摘要
通过对原煤、酸洗原煤、酸洗后负载NaOH的原煤在750-1050℃热解制得焦样，用X射线衍射技术考察了热解温度、NaOH负载量以及灰分对热解过程中煤焦微晶结构变化的影响，并运用高温高压热天平（PTGA）考察了热解后煤焦的气化反应活性。结果表明碱金属及灰分的存在可以明显减小煤焦的微晶结构参数的变化（堆垛高度Lc、微晶尺寸La、及晶层间距d002），阻碍煤焦的石墨化进程，提高煤焦的气化反应性。随着热解温度的升高，堆垛高度Lc增大显著，而微晶尺寸La和晶层间距d002变化较小。煤焦的气化反应性岛和煤焦微晶结构参数Lc、d002存在如下关系：lnk0=a（Lc/d002）＋b；研究还表明用氧化还原循环机理来描述碱金属的催化作用机理是不恰当的，但碱金属Na的存在可以明显降低煤焦的石墨化程度，提高煤的活性，对煤焦的气化起到部分催化作用。
The experimental research on pyrolysis of original coal, acid washing deashed coal and alkali metal （NaOH） loaded deashed coal was conducted in tubular furnace for investigating the effects of alkali metal and coal ash on the variation of crystallite structure of chars prepared from above coals, separately, at temperature of 750-1050 ℃by using X-Ray diffraction （XRD） technique, and the char gasification reactivity was investigated by pressurized thermogravimeteric analysis system （PTGA）. Results show that the existence of alkali metal and ash decreases the crystallite structure parameters of the chars （average stacking height Lc, carbon crystallite site La and interplanar spacing doo2） prominently, inhibits the progress of char graphitizing and increases the gasification reactivity of the char. Lc increases apparently and La, d002 change little with the increase of pyrolysis temperature. Char gasification reactivity/Co has the following linear relationship with Lc： In ko=a （Lc/doo2） ＋b, where a and b are constants related with char species, pyrolysis and gasification conditions. Results also show that it is not suitable to describe the catalysis mechanism of alkali metals Na for char gasification by the mechanism of redox mechanism. But the existence of Na decreases the degree of crystallite and increases the reactivity, which has the catalytic effect on char gasification.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2010年第1期64-70,共7页
Journal of Chemical Engineering of Chinese Universities
基金
国家重点基础研究发展规划(973计划)(2004BC217704)
教育部"长江学者与创新团队发展计划"(PCSIRT-IRT0620)
关键词
气化反应
碱金属
微晶结构
石墨化
gasification reaction
alkali metal
crystallite structure
graphitizing
