Lateral solids dispersion coefficient in large-scale fluidized beds
Lateral solids dispersion coefficient in large-scale fluidized beds
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DOI：
10.1016/j.combustflame.2010.04.020
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发表时间：
2010-11
影响因子：
4.4
通讯作者：
Daoyin Liu;Xiaoping Chen
中科院分区：
文献类型：
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作者：
Daoyin Liu;Xiaoping Chen
大型流化床燃烧室燃料进料口的设计取决于燃料特性和横向固体混合。然而，所报道的有效横向固体弥散系数（Dsr）的值分散在0.0001-0.1m2/s的宽范围内。为了预测Dsrin较宽的流化床（难以直接测量或从实验室规模的实验结果中推导出），提出了一种计算方法。它结合了Eulerian-Granular模拟和虚拟粒子追踪技术。根据示踪剂的移动计算的Dsris值。研究了在不同表观气速（U 0）水平下，床宽（W）从0.4 m到12.8 m对Dsrof的影响。研究发现，在保持U 0不变的情况下，增加W，Dsr先显著增加，然后增加率下降，最后保持在一个恒定值附近。本文对Dsrare的计算值进行了定量分析，并与80年代以来文献中的Dsrare实测值进行了比较。与中试规模流化床的测量结果一致，在较高流化速度下，Dsrin宽设备的值预计为0.1m2/s左右的数量级，远高于实验室规模的床。最后，讨论了Dsron对流化床内燃料颗粒在截面上分布的影响。
The design of fuel feed ports in a large-scale fluidized bed combustor depends on the fuel characteristics and lateral solids mixing. However, the reported values of the effective lateral solids dispersion coefficient (Dsr) are scattered in the broad range of 0.0001–0.1m2/s. With the aim of predicting Dsrin wider fluidized beds which is difficult to measure directly or deduce from experimental results in lab-scale facilities, a computational method is proposed. It combines the Eulerian–Granular simulation and fictitious particle tracing technique. The value of Dsris calculated based on the movement of the tracers. The effect on Dsrof bed width (W) ranging from 0.4m up to 12.8m at different levels of superficial gas velocity (U0) is investigated. It is found that increasing W whilst maintaining U0, Dsrinitially increases markedly, then its increase rate declines, and finally it stays around a constant value. The computed values of Dsrare examined quantitatively and compared with a thorough list of the measured Dsrin the literature since 1980s. Agreed with the measurements performed in the pilot-scale fluidized beds, the value of Dsrin wider facilities at higher fluidizing velocities is predicted to be around the order of magnitude of 0.1m2/s, much higher than that in lab-scale beds. Finally, the effect of Dsron the distribution of fuel particles over the cross section in fluidized beds with the specified layout of feed ports is discussed.