• Transactions of the Korean hydrogen and new energy society
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• v.20 no.3
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• pp.245-255
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• 2009

Effect of CO$_2$ concentration on reduction reactivity of oxygen carrier particles for chemical-looping combustor were investigated. Four particles, NiO/bentonite, OCN601-650, OCN702-1100, OCN702-1250, were used as oxygen carrier particles and two kinds of gases (CH$_4$, 5%, N$_2$ balance and CH$_4$ 5%, CO$_2$ balance) were used as reactants for reduction. For all oxygen carrier particles, higher maximum conversion, reduction rate, oxygen transfer capacity, and oxygen transfer rate were achieved when we used N$_2$ balance gas. OCN601-650 particle showed higher oxygen transfer rate for all gases than other particles, and therefore we selected OCN601-650 particle as the best candidate. For all particles, lower carbon depositions were observed when we used CO$_2$ balance gas.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.2
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• pp.151-160
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• 2009

Natural gas combustion characteristics of mass produced oxygen carrier particles were investigated in a batch type bubbling fluidized bed reactor. Five particles, NiO/bentonite, OCN601-650, OCN702-1100, OCN703-950, OCN703-1100 were used as oxygen carrier particles. Natural gas and air were used as reactants for reduction and oxidation, respectively. During reduction reaction, high fuel conversion and high $CO_2$ selectivity were achieved for most of oxygen carriers. During oxidation, NO emission was very low. These results indicate that inherent $CO_2$ separation and low NOx combustion are feasible for the natural gas fueled chemical-looping combustion system. Among the five oxygen carriers, OCN703-1100 particle was selected as the best candidate for demonstration of long-term operation in large-scale chemical-looping combustor from the viewpoints of fuel conversion, $CO_2$ selectivity, $CH_4$ concentration, and CO concentration.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.3
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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.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.5
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• pp.581-588
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• 2016

To compare reduction reactivity of oxygen carrier particles, $CH_4$ combustion characteristics were measured and investigated in a bubbling fluidized bed reactor with increasing $CH_4$ concentration from 10 to 100 %. Among five oxygen carriers (OC-1, OC-2, SDN70, C14, C28), OC-1, OC-2, SDN70 particles were selected as better oxygen carriers from the viewpoints of fuel conversion and $CO_2$ selectivity. However, some oxygen carriers showed lower fuel conversion and $CO_2$ selectivity even though they have high oxygen transfer capacity. Therefore, we could conclude that not only TGA tests to measure the oxygen transfer capacity but also fluidized bed tests to analyze exhaust gas concentration should be performed to select better oxygen carrier without misunderstanding of carriers reactivity.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.4
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• pp.412-420
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• 2016

Effect of $H_2S$ on reactivity of oxygen carrier was measured and discussed using fluidized bed reactor and SDN70 oxygen carrier. We could get 100% of fuel conversion and $CO_2$ selectivity even though $H_2S$ containing simulated syngas was used as fuel for reduction. Absorbed sulfur was released during oxidation and $N_2$ purge step after oxidation as $SO_2$ form. We could get 100% of fuel conversion and $CO_2$ selectivity during cyclic reduction-oxidation tests up to 10th cycle. However, only 6~7% of sulfur can be removed during oxidation and $N_2$ purge step and 93~94% of sulfur was accumulated in the oxygen carrier. Therefore we could conclude that total removal of sulfur was not possible. $SO_2$ emission during oxidation decreased as the number of cycle increased. Therefore we could expect that the reactivity of oxygen carrier will be decreased with time.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.1
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• pp.45-54
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• 2009

Reduction reactivity and carbon deposition characteristics of three oxygen carrier particles(OCN01, OCN02, OCN03) have been investigated by using hydrogen, methane, syngas, and natural gas as fuels. For all particles, the maximum conversion, the oxygen transfer capacity, and the degree of carbon deposition increased as the reactive carbon contents increased. The reduction rate and the oxygen transfer rate increased as the moles of required oxygen per input gas increased. The change of maximum conversion, reduction rate, oxygen transfer capacity, oxygen transfer rate and degree of carbon deposition for different fuels can be explained consistently by using parameters such as the reactive carbon contents and the moles of require oxygen per input gas.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.1
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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.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.43-48
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• 2019

This study investigated the feasibility of $CaSnO_3$ particles as an oxygen carrier in chemical looping combustion (CLC). $CaSnO_3$ particles had a perovskite crystal structure and showed the structural stability after repeated reduction-oxidation reactions. The oxygen transfer capacity was 15.4 wt% almost the same as the calculated theoretical value from the crystal structure transformation during reduction. After $10^{th}$ cycles of reduction and oxidation, the oxygen transfer capacity and rate were still maintained constantly at an operating temperature. In conclusion, $CaSnO_3$ particles could be a good alternative material as an oxygen carrier in CLC.

• Environmental Engineering Research
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• v.19 no.4
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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.

• The Korean Journal of Physiology
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• v.26 no.1
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• pp.37-44
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• 1992

The encapsulation of the Purified bovine hemoglobin with Phospholipids obtained from egg folk was performed using a rotary vacuum evaporator. The prepared Hb-containing liposome (hemosome) had good properties as artificial red blood cell. The shape and size of the hemosomes were measured by a phase contrast microscope and image analyzer. The function of the hemosome as oxygen carrier was tested by measuring oxygen saturation curve with blood gas analyzer and infusing it into rats. The prepared hemosome was 1.184 + 0.423 ${\mu}m$ in diameter and round in shape. $P_{50}$ value of the hemosome solution was 28 mmHg. The synthesized red cells seem to function as oxygen carrier, because the severely bled rats were prolonged in their life by transfusion of the hemosome solution containing bovine hemoglobin.