Competing Rates in Mixing Sensitive Processes: design fundamentals for meso-scale and transient effects

在化学过程工程领域，有两个有趣的全球趋势值得关注。在欧洲，土地稀缺，而且对流程集约化有着坚定的承诺。这导致了微型反应堆的发展，微型反应堆的体积非常小(体积约为微升)。在全球商品化学品市场，规模经济推动了工艺设计和“创纪录产能”工厂的定期投产。这些反应堆的体积通常为100万升。加拿大的两个重要行业--油砂开采和矿物加工--需要一些世界上最大的船只。这两个行业还面临着多相和部分可混溶的多组分混合的难题。纳米技术告诉我们，规模的急剧变化需要思维的转变：物理保持不变，但主导变量发生变化。从升到微升，粒子的质量变得微不足道，微小的表面电荷变得极其重要。从1L尺度移动到1ML尺度时，混合时间相对于关键工艺时间尺度变得如此之长，以至于基本上是无限的。在Mega级，局部混合条件变得极其重要，并且通常主导工艺性能。要成功地设计和操作1ml工艺容器，需要明确的混合规格。这需要了解局部湍流、局部分离(注入浓度)和混合时间如何与过程中的时间尺度、长度尺度和浓度尺度相互作用。我们有两个测试容器，可以有效地测量这些变量。第一种方法被应用于在非常高的湍流水平下缩小纳米颗粒沉淀的规模；第二种方法使我们能够在兆级改进破乳剂的性能。两者都通过更好地了解当地混合条件的重要性，为我们的工业合作伙伴提供了戏剧性的成功。在这项建议中，我们将从混合原则的实际设计和应用扩展到开发理论，该理论将允许对从微升到兆升的混合进行建模和预测。

There are two interesting global trends to watch in chemical process engineering. In Europe, land is scarce and there is a strong commitment to process intensification. This has led to the development of micro-reactors which are extremely small (volumes of the order of micro-litres). In the global commodity chemicals market, economies of scale drive process design and "record capacity" plants are regularly commissioned. These reactor volumes are typically 1 Mega-litre. Two important industries in Canada, oil sands extraction and mineral processing, require some of the largest vessels in the world. These two industries also face difficult problems in multi-phase and partially-miscible multi-component mixing.Nano-technology has taught us that dramatic changes of scale require a shift in thinking: the physics stays the same but the dominant variables change. On moving from the litre to the micro-litre scale, the particle mass becomes negligible and tiny surface charges become extremely important. On moving from the 1L to the 1 ML scale, the blend time becomes so long relative to the key process time-scales that it is essentially infinite. At the Mega-Scale, local mixing conditions become extremely important and often dominate process performance.To successfully design and operate 1ML process vessels, clear mixing specifications are needed. This requires an understanding of how local turbulence, local segregation (injection concentration), and mixing time interact with the time scales, length scales, and concentration scales in the process. We have two test vessels which allow efficient measurement of these variables. The first has been applied to scale-down of nano-particle precipitation at very high turbulence levels; the second has allowed us to improve demulsifier performance at the Mega-Scale. Both have provided dramatic successes for our industrial partners through a better understanding of the importance of local mixing conditions. In this proposal we expand from the practical design and application of mixing principles to developing the theory which will allow modelling and prediction of mixing from the micro-litre to the Mega-Litre scale.