几种年轻煤在氮热等离子体中的热解

PYROLYSIS OF LOW. RANK COALS IN NITROGEN PLASMA

研究了几种中国年轻煤在氮电弧热等离子体中的热解行为,考察了煤的基本性质、煤的粒度及加煤速率等条件对煤热解特性的影响.结果发现,煤在氮等离子体条件下热解所得气体产物中的主要成分是氢、乙炔、一氧化碳和丙炔腈,此外还有甲烷和乙烯等小分子烃.乙炔的收率随煤种的不同和操作条件的变化而波动.煤中的挥发分含量愈高、加煤速率愈低,乙炔收率则愈高.其中扎赉诺尔褐煤的乙炔收率最高可达22.3%(以煤中碳为基准);原料煤在氮等离子体中热解后,除部分芳香C—C键得以保留外,煤有机结构中的外围官能团全部消失,同时在热解半焦中有新的氮基官能团(如—C(?)N)引入.

The flash pyrolysis of three low rank coals in a nitrogen plasma jet at atmospheric pressure has been studied. The results show that coal undergoes very fast reactions with highly reactive plasma species, which produces a large amount of gas and char. The main components of the gas products are hydrogen, methane, carbon monoxide, acetylene and cyanoacetylene. The concentration of cyanoacety-lene in the gas is related to that of acetylene. It is believed that acetylene acts as the precursor of cyanoacetylene. The acetylene yield depends on the coal type and the experimental conditions, and increases as the volatile matter content of coal increases and as the coal feeding rate is reduced. A maximum acetylene yield of 22. 31% by weight on a carbon basis is obtained from Zhalainuoer lignite when the coal particle size is less than 74μm and the coal feed rate is 5.1 g·min-1. The FT-IR spectra reveal that all of the functional groups in coal except some aromatic C-C bonds have vanished during the pyrolysis, and some nitrogen - containing functional groups such as-CN groups are simultaneously introduced into the chars.