褐煤经四氢化萘处理后的结构及热解-气化特性分析

在小型反应釜上采用非极性有机溶剂四氢化萘(tetrahydronaphthalene, THN)对内蒙古锡林郭勒褐煤进行脱水,获取了不同温度下的脱水试样,运用傅里叶红外光谱(Fourier transform infrared spectroscopy,FT-IR)分析技术对比研究了在不同脱水温度下煤样中有机官能团的变化,通过FT-IR谱图的分峰拟合计算,对脱水煤样的化学结构变化特征进行半定量分析,并结合热重(thermal gravity analysis/differential thermal gravity,TG/DTG)和实验室固定床反应器(fixed bed reactor)考察了不同脱水温度下煤样的热解气化特性和热解气相产物分布规律,并对脱水煤样在最大失重速率区间的动力学参数进行了计算。试验结果显示:四氢化萘溶剂对褐煤的脱水提质是有效的,150~200℃时C O开始分解,而此时芳香环上的C C仍然相对稳定。随着脱水温度的升高,芳香类氢含量先减小后增大,脂肪类氢含量先增大后减小,芳香度和芳香碳在脱水温度范围内逐渐增大。煤样的脱水温度升高,热解气相产物H₂、CH₄、CO累积产率增大,CO₂累积产率减小;脱水煤样热解活化能随着脱水温度的升高而升高,进而导致脱水温度较高煤样热解失重率降低。

Analysis of structure and pyrolysis and gasification characteristics of lignite after tetrahydronaphthalene treatment

Dewatering and upgrading of Inner Mongolia Xilingol lignite in non-polar solvent (tetrahydronaphthalene, THN) were carried out in a miniature autoclave. The changes of organic functional groups in coal samples at different dewatering temperature were analyzed based on Fourier-transform infrared (FT-IR) analyzer. The fitting calculation for FT-IR spectra has been carried out. Besides, a semi-quantitative analysis for characteristics of chemical structure change was presented. The pyrolysis and gasification reactivity and distributive rules of gas phase product during pyrolysis and gasification of coal with various dewatering temperature were carried out by means of thermogravimetric analysis (TG) and a bench-scale fixed-bed pyrolysis reactor. The kinetic parameters of coal samples were calculated within the range of the maximum weight loss rate. The results showed that the non-polar solvent THN treatment was effective in dewatering and upgrading of Xilingol lignite. The C O bonds started decomposing between 150 and 200℃, while the aromatic C C bonds in the aromatic ring remained relatively stable. With increasing dewatering temperature, the content of aromatic hydrogen decreased first and then increased, while the content of aliphatic hydrogen increased first and then decreased. The aromaticity and aromatic carbon increased gradually with increasing dewatering temperature. When dewatering temperature was higher, the cumulative yields of gas phase products of H₂, CH₄ and CO were increased and CO₂ was dropped during pyrolysis. The reaction activation energy of the dewatered coal increased with increasing dewatering temperature, decreasing the pyrolysis reactivity of the coal samples.