热解条件对煤焦气化活性影响的研究进展

STUDY ON INFLUENCE OF PYROLYSIS CONDITIONS ON CHAR GASIFICATION REACTIVITY

简述了原煤性质与温度、压力和热解气氛等热解条件对煤焦结构和气化反应活性的影响;参考该领域的国内外研究成果,分析了热解条件影响煤焦气化反应活性的机理.由于实验设备和研究方法的差异,对温度和压力等热解条件对煤焦气化反应活性影响的评价不尽相同,但总体来讲,热解终温越高、停留时间越长、升温速率越快、热解压力越大,煤焦的气化反应活性越低;热解过程中,原煤性质的差异也会影响煤焦的结构和气化反应活性.煤焦的石墨化应该是导致煤焦气化反应活性下降的主要原因,因此,热解条件的改变,特别是温度和压力的改变对煤焦石墨化进程的影响值得进一步研究.

Effects of coal properties and coal pyrolysis conditions, such as temperature, pressure and pyrolysis atmosphere, on the physical and chemical structure as well as gasification reactivity of chars in the open literature have been reviewed. The mechanisms leading to the effectof pyrolysis conditions on char gasification reactivity were analyzed refering to another researchers results. Diverse conclusions about these effects on char gasification reactivity were obtained because of the differences among different research jobs. But, in general, from most of the previous studies it appears that gasification reactivity of coal chars decreases with increasing pyrolysis temperature, increasing residence time, decreasing heating rate and increasing pyrolysis pressure, also, the differences exist in properties of parent coals can arise changes of char structure then the gasification reactivity. Most researchers found that char structure became more ordered, i. e. graphitization of chars, after coal pyrolysis process. It has been proved that gasification reactivity of the graphitized carbon was less than that of the non-graphitized carbon. Graphitization is supposed to be the key factor which influences the char gasification reactivity. So progressing the understanding of the effect of pyrolysis conditions, especially pyrolysis temperature and pressure, on char graphitization and its relation to coal properties and char gasification reactivity is an obvious research need.