nates so much that catastrophic phase inversion occurs and O/A dispersion becomes A/O, the transition always occur- ring at higher concentrations when oil is dispersed [70]. As a result of these complexities, prediction of phase inversion has also proven elusive.
The simple application of Eq. (19) and (20) would suggest that in geometrically similar systems at equal ¯eT, the same size drops should be produced. On the other hand, some papers report that scale-up at constant tip speed gives simi- lar drop sizes. There are no good theoretical reasons for the latter, but the concept of intermittency is able to explain it
Figure 11. The different structures of high concen- tration liquid-liquid dis- persions; (a) 54 % water in chlorobenzene showing drops-in-drops (O/A/O) at phase inversion, mean
size ~1.2 mm; (b) 67 % chlorobenzene in water (O/A) at phase inversion, mean size, ~0.5 mm (modified from [70)].
[69]. It is difficult to establish which is correct, but a safe rule would be to use equal ¯eT and reduce speed towards constant tip speed in case drops should be too small. That rule would also ensure that if at small scale a dispersion does not have regions without drops at top or bottom of the STR, a satisfactory dispersion would be achieved on scale- up [12].
For the production of liquid-liquid dispersions and emul- sions, knowledge of the role of soluble surfactants and the impact of wettability, whether of the equipment surface, which may change with scale, or of added fine particles, all of which particularly impact coalescence, are of critical importance, but these topics are beyond the scope of this
摘要:搅拌釜使用于整个过程工业中。搅拌釜不仅用于化学工业,还用于新的工业领域,如生物制剂、药物、纳米技术和再生医学。某些功能多年来没有改进,但对其内部发生的物理过程的理解大大增加。由于知识的交叉,单相或多相、基础科学之间的相互作用的知识是至关重要的,而混合/搅拌的物理过程被认为是在过去75年间得以发展。
毕业论文关键词:计算流体力学,叶轮,柯尔莫格洛夫理论,单相系统,双相系统
1. 导言
搅拌和搅拌釜反应器(STR,包括生物反应器)普遍使用于整个工艺工业中;生物制剂,化学品(重质,特质和药物),化妆品,食品,油,矿物,油漆,纸张,塑料,聚合物,水等。商业上使用的STR小至15ml,最近开发的机器人操作ambr[1],这证明了从动物细胞培养物中选择用于治疗性蛋白质生产的克隆,多年来已经可用的多达100立方米的罐。出人意料的是,他们正在迅速成为首选的配置对干细胞之后他们收获异体治疗目的再生医学的微增长[2,3]。它们用于低粘度的湍流系统;并且用于非常高粘度和非牛顿流体的层流中。在许多情况下,存在多个相并且需要混合以增强在相之间发生速率的过程;或者产生一个具有长保质期的复杂流变学且稳定的产物。可能性是无止境的;并且应用范围是其固有灵活性的量度。
制造STR的材料众多有碳钢,也有用于清洁,无菌或耐腐蚀领域的耐腐蚀性金属或钢,更多外来钢材和耐腐蚀金属和搪玻璃设备[4]。最近,放置在金属容器中的简单密封的无菌塑料袋作为用于细胞培养的一次性生物反应器也变得流行[5]。大多数STR是圆柱形的,具有碟形或半球形底部,因为该形状更能够压力。在其他情况下,特别是对于矿物加工和油储存中的大型容器,使用平底,偶尔正方形或矩形横截面,以使容器/单位面积的数量最大化。
STR的第一个明显的例子是由Georg Bauer在1556年6月(图1)出版的关于开采和提取金属技术的书“De Re Metallica(拉丁文关于金属的性质)”中给出的。在许多方面,该图类似于现代STR,其中它具有原动机(在这种情况下是水轮,而不是电动机),齿轮箱以提供适当的速度(在这种情况下,增加旋转速率叶轮,而不是使其减速)和具有六个平叶片的桨,以提供输入到反应器中的能量(每个由木材制成,而不是如上所列的任何现代材料)以实现搅拌。与目前实践相比的主要区别是使用开放式反应器,其中每一个都包含用于从矿石中回收金的汞齐。它不会满足当前的健康和安全工作立法。