Fate of sulfur in coal-direct chemical looping systems

Effects of sulfur additive on the transformation behaviors of γ‐Fe2O3 and coal liquefaction performances under mild conditions

“…In sulfidation, α‐Fe was the dominant phase at the S/Fe atomic ratio below 0.6. These results demonstrated that sulfur played a crucial role in the transformation of γ‐Fe 2 O 3 , and it was reported that the sulfur added to the liquefaction system was easily converted to H 2 S . Consequently, the effect of H 2 S on the transformation behaviors of γ‐Fe 2 O 3 and liquefaction performances should be discussed deeply.…”

“…This could be due to the low sulfur content in coal, and the mild conditions might weaken the reactions to the formation of sulfur‐containing compounds in liquid products. Therefore, the distribution of sulfur was mainly discussed in gaseous and solid products, and the sulfur‐containing gas was mainly H 2 S . Based on the above assumptions and according to Equations –, the distribution of sulfur in gaseous (H 2 S) and solid products was calculated and the results are shown in Figures and .…”

Coal-Direct Chemical Looping Process with In Situ Sulfur Capture for Energy Generation Using Ca–Cu Oxygen Carriers

“…Previous studies indicate that CDCL possesses a relatively high tolerance toward sulfur present in the coal feed. The study reported by Chung et al shows that the sulfur deposits on the iron-based oxygen carrier particles are completely removed during air oxidation such that the amount of sulfur exiting the process in the form of SO 2 is well within the emission standards set up by the U.S. Environmental Protection Agency (EPA) . Consequently, the need for any expensive acid gas removal unit at the combustor outlet is eliminated.…”

“…The study reported by Chung et al shows that the sulfur deposits on the iron-based oxygen carrier particles are completely removed during air oxidation such that the amount of sulfur exiting the process in the form of SO 2 is well within the emission standards set up by the U.S. Environmental Protection Agency (EPA). 15 Consequently, the need for any expensive acid gas removal unit at the combustor outlet is eliminated. Some amount of sulfur entering the system through coal is lost in the coal ash as inorganic sulfur compounds, while more than 69% is emitted at the reducer outlet in the form of SO 2 along with CO 2 , thereby necessitating the placement of a flue gas desulfurization (FGD) unit downstream of the reducer for CO 2 −SO 2 separation.…”

“…The CDCL process has been successfully demonstrated at various scales ranging from a 2.5 kW th bench unit to a 250 kW th pilot unit. A 25 kW th sub-pilot scale unit designed at commissioned at OSU has been subjected to 200 h of continuous operation, whereas the 250 kW th pilot unit has been operated for 288 h for power generation and CO 2 capture with high coal conversion and CO 2 purity. − …”