生物质流化床热解焦油演化的CFD–DEM数值模拟研究

MODELING TAR EVOLUTION DURING BIOMASS PYROLYSIS IN A FLUIDIZED BED REACTOR BY USING A CFD–DEM METHOD

流化床热解是生物质热化学转化的重要方法,焦油生成是最为突出的瓶颈问题。本文采用欧拉–拉格朗日算法并结合多步热解模型和一种新型焦油裂解模型对高温热解条件下生物质焦油的演化进行数值模拟研究,给出了600℃~800℃热解中焦油裂解对小分子挥发分产量的影响规律。结果表明,本文所建立的多相反应流算法能够较好地捕捉中高温条件下焦油裂解对热解产物的影响规律。本研究为深入认识生物质流化床热解特性提供了一种有力工具。

Biomass gasification in fluidized bed reactors is one of the most important utilization methods through thermochemical conversion. Tar generation is the bottleneck of this technology. In this work, numerical simulations for biomass tar evolution under medium to high temperature pyrolysis conditions are carried out by combining a Euler– Lagrangian framework with a multistep pyrolysis model and a new tar cracking model.Comparison for the tar cracking under 600℃~ 800℃ operation conditions is studied and the corresponding effect on the light gas yield is also analyzed. Numerical results indicate that the established model can reasonably capture the influence of tar cracking on the pyrolysis yields. The current work provides a useful tool for the understanding of biomass pyrolysis in fluidized bed reactors.