煤非催化加氢热解过程中脱硫脱氮效应及硫变迁特性

DESULPHURIZATION AND DENITROGENATION AND SULPHUR TRANSFER DURING NON-CATALYTIC HYDROPYROLYSIS OF COAL

采用５ｇ固定床热解反应器和在线热解质谱，对煤加氢热解过程的脱硫脱氮效应及硫变迁特性进行了考察。结果表明，煤中几乎所有硫铁矿硫被脱除殆尽，半焦中残存的微量硫主要表现为硫酸盐硫。而热解过程中硫往焦油产物组分的变迁、转移主要取决于煤中噻吩类含硫化物的不完全氢化还原反应，而与煤中其它有机硫化物的含量关系不大，从而使高噻吩煤难于获得低硫甚至无硫洁净焦油产物。同时发现，由于氢传质扩散的相对滞后，微量硫与煤中内在氧发生氧化反应，生成ＳＯ２。与加氢热解脱硫效应相比，有机氮的脱除非常困难，且与煤种密切相关。兖州煤脱氮率视工艺条件可达２５～４５％，而红庙煤大部分含氮化合物则从固体产物转移至焦油组分中。

The desulphurization and denitrogenation as well as sulfur transfer during noncatalytic hydropyrolysis of two Chinese coals were systematically investigated in a 5g fixed bed reactor equipt with a online mass spectrometer The results indicated that pyritic and organic sulfur in coal were almost totally removed from chars, sulfur remaining in chars was therefore mainly sulfate sulfur However, the characteristics of sulfur transfer into tar products and sulfur content of tars are mainly related to the incomplete reduction of thiophenic sulfur and almost independent of sulfides content of coal Besides the majority of sulfur being reduced to H 2S it was also found that the sulfur transfer during hydropyrolysis involves formation of new organic sulfurcontaining compounds in tars by incomplete reduction of thiophenic sulphur Because of relative delay of hydrogen mass transfer sulfur oxidation by internal oxygen in coal also occurs which results in the formation of trace amount of SO 2 Compared with sulfur removal, the process denitrogenation is more notably related to coal types For Hongmiao lignite, almost all the nitrogen removed from coal is transferred and enriched into tar product, however, for Yanzhou bituminous coal, 25￣46% of nitrogen is removed in the process