Study On Structural Thermal Evolution And Spontaneous Combustion Tendency Of Shengli Lignite

Shengli lignite of Inner Mongolia Autonomous Region was treated as research object in this thesis.The chars were made at different temperature under inert gas atmosphere.Programmed temperature and gradient isothermal combustion experiments were carried out with fixed bed combustion device.The oxygen adsorption capacity of coal samples was measured by pulse adsorption.The structures of coal samples were characterized by XRD,Raman,XPS and FT-IR to reveal the structural thermal evolution in pyrolysis process and spontaneous combustion tendency of Shengli lignite.In the pyrolysis process of Shengli lignite,structural thermal evolution was accompanied.With rising pyrolysis temperature,fat side chains and oxygen functional groups in coal structure were gradually removed.The structure of coal was mainly intermolecular condensation in pyrolysis range of 500-700℃.When pyrolysis temperature exceeded 700℃,the half peak width of G and D peak decreased rapidly and fa increased obviously,which indicated the graphitization degree of char accelerated significantly.The adsorption capacity of chars increased firstly and then decreased with the increase of pyrolysis temperature,SL-600J was the largest one.Combustion reactivity decreased with the temperature went up.The combustion reaction in 300-500℃changed a little.The initial combustion temperature of SL-600J increased obviously.In combustion reaction,turning point of pyrolytic temperature for demineralization char was 500℃.The addition of LiOH,NaOH,KOH and Ca（OH）₂ changed combustion reaction performance of Shengli lignite.To prevent the spontaneous combustion of Shengli lignite,the best pyrolytic temperature was 600℃,and that of demineralization coal sample was 500℃.The inherent minerals had a significant effect on structural thermal evolution in pyrolysis process and combustion performance.The main reason was the existence of minerals delayed the process of graphitization.On the other hand,minerals changed combustion reaction performance of coal samples.The addition of NaOH put off the process of graphitization and improved the combustion reactivity significantly.