压力及温度对煤焦结构特性影响的实验研究

Pressure and Temperature Effects on the Structural Characteristics of Coal Char

煤颗粒进入加压气化炉中,首先经历快速热解形成煤焦,煤焦的结构特性与温度及压力密切相关,有必要对其进行系统深入的研究。采用加压沉降炉在不同终温、压力下制得柳沟烟煤煤焦样品,通过激光粒度分析仪、扫描电镜、比表面积仪和压汞仪等测试手段对所得焦样进行结构特性分析,并依据胶质体理论和挥发分气泡行为进行解释。结果表明,对于柳沟烟煤煤焦,常压条件下终温从1 000℃变化到1 400℃时,挥发分气泡聚并的现象减少进而形成量多而小的孔结构,氮吸附比表面积总体上升,孔隙率有所上升,膨胀率基本不变;终温1100℃条件下,表压从0 MPa变化到1.7 MPa时,挥发分气泡聚并的现象增多进而形成量少而大的孔结构,煤焦的氮吸附比表面积总体减小,孔隙率逐渐增大,膨胀率先增大后缓慢减小,在1.0 MPa时的膨胀率最大。

In a Pressurized entrained coal gasifier, fast pyrolysis of pulverized coal occurs at first so that char particles come into formation before reacting with water vapor and CO2. The formation of char is affected by temperature and pressure, which needs to be investigated. Liugou bituminous coal char samples were acquired under different temperature and pressure conditions by a pressurized drop tube furnace （PDTF） experimental system. Structure of the char samples were analyzed by the Malvern laser particle size analyzer （MLPSA）, the scanning electron microscope （SEM）, the specific surface area analyzer （SSA） and the mercury intrusion porosimeter （MIP）. The results were analyzed based on metaplast theory and volatile bubbles behavior. For the Liugou coal char at atmospheric conditions, when the maximum temperature increased from 1 000 ℃ to 1 400℃, the volatile bubble coalescence behavior decreased, a bigger amount of smaller pore structure was formed, the nitrogen adsorption specific surface area increased in general, the porosity slightly increased, and the swelling ratio of the particles basically had no change. For the Liugou coal char at 1100℃ conditions, when the gauge pressure increased from atmospheric pressure to 1.7 MPa, the volatile bubble coalescence behavior increased, a smaller amount of larger pore structure was formed, the nitrogen adsorption specific surface area decreased in general, the porosity had an increasing trend; and the swelling ratio of the particles increased to the maximum at 1.0 MPa and then slowly decreased.