Population balance modelling of drum granulation of materials with wide size distribution
Population balance modelling of drum granulation of materials with wide size distribution
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宽粒度分布物料转鼓造粒的群体平衡建模
DOI：
10.1016/0032-5910(94)02896-v
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发表时间：
1995
影响因子：
5.2
通讯作者：
B. J. Ennis
中科院分区：
文献类型：
--
作者：
A. A. Adetayo;J. Litster;S. Pratsinis;B. J. Ennis
建立了一个群体平衡模型来描述具有宽粒度分布的饲料（例如回收肥料颗粒）的转鼓造粒。颗粒生长的聚结模型与一个连续的两阶段的内核。造粒的第一阶段福尔斯落入Ennis等人（Powder Technol.，65（1991）257-272），生长通过随机聚结发生。观察到尺寸分布变窄并迅速达到平衡尺寸分布。然后，在第二个惯性造粒阶段内发生进一步的生长，其中颗粒尺寸分布变宽并且需要尺寸依赖的内核。这个阶段要慢得多，颗粒变形是重要的。使用非线性回归将模型拟合到Adetayo等人的实验数据（Chem Eng. Sci.，48（1993）3951-3961），用于硫酸铵、磷酸一铵和磷酸二铵的造粒，其具有一定范围的水分含量、造粒时间和初始尺寸分布。该模型准确地描述了整个数据范围内的颗粒尺寸分布的形状。在第一阶段内发生的造粒程度由k1 t1给出;增长程度k1 t1与颗粒的液体饱和分数Ssat成比例，并随粘合剂粘度增加而增加。这里，k1表示第一生长阶段的速率常数，t1表示第一阶段达到最终平衡尺寸分布所需的时间。初始粒度分布的变化通过改变颗粒孔隙率以及液体饱和度来影响k1 t1。一个临界饱和度，Scrit，是必要的第二阶段的造粒发生，导致进一步的增长。对于Ssat≤Scrit，在造粒时间5 min之前达到最终平衡粒度分布。对于Ssat>Scrit，颗粒可充分变形以继续生长长达25 min。Scrit随着粘合剂粘度的增加而降低。该模型适用于造粒回路的动态模拟，其中水分含量和循环粒度分布可能随时间显著变化。
A population balance model is developed to describe the drum granulation of feeds with a broad size distribution (e.g. recycled fertiliser granules). Granule growth by coalescence is modelled with a sequential two-stage kernel. The first stage of granulation falls within a non-inertial regime as defined by Ennis et al. (Powder Technol., 65 (1991) 257–272), with growth occurring by random coalescence. The size distribution is observed to narrow and quickly reach an equilibrium size distribution. Further growth then occurs within a second inertial stage of granulation in which the granule size distribution broadens and requires a size-dependent kernel. This stage is much slower and granule deformation is important. Non-linear regression is used to fit the model to the experimental data of Adetayo et al. (Chem Eng. Sci., 48 (1993) 3951–3961) for granulation of ammonium sulfate, mono-ammonium phosphate and di-ammonium phosphate for a range of moisture contents, granulation times and initial size distributions. The model accurately describes the shape of the granule size distributions over the full range of data. The extent of granulation occurring within the first stage is given by k1t1; the extent of growth k1t1is proportional to the fractional liquid saturation of the granule, Ssat, and increases with binder viscosity. Here, k1represents the rate constant for the first stage of growth and t1represents the time required to reach the final equilibrium size distribution for the first stage. Changes to the initial size distribution affect k1t1by changing granule porosity and, therefore, liquid saturation. A critical saturation, Scrit, is necessary for the second stage of granulation to occur, leading to further growth. For Ssat≤Scrit, a final equilibrium size distribution is reached before 5 min of granulation time. For Ssat>Scrit, granules are sufficiently deformable to continue growing for up to 25 min. Scritdecreases with increasing binder viscosity. This model is suitable for use in dynamic simulation of granulation circuits where both moisture content and recycle size distribution may vary significantly with time.