多段分级转化流化床提升管速度场的研究

针对流化床煤气化过程中需要长气固接触时间和高固体浓度,开发了耦合灰熔聚流化床和提升管的多段分级转化流化床。为了研究多段分级转化流化床提升管中局部颗粒速度的径向、轴向分布,在不同的操作条件下,采用PV-6型颗粒速度测量仪在冷态实验装置中系统测定提升管内局部颗粒速度。实验结果表明:提升管中任何径向、轴向位置的颗粒速度随着操作气速的增大而增大,随循环量的增加而减小。操作条件对中心区颗粒速度变化的影响明显高于边壁区。颗粒的加速首先发生在提升管中心区域,然后向边壁区域扩展。颗粒速度径向分布的不均匀性沿轴向逐渐增大,并且受操作气速影响比较大。

Particle velocities field in the riser of multi-stage conversion fluidized bed

According to fluidized bed coal gasification process requiring the long gas-solid contact time and high solid holdup,a new concept of a multi-stage conversion fluidized bed(MFB) which couples ash agglomerated fluidized bed with riser was developed.The radial and axial distributions of local particle velocities in the riser of MFB cold model apparatus were investigated by PV-6 optical fiber probe in different operating conditions.The results show that both radial and axial particle velocities increase with the increase of operational gas velocities,decrease with the increase of solid circulation rate under the same operating conditions.The effects of operating conditions on the particle velocities in the riser center region are greater than those near the wall.Acceleration of particle primarily happens in the riser center and then extends toward the wall region.The radial non-uniformity degree of local particle velocity increases with the increase of bed height and is affected strongly by riser gas velocity.