Experimental Research On Transformation Of Sulfur Of Demineralized Coal During Pyrolysis Base On OCCSS

CO₂ mitigation is gaining more and more attention for the global warming problem getting worse.Oxy-Coal Combustion Steam System for power generation with near-zero emissions?OCCSS?as the latest CO₂ mitigation technology has broad prospects,it is need to research the basic problems in depth due to O₂/H2 O combustion is a new type of combustion,including the evolution of sulfur related components during combustion under high steam concentration.To achieve this purpose,the samples of Guizhou high sulfur,Datong high sulfur and their demineralized coals which meeting the requirements of OCCSS are used to investigate the transformations of sulfur with different temperature from 700?to 1200?in drop tube furnace during pyrolysis.The effects of temperature and minerals on sulfur transformations during high temperature in drop tube furnace are examined by XPS,XRD combined with total sulfur analysis method analyses on the resulting chars.The raw coals are demineralized by HCl-HF-HCl characteristics of coals are analyzed by TG,FTIR,XPS,XRD,weight loss is increasing and rate of maximum weight loss is decreasing after acid washing;demineralization can remove clay,silicate and so on while it do not change the main structure of coal;it makes little difference to total sulfur and various sulfur forms between raw and demineralized coal,thiophenes and sulphides are the major sulfur components of the two coals whatever they are demineralized or not.The results of TG show that volatile yields gradually increased,char yields gradually decreased and the degree of pyrolysis gradually deepened with increasing temperature.Total sulphur in Guizhou char gradually decreased with increasing temperature,slightly increased except at 1100?as a result of more stable thiophenic structures formed.It is difference for Datong char which total sulfur sharply decreased from 700? to 800?,while continuously increased above 800 ?.The sulfur retention by minerals can be confirmed for the fact that total sulfur in raw coals always higher than in the acid washed samples at different temperature.Thiophenes are the major sulfur components of char surface during coal pyrolysis at different temperature by XPS,sulfur forms decreased with increasing temperature.At high temperature,sulfur in different forms can decompose and transform,sulphide sulfur in surface decomposed totally at 1000?,sulphide sulfur,unstable thiophenes will transform into more stable thiophenic structures.Pyrite initially decomposes to form pyrrhotite,further decomposes to troilite.