Carbon dioxide emissions are considered a major environmental threat. To enable power\nproduction from carbon-containing fuels, carbon capture is required. Oxy-fuel combustion technology\nfacilitates carbon capture by increasing the carbon dioxide concentration in flue gas. This study\nreports the results of calcium rich oil shale combustion in a 60 kWth circulating fluidized bed (CFB)\ncombustor. The focus was on the composition of the formed flue gas and ash during air and oxy-fuel\ncombustion. The fuel was typical Estonian oil shale characterized by high volatile and ash contents.\nNo additional bed material was used in the CFB; the formed ash was enough for the purpose. Two\nmodes of oxy-fuel combustion were investigated and compared with combustion in air. When N2\nin the oxidizer was replaced with CO2, the CFB temperatures decreased by up to 100 ââ??¦C. When\noil shale was fired in the CFB with increased O2 content in CO2, the temperatures in the furnace\nwere similar to combustion in air. In air mode, the emissions of SO2 and NOx were low (<14\nand 141 mg/Nm3 @ 6%O2, respectively). Pollutant concentrations in the flue gas during oxy-fuel\noperations remained low (for OXY30 SO2 < 14 and NOx 130 mg/Nm3 @ 6%O2 and for OXY21 SO2\n23 and NOx 156 mg/Nm3 @ 6%O2). Analyses of the collected ash samples showed a decreased extent\nof carbonate minerals decomposition during both oxy-fuel experiments. This results in decreased\ncarbon dioxide emissions. The outcomes show that oxy-fuel CFB combustion of the oil shale ensures\nsulfur binding and decreases CO2 production.
Loading....