Study on pore and chemical structure characteristics of atmospheric circulating fluidized bed coal gasification fly ash

The pore and chemical structure characteristics of the raw coal and the coal gasification fly ash (CGFA) in an atmospheric pressure circulating fluidized bed gasifier with a gas production capacity of 20000 and 40000 Nm³ h⁻¹ were studied. The results indicated the presence of developed pore structure and high carbon content of the CGFA. The comprehensive fractal dimension method was proposed to analyze the pore structure of the pore section. The comprehensive fractal dimension was found to be > 2.6. The surface of CGFA is rough and porous. When compared to raw coal, the relative content of the CGFA carbon functional group is lower than 20%, and that of aliphatic carbon gets reduced. The interlamellar spacing (0.3489 nm, 0.3501 nm) of the A-filter cake ash (FCA^A), A-dry ash (DA^A), B-filter cake ash (FCA^B), and B-dry ash (DA^B) carbon is higher than that of the standard graphite (0.3354 nm), lean coal (0.3468 nm), and anthracite (0.344 nm). Moreover, the carbon structure is loose. The comprehensive results of physical and chemical structure revealed that CGFA showed a good chemical reaction activity and also the value of secondary combustion and gasification as fuel. This study exhibits significance and importance in the field of waste valorization towards a circular economy.