Study On Active Functional Groups And Characteristic Temperature Of Spontaneous Combustion Variation Of Soaked Bituminous Coal

This paper uses three kinds of bituminous coal which soaked by water and dried as the research object,to study the change of chemical structure,characteristic temperature and activation energy in the process of oxidation spontaneous combustion of the raw coal samples and soaked bituminous coal by combining the theoretical analysis and the experiment.The influence of the water on the spontaneous combustion of coal was investigated.The Fourier transform infrared spectroscopy was used to analyze the function group of three kinds of coal samples with three particle sizes and five kinds of soaking days.With the increasing of soaking time,the content of the intramolecular hydroxyl group increased obviously,the content of fatty hydrocarbons increases slightly.But the functional groups such as carbonyl,aromatic ring,ether and carboxyl group have no obvious change.The X ray photoelectron spectrometer was used to study the law of changes in surface molecular structure and atomic valence state of different water immersion time of three kinds of raw coal samples and soaked bituminous coal with a particle size of 60-80.C,N,O,S and other elements are mainly included in five kinds of soaking time coal samples.The relative content of C atoms decreased with the increasing of soaking time,while the relative content of O atoms changes in the opposite order.The analysis of TG and DTG curves of coal samples of five kinds of soaking time of Wangwa can be found that the effect of water immersion is mainly on the active temperature T3 and the growth temperature T4.Temperature changes on other characteristic temperature points has a less effect.As the soaking time of the coal sample increasing,characteristic temperature of T2-T7 was all reduced.After soaking,the relative content of-OH in coal samples has increased.The increasing of the content of-OH weakens the C-C bond energy which linked between the benzene ring and the side chain,improving the activity of side chain structure.To a certain extent,the temperature of the coal sample is reduced to the dynamic equilibrium.The activation energy E and the pre finger factor A were calculated in four stages.The activation energy of the evaporation and desorption stage of water and combustion stage of the soaked coal was higher than raw coal,and the reaction activation energy in the phase of thermal decomposition showed the opposite rule.Through the analysis of the DSC and its integral curve of coal samples with five kinds of soaking time by Wangwa,The effect of water immersion on the three parameters has less effect,such as the maximum heat absorption temperature Tf1,the equilibrium point temperature Tb and the total heat absorption S1 of the coal sample.It has a significant influence on the maximum heat release temperature Tf2 and the total heat release S2.The maximum temperature Tf2 of coal oxidation reaction gradually decreases,which makes coal samples easier to oxidize,and coal is easier to burn.