低温热解提质对褐煤半焦影响的研究

Effects of Low-Temperature Pyrolysis Upgrading on Semi-Char of Lignite

为研究低温热解提质对褐煤半焦的影响,选取一种锡林郭勒褐煤利用固定床反应器在250 ℃、350 ℃、450 ℃、550 ℃ 4个温度下进行热解提质处理,对不同提质温度下制得的半焦从煤质参数、表观形貌、粒径分布、官能团、着火燃尽特性等方面进行表征。结果表明:热解提质显著降低半焦中挥发分含量,提高煤阶;在提质温度为350 ℃时,煤焦颗粒开始发生明显破碎;醇、酚、醚类、羧酸等含氧官能团在350 ℃下开始脱除。热重分析表明,随提质温度升高,半焦着火点先降低再升高,在350 ℃时达到最低;在提质温度低于350 ℃时,煤焦破碎对于着火温度的影响起主要作用;而提质温度高于350 ℃时,挥发分含量对于着火温度的影响占主导。

To investigate the effects of low-temperature upgrading on lignite semi-char, a typical Xilin Gol lignite was chosen to undergo pyrolysis upgrading in a fixed bed reactor at 250 ℃, 350 ℃, 450 ℃ and 550 ℃ separately. The semi-char samples produced under different upgrading temperatures were characterized from different aspects, including coal property, morphology, particle size, functional groups, ignition and burnout properties. The results showed that pyrolysis upgrading significantly lowered the volatile matter content, and upgraded coal rank;apparent fragmentation of coal particle was observed at 350 ℃, oxygen-containing functional groups like hydroxyl, phenols, linkage and carboxyl began to be removed at 350 ℃. Thermal gravimetric analysis showed that with the increase of upgrading temperature, ignition temperature of semi-chars decreased first and then increased, reaching the minimum at 350 ℃. When upgrading temperature is lower than 350 ℃, coal fragmentation has a major influence on ignition temperature. When upgrading is higher than 350 ℃, volatile content is the dominant factor affecting ignition temperature.