褐煤水分和挥发分析出特性研究

Moisture and volatile releasing characteristics of lignite

为研究我国典型褐煤的水分和挥发分析出特性,以宝日希勒褐煤为原料,采用烘箱和热重等温实验在不同温度和粒径下对褐煤的水分析出特性进行研究,并对褐煤水分析出机理进行探讨,建立了相应的机理方程。采用马弗炉等温热解实验对褐煤的挥发分析出过程进行研究。结果表明,褐煤中水分的析出过程受温度和粒径2种因素影响,温度的升高可以弥补大颗粒传热传质阻力的影响。由于水分赋存形式的不同,褐煤低温脱水过程可分成2个阶段,分别对应不同结合形式水分的析出,有着不同的干燥机理方程,而相对较高温度脱水时则没有明显的界限差别,比较适合的褐煤脱水温度和脱水粒径分别为150-200℃和15 mm以下。挥发分的析出则主要与温度有关,从200℃开始析出,400℃后大量析出,1 000℃以下,温度升高,析出量增多,但随着温度上升,增加趋势变缓。

In order to study the moisture and volatile releasing properties of Chinese typical lignite,a Mengdong lignite was adopted as research object at different temperature and particle size using isothermal oven and thermo-gravimetric to study its moisture releasing properties. The mechanism equations were gained. The volatile releasing properties were also studied using the isothermal muffle furnace. The results showed that the moisture releasing process was affected by temperature and particle size,which dramatically hampered the heat and mass transfer but it could be modified by increasing temperature. Due to different moisture storage forms,two stages existed during the low heating temperature dewatering process,corresponding to different kinds of moisture releasing and mechanisms. Whereas dewatering under the relative high temperature was not complex. The appropriate condition for dewatering was that,the temperature ranged from 150 ℃ to200 ℃ and the coal particle size was below 15 mm. The volatile releasing process,which was mainly related to the temperature,lasted from200 ℃ to 1 000 ℃,and enhanced after 400 ℃. Besides,the releasing amount increased with the temperature rising,then increased gradually unobvious at high temperature.