SOx emission during the oxy-fuel combustion of density separated coal fractions

A Chinese bituminous coal was separated into three density fractions using the float-sink method: heavy (> 2.0 g/cm3), medium (1.4-2.0 g/cm3) and light (3). First of all, organic S, inorganic S and sulfate S contents in the three different coal samples were analyzed chemically. In this study Inorganic S was mostly made up of pyrite S in raw coal sample; Organic S almost contained in light fraction; Inorganic S mainly contained in heavy fraction; Most of Sulfate S and part of pyrite S and organic S mainly contained in medium fraction; Fundamental release of SO2 and other S-species have been investigated in a programmed-temperature horizontal quartz tube furnace by means of pollutants on-line analyzer and infrared gaseous analyzer. The experimental results indicated that two obvious peaks were observed for SO2 emissions of high and medium density fractions under O2/CO2 atmosphere, while the light density fraction emission curve was low and smooth without obvious peak. The concentration of CO increased under O2/CO2 atmosphere, which is favorable for COS formation in flue gas. Meanwhile, the increase of S compounds in ash and SO3 emission during the process, which were all factors that leaded to the decreasing of SO2 emission in O2/CO2 atmosphere.