油页岩固定床干馏过程三维数值模拟

主要研究了固定床内油页岩干馏过程的三维数值模拟。通过对固定床内气固相间传热传质过程的分析,建立了完整的气固两相传热传质模型,并采用多孔介质模型与流动模型相结合,将干馏过程中水分析出和干馏油气的析出过程通过用户自定义接口添加到模拟过程中。针对实际工况进行了模拟研究并与实验结果进行比对,吻合程度较好。此外,分别从进气速度和进气温度等方面进行对比分析,研究结果表明当进气速度提高0.5倍时,干馏进程加快1 600 s。当进气速度降低0.5倍时,干馏进程延缓4 200 s,换热效率明显降低。进气温度提高100℃,干馏进程加快600 s,油页岩中干酪根热解过程前期水分最大蒸发速率提高约11.4%。当进气温度降低100℃时,干馏进程延缓1 300 s,干酪根热解过程前期水分最大蒸发速率降低约24.7%。在气体热载体和传质过程的共同作用下,靠近进气位置的底部颗粒与周围环境气体中水蒸气及干馏油气之间的浓度梯度小于上部颗粒,这也是固定床内上部颗粒干馏进程较慢的一个重要原因。

Three-dimensional Numerical Simulation of Retorting Process of Oil Shale in Fixed Bed

The three-dimensional numerical simulation of the oil shale retorting process in a fixed bed is studied in this paper. Through the analysis of the heat and mass transfer process between gas-solid phase in the fixed bed, a complete gas-solid two-phase heat and mass transfer model was established, and combined with porous medium model and flow model, the precipitation process of moisture and the precipitation process of dry distillation oil and gas during dry distillation were added to the simulation process through user-defined interface. In this paper, the simulation study was carried out for the actual working conditions and compared with the experimental results, and the degree of consistency is better. In addition, comparative analysis was carried out from the aspects of intake speed and intake air temperature respectively. The results show that when the intake speed is increased by 0.5 times, the dry distillation process is accelerated by 1600s. When the intake speed is reduced by 0.5 times, the dry distillation process is delayed by 4200 s, and the heat exchange efficiency is significantly reduced. The intake air temperature is increased by 100 ° C, the dry distillation process is accelerated by 600 s, and the maximum evaporation rate of the kerogen pyrolysis process in the oil shale is increased by about 11.4%. When the intake temperature is lowered by 100 °C, the dry distillation process is delayed by 1300 s, and the maximum evaporation rate of the kerogen pyrolysis process is reduced by about 24.7%. Under the combined action of the gas heat carrier and the mass transfer process, the concentration gradient between the bottom particles near the intake position and the water vapor and dry distillation oil in the ambient gas is smaller than that of the upper particles. This is also an important reason for the slow distillation process of the upper particles in the fixed bed.