Experimental Study On The Effect Of Ca-based Additives On Pyrolysis And Combustion Characteristics Of Bituminous Coal

Energy is the material basis of human existence and the source of social development.In China's current energy pattern,coal still occupies the dominant position in the energy market,and will not change in the short term.At present,the two most important utilization modes of coal in China are pyrolysis and combustion.Many scholars at home and abroad have done a lot of research on the catalytic effect of Ca-based additives in the process of coal pyrolysis and sulfur fixation in the process of coal combustion,but there are few reports on the types and amounts of Ca-based additives.Therefore,this paper makes an in-depth study on the effects mechanism of the types and amounts of Ca-based additives on coal pyrolysis and combustion characteristics.The typical bituminous coal(mianchi coal,yima,henan province)was selected as the sample for analysis.Ca-based minerals(CaO,Ca(OH)2,CaCO3)were mixed with coal samples in a certain proportion to prepare analysis samples.By reforming the existing tubular furnace,adding the atmosphere control and regulating system,simulating the atmosphere environment of pyrolysis and combustion,to prepare pyrolysis and combustion of coal coke samples.The samples of coal coke after pyrolysis and combustion were analyzed one by one with FTIR to study the effects of Ca-based additives on functional groups during pyrolysis and combustion of bituminous coal.The samples of coal coke samples after pyrolysis and combustion was tested by SEM to study the effects of Ca-based additives on the microstructure of bituminous coal during pyrolysis and combustion.The pyrolysis and combustion characteristics of the samples were analyzed by thermodynamic and kinetic analysis using thermogravimetric analyzer to study the effects of Ca-based additives on the pyrolysis and combustion of bituminous coal.The results show that CaO,Ca(OH)2 and CaCO3 all accelerate the cleavage of-COOH and-OH functional groups during coal pyrolysis.CaO,Ca(OH)2 and CaCO3 all promote the decomposition of oxygen-containing functional groups and aromatic functional groups during coal combustion.During the pyrolysis of raw coal,the phenomenon of hardening occurs,which hinders the precipitation of pyrolytic gas.Ca-based additives can avoid this phenomenon.Ca-based additives have little effect on the microstructure of coal combustion coke.CaO,Ca(OH)2 and CaCO3 have catalytic pyrolysis effect on coal.Moderate addition can accelerate the pyrolysis rate,while excessive addition may inhibit the pyrolysis rate.Ca-based additives can reduce the activation energy of coal pyrolysis,and Ca(OH)2 has the most significant effect.Ca-based additives can only promote the combustion process in the initial stage,can reduce the ignition temperature,the impact of combustion characteristics are reflected in side effects;The combustion activation energy of coal can be reduced by adding CaO,and can be increased by adding Ca(OH)2 and CaCO3.