bed (air reactor) were confirmed for two oxygen carriers. A continuous long-term operation of steady-state solid circulation more than 24 hours was also demonstrated within the operating windows. Finally we could confirm that those two oxygen carriers are suitable for chemical looping combustion system with high solid circulation rate and smooth solid circulation.

• 한국수소및신에너지학회논문집
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• 제14권3호
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• pp.258-267
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• 2003

A new kind of oxygen carrier material is tested for chemical-looping combustion. NiO, CoO, $Fe_2O_3$ is chosen as metal oxide and YSZ as a binder. Hydrogen fuel is reacted with metal oxide (reduction of metal oxide) and then the reduced metal is successively oxidized by air. Dissolution method is examined to prepare the oxygen carriers. The effects of reaction temperature are measured by a TGA, mechanical strength and regenerability after 10 cycle are examined. $Fe_2O_3/YSZ$ oxygen carrier is bested in mechanical strength and we consider that NiO/YSZ after 3rd cycle are good oxygen carrier in according to reactor design.

• 에너지공학
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• 제12권4호
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• pp.289-301
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• 2003

매체순환식 가스연소기의 개발을 위해 산화반응기와 환원반응기가 연계된 2탑 가압순환유동층 조건의 50kWth 매체순환식 가스연소기에 대해 물질수지와 에너지수지를 통한 개념설계를 수행하였다. 매체순환식 가스연소기의 물질수지를 통해 산화반응기는 상승관 형태의 고속유동층 조건으로, 환원반응기는 기포유동층 조건으로 반응기 형태를 결정하였다. 물질수지와 에너지수지에 의해 계산된 층내 고체량, 고체순환량 및 반응기 크기는 장치제작 및 실제조업에 적당한 범위의 값을 나타내었으며 산소공여입자의 반응속도는 만족할 만한 수준에 도달하는 것으로 확인되었다. 본 연구의 개념설계 결과에 의하면 매체순환식 가스연소기의 조업조건은 상용 순환유동층의 조업조건과 유사하였으며 실제공정에 적용하기에 무리가 없는 것으로 사료되었다. 본 연구에서 개발된 설계 tool을 이용하여 시스템의 용량, 조업압력, 산소공여입자 중의금속산화물의 함량, 수증기 주입량, 기체유속 및 고체층 높이 등의 변화에 따른 설계 값의 변화를 해석하였으며 이를 통해 조업조건 변화에 따른 시스템의 성능변화를 예측할 수 있었다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.141-147
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• 2005

LNG combustion characteristics of oxygen carrier particles were investigated in a batch type bubbling fluidized bed reactor. Three particles, NiO/bentonite, $NiO/NiAl_2O_4$, $CO_xO_y/CoAl_2O_4$, were used as oxygen carrier particles and LNG and air were used as reactants for reduction and oxidation, respectively. In the reducer, high gas conversion and high $CO_2$ selectivity were achieved for all three particles. In the oxidizer, NOx was not detected. The results of exhaust gas analysis showed that inherent $CO_2$ separation and NOx-free combustion are possible in the LNG fueled chemical-looping combustion system with NiO/bentonite, $NiO/NiAl_2O_4$ and $Ca_xO_y/CoAl_2O_4$ particles.

• Environmental Engineering Research
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• 제19권4호
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• pp.299-308
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• 2014

This study presents a review on Chemical looping combustion (CLC) development, design aspects and modeling. The CLC is in fact an unmixed combustion based on the transfer of oxygen to the fuel by a solid oxygen carrier material avoiding the direct contact between air and fuel. The CLC process is considered as a very promising combustion technology for power plants and chemical industries due to its inherent capability of $CO_2$ capturing, which avoids extra separation costs of the of $CO_2$ from the rest of flue gases. This review covers the issues related to oxygen carrier materials. The modeling works are reviewed and different aspects of modeling are considered, as well. The main drawbacks and future research and prospects are remarked.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2002년도 춘계 학술발표회 논문집
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• pp.79-83
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• 2002

새로운 가스연소 개념인 매체순환식 가스연소기(Chemical-Looping Combustor, CLC)는 공기와 기체연료(H$_2$, CO, CH$_4$ 등)가 직접 접촉하여 연소하는 기존의 연소-발전 시스템에 비해 많은 장점들을 가지고 있다. 매체순환식 가스연소기의 기본개념은 Fig. 1에 나타내었다.(중략)

• 한국정밀공학회지
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• 제11권1호
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• pp.157-165
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• 1994

A general-purpose program for automatic two-dimensional finite-element modelling with quadrilateral elements was developed in this research. The conventional looping method employed in the program was introduced with emphasis on a new splitting criterion and a splitting scheme developed for improving the method. Some application examples were given, which show versatility and applicability of the developed program.

• 한국수소및신에너지학회논문집
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• 제26권6호
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• pp.516-523
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• 2015

Nickel based oxygen transfer materials supported on two different YSZs were tested to evaluate their performance in methane chemical-looping reforming. The oxygen transfer materials of YSZs were selected with different amount of the doped yittrium in the $ZrO_2$ structure. The yittrium of 8 mol% stabilized the zirconia oxide to a cubic structure compare to the 3 mol% doping, which is known to be a good for oxygen transfer. Various nickel amounts (16wt.%, 32wt.%, 48wt.%) were loaded on the selected supports. The nickel amount of 32% shows the optimized catalyst structure with good physical properties and reducibility from the XRD, BET and H2-TPR analysis, especially when the support of 8YSZ was used. From the methane chemical-looping reforming, hydrogen was produced by methane decomposition catalyzed by Ni on both YSZs. Comparing two YSZ supports of 3YSZ and 8YSZ during the cycling tests, the catalyst with 8YSZ (Ni 32%) exhibits not only the higher methane conversion and hydrogen production but also a faster reaction rate reaching to the stable point.

• 한국수소및신에너지학회논문집
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• 제15권1호
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• pp.46-53
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• 2004

Redox characteristics of cobalt oxide-based oxygen carriers were tested for chemical-looping combustion. Cobalt oxide was chosen as active metal oxide and $CoAl_2O_4$ was compared with YSZ(yttria-stabilized zirconia) as a binder. Cobalt oxide/$CoAl_2O_4$ was prepared by sol-gel method. Hydrogen fuel was reacted with metal oxide and then the reduced metal was successively oxidized by air. The effects of reaction temperature were measured and the regenerabilies during 10 cycles were examined by a TGA. In regenerability of cobalt oxide/YSZ and cobalt oxide/$CoAl_2O_4$, after they showed above 90% conversion in first reduction, they were stabilized in about 70-75% conversion. From reaction rate constant obtained, the activation energies of cobalt oxide/YSZ in oxidation and reduction were 51.47kJ/mol and 7.71kJ/mol respectively.

• 한국수소및신에너지학회논문집
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• 제14권1호
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• pp.24-34
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• 2003

For gaseous fuel combustion with inherent $CO_2$ capture and low NOx emission, chemical-looping combustion may yield great advantages for the savings of energy to $CO_2$ separation and suppressing the effect on environment, In chemical-looping combustor, fuel is oxidized by metal oxide medium in a reduction reactor. Reduced particles are transported to oxidation reactor and oxidized by air and recycled to reduction reactor. The fuel and the air are never mixed, and the gases from reduction reactor, $CO_2$ and $H_2O$, leave the system as separate stream. The $H_2O$ can be easily separated by condensation and pure $CO_2$ is obtained without any loss of energy for separation. In this study, five oxygen carrier particles such as NiO/bentonite, NiO/YSZ, $(NiO+Fe_2O_3)VYSZ$, $NiO/NiAl_2O_4$, and $Co_{\chi}O_y/CoAl_2O_4$ were examined &om the viewpoints of reaction kinetics, oxygen transfer capacity, and carbon deposition characteristics. Among five oxygen particles, NiO/YSZ particle is superior in reaction rate, oxygen carrier capacity, and carbon deposition to other particles. However, at high temperature ($>900^{\circ}C$), NiO/bentonite particle also shows enough reactivity and oxygen carrier capacity to be applied in a practical system.