Study On The Change Of Functional Groups And Pore Structure Of Low Volatile Coal During Combustion Under Weak Reducing Atmosphere

China is rich in low-volatility coal,and it is the country with the most production in the world.More and more coal-fired power plants use low-volatility coal.In the process of combustion,there are unstable combustion,low combustion efficiency and high pollutant emissions.And other issues.In order to achieve efficient and clean combustion of coal,many scholars at home and abroad have studied the changes of physical and chemical structure of coal during combustion,but little research on the changes of coal functional groups and pore structure and the effect of low oxygen concentration on combustion in the combustion process..Therefore,this subject has conducted in-depth research on the evolution of coke functional groups and pore structures during the combustion of coal under weak reducing atmosphere conditions.Based on the low-volume coal production in different regions of China and the status of coal-fired thermal power plants,three typical coal types were selected for fuel characteristics analysis.Thermogravimetric analysis method combined with combustion kinetics analysis was conducted to study the combustion process of different oxygen concentrations on coal types.The effects of combustion characteristics such as ignition,steady combustion and burnout were carried out.Secondly,coal char samples with different oxygen concentrations and different combustion stages were prepared on the modified tubular furnace,and functional group structure analysis was carried out by means of Fourier transform infrared spectroscopy(FTIR).The change law of coal char functional group and the effect of different oxygen concentration on the functional group change were studied.Finally,the pore structure analysis and SEM surface morphology analysis of the prepared coal char sample were carried out by isothermal N2 adsorption method and SEM scanning electron microscopy.The variation of coal coke specific surface area,pore structure and surface morphology during combustion and the effect of different oxygen concentration on the pore structure of coal char.The results show that with the decrease of O2 concentration,the ignition index of the ignition point decreases,the ignition is more difficult,the comprehensive combustion characteristic index value and the apparent activation energy also decrease,and the different coal types change differently.In the functional group,with the burning During the process,the relative content of functional groups such as hydroxyl,aliphatic and aromatic hydrocarbons in the functional group of coal char is reduced,and the relative content of ether groups is increased.The combustion of coal char functional groups has similar changes under different O2 concentrations;coal is burning During the process,the specific surface area and pore volume experienced a process of increasing first and then decreasing.The surface of the raw coal was smooth and the pore structure was less.The coal char had a more continuous pore structure,and a similar change trend occurred during the combustion process:in the early stage of combustion.The mesoporous part(2?20nm)fluctuates greatly,and the general trend is that the medium and large holes increase.As the O2 concentration decreases,the temperature corresponding to the specific surface area and pore volume reaches a maximum,and the maximum specific surface area also decreases.