Investigation on the forming property of chars physicochemical structure during biomass and lignite co-gasification

Thermo gravimetric analyzer (TGA) experiments for gasification of lignite, pine sawdust, rice husk, straw and co-gasification of their mixtures in CO2 atmosphere are conducted. The physic-chemical property is analyzed with Scanning Electron Microscope (SEM) and Fourier Transform Infrared Analysis (FTIR) of different gasification chars (320-850 ℃). The studies shown that the staring temperature and the end temperature of gasification are decreased under the mixed ratio of pine sawdust to lignite is 1:1. Explained that characteristics of mixture gasification is good; There are many spherical particles in pine sawdust chars. Alkali metal such as K, Ca etc. content is higher of the spherical particle, along with the gasification temperature rises in turn have the changing process of deformation, fold and collapse. The volatilization of alkali metals are mainly concentrated in coke gasification stage; Compared with the lignite, the pine sawdust have higher content of hydroxyl groups, aliphatic hydrocarbon keys etc.. The aliphatic structure of the pine sawdust fractures earlier than other functional groups in the co-gasification process, to provide plenty of reducing atmosphere for gasification reaction. The small molecular side chain -NH-, alkyl group -CH2-, -CH3, the structure of the aromaticity alkanes keys such as -CH2-, -CH3, C=C and ether have released combined with volatile matters emission during co-gasification process. It is eliminated earlier presented decreased FTIR spectrum peaks during gasification segment than the lignite gasification alone. It is shown that the biomass joined have accelerated the -NH-, -CH2-, -CH3, C=C and ether bond rupture during the gasification process. To further confirmed the co-gasification of biomass and coal from the microscopic view have synergism. © 2015, Science Press. All right reserved.