Kyeongsook Kim

A long-term test of a new CO2 sorbent (KEP-CO2P2) in a 0.5 MWe CO2 capture test bed

The performance of a new dry CO2 sorbent KEP-CO2P2 was tested for an extended period of time of 650 hours in a 0.5 MWe CO2 capture test bed at Hadong coal-fired power plant. The mass-produced CO2 dry sorbent, KEP-CO2P2 was tested for CO2 sorption and regeneration capacity. With modification of the process as well as the use of KEP-CO2P2 sorbent in a 0.5 MWe CO2 capture test bed, 85% (81–90%) CO2 removal rate was achieved in continuous operation of 650 hours. Samples were collected and analyzed using particle size analyzer (PSA), ion chromatograph (IC), inductively coupled plasma (ICP), field emission-scanning electron Microscope (FE-SEM), electron probe X-ray micro-analyzer (EPMA) and X-ray diffractometer (XRD). The analysis showed that KEP-CO2P2 was not affected by SOx, and there were no side reactions to consume K2CO3. However, the regeneration of the sorbent was not complete to need future investigation.

Distribution of NiO/Al2O3/NiAl2O4 in the Fabrication of Spray-Dry Oxygen Carrier Particles for Chemical-Looping Combustion

NiO/Al2O3, known as one of the most efficient oxygen carrier, has been fabricated by spray-drying method and calcinated at 1100 °C and 1300°C, and the structural characteristics are investigated using XRD, SEM, TEM and XPS. For the characterization of surface and bulk microstructure of the fabricated NiO/Al2O3 oxygen carrier particle, investigated were 1) as-fabricated powders, 2) internal structure of the crumbled particles, and 3) cross-sectional specimens. The results showed that the fabricated oxygen carrier formed well distributed NiAl2O4 with NiO particles of 100~500 nm via reaction keeping on the mole ratio. The oxygen carriers developed in this study showed pertinent characteristics for chemical-looping combustion, and good effect on the strength, indicating a potential for wide application in the future. The calcination at 1100 °C was good enough and as efficient as that at 1300 °C.

Effect of the Addition of CeO2 or MgO on the Oxygen Carrier Capacity and Rate of Redox Reactions of NiO/Fe2O3/Al2O3 Oxygen Carriers

Two compositions of mixed oxygen carriers (OCs), N1F1A1 (mole ratio of NiO to Fe2O3 is 1:1) and N1F2 (mole ratio of NiO to Fe2O3 is 1:2), were fabricated by mechanical mixing, and the effects of CeO2 and MgO additives on the oxygen-transfer capacity (OTC) and crystal structure were analyzed. In addition, X-ray diffractometry after the oxidation and the reduction steps was carried out to determine the reaction mechanism. Potential mixed OCs of the candidates of various OCs, such as NiO/Fe2O3, are proposed based on the OTC and oxygen-transfer rate evaluated via X-ray diffraction (XRD) phase analysis and thermogravimetric analysis. The chemical reaction equation for the oxidation and reduction was suggested based on the XRD characterization of the phases including NiFe2O4 and MgAl2O4 in N1F1A1 (①) and N1F1A1-Mg5 (④). Addition of MgO is confirmed to enhance the OTC and oxygen-transfer rate. The mechanism of the oxidation and reduction of metal oxides and the role of MgO were suggested. Even though the addition of MgO does not transfer oxygen to the fuel, it does accelerate the oxidation and reduction reactions of NiFe2O4.