CAJ | 학술논문

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L_c、微晶尺寸L_a、及晶层间距d_(002)),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L_c增大显著,而微晶尺寸L_a和晶层间距d_(002)变化较小.煤焦的气化反应性k0和煤焦微晶结构参数L_c、d_(002)存在如下关系:lnk_0= a (L_c/d_(002))+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.
통과대원매、산세원매、산세후부재NaOH적원매재750～1050℃열해제득초양,용X사선연사기술고찰료열해온도、NaOH부재량이급회분대열해과정중매초미정결구변화적영향,병운용고온고압열천평(PTGA)고찰료열해후매초적기화반응활성.결과표명감금속급회분적존재가이명현감소매초적미정결구삼수적변화(퇴타고도L_c、미정척촌L_a、급정층간거d_(002)),조애매초적석묵화진정,제고매초적기화반응성.수착열해온도적승고,퇴타고도L_c증대현저,이미정척촌L_a화정층간거d_(002)변화교소.매초적기화반응성k0화매초미정결구삼수L_c、d_(002)존재여하관계:lnk_0= a (L_c/d_(002))+b;연구환표명용양화환원순배궤리래묘술감금속적최화작용궤리시불흡당적,단감금속Na적존재가이명현강저매초적석묵화정도,제고매적활성,대매초적기화기도부분최화작용.
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 L_c, carbon crystallite site L_a and interplanar spacing d_(002)) prominently, inhibits the progress of char graphitizing and increases the gasification reactivity of the char. L_c increases apparently and L_a, d_(002) change little with the increase of pyrolysis temperature. Char gasification reactivity k_0 has the following linear relationship with L_c: ln k_0=a (L_c/ d_(002)) +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.