哈密煤液化残渣焦气化反应活性

Gasification reactivity of Hami coal liquefaction residue char

  • 摘要: 液化残渣是煤炭液化过程的重要副产物,将其作为气化原料进行利用有助于提高煤炭综合利用效率。 基于高频炉开展不同温度条件下(1 000,1 300 ℃)快速热解实验制取哈密淖毛湖长焰煤焦及其液化残渣焦,采用热重分析仪考察不同气化温度(1 000,1 100,1 200,1 300 ℃)下煤焦和液化残渣焦的气化反应活性,并借助扫描电子显微镜、物理吸附仪和激光拉曼光谱仪对样品的理化特性(孔隙结构与碳结构)进行系统表征以关联解释焦样气化反应活性。 结果表明,哈密煤焦及其液化残渣焦的气化反应活性受气化温度、孔隙结构和碳结构的共同影响。相同热解和气化温度下煤焦气化反应活性高于液化残渣焦,主要由于煤焦和液化残渣焦孔隙结构和碳结构的差异:前者孔隙结构较后者更为发达,且碳结构有序度低于后者、无定形碳结构数量高于后者;气化温度从1 000 ℃升至1 300 ℃时,煤焦与液化残渣焦的反应性指数分别从0.43和0.38提高到0.81和0.79,反应指数比值从0.88提高到0.98,表明提高气化温度可以促进气化反应进行,但孔隙结构与碳结构对气化反应活性的影响减弱;气化温度为1 300 ℃时,温度成为影响气化反应活性的主要因素,液化残渣焦的气化反应活性接近煤焦,这表明从气化反应活性角度而言,液化残渣可以作为气流床气化原料加以利用。

     

    Abstract: Liquefaction residue is an important by-product of the coal liquefaction process and its application as gasifi- cation feedstock would help to improve the comprehensive utilization efficiency of coal resource. In this study,the rapid pyrolysis chars of Hami Naomaohu long flame coal and its liquefaction residue were prepared at different pyrolysis tem- peratures (1 000 ℃ and 1 300 ℃ ) using a high-frequence furnace. The gasification reactivity of chars was investiga- ted using a Thermogravimetric Analyzer (TGA) at different gasification temperatures (1 000 ℃ ,1 100 ℃ ,1 200 ℃and 1 300 ℃ ). In addition, Scanning Electron Microscopy, Physisorption Analyzer and Laser Raman Spectrometer were used to systematically characterize the physicochemical properties (pore and carbon structure) of samples so as to correlate the char gasification reactivity. The results show that the gasification reactivity of coal char and the lique- faction residue char was affected by gasification temperature,pore structure and carbon structure. The gasification reac- tivity of coal char was higher than that of liquefaction residue char at the same pyrolysis and gasification temperature, which was mainly due to the difference in physicochemical properties between coal char and liquefaction residue char. The former showed the more developed pore structure,the higher order degree of carbon structure and the greater a- mount of amorphous carbon structure than the later. The reactivity index of coal char and liquefaction residue char in- creased from 0. 43 and 0. 38 to 0. 81 and 0. 79,respectively,and the reactivity index ratio increased from 0. 88 to 0. 98 as the gasification temperature increased from 1 000 ℃ to 1 300 ℃ ,indicating that the increase of the gasification tem- perature can promote the gasification reaction,but the influences of pore structure and carbon structure on the char gasification reactivity was weakened. Specifically for the gasification temperature of 1 300 ℃ ,the temperature becomes the main factor affecting the gasification reactivity and the gasification reactivity of the liquefaction residue char was closed to that of coal char,demonstrating that the liquefaction residue could be utilized as a raw material in entrained- flow gasification based on the viewpoint of gasification reactivity.

     

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