Coal Char-fueled Chemical Looping Combustion Use Different Iron-Based Oxygen Carriers

Solid-fueled chemical looping combustion (SF-CLC) is an advanced process for highly efficient coal combustion with in-situ CO2 capture. The key issue in the development of SF-CLC is the ability of the oxygen carrier (OC) material to improve the gasification rate and combustion efficiency. In this study five iron-based materials were investigated as OCs using a bench-scale fluidized bed reactor. These materials were ilmenite ore (N-FeOC-1), an industrial by- product based iron OC (N-FeOC-2), 50% Fe2O3 supported on Al2O3(S-FeOC-1), 50% Fe2O3 supported on 48% Al2O3 and 2% Na2O (S-FeOC-2), and the third OC with 2% Na2O being coated on the particle surface (S-FeOC-3). Char prepared from Eastern and Western Kentucky Coal (USA) and 50 vol% water vapour were used as the fuel and the gasification/fluidizing agent, respectively. The rate of char conversion and in-situ syngas conversion in SF-CLC were the primary focus of this study and an attempt at improvement was made by adding a small amount alkaline metal using various methods. It was found that N-FeOC-2 and S-FeOC-3 showed excellent performance. Additionally, the method of adding the alkaline metal (Na+) to SF-CLC system showed an important effect on the gasification rate and in-situ syngas conversion.