两种不同脱水方式对褐煤热解特性的影响

Effects on two dewatering methods of lignite pyrolysis characteristics

为了对脱水提质后的褐煤规模利用提供基础数据,采用热风转筒干燥和微波脱水对褐煤进行脱水,对所得干燥褐煤进行固定床热解试验。采用热重分析仪(TG)和热重质谱联用分析仪(TG-MS)等实验设备对比研究了不同干燥煤样热解特性的变化规律,在此基础上采用模拟蒸馏分析仪以及粒度分析仪研究了热解焦油组成和热解半焦粒度的分布规律。随着微波干燥功率的增大和热风转筒干燥时间的延长,干燥煤样热解活化能增大。原煤和不同的干燥方式下煤样在热解过程中达的到最大释放强度在487.5℃左右,虽然褐煤在微波干燥后热解活性有所下降,但改变并不剧烈,干燥煤样仍保持了较高的热解活性。微波干燥煤样的挥发分产率小于热风转筒干燥煤样,且热风转筒干燥煤样细粒径含量更多,这对于热解过程中挥发分的释放具有促进作用。

In order to provide basic data for the scale utilization of lignite after dehydration and upgrading, the authors con- ducted lignite dewatering by using hot air rotary kiln drying and microwave dehydration, and pyrolyzed the dried lignite in a fixed bed reactor. According to comparative study the pyrolysis characteristics＂ change rules of different dried coal samples by using thermogravimetric analyzer （TG） and thermogravimetric mass spectrometry （TG-MS）, the composition of pyrolysis tar and par- ticle size distribution of pyrolysis char were studied by means of simulated distillation analyzer and particle size analyzer. With the increase of microwave drying power and the drying time of hot air rotary kiln drying, the pyrolysis activation energy of dried coal sample increased. The maximum release intensity was at 487. 5 ~C during pyrolysis process between raw coal and coal samples with different drying methods. Although the microwave drying of lignite pyrolysis activity decreased, changes was little, and the dried coal samples still maintained high pyrolysis activity. The yield of volatile matter in microwave drying coal sample was less than that of hot air rotary kiln drying coal sample, and the hot air rotary kiln drying coal contained more thin particles, which pro- moting to release volatile during pyrolysis process.