生物质与褐煤气化特性及半焦物化特性的演变规律

INVESTIGATION ON THE FORMING PROPERTY OF CHARS PHYSICOCHEMICAL STRUCTURE DURING BIOMASS AND LIGNITE CO-GASIFICATION

对褐煤、松木屑、稻壳、秸秆及其掺混试样在CO2气氛下进行共气化热重实验，采用扫描电镜与傅里叶红外光谱仪对不同温度下（320～850℃）所得半焦的物化结构进行研究分析。研究发现：松木屑与褐煤按质量比1：1掺混时，其开始气化温度和气化终止温度有所降低，说明混合燃料的气化特性较好；松木屑半焦中存在K、Ca等碱金属含量较高的球形颗粒物；随着气化温度的升高依次发生变形一褶皱一塌陷的变化过程，而碱金属的挥发主要集中在焦炭气化阶段；与褐煤相比，松木屑中羟基、脂肪族烷烃键等含量较高，气化时较低温度时即会断裂，从而为气化反应提供充足的还原性气氛。共气化过程中，小分子侧链-NH-键、烷基-CH2-、-CHSs键、芳香性烷键结构上的-CH2-、-CH，键、C=C键、醚键等含氧官能团的谱峰消失温度较褐煤单独气化时提前，表明共气化过程中生物质的加入加速了-NH-、-CH2-、-CH3、C=C及醚键等的断裂，进一步从微观角度证实生物质与煤共气化的协同作用。

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.