采用热重分析仪和固定床反应器,对典型新疆煤(和丰煤)的单段热解(定义为过程1)和不同温度停留的分段热解过程进行了较详细研究。结果发现不同热解过程的煤样总失重率差异较小。不同温度段停留时均导致焦油产率下降和气体产率增加。与仅在350℃停留30 min(过程2)相比,继续于450℃(过程3)停留使得焦油产率进一步下降15.42%,且此温度区间的H2生成量仅为1.94 m L/g,较过程2降低94.47%,而450~600℃的气体产率占过程3总产率的60.87%,其中H2,CH4和C2-C4产率分别占各自总产率的95.02%,77.27%和66.08%,说明450~600℃以产气为主。不同温度段获得的半焦的红外分析发现350℃的半焦中官能团变化较小;而450℃的半焦中大部分官能团的振动峰几乎消失。模拟蒸馏和核磁结果表明,不同温度段停留均使得焦油中沥青质分率下降,焦油品质提升,焦油的芳香度降低,且两段停留段停留所得焦油的芳香度最低。通过上述研究,可以对新疆低阶煤的分级分质转化利用提供理论基础。

The pyrolysis technology for cascade utilization of low rank coal have been attracted much attention in recent years. Xinjiang is one of the important coal-chemical industrial base in China. But the fundamental research on pyroly- sis of Xinjiang coal is relatively few. In this paper,the single stage ( without iso-thermal stage,defined as process 1) and multi stage ( with iso-thermal stage at 350 ℃ and defined as process 2,with iso-thermal stages at 350 ℃ and 450 ℃ and defined as process 3) pyrolysis characteristics of a typical Xinjiang coal (Hefeng coal) were first investi- gated by using a thermogravimetric analyzer(TGA) and a fixed bed reactor. The results showed that the weight loss of coal samples during the single stage and multi stage pyrolysis in TGA exhibited a little difference. The multi stage py- rolysis led to the increase of gas yield and decrease of tar yield,especially for process 3,in which the tar yield further decreased to 11. 35% ,about 15. 42% decrement compared with that in process 2. The H2 yield was only 1. 94 mL / g when temperature was lower than 450 ℃ . Further increase temperature from 450 ℃ to 600 ℃ ,no tar was formed, while gas yield accounted for 60. 87% of total gas amount,especially for H2 which accounted for 95. 02% of total H2 yield. It indicates that gaseous products was mainly collected in this temperature range. FTIR analysis showed that only slight difference of the functional groups between the char obtained at 350 ℃ pyrolysis and raw coal was observed. While these functional groups nearly disappeared in char obtained at 450 ℃ . The simulating distillation and NMR a- nalysis results showed that holding stage in coal pyrolysis was favorable to upgrade the tar quality,which was embodied by the decrease of pitch content and the aromatic carbon ratio,especially for the two stage holding pyrolysis. Based on that,a theoretical basis for staged thermal conversion of low rank coal was supplied.