Carbon deposition characteristics and regenerative ability of oxygen carrier particles for chemical-looping combustion

For gaseous fuel combustion with inherent CO2 capture and low NOx emission, chemical-looping combustion (CLC) may yield great advantages for the savings of energy to CO2 separation and suppressing the effect on the environment. In a chemical-looping combustor, fuel is oxidized by metal oxide medium (oxygen carrier particle) in a reduction reactor. Reduced particles are transported to the oxidation reactor and oxidized by air and recycled to the reduction reactor. The fuel and the air are never mixed, and the gases from the reduction reactor, CO2 and H2O, leave the system as separate streams. The H2O can be easily separated by condensation and pure CO2 is obtained without any loss of energy for separation. In this study, NiO based particles are examined from the viewpoints of reaction kinetics, carbon deposition, and cyclic use (regenerative ability). The purpose of this study is to find appropriate reaction conditions to avoid carbon deposition and achieve high reaction rate (e.g., temperature and maximum carbon deposition-free conversion) and to certify regenerative ability of NiO/bentonite particles. In this study, 5.04% methane was used as fuel and air was used as oxidation gas. The carbon deposition characteristics, reduction kinetics and regenerative ability of oxygen carrier particles were examined by TGA (Thermal Gravimetrical Analyzer).