Solids suspension behaviour in profiled bottom and flat bottom mixing tanks
Solids suspension behaviour in profiled bottom and flat bottom mixing tanks
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DOI：
10.1016/0009-2509(85)85100-9
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发表时间：
1985
影响因子：
4.7
通讯作者：
M. W. Chudacek
中科院分区：
文献类型：
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作者：
M. W. Chudacek
对经典平底搅拌槽中的固体悬浮进行了现象学分析。在平底罐的中心和外围流动的突然重新定向产生了诱导再循环回路，这解释了中心和外围非悬浮固体圆角的形成。这些再循环回路的范围对实现完全离底悬浮具有控制性影响。因此，在平底罐中使用完全离底悬浮状态作为放大的唯一标准很可能导致放大参数不能代表罐体的行为。一个完全异形的罐底及其近似，“圆锥形和圆角”底部设计被用作替代几何形状，以减轻再循环回路。混合槽的流线型大大提高了固体和悬浮效率，并且在槽底区域产生了更均匀的水动力状态。后一种效应可能会简化固体悬浮的理论建模，并进一步证明了采用异形底混合罐而不是平底罐的合理性。
Solids suspension in the classical flat bottom mixing tank was analysed phenomenologically in detail. Abrupt re-direction of the flow in the centre and the periphery of the flat bottom tank gives rise to induced recirculation loops which account for the formation of central and peripheral fillets of unsuspended solids. The extent of these recirculation loops has a controlling influence on the attainment of complete off-bottom suspension in this tank geometry. Therefore the use of the complete off-bottom suspension condition in the flat bottom tank as the sole criterion for scale-up is likely to lead to scale-up parameters which do not represent the behaviour of the bulk of the tank.A fully profiled tank bottom and its approximation, a “cone and fillet” bottom design were used as alternative geometries to mitigate recirculation loops. Streamlining of the mixing tank substantially improved solid and suspension efficiency and also produced a more homogeneous hydrodynamic regime in the bottom zone of the tank. This latter effect potentially simplifies theoretical modelling of solids suspension and further justifies the preference for profiled bottom mixing tanks rather than the flat bottom tank.