Abstract: Physicochemical properties of char made by pyrolyzing a kind of low-rank particulate coal in O2-containing atmosphere and a quartz sand fluidized bed were investigated. The tested conditions included coal particle size, O2 concentration, pyrolysis temperature and residence time. The char with fixed carbon content over 82%(w) and volatile matter below 7%(w) was obtained by pyrolyzing the coal with particle size of 1~13 mm at the temperatures above 850℃ in the atmosphere with O2 content not below 3%(j) for pyrolysis time not shorter than 120 s. With the increase of temperature from 650℃ to 950℃, the corresponding interlayer spacing (d002) of the crystallite structure calculated from the XRD intensities was in the range from 0.383 to 0.372 nm, indicating a gradually condensed and ordered structure. BET specific surface area first increased then decreased with O2 concentration, and reached its maximum 242.71 m2/g at O2 7%(j), corresponding to the highest oxidation reactivity of char. The char produced via long-time pyrolysis in the O2-contaning atmosphere lowered the specific surface area and reactivity due to the burn-off of some formed pores.

Key words: low-rank coal, char, pyrolysis, O2-containing atmosphere

摘要： 以流化石英砂为介质，研究了热解温度、O2浓度、原煤停留时间及粒径等流化条件对由小粒径低阶碎煤所制半焦的理化性质的影响. 结果表明，1~13 mm小粒径低阶煤在热解温度大于850℃及O2浓度、热解时间分别不低于3%(j)和120 s的条件下，可制得固定碳含量高于82%(w)、挥发分含量低于7%(w)的兰炭. 热解温度由650℃升至950℃，碳晶格的微晶晶面间距(d002)由0.383 nm减小至0.372 nm，半焦晶格的有序化程度增加. 氧气浓度为7%(j)时，半焦的比表面积最大，为242.71 m2/g，同时氧化反应活性也最大. 延长有氧气氛下的热解时间，半焦孔隙结构因烧蚀而坍塌，半焦的比表面积和活性降低.

关键词: 低阶煤, 半焦, 热解, 有氧气氛