秸秆水热生物炭燃烧特性评价

Evaluation on Combustion Characteristics of Straw Hydrothermal Bio-char

摘要:

为推动水热生物炭燃料化利用，以不同水热炭化温度（200、240、280、320、360℃）下得到的小麦秸秆水热生物炭为原料，利用生物炭化学组成、动力学参数、燃烧指数对水热生物炭燃烧特性进行了评价，并研究了水热炭化温度对燃烧特性的影响。研究结果表明，随着水热炭化温度由200℃增加到360℃，由于脱水、脱羧反应的发生，水热生物炭的燃料比由0.34增加到1.2，O/C和H/C物质的量比分别由0.5、1.17降至0.07、0.67，水热生物炭的煤化程度升高；水热生物炭在低温段、高温段的活化能分别由14、67kJ/mol增加到41.4、76.5kJ/mol，水热生物炭燃烧反应活性降低；无量纲燃烧指数Z由3.49×10-2降至6.64×10-3，表明燃烧反应活性降低，这与化学组分和表观活化能的评价结果一致，指数Z可用于衡量水热生物炭的燃烧活性。

关键词:秸秆;水热生物炭;燃烧特性;无量纲燃烧指数;动力学参数

Abstract:

Hydrothermal bio-char (ht-biochar) produced from hydrothermal carbonization at different temperatures (200℃, 240℃, 280℃, 320℃ and 360℃) were used as material. Chemical composition, kinetic parameters, combustion index were applied in evaluating the combustion characteristics of ht-biochar.The effects of hydrothermal temperature on the combustion characteristics were also studied. It can be concluded that with the temperature increasing from 200℃ to 360℃, the weight ratio of fixed carbon to volatiles in ht-biochar was increased from 0.34 to 1.2, accompanying with the decrease of O/C (mol/mol) and H/C (mol/mol) from 0.5 and 1.17 to 0.07 and 0.67, respectively. The increase of temperature deepened the coalification degree of ht-biochar. When the hydrothermal temperature was amounted to 320℃, the chemical composition of ht-biochar resembled that of bitumite. At elevated temperature, combustion index Z of ht-biochar was decreased from 3.49×10-2 to 6.64×10-3， indicating that the increase of temperature reduced the combustion activity, which could be confirmed by the variation of chemical composition and calculation results of kinetic parameters. This proved that dimensionless combustion index Z could be used to rate the combustion characteristics accurately.

Key words:straw;hydrothermal bio-char;combustion characteristics;dimensionless combustion index;kinetic parameters