The evolution and desulfurization of sulfur in chemical looping combustion of coal

Chemical-looping combustion (CLC) is a new technology that has gained great attention due to its advantages in CO₂ capture during combustion. Sulfur in coal maybe harmful to the CLC process. The interactions between sulfur and oxygen carrier may reduce the purity of carbon captured, and affect the characteristics of the oxygen carrier. Therefore, the evolution of sulfur in Xinzhou coal and the desulfurization performance in this process were studied by using iron ore as an oxygen carrier. Experimental results showed that the main sulfur-containing component released was SO₂, and the fractions of sulfur during the reduction and oxidation periods reached 64.28 and 3.91%, respectively. The addition of desulfurization agent (CaO) could control the release of sulfur and a higher molar ratio of Ca/S resulted in less emission of sulfur-containing gases. The desulfurization efficiency reached 36.61%, 50.72%, and 55.45% when the Ca/S molar ratio was 1.5, 2.0, and 2.5 respectively. Considering the investment and operation costs, the recommended molar ratio of Ca/S was 2.0. The formation of CaSO₄ was confirmed after reaction, but the stability of CaSO₄ and its effect on oxygen carrier over a longer period of time still need to be further studied.