摘要
为了解褐煤热转化过程中锗元素的迁移规律和机理,采用固定床反应器,在1 173、1 273和1 373 K条件下,分别测量了热解(100%N2)和燃烧(3%O2+97%N2)2种不同气氛下褐煤内锗元素的气态释放比例。结果表明,在2种气氛条件下,锗元素的气态释放比例均随着热转化温度的升高而增加,在1 373 K的条件下分别达到了91.0%和95.6%。在3种温度情况下,燃烧过程中锗元素的气态释放比例均低于相同温度条件下的热解过程。分析表明,主要是由于焦炭内的部分含锗有机物被氧化为二氧化锗,而二氧化锗在氧化性气氛中难以气化所导致的。基于上述规律,首次提出了含锗飞灰(锗精矿)的形成机理:褐煤中的锗元素完全以含锗有机物的形式存在,这些含锗有机物会在高温条件下首先热分解为短碳链的含锗气态小分子(X-Ge),随后这些气态小分子在飞灰细颗粒表面发生异相沉积,并最终被氧化为二氧化锗。
To investigate the transformation mechanism of Ge,a fixed bed reactor was used to measure the volatilization of Ge during lignite thermal transition at the heating temperature of 1 173 K,1 273 K and 1 373 K respectively. Two types of atmospheres were considered：100% N2 to simulate pyrolysis and 3% O2 in N2balance to simulate combustion. The results showed that the volatilization of Ge increased with the increase of temperature in both oxidizing and inert atmospheres,and it reached 91. 0% and 95. 6% at 1 373 K respectively. However,the oxidizing atmosphere suppressed the volatilization of Ge at 1 173,1 273,and 1 373 K,which was mainly caused by the oxidation of organic compounds of germanium in lignite,and followed by formation of germanium dioxide. Based on the experimental results,the enrichment mechanism of Ge in fly ash during lignite combustion was proposed for the first time. Ge mainly existed in organic form in lignite.During combustion process,it first decomposed into Ge-bearing small gaseous molecules（X-Ge）. Then these gaseous molecules condensed on the surface of fly ash particles,and they were oxidized into germanium dioxide in the final stage.
出处
《洁净煤技术》
CAS
2016年第3期69-73,89,共6页
Clean Coal Technology
基金
国家国际科技合作专项资助项目(2014DFA41100)
关键词
褐煤
锗
燃烧
热解
气态释放
lignite
germanium（Ge）
combustion
pyrolysis
volatilization
