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

化学过程工程中有两个有趣的全球趋势值得关注。在欧洲，土地稀缺，人们对流程集约化有着坚定的承诺。这导致了极小（体积为微升）的微反应器的发展。在全球大宗化学品市场，规模经济推动工艺设计和“创纪录产能”工厂定期投产。这些反应器体积通常为 1 兆升。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舶。这两个行业还面临着多相和部分混溶的多组分混合方面的难题。纳米技术告诉我们，规模的巨大变化需要思维的转变：物理原理保持不变，但主导变量发生变化。从升到微升尺度，颗粒质量变得可以忽略不计，微小的表面电荷变得极其重要。从 1L 规模转向 1 ML 规模时，混合时间相对于关键过程时间尺度变得如此之长，以至于基本上是无限的。在超大规模中，局部混合条件变得极其重要，并且常常主导工艺性能。为了成功设计和操作 1ML 工艺容器，需要明确的混合规范。这需要了解局部湍流、局部偏析（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测量这些变量。第一个已应用于在非常高的湍流水平下按比例缩小纳米颗粒沉淀；第二个使我们能够提高超大规模破乳剂的性能。通过更好地了解局部混合条件的重要性，两者都为我们的工业合作伙伴带来了巨大的成功。在本提案中，我们从混合原理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规模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.